The Moosehorn Plutonic Suite, southeastern Maine and southwestern New Brunswick: age, petrochemistry, and tectonic setting.
The Moosehorn Plutonic plu·ton·ic
Of deep igneous or magmatic origin: plutonic rocks.
[From Latin Pl Suite in the coastal Maine magmatic province covers an area of approximately 250 [km.sup.2] in the area of Calais, Maine Calais is a city in the state of Maine in the United States, situated on the St. Croix River at the border with St. Stephen, New Brunswick, Canada. It is in Washington County, Maine, United States. The population was 3,447 at the 2000 census. , and St. Stephen, New Brunswick New Brunswick, province, Canada
New Brunswick, province (2001 pop. 729,498), 28,345 sq mi (73,433 sq km), including 519 sq mi (1,345 sq km) of water surface, E Canada. . Based on a compilation of previous work combined with new field mapping, geochronology geochronology
Dating and interpretation of geologic events in the history of the Earth. The classical technique of geochronology was stratigraphy, including faunal succession. , and petrochemical data, the Moosehorn Plutonic Suite (MPS) is interpreted to consist mainly of five approximately contemporaneous plutons: Staples Mountain Gabbro gabbro: see basalt.
Any of several medium- or coarse-grained rocks that consist primarily of plagioclase feldspar and pyroxene. Gabbros are found widely on the Earth and on the Moon. , St. Stephen Gabbro, Calais Quartz Diorite Quartz diorite is an igneous, plutonic (intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz is present at between 5 to 20% of the rock. , Baring Granite, and Elliott Mountain Diorite diorite
Medium- to coarse-grained igneous rock that commonly is composed of about two-thirds plagioclase feldspar and one-third dark-coloured minerals, such as hornblende or biotite. . The layered, sill-like Staples Mountain Gabbro is mainly mafic maf·ic
Containing or relating to a group of dark-colored minerals, composed chiefly of magnesium and iron, that occur in igneous rocks. , whereas the larger St. Stephen Gabbro consists of a core of dunite dunite
Yellowish green to green igneous rock composed almost entirely of olivine. Chromite and magnetite also occur in dunite, as do spinel, ilmenite, pyrrhotite, and platinum in some cases. Dunites may be a source of chromium. Places of occurrence include Dun Mtn. and troctolite Troctolite is a rare ultramafic intrusive rock type. It consists essentially of variable amounts of olivine and calcic plagioclase along with variable minor pyroxene. It thus is midway between peridotite and anorthosite. , surrounded by olivine olivine (ŏlĭv`ēn), an iron-magnesium silicate mineral, (Mg,Fe)2SiO4, crystallizing in the orthorhombic system. gabbro and gabbro layers. The latter unit grades to quartz diorite of the Calais Quartz Diorite, the most extensive component of the MPS. The Baring Granite consists of medium-grained biotite biotite (bī`ətīt'), iron-rich variety of phlogopite, most abdunant of the mica minerals.
or black mica
Silicate mineral in the common mica group. monzogranite, which is widely mingled with quartz diorite and diorite of the Calais Quartz Diorite. The latest pluton plu·ton
A body of igneous rock formed beneath the surface of the earth by consolidation of magma.
[German, back-formation from plutonisch, plutonic, from Latin of the MPS appears to be the Elliott Mountain Diorite, which consists mainly of texturally varied dioritic di·o·rite
Any of various dark, granite-textured, crystalline rocks rich in plagioclase and having little quartz.
[French, from Greek diorizein, to distinguish : dia-, rocks. Each pluton of the MPS is interpreted to have formed by magma differentiation to produce a range of derived compositions. Evidence for mingling and mixing between magmas is also widespread in the MPS, but was not investigated during this study.
A sample from the Baring Granite yielded a U-Pb (zircon zircon
Silicate mineral, zirconium silicate, ZrSiO4, the principal source of zirconium. Zircon is widespread as an accessory mineral in acid igneous rocks; it also occurs in metamorphic rocks and, fairly often, in detrital deposits. ) crystallization Crystallization
The formation of a solid from a solution, melt, vapor, or a different solid phase. Crystallization from solution is an important industrial operation because of the large number of materials marketed as crystalline particles. age of 421.1 [+ or -] 0.8 Ma) and phlogopite phlog·o·pite
A yellow to dark brown mica, K(Mg,Fe)3AlSi3O10(OH)2, used in insulation.
[Greek phlog from the olivine gabbro unit of the St. Stephen Gabbro yielded a [sup.40]Ar/[sup.39]39Ar cooling age of 421 [+ or -] 4 Ma. The gabbroic parts of the St. Stephen Pluton and the Calais Quartz Diorite are similar in petrochemistry pet·ro·chem·is·try
1. The chemistry of petroleum and its derivatives.
2. The branch of geochemistry that deals with the chemical composition of rocks. to mafic and intermediate parts of the Bocabec Pluton of the Saint George Saint George, town (1991 pop. 1,648), on St. George's Island, Bermuda. It was the capital of Bermuda until 1815, when it was replaced by Hamilton. During the American Civil War it harbored Confederate blockade-runners. Batholith batholith, enormous mass of intrusive igneous rock, that is, rock made of once-molten material that has solidified below the earth's surface (see rock). Batholiths usually are granitic (see granite) in composition, have steeply inclined walls, have no visible floors, whereas the Baring Granite is similar to the granitic parts of the Bocabec Pluton. Plutons of the MPS generally have calc-alkalic to within-plate chemical characteristics, and their slightly negative (-0.4) to moderately positive (+3.4) [[epsilon].sub.Nd] values are consistent with formation by melting of primitive lower crust, such as may have been present below the Mascarcne and Ellsworth terranes. Melting likely occurred in a back-arc setting related to juxtaposition in the late Silurian between these terranes and more outboard terranes of the northern Appalachian orogen.
Le cortege plutonique de Moosehorn dans la province magmatique et cotiere du Maine couvre une superficie d'environ 250 kilometres carres dans la region de Calais, au Maine, et de St. Stephen, au Nouveau-Brunswick. Selon une compilation de travaux anterieurs combines a de nouvelles donnees petrochimiques, geochronologiques et cartographiques obtenues sur le terrain, le cortege plutonique de Moosehorn (CPM) est interprete comme un ensemble principalement compose de cinq plutons plus ou moins cinq syngenetiques: le gabbro du mont Staples, le gabbro de St. Stephen, la diorite quartzite quartzite, usually metamorphic rock composed of firmly cemented quartz grains. Most often it is white, light gray, yellowish, or light brown, but is sometimes colored blue, green, purple, or black by included minerals. de Calais, le granite de Baring et la diorite du mont Elliott. Le gabbro stratifie en filons-couches du mont Staples est principalement mafique, tandis que le gabbro plus vaste de St. Stephen est constitue d'un noyau Noy`au´
n. 1. A cordial of brandy, etc., flavored with the kernel of the bitter almond, or of the peach stone, etc. de dunite et de troctolite, entoure de strates de gabbro et de gabbro a olivine. Cette derniere unite se classe parmi la diorite quartzite du pluton de diorite quartzite de Calais, l'element le plus etendu du CPM. Le granite de Baring est constitue de monzogranite a biotite a grain moyen, abondamment mele a de la diorite quartzite et a de la diorite du pluton de diorite quartzite de Calais. Le pluton le plus recent du CPM semble etre la diorite du mont Elliott, principalement constituee de roches dioritiques de textures diverses. Chaque pluton du CPM se serait, selon les interpretations, forme forme (form) pl. formes [Fr.] form.
forme fruste (froost) pl. formes frustes an atypical, especially a mild or incomplete, form, as of a disease. par differenciation magmatique ayant produit un eventail de compositions derives. Les indices temoignant d'un melange mé·lange also me·lange
A mixture: "[a] building crowned with a mélange of antennae and satellite dishes" Howard Kaplan. et d'un mixage entre les magmas sont egalement repandus dans le CPM, mais ils n'ont pas ete analyses dans le cadre de la presente etude e·tude
1. A piece composed for the development of a specific point of technique.
2. A composition featuring a point of technique but performed because of its artistic merit. .
Un echantillon du granite de Baring a ete situe a 421,1 [+ or -] 0,8 Ma par cristallisation au u-Pb (a partir du zircon) et une datation de la phlogopite de l'unite de gabbro a olivine du gabbro de St. Stephen a situe son age de refroidissement [sup.40]Ar/[sup.39]Ar a 421 [+ or -] 4 Ma. Les parties gabbroiques du pluton de St. Stephen et de la diorite quartzite de Calais presentent une petrochimie semblable sem·bla·ble
1. Having a resemblance; resembling or like: unfamiliar symbols semblable to religious icons.
2. Seeming; apparent.
n. aux parties mafiques et intermediaires du pluton de Bocabec du batholite de Saint George, tandis que le granite de Baring ressemble aux parties granitiques du pluton de Bocabec. Les plutons du CPM possedent generalement des caracteristiques chimiques calco-alcalines a intra-plaque, et leurs valeurs [[epsilon].sub.Nd] legerement negatives (-0,4) a moyennement positives (+3,4) correspondent a une formation par fusion de la croute inferieure primitive, comme celle Celle (tsĕl`ə), city (1994 pop. 73,670), Lower Saxony, N Germany, on the Aller River. Its manufactures include food products, electronic components, chemicals, and textiles. Wax processing and horse breeding are important locally. pouvant etre survenue au-dessous des terranes de Mascarene et d'Ellsworth. La tusion est probablement survenue dans un cadre arriere-arc apparente a une juxtaposition de ces terranes et des terranes plus limitrophes de l'orogene du nord des Appalaches au cours du Silurien tardif.
[Traduit par la redaction]
The coastal Maine magmatic province (Fig. 1) contains voluminous plutonic and volcanic rocks rocks which have been produced from the discharges of volcanic matter, as the various kinds of basalt, trachyte, scoria, obsidian, etc., whether compact, scoriaceous, or vitreous.
See also: Volcanic of Silurian and Devonian age (Geol.) the age next older than the Carboniferous and later than the Silurian; - called also the Age of fishes ltname>. The various strata of this age compose the Devonian formation or system, and include the old red sandstone of Great Britain. and dominantly mafic and felsic fel·sic
Containing a group of light-colored silicate minerals that occur in igneous rocks.
[fel(dspar) + s(ilica) + -ic. compositions (e.g., Hogan and Sinha 1989; Seaman et al. 1999). The focus of this study, the Moosehorn Plutonic Suite (MPS), is part of the coastal Maine magmatic province, exposed over an area of about 250 [km.sup.2] in the vicinity of Calais, Maine, and St. Stephen, New Brunswick (Fig. 1). The MPS was previously termed the Moosehorn Igneous ig·ne·ous
1. Of, relating to, or characteristic of fire.
a. Formed by solidification from a molten state. Used of rocks.
b. Of or relating to rock so formed; pyrogenic. (or Intrusive) Complex (e.g., Ludman and Hill 1986; Hogan and Sinha 1989; Jurinski 1990; Hill 1991), and includes gabbroic, dioritic, and granitic plutons in the vicinity of the Moosehorn Wilderness Preserve south of Calais, Maine. Complex intrusive relationships between the mafic and felsic components of these units were documented by the above authors and also by others such as Abbott (1986) and Hill and Abbott (1989). They described evidence of magma mingling, and concluded that the gabbroic, dioritic, and granitic magmas that formed these plutons were coeval co·e·val
Originating or existing during the same period; lasting through the same era.
One of the same era or period; a contemporary. . Abbott (1977, 1986) demonstrated that the plutonic rocks assigned here to the MPS are older than the Devonian Red Beach Granite and hence suggested a Silurian-Devonian age. A Devonian age was suggested by Ludman and Hill (1990), but Jurinski (1990) suggested that a Silurian age is more likely, based on his U-Pb (zircon) age of 434 [+ or -] 9 Ma.
[FIGURE 1 OMITTED]
The purpose of this paper is to describe the distribution and petrology petrology, branch of geology specifically concerned with the origin, composition, structure, and properties of rocks, primarily igneous and metamorphic, and secondarily sedimentary. of plutons that make up the Moosehorn Plutonic Suite, to present new U-Pb (zircon) and [sup.40]Ar/[sup.39]Ar data that closely constrain the age of the MPS, and to interpret its petrogenesis pet·ro·gen·e·sis
The branch of petrology that deals with the origin of rocks, especially igneous rocks.
pet and tectonic setting at the time of emplacement. Based on petrological and age similarities, we further suggest that the Bocabec Pluton and Utopia Granite of the Saint George Batholith in southwestern New Brunswick are equivalent to parts of the MPS, and hence that the coastal Maine magmatic province should be extended into southwestern New Brunswick.
Several fault-bounded geological terranes have been recognized in southern Maine and southwestern New Brunswick (Fig. 1). The MPS stitches the boundary between the St. Croix on the northwest and Mascarene (on the southeast) terranes of Fyffe and Fricker (1987) or St. Croix and Ellsworth terranes of Robinson et al. (1998). Rocks of the St. Croix terrane ter·rane also ter·rain
1. A series of related rock formations.
2. An area having a preponderance of a particular rock or rock groups.
[Alteration of terrain.] intruded by the MPS are mainly shale and quartz-rich sandstone of the Cambrian-Ordovician Cookson Group Cookson Group plc is a leading materials technology company headquartered in London, England, which provides materials, processes and services to customers worldwide. The Group's operations are formed into three divisions – Electronics, Ceramics and Precious Metals. . The Mascarene terrane in the study area is represented by Silurian rocks of the Mascarene Group, including conglomerate, volcanic and volcaniclastic rocks, sandstone, and shale (Fyffe et al. 1999). These Cambrian-Ordovician and Silurian rocks are contact metamorphosed and locally migmatized (Hussey et al. 1967; Ludman and Hill 1990) by the MPS, and also occur as xenoliths and roof pendants in the MPS.
Other plutonic rocks occur around the MPS, including the Pocomoonshine Gabbro-Diorite (Westerman 1972) to the west, the Meddybemps and Charlotte granites to the south and southeast, and the Red Beach Granite to the east (Figs. 1, 2). Small bodies of granite intruded into the Elliott Mountain Diorite may be related to the Red Beach or Charlotte granites (Abbott 1986). All of these granitic bodies intruded plutons of the MPS, although the age difference is not well constrained by existing geochronology (e.g., Hill and Abbott 1989). The Pocomoonshine Gabbro-Diorite, for which a [sup.40]Ar/[sup.39]Ar (hornblende hornblende: see amphibole.
Any of a subgroup of amphibole minerals that are calcium-iron-magnesium-rich and monoclinic in crystal structure. ) age of 422.7 [+ or -] 3 Ma has been reported (West et al. 1992), is not in contact with units of the MPS but may be of similar age. The other granitic units are assumed to be significantly younger (Devonian) and not included in the MPS (e.g. Amos 1963; Abbott 1986; Ludman and Hill 1990).
[FIGURE 2 OMITTED]
Although Hogan and Sinha (1989) stopped their map of the coastal Maine magmatic province at the Canadian border, the presence of Silurian-Devonian gabbroic to granitic plutons of the Saint George Batholith (e.g., McLeod 1990; McLeod et al. 1994) suggests that it extends across the international border into southwestern New Brunswick (Fig. 1, 2). The few maps that show details of plutonic units on both sides of the border (e.g., Ruitenberg and McCutcheon 1978) suggest continuity between the Bocabec Pluton of the Saint George Batholith and the unit of the MPS here termed the Elliott Mountain Diorite. The Bocabec Pluton consists of gabbroic, dioritic, granodioritic, and granitic rocks with complex contact relationships (Fyffe 1971; McLeod et al. 1994) that appear analogous to those among some plutons of the MPS. The Utopia Granite part of the Saint George Batholith intruded the Bocabec Pluton, but locally is veined by granodiorite granodiorite
Medium- to coarse-grained rock that is one of the most abundant intrusive rocks. It contains quartz and is distinguished from granite by having more plagioclase feldspar than orthoclase feldspar; its other mineral constituents include hornblende, biotite, and of the Bocabec Pluton; the granodiorite was interpreted by McLeod (1990) and Fyffe (1971) as a zone of commingled rocks between the two plutons, and McLeod (1990) referred to the Bocabec and Utopia plutons collectively as the Digdeguash Lake Intrusive Suite.
PLUTONS OF THE MOOSEHORN PLUTONIC SUITE
As noted in the Introduction, consistency has yet to be attained in published terminology for plutonic units in the study area. Ludman and Hill (1986) used Moosehorn Intrusive Complex as a collective term for plutonic units in the Calais area; however, Jurinski (1987) and Hogan and Sinha (1989) used the term Moosehorn Igneous Complex. Ludman and Hill (1986) excluded Staples Mountain Gabbro from their Moosehorn Intrusive Complex, although its close spatial association and petrographic pe·trog·ra·phy
The description and classification of rocks.
pe·trogra·pher n. features (Fig. 2, Table 1) appear to justify its inclusion.
Hence, as used here, the MPS consists of five plutons termed the Staples Mountain Gabbro, St. Stephen Gabbro, Calais Quartz Diorite, Baring Granite, and Elliott Mountain Diorite (Fig. 2), each named according to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. its dominant and most characteristic rock type, although each contains a variety of components (Table 1). Smaller bodies of gabbro, diorite, and granite are present throughout these main plutons. The individual pluton names were used by previous workers, except for Elliott Mountain, a new name introduced by McLaughlin (2003) for part of the Calais gabbro/diorite of Hogan and Sinha (1989). Hogan and Sinha (1989) included all of the mafic-intermediate plutonic rocks between the Baring and Red Beach granite bodies in the Calais gabbro/diorite; however, we use the term Calais Quartz Diorite only for the gabbro-diorite intrusive complex of Ludman and Hill (1986, 1990), which also contains a substantial component of granite and metasedimentary xenolithic material. We use the name Elliott Mountain Diorite to refer to the gabbro unit of Ludman and Hill (1986, 1990). That unit extends into the adjacent map area of Abbott (1986), who described it as complex mixture of mainly gabbro, diabase diabase: see basalt.
Fine- to medium-grained, dark gray to black intrusive igneous rock. Diabase is one of the dark rocks known commercially as “black granite. , and granodiorite, intruded by younger granite. We consider the Calais and Elliott Mountain units to be different from one another overall, although both contain a wide variety of rock types and distinction between them at the outcrop scale is ambiguous (see below). Similar and probably co-magmatic mafic rock mafic rock
In geology, any igneous rock dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferrous iron, and their presence gives mafic rock its characteristic dark colour. It is usually contrasted with felsic rock. types also occur throughout the Baring Granite unit, as well as in the Meddybemps Granite to the south. Like previous workers, we exclude clearly younger (Devonian?) granitic plutons in the area, such as Meddybemps, Charlotte, and Red Beach (Fig. 2), from the MPS.
Distinction between gabbro and diorite is problematic in the MPS, especially in outcrop and hand specimen. We use the term gabbro when we consider that the rock is, or was originally before alteration, dominated by pyroxene pyroxene (pī`rŏksēn), name given to members of a group of widely distributed rock minerals called metasilicates in which magnesium, iron, and calcium, often with aluminum, sodium, lithium, manganese, or zinc occur as X in the chemical as the ferromagnesian fer·ro·mag·ne·sian
Containing iron and magnesium.
Containing iron and magnesium. Magnetite and hornblende are ferromagnesian minerals. mineral component, and diorite when amphibole amphibole (ăm`fəbōl'), any of a group of widely distributed rock-forming minerals, magnesium-iron silicates, often with traces of calcium, aluminum, sodium, titanium, and other elements. is the dominant ferromagnesian mineral. Hence we term the hornblende gabbro of some earlier workers (e.g., Abbott 1986) as diorite.
The MPS is characterized by complex zones in which diorite forms enclaves in granite, suggesting that the diorite magma was only partially crystallized at the time of emplacement of the granite magma, and that the two magmas commingled (Hill and Abbott 1989; Jurinski 1990; Ludman and Hill 1990; Hill 1991). These enclaves vary in shape from amoeboid a·moe·boid
Variant of ameboid. to angular, and in size from cm-scale to m-scale, and were described in detail by previous workers (e.g., Hill and Abbott 1989; Jurinski 1990). The dioritic component dominates in the areas included in this study in the Calais Quartz Diorite and Elliott Mountain Diorite, whereas the granitic component dominates in the area shown as Baring Granite (Fig. 2). A complex relationship also appears to exist between dioritic and gabbroic magmas in the MPS, as locally diorite and quartz diorite appears to cross-cut gabbro, and xenoliths of gabbro are present in diorite and quartz diorite, but overall their petrographic and chemical features are gradational gra·da·tion
a. A series of gradual, successive stages; a systematic progression.
b. A degree or stage in such a progression.
2. . In this study, the boundary between the St. Stephen Gabbro and Calais Quartz Diorite units is drawn so as to exclude, in so far as possible, gabbroic rocks from the latter pluton. Dykes of granite occur in gabbro in both the Staples Mountain and St. Stephen plutons, indicating that the granite is at least slightly younger than (and not mingled with) the gabbro magma. Because they are similar in appearance, these granite dykes are assumed to be co-magmatic with the granite that dominates the Baring Granite unit of the MPS.
The Elliott Mountain Diorite is dominated by dioritic rocks (gabbro of Abbott 1986 and Ludman and Hill 1990), although granodiorite and granite are also present, especially in the eastern part of the unit (Abbott 1986). Where observed, the contact between the Calais Quartz Diorite and the Elliott Mountain Diorite appears to be sharp and marked by a reduction in grain size in the diorite as the contact is approached, suggesting the presence of a chilled margin. Based on the lack of observed mingling relationships during this study, we suggest that the Elliott Mountain Diorite may be at least somewhat younger that the Baring Granite, but more detailed mapping is needed along their contact in order to confirm this suggestion. The Elliott Mountain Diorite is older than the Charlotte, Magurrewock Lakes, and Red Beach granites that intrude intrude,
v to move a tooth apically. it on the south and east, and which are excluded from the MPS.
In addition to units included in the five main plutons, small bodies of dioritic and gabbroic rocks (e.g., Woodland Dump gabbro of Ludman and Hill 1990) also are present in the MPS and adjacent units. A few samples were collected from these units for comparison with the main dioritic and gabbroic units of the MPS.
The description and classification of rocks.
Petrographic features of die main units of the MPS are summarized in Table 1, and commented on briefly below.
Staples Mountain Gabbro
Coughlan (1986) recognized five units in the Staples Mountain Gabbro, designated I to V from inferred bottom to top: I--gabbro, anorthositic gabbro, and olivine gabbro; II--subophitic augite augite
Most common pyroxene mineral, occurring chiefly as blocky crystals in basalts, gabbros, andesites, and various other dark igneous rocks. It also is a common constituent of lunar basalts and meteorites and may be found in certain metamorphic rocks, such as pyroxenites. gabbro; III--interlayered norite nor·ite
[Norwegian Norge, Norway + -ite1.]
nor·it and anortbosite; IV--unlayered augite gabbro and minor olivine gabbro; V --unlayered gabbronorite, with increased orthopyroxene orthopyroxene
Any variety of the mineral pyroxene that crystallizes in the orthorhombic system and contains no calcium and little or no aluminum. Enstatite is an orthopyroxene. and no olivine, in contrast to unit IV. She interpreted the pluton to be a layered sill-like body, formed by crystal fractionation fractionation /frac·tion·a·tion/ (frak?shun-a´shun)
1. in radiology, division of the total dose of radiation into small doses administered at intervals.
2. processes; more details are available in Coughlan (1986).
St. Stephen Gabbro
Paktunc (1989) divided what he termed the St. Stephen Intrusion into ultramafic ul·tra·maf·ic
Containing mainly mafic minerals. Used of igneous rocks and often used interchangeably with ultrabasic. Dunite is an ultramafic rock. , olivine-bearing mafic, and mafic zones, and interpreted compositional variation and local crude layering to fractional crystallization fractional crystallization
A process by which a chemical compound is separated into components by crystallization. In fractional crystallization the compound is mixed with a solvent, heated, and then gradually cooled so that, as each of its constituent . We instead include most of the mafic zone of Paktunc (1989) in the Calais Quartz Diorite, and the remainder of the St. Stephen Pluton is divided into four units: dunite, troctolite, olivine gabbro, and gabbro (Fig. 2). The pluton has crudely concentric zoning in map view, with the central dunite unit surrounded by the locally well layered troctolite unit, then the olivine gabbro unit, and finally the gabbro unit around the margin. Contacts between these units appear to be gradational, implying that they formed as a result of differentiation processes in a single parent magma. The St. Stephen Gabbro contains significant sulphide mineralization of potentially economic importance, especially for Ni and Co (Houston 1986; Kooiman 1996).
The dunite typically contains 95-100% olivine with minor plagioclase plagioclase
Any member of the series of abundant feldspar minerals that usually occur as light- to medium-grey-coloured, transparent to translucent grains or crystals. Plagioclase ranges in composition from albite to anorthite. , pyroxene, and chromite chromite (krō`mīt), dark brown to black mineral. It is an iron-chromium oxide, FeCr2O4, with traces of magnesium and aluminum. , and has a coarse-grained adcumulate texture (Fig. 3a). It is partially serpentinized, and in the smaller satellite bodies, olivine has been completely replaced by serpentine serpentine (sûr`pəntēn, –tīn), hydrous silicate of magnesium. It occurs in crystalline form only as a pseudomorph having the form of some other mineral and is generally found in the form of chrysotile (silky fibers) and and magnetite magnetite (măg`nətīt), lustrous black, magnetic mineral, Fe3O4. It occurs in crystals of the cubic system, in masses, and as a loose sand. . Sulphide minerals appear to be concentrated in the serpentinized parts of the dunite, suggesting that they also may be secondary. With decreasing cumulus cumulus: see cloud. olivine and increasing cumulus plagioclase, the dunite grades into troctolite (Fig. 3b). Some parts of the troctolite consist of interlayered olivine-rich troctolite and anorthosite anorthosite
Type of igneous rock composed predominantly of calcium-rich feldspar. It is considerably less abundant than either basalt or granite, but the complexes in which it occurs are often immense. . Pyroxene, hornblende, and magnetite are minor components of the troctolite. With increasing amounts of pyroxene, the troctolite in turn grades to olivine gabbro (Fig. 3c), olivine gabbronoritc, and anorthositic gabbro all included in the olivine gabbro unit of the pluton. In addition to olivine and plagioclase, both orthopyroxene and clinopyroxene clinopyroxene
Any variety of the mineral pyroxene that crystallizes in the monoclinic system. Diopside and augite are clinopyroxenes. are typically present, as well as varying amounts of amphibole and phlogopite, and accessory apatitc, titanite ti·tan·ite
See sphene. , and zircon. The southwestern and southeastern parts of the pluton consist mainly of gabbro, in which large grains of clinopyroxene enclose plagioclase laths, and orthopyroxene is minor or absent (Fig. 3d).
[FIGURE 3 OMITTED]
Although both the St. Stephen and Staples Mountain plutons contain abundant olivine-bearing rocks, the Staples Mountain Gabbro appears to lack the ultramafic component that is present in the St. Stephen Gabbro, and the latter lacks the aligned plagioclase grains that are characteristic of the Staples Mountain body, at least at the current levels of exposure. These differences may be related to the smaller size of the Staples Mountain body.
Calais Quartz Diorite
The Calais Quartz Diorite unit consists mainly of quartz diorite grading to diorite. The rocks are typically fine to medium grained with hypidiomorphic granular to locally ophitic o·phit·ic
1. Of or relating to ophite.
2. Having a texture composed of lath-shaped plagioclase crystals in a matrix of pyroxene crystals. texture involving amphibole and plagioclase (Fig. 3e). Two types of amphibole are present, an earlier generation of magnesio-hornblende with greenish brown-brown-tan pleochroism Pleochroism
In some colored transparent crystals, the effect wherein the color is quite different in different directions through the crystals. In such a crystal the absorption of light is different for different polarization directions. and later pale green-green actinolitic hornblende. Most samples also contain augite and biotite. Interstitial In a separate window. See interstitial ad.
(World-Wide Web) interstitial - A World-Wide Web page that appears before the expected content page. Interstitials can be used for advertising (intermercial, transition ad) or to confirm that the user is old enough to view the quartz makes up 5 to 8% of the rock. Minor K-feldspar is present locally, and may reflect places where mixing occurred between mafic and granitic magmas. In some areas, generally near contacts with the Baring Granite unit, quartz diorite has hiatal porphyritic por·phy·rit·ic also por·phy·rit·i·cal
1. Of or containing porphyry.
2. Containing relatively large isolated crystals in a mass of fine texture.
Adj. 1. texture with plagioclase phenocrysts 2 to 4 cm in length, set in a fine-grained intersertal to intergranular matrix of augite, plagioclase, and quartz. Outcrop-scale areas of gabbro within the Calais Quartz Diorite unit may be xenolithic or mingled material from the Staples Mountain and St. Stephen plutons, although some may be younger intrusions, perhaps related to the Elliott Mountain Diorite.
Typical granite of the Baring Granite unit is coarse-grained with hypidiomorphic sub-equigranular texture (Fig. 3f, g). Modal composition is mainly syenogranite to monzogranite, with quartz, plagioclase, and potassium feldspar potassium feldspar
A type of alkali feldspar that contains the molecule KAlSi3O8. Microcline and orthoclase are types of potassium feldspar. present in approximately equal amounts, and biotite [+ or -] hornblende forming approximately 6 to 8%. Plagioclase locally mantles the potassium feldspar in rapakivi texture. Accessory phases include zircon, apatite apatite (ăp`ətīt), mineral, a phosphate of calcium containing chlorine or fluorine, or both, that is transparent to opaque in shades of green, brown, yellow, white, red, and purple. , allanite Al´lan`ite
n. 1. (min.) A silicate containing a large amount of cerium. It is usually black in color, opaque, and is related to epidote in form and composition. , and titanite. Near the margins of the pluton, the granite contains numerous xenoliths, composed primarily of metasedimentary rocks from the St. Croix terrane in the west, as well as displaying the complex mingling relations with the Calais Quartz Diorite described by Hill and Abbott (1989), Jurinski (1990), Ludman and Hill (1990), and Hill (1991)
Elliott Mountain Diorite
The Elliott Mountain Diorite unit, although heterogeneous, consists mainly of diorite grading to quartz diorite. Typical diorite (Fig. 3h) is made up of plagioclase, hornblende, augite, orthopyroxene, quartz, magnetite, titanite, and apatite. Augite is typically interstitial to plagioclase, whereas orthopyroxene occurs as relict RELICT. A widow; as A B, relict of C D. cores in hornblende. The diorite contains pillow-shaped bodies of fine-grained diorite (diabase of Abbott 1986), which appears to be of similar composition to the host diorite. They may have formed by disruption of early crystallized parts of the magma by subsequent magma movement. A swarm of northeast-southwest trending bodies tapering to dykes composed of blue-grey biotite-hornblende granodiorite is present throughout the Elliott Mountain diorite, as mapped by Abbott (1986). These dykes contain numerous angular blocks composed of diorite, and are likely to be related to one of the adjacent younger granitic plutons.
Minor gabbroic and dioritic units
The gabbro body in the vicinity of the Woodland Dump was described by Ludman and Hill (1990) to consist of olivine norite. Our sample (SS00-129; Fig. 2) consists of medium-grained plagioclase, orthopyroxene, olivine, brown amphibole, and phlogopite, and is similar to samples from the olivine gabbro unit of the St. Stephen Gabbro. A mafic dyke-like body (SS00-108) sampled in the Baring Granite consists mainly of plagioclase, with minor quartz, K-feldspar, green-brown amphibole, clinopyroxene, and orthopyroxene.
Dated sample SS00-124 is a white, medium- to coarse-grained monzogranite, typical of the Baring Granite unit. Zircon grains were separated from a 20 kg sample in the geochronology laboratory at the Massachusetts Institute of Technology by standard techniques, abraded to obtain clean, unaltered grains, and dated using methodology as described by Schmitz and Bowring (2003). Two pale yellow, slender prisms (length:width 2.8:1) with blunt terminations, as well as two fragments of such prisms, were analyzed (Table 2). All four fractions are concordant, yielding a precise crystallization age of 421.1 [+ or -] 0.8 Ma (Fig. 4), at 2 [sigma] error.
[FIGURE 4 OMITTED]
This age is the same, within error, as the age of 423 [+ or -] 3 Ma obtained by the U-Pb (zircon) method for the Utopia Granite (M.L. Bevier, 2001, personal communication to S.M. Barr). The age is similar also to ages of various other plutons of the coastal Maine magmatic province (Fig. 1), such as the South Penobscot Pluton (419 [+ or -] 2 Ma, U-Pb, zircon; Stewart et al. 2001), Spruce Head Pluton (421 [+ or -] 1 Ma, U-Pb, zircon; Tucker et al. 2001), Cadillac Mountain Cadillac Mountain, with an elevation of 1,530 feet (466 m), is the highest point along the East Coast of the United States. intrusive complex (424 [+ or -] 2 and 419 [+ or -] 2 Ma, U-Pb, zircon; Seaman et al. 1995), and Sedgwick Pluton (419.5 [+ or -] 1 Ma, U-Pb, zircon; Stewart et al. 2001).
Sample SS98-36 from the olivine gabbro unit of the St. Stephen Gabbro (location shown on Fig. 2) contained relatively large and abundant interstitial phlogopite suitable for [sup.40]Ar/[sup.39]Ar dating. Phlogopite grains were picked from the crushed sample using tweezers tweezers An instrument with pincers used to grasp or extract. See Optical tweezers. under a binocular microscope binocular microscope
A microscope having two eyepieces, one for each eye, so that the object can be viewed with both eyes. . For irradiation in the McMaster University McMaster University, at Hamilton, Ont., Canada; nondenominational; founded 1887. It has faculties of humanities, science, social sciences, business, engineering, and health sciences, as well as a school of graduate studies and a divinity college. nuclear reactor (in Hamilton, Ontario), the selected grains were placed individually into holes machined in aluminum disks. The flux monitor was the hornblende standard, MMhb-1 (assumed age = 520 Ma; Samson and Alexander 1987). Laser analyses were made with a Nd-YAG system operated in continuous mode with the beam expanded to approximately cover the grain. Power was then increased in a series of steps until complete fusion was achieved. Isotopic analyses were made using a VG 3600 mass spectrometer spectrometer
Device for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emission (as of electromagnetic radiation or particles) is spread out according to some .
The single grain ages are plotted against [sup.39]Ar abundance for each analysed grain (Fig. 5). With one exception (Spot 5), no significant differences in apparent age were observed among the fourteen grains. The mean age is 421 [+ or -] 4 Ma (2[sigma] uncertainty, which includes the estimated error in the irradiation parameter, J). This age is interpreted to be the time of cooling of phlogopite through its argon argon (är`gŏn) [Gr.,=inert], gaseous chemical element; symbol Ar; at. no. 18; at. wt. 39.948; m.p. −189.2°C;; b.p. −185.7°C;; density 1.784 grams per liter at STP; valence 0. closure temperature (ca. 300-400[degrees]C, McDougall and Harrison 1999), and likely approximates the time of crystallization of the gabbro. It is similar within error to a previously reported amphibole K-Ar age of 418 Ma (Wanless et al. 1973) from the St. Stephen Gabbro. However, it is significantly older than the biotite (presumably pre·sum·a·ble
That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. phlogopite) K-Ar age from the same pluton (Wanless et al. 1973). It is also similar to the previously reported [sup.40]Ar/ [sup.39]Ar age of 422.7 [+ or -] 3 Ma reported for hornblende from the Pocomoonshine Gabbro-Diorite (West et al., 1992).
[FIGURE 5 OMIITED]
GEOCHEMISTRY geochemistry, study of the chemical changes on the earth. More specifically, it is the study of the absolute and relative abundances of chemical elements in the minerals, soils, ores, rocks, water, and atmosphere of the earth and the distribution and movement of
Although complex mingling, mixing, and gradational contacts characterize relations in the MPS, as described above, heterogeneous rocks were avoided in sampling for geochemistry in this study. We focused on homogeneous-looking samples that appeared characteristic of the main units of the MPS (Table 4). Some of the samples analysed as part of this study (MH designation in Table 4) were obtained from the collection of M. Hill and analyzed as part of the present project. The geochemical data of Gaskill (1999) were integrated into our study after a re-examination of his thin sections and samples. However, we have not included the large chemical data base of Paktunc (1989) because of uncertainty in locations and petrographic features of the analyzed samples. As demonstrated by McLaughlin (2003), they do not significantly change the conclusions of this study.
Also included in Table 4 are data for the Bocabec Pluton. The major element data for these samples are from Fyffe (1971), and trace element analyses were obtained from the same sample powders as part of the present study. In addition, four other granitic samples from the thesis collection of Fyffe (1971) were analyzed by K. Thorne and D. Lentz, and those unpublished data are included, with permission, in Table 3. Additional data from Ludman and Hill (1990), Coughlin (1986), McLeod (1990) (including data listed in his Appendix 4), and Thorne and Lentz (2001) are included on the diagrams, but not listed in Table 4.
Major element compositions
Plots against Si[O.sub.2] are used to illustrate chemical characteristics of the units of the MPS (Fig. 6). Dioritic and gabbroic samples from the Staples Mountain, St. Stephen, and Elliott Mountain plutons all have less than about 50% Si[O.sub.2], but show differences in other major element oxides. The Staples Mountain samples show a wide range in most elements, consistent with their wide range in rock types and cumulate features as described by Coughlin (1986). Their most distinctive characteristics compared to the dioritic and gabbroic samples are their high Fe and Ti contents (Fig. 6a, c). The Elliott Mountain samples tend to overlap in composition with gabbro from the St. Stephen Gabbro, but have higher Ti[O.sub.2], [Na.sub.2]O, and [P.sub.2][O.sub.5] and lower MgO contents (Fig. 6a, f, h, d). Compared to samples from the gabbro unit in the St. Stephen Gabbro, the olivine gabbro and troctolite samples have lower Si[O.sub.2] but also a trend toward lower Ti[O.sub.2], [Na.sub.2]O, and [P.sub.2][O.sub.5] contents. Variations in [Al.sub.2][O.sub.3], [Fe.sub.2][O.sup.t.sub.3], MgO, and CaO are consistent with the occurrence of cumulate textures in most of the analysed samples, and can be accounted for by olivine, pyroxene, and plagioclase separation or accumulation. In general, the trend from the more mafic samples of the St. Stephen Gabbro to the higher Si[O.sub.2] samples of the Calais Quartz Diorite can be explained by fractionation of plagioclase, olivine, and pyroxene, and it is likely that these plutons are co-magmatic. In comparison, both the Staples Mountain Gabbro and Elliott Mountain Diorite units show differences in major element compositions which suggest that they are not genetically related to the St. Stephen and Calais plutons. Sample SS00-108 from a gabbroic dyke(?) in the Baring Granite has higher Si[O.sub.2] than any samples analyzed from the Staples Mountain Gabbro, but also shows high [F.sub.2][O.sub.3] and low MgO, as well as high [Na.sub.2]O and [P.sub.2][O.sub.5] contents (Fig. 6f, h). In contrast, sample SS00-129 from the Woodland Dump gabbro of Ludman and Hill (1990) is similar to samples of similar Si[O.sub.2] content from the St. Stephen Gabbro.
[FIGURE 6 OMITTED]
With one exception (granodiorite SS00-142), analyzed samples from the Baring Granite are all of granite composition, and have high Si[O.sub.2] contents (more than 68%), and correspondingly low contents of other major elements except [Na.sub.2]O and [K.sub.2]O (Fig. 6). These chemical features are consistent with the high contents of sodic so·dic
Relating to or containing sodium.
[sod(ium) + -ic.]
Relating to or containing sodium. plagioclase, K-feldspar, and quartz and low abundance of ferromagnesian minerals in the samples. Chemical similarity between the Baring Granite and the Utopia Granite (data from McLeod 1990) is apparent, although the compositional range reported for the Utopia Granite extends to higher Si[O.sub.2] content.
Data from the Bocabec Pluton are also shown on Fig. 6. As described in detail by Fyffe (1971) and McLeod (1990), these samples represent the mafic and felsic components in the suite, and also the intermediate units This is a complete list Pennsylvania's 29 of Intermediate Units by their assigned IU number:
PA Intermediate Unit Web site
1. crossbreeding; the act or process of producing hybrids.
2. molecular hybridization
3. between the mafic and felsic magmas. The range of compositions encompasses most of the samples from the Calais Quartz Diorite, as well as the gabbro unit of the St. Stephen Gabbro, thus supporting their co-genetic relationship. In contrast, the Staples Mountain and Elliott Mountain samples generally lie outside the Bocabec trend, implying that they are not closely linked to the other mafic magmas. The data also show that the granitic component of the Bocabec Pluton is chemically similar to the Baring Granite, and support the interpretation (Fyffe 1971; McLeod 1990) that the intermediate samples formed by a mixing process. Intermediate sample (SS00-142) from the MPS is chemically similar to intermediate samples from the Bocabec Pluton, suggesting that it may have had a similar origin, as a result of mixing between Baring Granite and Calais Quartz Diorite magmas.
Trace element compositions
Trace element data are more limited than major element data, and are mainly for samples from the present study (Table 4). Trace elements Trace elements
A group of elements that are present in the human body in very small amounts but are nonetheless important to good health. They include chromium, copper, cobalt, iodine, iron, selenium, and zinc. Trace elements are also called micronutrients. are available for only one sample from Staples Mountain Gabbro and variable numbers of samples from the Bocabec Pluton and Utopia Granite, depending on the element. Trends in Rb, Sr, and Ba within the mafic and felsic sample sets are generally consistent with feldspar feldspar (fĕl`spär, fĕld`–) or felspar (fĕl`spär), an abundant group of rock-forming minerals which constitute 60% of the earth's crust. fractionation (Figs. 7a-c). Gabbroic samples have mainly low Rb and Ba, and high Sr, whereas the Calais Quartz Diorite generally has less Sr and more Rb and Ba. Some Utopia Granite samples and one Baring Granite sample have high Rb and low Ba, indicative of a highly evolved composition in which Ba has been partitioned into and removed with K-feldspar (Fig. 6g). However, overall, the Baring Granitc is characterized by high Ba content (up to almost 1100 ppm).
[FIGURE 7 OMITTED]
Elements Zr, Nb, Y, and V display wide variation and few trends on silica variation diagrams (Figs. 8a-d), related to the control of these elements by the abundance of mainly pyroxene and magnetite (e.g., Miyashiro and Shido 1975; Pearce and Norry 1979) Maich vary widely in the dioritic and gabbroic samples. The Utopia Granite overlaps the composition of the Baring Granite, but generally has higher Nb and Y, and lower Zr (Figs. 8a-c). Some of the intermediate to granitic Bocabec Pluton samples have elevated Zr, Nb, and Y, and low V (Fig. 8). High Zr content in intermediate samples may represent the build-up of that element in the magma prior to onset of zircon crystallization.
[FIGURE 8 OMITTED]
Ni and Cr show wide spread in the gabbroic and dioritic samples (Figs. 9a, b) related to variations in olivine and pyroxene contents. The Staples Mountain Gabbro sample (NB00-133) is low in both elements compared to most St. Stephen Gabbro samples, further support for their lack of genetic relationship. Cu and Co also display a wide range in gabbroic to intermediate samples, with a few high values up to 150 and nearly 100 ppm, respectively (Figs. 9c, d). Ni, Cr, and Cu are low in all the granitic samples, but Co contents are high in the Baring Granite compared to most granitic Bocabec Pluton and Utopia Granite samples. Pb and Zn also differ between the Baring and Utopia granites, being generally higher in the Baring samples (Figs. 9e, f). Zn contents are highest in the intermediate rocks.
[FIGURE 9 OMITTED]
Chemical affinity In physical chemistry, chemical affinity, historically, refers to the "force" that causes chemical reactions. A broad definition, used generally throughout history, is that chemical affinity is that whereby substances enter into or resist decomposition. and tectonic setting
Interpretation of chemical affinity and tectonic setting for units of the MPS is somewhat ambiguous, as illustrated by representative, commonly used diagrams in Fig. 10. With the exception of the Staples Mountain and Woodland Dump samples, which appear tholeiitic, gabbroic and dioritic samples show little iron enrichment, and calc-alkaline affinity is suggested (Fig. 10a). Most samples have low Nb/Y ratios indicative of subalkalic affinity, although some St. Stephen and Bocabec samples plot in alkalic fields (Fig. 10b). Alkalic affinity is not supported by the V-Ti diagram (Fig. 10c), which suggests with in-plate tholeiitic character for mafic samples. On the other hand, the Ti-Zr-Y diagram suggests calc-alkaline (arc) setting (Fig. 10d).
Granitic samples from the Baring Granite have lower Y and Nb contents, consistent with origin in a volcanic arc volcanic arc
A usually arc-shaped chain of volcanoes located on the margin of the overriding plate at a convergent plate boundary.
volcanic arc setting, whereas granitic samples from the Bocabec Pluton and Utopia Granite are generally more evolved and plot mainly in the within-plate granite field (Fig. 10e). Elevated Zr and Ga/Al ratio suggest A-type characteristics for these samples (Fig. 10f).
Rare-earth element rare-earth element
See lanthanide. (REE) data were obtained for 15 samples from the MPS during the present study (Table 5). Additional REE data for the MPS were taken from Ludman and Hill (1990) and data for the Bocabec pluton and Utopia Granite are from McLeod (1990). Some of the data from McLeod (1990) show erratic features that suggest analytical error, but the overall patterns are consistent enough to enable comparison with the MPS.
In comparison with the other units, the St. Stephen gabbro has low REE abundance and a relatively flat REE pattern (Fig. 11a). The positive Eu anomalies suggest plagioclase accumulation. The sample with highest REE abundance shows some enrichment in light REE relative to heavy REE, and the pattern is very similar to that of the Calais Quartz Diorite sample with lowest REE abundance. The samples from the Calais Quartz Diorite show parallel chondrite-normalized patterns, with a change from a slight positive to a slight negative Eu anomaly with increasing REE abundance and increasing Si[O.sub.2] content.
[FIGURE 11 OMITTED]
Mafic samples from the Bocabec Pluton display patterns similar to the Calais Quartz Diorite (Fig. 11b). However, an intermediate sample with over 58% Si[O.sub.2] has higher REE abundances and a pattern more similar to those of the Baring Granite samples (Fig. 11c). Three samples from the Elliot Mountain Diorite (Fig. 11c), all from Ludman and Hill (1990) are similar to the Calais Quartz Diorite, but do not show the small negative Eu anomalies that characterize the Calais samples.
Samples from the Baring Granite, Utopia Granite, and granite in the Bocabec Pluton all show strong negative Eu anomalies that could be explained by feldspar fractionation (Fig. 11c, e). They are most pronounced in the Utopia Granite, consistent with its more evolved character (e.g., Fig. 7e). However, in general the REE patterns are indicative of similar and related origins for these units.
Gabbro dyke(?) sample SS00-108 in the Baring Granite has high total REE abundance and a positive Eu anomaly (Fig. 11d). The high REE content, light REE enrichment compared to heavy REE, and strong positive Eu anomaly set it apart from other samples. It may be related to the Staples Mountain Gabbro, as suggested by some of its other chemical features, but no REE data are yet available from Staples Mountain for comparison.
Five samples were analyzed for Sm-Nd isotopes (Table 6). The calculated [[epsilon].sub.Nd] at 421 Ma for gabbro sample SS98-9 from the St. Stephen Gabbro is 0.4, with a depleted mantle model age of 1567 Ma, whereas two dioritic samples from the Calais Quartz Diorite have higher [[epsilon].sub.Nd] values of 1.03 and 3.4 at 421 Ma, with depleted mantle ages of 1184 and 881 Ma, respectively. For the Baring Granite, the [[epsilon].sub.Nd] is only slightly lower at -0.40, with a similar depleted mantle age of 1250 Ma. The gabbro dyke(?) in the Baring Granite has a positive [[epsilon].sub.Nd] of 1.51. All of these values are well below depleted Mantle values (ca. +7 to 8 at ca. 421 Ma), showing that significant crustal crust·al
Of or relating to a crust, especially that of the earth or the moon.
Adj. 1. crustal - of or relating to or characteristic of the crust of the earth or moon material was inched to produce even the mafic units in the MPS. On the other hand, the [[epsilon].sub.Nd] values, even for the Baring Granite, are too high for the magmas to have had an ancient crustal source (likely to be -7 or less at ca. 421 Ma; DePaolo 1988).
These results are consistent with those reported by Whalen et al. (1994), which were in the order of +2 to +3 for the Utopia Granite and granite in the Bocabec Pluton. Gabbro in the Bocabec Pluton yielded a higher value of +5 (all values recalculated to 421 Ma).
Field relations and petrological features, as well as geochronology, are consistent with a co-magmatic relationship among the St. Stephen Pluton, Calais Quartz Diorite, Bocabec Pluton, and Baring Granite. The Staples Mountain Gabbro may also be closely related to this suite, but it shows some chemical differences that need to be investigated further.
A likely model is that a mafic magma (possibly mantle derived) of the MPS was emplaced first and underwent substantial crystal fractionation to produce the mafic and ultramafic St. Stephen Gabbro and the more evolved dioritic magma represented by the Calais Quartz Diorite. The evolved dioritic magmas then mingled with crustal melts of granitic composition, represented by the Baring Granite, to locally produce hybrid rocks such as the granodiorite documented by Fyffe (1971) in the Bocabec Pluton. Disruption of earlier layered mafic bodies by younger granite magmas was proposed by Amos (1963). However, in their study of the Cadillac Mountain intrusive complex, similar to the MPS in age and range of rock types, Wiebe et al. (1997) demonstrated that felsic magmas interacted with subsequent infusions of mafic magma. Such later infusions of mafic magma are represented in the MPS by the Elliott Mountain Diorite and small gabbroic and dioritic bodies scattered through the MPS.
Although the mafic component in the coastal Maine province has generally been considered a mantle melt, the low epsilon Nd values and especially the small difference in epsilon Nd between the Baring and Utopia granites and the Calais Quartz Diorite suggests a major component of crustal material. Isotopic studies of other plutonic suites in the region may enable a better understanding of magma generation processes.
The late Silurian (ca. 421 Ma) age for components of the MPS is similar to ages reported for other mafic-felsic plutonic complexes of the Coastal Maine magmatic province, although voluminous younger Devonian plutons are also present (e.g., Hogan and Sinha 1989; McLeod 1990; Tucker et al. 2001). Like the MPS, many of the other Silurian plutons are bimodal bi·mod·al
1. Having or exhibiting two contrasting modes or forms: "American supermarket shopping shows bimodal behavior , and display mingling relationships that suggest that the mafic and felsic components were contemporaneous (e.g., Hogan and Sinha 1989; Wiebe et al. 1997). Although these plutons are generally considered to be related to the "Acadian orogeny Acadian orogeny
Mountain-building event that affected the northern portion of the Appalachian Geosyncline from present-day New York to Newfoundland during the Devonian period. The orogeny was most intense in northern New England. ", the details of tectonic activity during this protracted pro·tract
tr.v. pro·tract·ed, pro·tract·ing, pro·tracts
1. To draw out or lengthen in time; prolong: disputants who needlessly protracted the negotiations.
2. orogenic event are unclear. Widespread evidence for voluminous late Silurian volcanic and plutonic activity throughout the coastal Maine magmatic province and adjacent New Brunswick shows that igneous activity was a major characteristic of this event, but the specific tectonic setting is uncertain.
The bimodal character of the plutons, and their tendency to A-type affinities, has led to the suggestion that the magmatism was related to regional extension and mafic underplating (e.g., Hogan and Sinha 1989). However, regional tectonic models (e.g., Robinson et al. 1998; van Staal et al. 1998; Tucker et al. 2001) are more consistent with plate convergence and subduction sub·duc·tion
A geologic process in which one edge of one crustal plate is forced below the edge of another.
[French, from Latin subductus, past participle of in the Late Silurian. Although somewhat ambiguous, chemical data front the MPS are more indicative of calc-alkalic affinity and a subduction environment than within-plate extension (Fig. 10). One interpretation that may be consistent with both ideas is that Late Silurian plutons in the coastal Maine magmatic province formed in a back-arc position with respect to the early Silurian Kingston arc (Fyffe et al. 1999; Barr et al. 2002). Isotopic data do not indicate a major component of directly mantle-derived magmas in these suites, although isotopic data are not yet available from the more mafic components. Melts may have been generated by large-scale melting of relatively primitive arc-type crust underlying the Mascarene and Ellsworth terranes. The presence of such crust has been suggested by isotopic data from southern New Brunswick (Whalen et al. 1994; Samson et al. 2000).
This work has demonstrated that the St. Stephen Gabbro, Calais Quartz Diorite, and Baring Granite components of the Moosehorn Plutonic Suite are approximately contemporaneous and late Silurian in age. The close petrochemical similarity of the St. Stephen Gabbro and Calais Quartz Diorite to the mafic and intermediate components of the Bocabec Pluton of the Saint George Batholith suggests that all of these plutons were comagmatic. The granitic component of the Bocabec Pluton is generally more similar to the Baring Granite than to the Utopia Granite, which is more evolved. The Elliott Mountain Diorite shows petrological differences that suggest that it may be somewhat younger than the other units of the MPS, although the number of samples is limited and more work is required to better define the characteristics of the Elliott Mountain Diorite and its relationship to the Bocabec Pluton and Calais Quartz Diorite. The Staples Mountain Gabbro is unlike the other mafic plutons of the MPS in its iron-enrichment trend, and is therefore likely to be a separate intrusion, although of similar age. Neodymium isotopic data show that even the mafic parts of these plutons have a significant crustal component in their source, but the values even in granitic samples are too high for significant amounts of ancient crustal material to be involved. Their petrochemical features are most consistent with origin in a supra-subduction zone extensional environment (back-arc basin) in relatively young continental crust.
Table 1. Summary of petrographic features of main units * in the MPS. Staples Mountain Gabbro St. Stephen Gabbro Principal olivine gabbro, anorthositic dunite, troctolitc, oli- rock types gabbro, norite, anorthosite, vine gabbro, anorthositic gabbro gabbro, anorthosite, norite, gabbro Primary olivine ([FO.sub.53-55]), olivine ([Fo.sub.80-58]), minerals plagioclase ([An.sub.72-53]), plagioclase cpx (augite and pigeonite), ([An.sub.95-35]), opx hornblende (ferroan ([En.sub.80-70]), cpx pargasite), [+ or -] ortho- (augite-diopside), pyroxene ([En.sub.70-62]) [+ or -] hornblende (pargasite-pargasitic hornblende), phlogopite- biotite (Fe/Fe+Mg = 12-40) Accessory magnetite, ilmenite, apatite apatite, titanite, minerals pyrrhotite, chalcopyrite, pentlandite, Textures layering, cumulate layering, cumulate, ophitic Calais Quartz Diorite Baring Granite Principal quarts diorite, diorite, syenogranite, rock types tonalite, granodiorite, monzogranite, quartz monzonite granodiorite, tonalite Primary plagioclase ([An.sub.80-20]), plagioclase minerals brown amphibole (ferroparga- ([An.sub.29-19]), K- sitic hornblende to edenitic feldspar (microcline), hornblende); green quartz, biotite amphibole (Fe/Fe+Mg=72-80), [+ or -] (magnesiohornblende to hornblende actinolite), cpx (augite), opx (En50), quartz, biotite (Fe/Fe+Mg = 40-60) Accessory apatite, magnetite, zircon, apatite, zircon minerals titanite Textures medium-grained (m.g.) m.g. hypidiomorphic hypidiomorphic inequigranular/ seriate inequigranular, sub-ophitic porphyritic Elliott Mountain Diorite Principal diorite, quartz diorite, rock types tonalite, gabbro Primary plagioclase ([An.sub.60-25]), minerals amphibole (magnesiohornblende- actinolite), cpx (augite- diopside), opx ([En.sub.50]), quartz, [+ or -] K-feldspar Accessory magnetite, apatite, zircon minerals Textures m.g. hypidiomorphic inequigranular, sub-ophitic * Compiled mainly from McLaughlin (2003), except Staples Mountain Gabbro data from Coughlan (1986). Table 2. U-Pb data for sample SS00-124 Concentrations Ratios Sample Weight U Pb Pb(c) [sup.206]Pb/ Fractions ([micro]g) (ppm) (ppm) (pg) [sup.204]Pb (a) (b) (c) z1 2.9 138 9.3 0.5 3659.1 z3 2.2 284 19.3 0.6 4863.6 z4 4.5 169 11.7 0.8 3945.1 z5 3.7 334 23.7 0.4 14419.9 Weighted Mean Age: [+ or -] MSWD Ratios Sample [sup.206]Pb/ [sup.206]Pb/ Fractions [sup.238]Pb [sup.238]U err (d) (e) (2[sigma]%) z1 0.105 0.067557 0.30 z3 0.111 0.067560 0.08 z4 0.136 0.067636 0.07 z5 0.165 0.067616 0.06 Weighted Mean Age: [+ or -] MSWD Ratios Sample [sup.207]Pb/ [sup.206]Pb/ Fractions [sup.206]Pb err [sup.238]U (e) (2[sigma]%) (e) z1 0.5143 0.32 0.05522 z3 0.5147 0.12 0.05525 z4 0.5150 0.10 0.05522 z5 0.5147 0.08 0.05520 Weighted Mean Age: [+ or -] MSWD Ratios Age (Ma) Sample err [sup.207]Pb/ [sup.207]Pb/ Fractions (2[sigma]%) [sup.238]U [sup.235]U z1 0.11 421.4 421.4 z3 0.09 421.4 421.6 z4 0.07 421.9 421.8 z5 0.06 421.8 421.6 Weighted Mean Age: 421.7 421.6 [+ or -] 0.4 0.3 MSWD 1.58 0.29 Age (Ma) Sample [sup.207]Pb/ corr. Fractions [sup.206]Pb coef. z1 421.1 0.937 z3 422.5 0.641 z4 421.3 0.729 z5 420.5 0.718 Weighted Mean Age: 421.1 [+ or -] 0.8 MSWD 0.91 Notes: (a) Sample weights are estimated by using a video monitor and are known to within 40%. (b) Total common-Pb in analyses. (c) Measured ratio corrected for spike and fractionation only. (d) Radiogenic Pb. (e) Corrected for fractionation, spike, blank, and initial common Pb. Mass fractionation correction of 0.15%/amu [+ or -] 0.04%/amu (atomic mass unit) was applied to single-collector Daly analyses and 0.12%/amu [+ or -] 0.04% for dynamic Faraday-Daly analyses. Total procedural blank less than 0.4 pg for Pb and less than 0.1 pg for U. Blank isotopic composition: [sup.206]Pb/[sup.204]Pb=19.10 [+ or -] 0.1, [sup.207]Pb/[sup.204]Pb =15.71 [+ or -] 0.1, [sup.208]Pb/[sup.204]Pb = 38.65 [+ or -] 0.1. Corr. coef. = correlation coefficient; err = error. Age calculations are based on the decay constants of Steiger and Jager (1977). Common-Pb corrections were calculated by using the model of Stacey and Kramers (1975) and the interpreted age of the sample. Table 3. [sup.40]Ar/[sup.39]Ar data for sample SS98-36. Spot Code mV 39 Age [+ or -] 1[sigma] % ATM (Ma) 1 C66-3-1 197.1 417.7 [+ or -] 7.3 1.2 2 C66-7-2 154 422.3 [+ or -] 9.1 0.8 3 C66-2-2 228.9 427.5 [+ or -] 6.2 0 4 C66-6-1 40.8 420.2 [+ or -] 31 6 5 C66-11-2 86 440.4 [+ or -] 6.5 0.6 6 C66-14-2 200.9 425.0 [+ or -] 3.7 2.6 7 C66-4-2 250.9 420.2 [+ or -] 3 1.6 8 C66-5-2 157.2 424.6 [+ or -] 4 0.6 9 C66-1-2 613.4 417.1 [+ or -] 2.1 1.4 10 C66-8-1 289 416.8 [+ or -] 2.7 1.6 11 C66-9-1 222.8 417.4 [+ or -] 3.2 2.3 12 C66-10-2 138 432.6 [+ or -] 4.9 5.5 13 C66-12-2 226 423.0 [+ or -] 3.1 0.4 14 C66-13-2 113.9 417.8 [+ or -] 5.6 6.6 Spot [sup.37]Ar/ [sup.36]Ar/ [sup.39]Ar/ % IIC [sup.39]Ar [sup.40]Ar [sup.40]Ar 1 1.17 0.000041 0.009593 0.16 2 1.19 0.000030 0.009504 0.16 3 0.38 0.000001 0.009460 0.05 4 3.47 0.000204 0.009041 0.47 5 1.13 0.000023 0.009092 0.15 6 0.23 0.000089 0.009276 0.03 7 0.07 0.000054 0.009496 0.01 8 0.06 0.000021 0.009478 0 9 0.30 0.000048 0.009595 0.04 10 0.12 0.000054 0.009584 0.01 11 0.36 0.000080 0.009494 0.05 12 0.8 0.000186 0.008826 0.1 13 0.53 0.000014 0.009540 0.07 14 0.99 0.000224 0.009068 0.13 Mean age = 421 [+ or -] 4 Ma (2[sigma] uncertainty, including error in J). Grain 4 omitted from mean age calculation because probably polymineralic. J = 0.002533 [+ or -] 0.000025 (0.9%). [sup.27]Ar/[sup.39]Ar, [sup.36]Ar/[sup.40]Ar, and [sup.39]Ar/[sup.40]Ar are corrected for mass spectrometer discrimination, interfering isotopes, and system blanks. % IIC--Interfering isotopes correction. Table 4. Chemical data for samples from the Moosehorn Plutonic Suite, Bocabec Pluton, and spatially associated units [Al.sub.2] [Fe.sub.2] Sample Si[O.sub.2] Ti[Os.ub.2] [O.sub.3] [O.sub.3] Staples Mountain Gabbro SS00-133 44.19 4.40 16.16 15.86 St. Stephen Gabbro troctolite SS98-26A 47.71 0.22 23.34 5.77 SS98-52 43.58 0.22 19.26 9.01 olivine gabbro SS00-110 46.27 0.51 21.50 6.57 SS98-02B 43.82 0.39 15.50 10.11 SS98-31B 47.33 0.30 25.07 5.02 SS98-36 45.29 0.89 16.93 10.92 SS98-45 42.26 0.23 22.39 9.15 gabbro SS97-1-151 48.87 1.12 15.99 11.58 SS97-5-54.5 51.51 1.93 18.05 12.02 SS98-29 48.51 0.57 19.23 6.71 SS98-32a 48.87 0.64 17.13 10.21 SS98-54 49.31 1.31 16.43 9.94 SS98-67 49.25 0.47 19.33 9.04 SS98-90 46.76 0.61 20.35 9.53 Calais Quartz Diorite MH-79 49.99 2.28 15.94 12.04 MH-1758 59.77 0.99 15.88 7.39 SS00-119 56.56 1.33 15.55 8.43 SS00-120 53.50 1.25 15.33 10.62 SS00-122 54.77 1.57 15.74 10.21 SS00-123 58.14 0.87 15.21 8.27 SS00-131 55.98 0.76 17.91 7.98 SS00-140 51.49 1.45 17.38 10.71 SS00-144A 59.14 1.34 16.54 7.58 SS00-144B 57.83 1.44 16.07 8.19 SS98-09 54.26 1.00 17.06 7.99 SS98-72 56.33 1.43 16.11 9.31 Baring Granite MH-153 74.31 0.25 12.88 2.34 MH-159 74.81 0.24 12.86 2.30 LH-258 76.06 0.15 13.83 1.28 MH-382 73.16 0.26 13.81 2.51 SS00-104 72.66 0.29 14.18 2.72 SS00-107 72.69 0.27 14.62 2.60 SS00-113 72.11 0.36 14.77 3.21 SS00-117 72.12 0.32 14.88 2.89 SS00-118 71.96 0.31 14.54 2.53 SS00-121 68.80 0.51 15.02 3.93 SS00-124 72.73 0.36 14.68 2.39 SS00-137 71.25 0.34 14.33 2.64 SS00-139 72.38 0.32 14.45 2.48 SS00-141 69.67 0.36 15.05 2.80 SS00-142 63.34 0.75 16.53 6.59 SS00-148 71.96 0.32 15.41 2.60 Elliot Mountain Diorite MH-43 50.18 1.51 16.86 10.38 MH-58A 48.30 2.26 16.07 12.65 LH-58 48.06 2.26 15.65 11.93 LH-72A 49.05 2.05 16.56 11.00 LH-72B 48.38 2.28 15.52 12.04 SS00-126 49.47 2.40 13.87 12.17 SS00-127 48.41 2.10 16.32 12.08 Unnamed Gabbro Diorite Bodies SS00-108 52.88 1.66 14.31 16.64 SS00-129 47.79 1.22 17.69 9.96 Bocabec Pluton Fyffe04 50.10 1.20 14.70 10.29 Fyffe13 69.15 0.68 13.12 5.45 Fyffe17 60.60 1.30 14.80 8.90 Fyffe32 68.80 0.50 14.50 3.32 Fyffe33 60.00 1.40 14.20 9.29 Fyffe35 60.90 1.30 15.20 8.85 Fyffe38 68.78 0.65 13.32 5.01 Fyffe42 68.80 0.65 13.21 5.00 Fyffe43 68.20 0.67 13.26 5.29 Fyffe49 53.00 1.50 14.00 11.44 Fyffe59 61.60 0.80 15.90 4.93 Fyffe6l 52.80 1.30 15.00 8.61 Fyffe64 62.50 1.00 14.90 7.59 Fyffe67 46.70 1.00 18.20 8.85 Fyffe72 64.10 0.80 15.20 4.75 Sample MnO MgO CaO [Na.sub.2]O [K.sub.2]O Staples Mountain Gabbro SS00-133 0.21 6.34 10.64 2.78 0.33 St. Stephen Gabbro troctolite SS98-26A 0.10 5.20 10.98 2.82 0.75 SS98-52 0.11 15.03 9.97 1.48 0.10 olivine gabbro SS00-110 0.10 9.04 11.95 1.94 2.78 SS98-02B 0.14 16.56 10.99 0.62 0.10 SS98-31B 0.08 5.30 13.69 2.07 0.12 SS98-36 0.15 12.78 8.15 1.96 0.48 SS98-45 0.08 8.85 11.05 1.49 0.67 gabbro SS97-1-151 0.17 11.20 7.22 2.00 1.30 SS97-5-54.5 0.16 4.91 6.06 2.55 1.14 SS98-29 0.11 7.25 12.90 2.56 0.31 SS98-32a 0.17 10.59 9.96 1.42 0.12 SS98-54 0.16 8.09 9.51 2.73 0.75 SS98-67 0.14 9.06 9.46 1.34 0.28 SS98-90 0.13 7.70 10.72 2.17 0.41 Calais Quartz Diorite MH-79 0.19 5.42 8.21 3.46 1.23 MH-1758 0.14 2.97 5.32 3.55 2.39 SS00-119 0.14 4.55 7.61 3.08 2.08 SS00-120 0.17 5.97 8.38 3.13 1.69 SS00-122 0.17 4.12 7.73 3.23 1.44 SS00-123 0.14 4.75 7.33 3.13 2.07 SS00-131 0.17 3.74 6.66 3.12 3.07 SS00-140 0.20 5.40 8.24 3.03 1.19 SS00-144A 0.15 2.47 5.70 3.85 1.80 SS00-144B 0.13 3.00 6.05 3.56 1.94 SS98-09 0.13 5.71 7.07 3.20 1.89 SS98-72 0.17 3.61 6.87 3.36 2.04 Baring Granite MH-153 0.06 0.21 0.79 3.21 5.01 MH-159 0.06 0.22 0.55 3.34 4.63 LH-258 0.03 0.78 0.48 4.47 4.57 MH-382 0.05 0.24 1.43 3.56 4.59 SS00-104 0.06 0.34 1.58 3.62 4.54 SS00-107 0.06 0.27 1.02 3.89 5.02 SS00-113 0.07 0.43 1.56 3.61 4.53 SS00-117 0.06 0.39 1.75 3.41 4.68 SS00-118 0.06 0.50 1.68 3.50 4.60 SS00-121 0.08 0.94 2.72 3.67 3.78 SS00-124 0.05 0.29 1.58 3.52 5.28 SS00-137 0.05 0.56 1.87 3.54 3.94 SS00-139 0.06 0.38 1.58 3.44 5.14 SS00-141 0.06 0.79 2.33 3.80 3.27 SS00-142 0.15 0.92 3.11 3.50 3.33 SS00-148 0.06 0.68 2.37 4.08 3.34 Elliot Mountain Diorite MH-43 0.14 5.51 8.71 3.19 1.21 MH-58A 0.20 6.60 8.83 3.42 1.10 LH-58 0.18 6.69 8.82 3.84 1.12 LH-72A 0.17 6.14 8.95 4.58 0.93 LH-72B 0.19 6.20 9.10 4.39 1.21 SS00-126 0.20 5.09 8.09 3.25 1.30 SS00-127 0.19 6.11 9.30 3.33 0.66 Unnamed Gabbro Diorite Bodies SS00-108 0.61 1.68 6.75 4.12 1.50 SS00-129 0.15 9.76 9.16 2.74 0.60 Bocabec Pluton Fyffe04 0.20 6.60 9.10 3.40 1.10 Fyffe13 0.15 0.61 1.14 4.57 2.83 Fyffe17 0.23 1.80 4.40 4.20 2.10 Fyffe32 0.05 2.40 2.80 3.50 2.40 Fyffe33 0.22 2.10 4.80 4.00 2.10 Fyffe35 0.19 1.40 4.20 4.40 2.00 Fyffe38 0.11 0.62 1.73 4.11 3.24 Fyffe42 0.15 0.58 1.93 4.12 3.28 Fyffe43 0.15 0.62 2.04 4.27 3.19 Fyffe49 0.30 5.00 8.70 3.40 0.90 Fyffe59 0.08 2.10 4.80 4.80 1.40 Fyffe6l 0.15 5.80 8.20 3.40 1.30 Fyffe64 0.17 1.10 3.00 3.70 3.10 Fyffe67 0.16 7.60 10.50 2.40 0.70 Fyffe72 0.08 1.80 4.30 3.70 2.60 [P.sub.2] Sample [O.sub.5] LOI Total Ba Rb Sr Staples Mountain Gabbro SS00-133 0.47 0.09 101.47 3 14 446 St. Stephen Gabbro troctolite SS98-26A 0.03 3.82 100.74 315 49 513 SS98-52 0.03 1.54 100.33 101 27 244 olivine gabbro SS00-110 0.09 2.00 102.75 23 17 316 SS98-02B 0.02 1.96 100.21 191 26 199 SS98-31B 0.02 1.08 100.08 0 32 341 SS98-36 0.12 1.45 99.12 87 33 316 SS98-45 0.04 4.07 100.28 117 41 400 gabbro SS97-1-151 0.19 0.71 100.35 229 46 278 SS97-5-54.5 0.13 1.34 99.80 304 47 305 SS98-29 0.02 2.13 100.30 270 35 328 SS98-32a 0.03 0.78 99.92 0 25 233 SS98-54 0.09 0.88 99.20 0 38 269 SS98-67 0.03 0.87 99.27 5 33 271 SS98-90 0.06 2.06 100.50 356 34 380 Calais Quartz Diorite MH-79 0.45 1.50 100.71 50 170 374 MH-1758 0.19 1.30 99.88 280 75 250 SS00-119 0.23 0.81 100.37 353 70 285 SS00-120 0.19 0.65 100.88 495 46 294 SS00-122 0.23 0.84 100.05 386 44 257 SS00-123 0.12 0.93 100.96 561 59 240 SS00-131 0.11 1.11 100.62 674 87 310 SS00-140 0.19 0.98 100.26 381 39 331 SS00-144A 0.38 0.76 99.72 338 74 342 SS00-144B 0.31 1.13 99.65 275 68 326 SS98-09 0.17 0.93 99.41 588 75 336 SS98-72 0.30 0.87 100.40 606 59 325 Baring Granite MH-153 0.08 0.80 99.93 685 175 55 MH-159 0.08 0.99 100.08 631 175 47 LH-258 0.03 0.30 101.98 160 204 25 MH-382 0.06 0.50 100.17 803 198 87 SS00-104 0.06 0.28 100.33 802 191 90 SS00-107 0.06 0.28 100.77 1073 152 100 SS00-113 0.08 0.28 101.00 1092 131 133 SS00-117 0.13 0.40 101.03 973 172 113 SS00-118 0.06 0.59 100.32 124 148 140 SS00-121 0.09 0.72 100.25 786 118 192 SS00-124 0.06 0.18 101.11 853 199 92 SS00-137 0.09 0.78 99.39 745 160 128 SS00-139 0.06 0.20 100.49 869 173 100 SS00-141 0.12 0.59 98.84 604 134 236 SS00-142 0.24 0.99 99.45 1412 85 233 SS00-148 0.11 0.48 101.41 671 152 214 Elliot Mountain Diorite MH-43 0.18 0.78 98.65 52 34 344 MH-58A 0.38 0.89 100.70 -- 27 348 LH-58 0.37 0.90 99.82 224 36 349 LH-72A 0.36 1.00 100.79 210 27 394 LH-72B 0.40 1.00 100.71 219 36 363 SS00-126 0.48 1.22 97.53 102 29 304 SS00-127 0.34 0.81 99.65 49 16 325 Unnamed Gabbro Diorite Bodies SS00-108 0.63 0.00 100.78 970 28 428 SS00-129 0.23 0.99 100.29 50 18 353 Bocabec Pluton Fyffe04 0.20 -- 96.89 -- 59 363 Fyffe13 0.23 -- 98.70 628 74 137 Fyffe17 0.30 -- 98.63 -- 36 213 Fyffe32 0.10 -- 98.37 -- 93 188 Fyffe33 0.20 -- 98.31 -- 23 345 Fyffe35 0.40 -- 98.84 -- 57 214 Fyffe38 0.21 -- 98.92 599 110 121 Fyffe42 0.20 -- 98.25 564 118 122 Fyffe43 0.21 -- 97.44 561 115 121 Fyffe49 0.20 -- 98.44 -- 88 192 Fyffe59 0.20 -- 96.61 -- 60 177 Fyffe6l 0.20 -- 96.76 -- 138 167 Fyffe64 0.20 -- 97.26 -- 59 208 Fyffe67 0.00 -- 96.11 -- 42 246 Fyffe72 0.00 -- 97.33 -- 31 187 Sample Y Zr Nb Th Pb Ga Zn Cu Staples Mountain Gabbro SS00-133 17 72 6 3 1.5 17 67 17 St. Stephen Gabbro troctolite SS98-26A 6 48 7 0 14 -- 43 24 SS98-52 12 36 14 0 8 -- 59 28 olivine gabbro SS00-110 14 47 2 1 5 15 42 25 SS98-02B 16 43 17 2 13 -- 57 69 SS98-31B 7 36 6 0 4 -- 29 25 SS98-36 21 82 20 0 0 -- 71 38 SS98-45 16 47 17 0 17 -- 39 544 gabbro SS97-1-151 31 109 24 1 64 -- 92 150 SS97-5-54.5 34 150 29 5 22 -- 121 106 SS98-29 11 37 10 0 9 -- 41 18 SS98-32a 19 39 19 0 10 -- 90 49 SS98-54 26 86 21 0 8 -- 79 25 SS98-67 15 41 14 0 0 -- 72 14 SS98-90 17 57 16 1 11 -- 73 89 Calais Quartz Diorite MH-79 50 233 24 13 39 20 101 <4 MH-1758 38 154 9 5 7 19 79 <4 SS00-119 31 186 11 7 11 19 77 4 SS00-120 28 125 12 7 10 17 84 65 SS00-122 34 259 12 6 10 20 87 17 SS00-123 27 107 9 6 10 17 71 62 SS00-131 58 130 13 3 11 20 99 33 SS00-140 29 158 11 3 4 20 101 12 SS00-144A 26 191 15 10 8 20 96 2 SS00-144B 42 178 14 6 8 19 80 6 SS98-09 26 107 14 5 29 -- 68 58 SS98-72 43 196 21 7 19 -- 99 19 Baring Granite MH-153 52 243 16 20 39 20 69 <4 MH-159 52 247 19 21 39 22 64 <4 LH-258 71 134 14 19 12 17 31 -- MH-382 64 217 11 13 43 19 53 <4 SS00-104 45 220 10 16 53 20 51 2 SS00-107 43 226 7 14 31 18 41 2 SS00-113 40 263 10 12 32 21 65 4 SS00-117 34 245 9 8 34 19 51 2 SS00-118 29 188 5 14 30 16 40 2 SS00-121 32 286 16 15 25 19 55 2 SS00-124 42 172 14 15 34 19 47 2 SS00-137 42 169 13 12 120 17 48 5 SS00-139 29 207 16 14 49 17 45 2 SS00-141 37 176 11 15 28 18 45 2 SS00-142 56 598 23 13 23 23 120 2 SS00-148 33 167 7 13 28 18 43 2 Elliot Mountain Diorite MH-43 23 130 9 5 6 16 70 55 MH-58A 30 205 19 4 1.5 22 95 36 LH-58 35 200 20 2 -- 21 102 41 LH-72A 33 184 16 3 -- 18 98 54 LH-72B 39 196 16 3 -- 19 111 64 SS00-126 35 239 21 4 7 19 99 11 SS00-127 30 187 19 4 3 19 93 43 Unnamed Gabbro Diorite Bodies SS00-108 52.1 127 9 3 7 21 126 2 SS00-129 22 144 8 4 6 18 75 39 Bocabec Pluton Fyffe04 40 190 -- 10 24 78 -- Fyffe13 89 506 31 13 14 19.1 96 -- Fyffe17 31 122 -- 5 9 -- 134 -- Fyffe32 52 476 -- 12 9 -- 115 -- Fyffe33 21 89 -- 1 10 -- 127 -- Fyffe35 56 503 -- 8 9 -- 82 -- Fyffe38 77 438 35 15 11 19.5 86 -- Fyffe42 85 447 36 15 0.5 19.3 93 -- Fyffe43 92 500 25 13 6 20.5 84 -- Fyffe49 37 141 -- 10 13 -- 71 -- Fyffe59 56 209 -- 9 11 -- 89 -- Fyffe6l 45 184 -- 13 25 -- 75 -- Fyffe64 60 245 -- 7 10 -- 130 -- Fyffe67 28 112 -- 5 7 -- 130 -- Fyffe72 53 104 -- 4 11 -- 143 -- Sample Ni V Cr Co U Staples Mountain Gabbro SS00-133 14 551 17 53 1 St. Stephen Gabbro troctolite SS98-26A 22 45 150 24 0 SS98-52 19 72 159 58 0 olivine gabbro SS00-110 138 83 122 52 2 SS98-02B 331 176 898 81 0 SS98-31B 86 99 336 33 0 SS98-36 121 121 297 67 0 SS98-45 1022 47 193 77 0 gabbro SS97-1-151 142 139 240 77 1 SS97-5-54.5 148 257 103 60 2 SS98-29 7 153 342 42 0 SS98-32a 112 235 376 61 0 SS98-54 41 172 66 52 0 SS98-67 57 151 224 48 0 SS98-90 307 108 293 70 0 Calais Quartz Diorite MH-79 31 288 118 93 5 MH-1758 5 149 9 59 3 SS00-119 15 201 120 44 2 SS00-120 63 221 159 51 1 SS00-122 15 243 52 58 2 SS00-123 47 162 104 48 3 SS00-131 23 127 27 39 2 SS00-140 6 252 52 45 1 SS00-144A 3 169 2 46 2 SS00-144B 1.5 202 16 41 2 SS98-09 99 149 167 42 2 SS98-72 10 204 10 41 3 Baring Granite MH-153 <3 34 <4 75 6 MH-159 11 33 <4 77 6 LH-258 6 16 1.7 0.82 4.91 MH-382 <3 35 <4 84 SS00-104 1.5 41 2 59 SS00-107 1.5 38 2 47 SS00-113 5 47 2 51 SS00-117 9 43 2 53 SS00-118 14 43 2 65 SS00-121 10 66 2 53 SS00-124 7 37 2 57 SS00-137 1.5 46 2 57 SS00-139 3 40 2 52 SS00-141 4 51 2 62 SS00-142 24 88 2 45 SS00-148 5 45 2 59 Elliot Mountain Diorite MH-43 54 252 68 64 MH-58A 60 288 90 48 LH-58 69 268 93 44.1 LH-72A 64 245 81.3 39.7 LH-72B 64 297 102 43.9 SS00-126 14 297 128 57 SS00-127 59 272 105 66 Unnamed Gabbro Diorite Bodies SS00-108 1.5 142 2 47 SS00-129 88 172 309 61 Bocabec Pluton Fyffe04 22 112 52 31 Fyffe13 13 19 7 23 Fyffe17 94 203 179 50 Fyffe32 5 121 35 41 Fyffe33 101 186 156 49 Fyffe35 2.5 128 37 58 Fyffe38 9 23 7 50 Fyffe42 7 20 10 54 Fyffe43 8 24 6 13 Fyffe49 18 110 44 49 Fyffe59 2.5 181 41 34 Fyffe6l 18 70 47 37 Fyffe64 2.5 154 37 59 Fyffe67 35 215 170 48 Fyffe72 34 230 148 41 Notes: Major element analyses for Fyffe samples are from Fyffe (1971) but trace element data were obtained on the same powders during the present study, except 13, 38, 42, and 43, which were provided by K. Thorne and D. Lentz. Data for LH samples are from Ludman and Hill (1990). M. Hill provided the MH samples for analysis. Analyses were done by X-ray Fluorescence at the Regional Geochemical Centre, Saint Mary's University, Halifax, Nova Scotia (see http://www.stmarys.ca/academic/science/geology/rgc/rgc home.htm for a description of the methodology, and information about accuracy and precision). Analytical error is generally less than 5% for major elements and 2-10% for trace elements. [Fe.sub.2][O.sub.3] is total Fe as [Fe.sub.2][O.sub.3]. LOI is loss on ignition at 1000[degrees]C. Dash means is not determined and 0 indicates below or 2 ppm. Table 5. Rare-earth element, Hf, and Ta data * from the Moosehorn Plutonic Suite and spatially associated units. Sample La Ce Pr Nd Sm Eu St. Stephen Gabbro-gabbro unit SS98-29 1.164 2.800 0.476 2.707 0.933 0.619 SS98-32a 2.636 5.672 0.766 3.609 0.986 1.081 SS98-54 8.780 19.863 2.620 11.520 2.846 1.194 Calais Quartz Diorite SS00-120 20.845 43.10 5.304 21.625 4.980 1.458 SS00-122 18.748 39.687 5.416 24.120 5.746 1.675 SS00-123 15.910 36.634 4.457 18.291 4.538 1.350 SS00-140 16.516 36.574 4.775 20.900 5.630 1.689 SS00-144A 23.569 51.282 6.259 26.133 6.065 1.689 SS98-09 11.956 26.073 3.414 15.001 3.490 1.248 SS98-72 27.125 57.960 7.316 31.034 7.129 1.902 Baring Granite SS00-104 25.574 79.216 6.992 28.172 6.713 1.106 SS00-121 32.520 64.693 7.713 26.695 5.957 1.201 SS00-124 36.197 79.388 9.359 36.224 8.428 1.063 SS00-139 44.236 85.748 10.161 39.640 7.897 1.095 Diorite dyke(?) in Baring Granite SS00-108 54.481 124.342 15.847 49.000 13.389 7.952 Sample Gd Tb Dy Ho Er Tm St. Stephen Gabbro-gabbro unit SS98-29 1.302 0.215 1.424 0.279 0.797 0.110 SS98-32a 1.284 0.222 1.537 0.323 1.012 0.158 SS98-54 3.230 0.539 3.444 0.663 1.991 0.291 Calais Quartz Diorite SS00-120 5.790 0.947 5.903 1.136 3.285 0.490 SS00-122 7.016 1.149 7.323 1.392 3.983 0.588 SS00-123 5.287 0.896 5.802 1.030 3.111 0.478 SS00-140 6.591 1.055 6.807 1.129 3.260 0.468 SS00-144A 6.421 1.000 6.115 1.022 2.981 0.433 SS98-09 3.902 0.625 3.972 0.778 2.341 0.336 SS98-72 7.537 1.213 7.516 1.477 4.297 0.628 Baring Granite SS00-104 6.829 1.212 7.772 1.544 4.567 0.687 SS00-121 6.431 1.047 6.718 1.269 3.711 0.575 SS00-124 9.012 1.458 9.334 1.574 4.580 0.673 SS00-139 7.243 1.080 6.498 1.073 3.139 0.477 Diorite dyke(?) in Baring Granite SS00-108 14.539 2.151 12.605 2.238 5.997 0.784 Sample Yb Lu Hf Ta St. Stephen Gabbro-gabbro unit SS98-29 0.705 0.098 0.428 0.187 SS98-32a 1.107 0.162 0.359 0.271 SS98-54 1.899 0.268 2.561 0.538 Calais Quartz Diorite SS00-120 3.200 0.466 3.305 0.597 SS00-122 3.383 0.547 4.500 0.584 SS00-123 3.360 0.563 3.013 0.815 SS00-140 3.134 0.519 3.720 0.437 SS00-144A 2.909 0.486 3.715 1.047 SS98-09 2.275 0.318 3.153 0.467 SS98-72 4.126 0.611 6.024 0.922 Baring Granite SS00-104 4.582 0.651 5.916 2.184 SS00-121 3.808 0.549 5.051 1.185 SS00-124 4.473 0.716 4.253 1.391 SS00-139 3.250 0.537 5.021 1.492 Diorite dyke(?) in Baring Granite SS00-108 4.860 0.703 2.344 0.437 * Analyses at Memorial University of Newfoundland by ICP-MS, using the [Na.sub.2][O.sub.2] sinter method (Longerich et al. 1990). Table 6. Sm-Nd isotopic data for the Moosehorn Plutonic Suite [sup.143]Nd/ Unit Sample [sup.144]Nd 2 [sigma] St. Stephen Gabbaro SS98-32a 0.512581 0.000050 Calais Quartz Diorite SS98-09 0.512687 0.000050 Calais Quartz Diorite SS00-123 0.512571 0.000020 Raring Granite SS00-124 0.512484 0.000013 Gabbro dyke(?) SS00-108 0.512568 0.000017 [sup.147]Sm/ Unit [sup.144]Nd [micro]g/g Nd [micro]g/g Sm St. Stephen Gabbaro 0.1691 3.752 1.05 Calais Quartz Diorite 0.1514 14.75 3.70 Calais Quartz Diorite 0.1533 18.92 4.70 Raring Granite 0.1485 34.59 8.32 Gabbro dyke(?) 0.1431 64.43 14.95 [[epsilon].sub.Nd] Unit (421 Ma) T(DM) St. Stephen Gabbaro 0.37 1567 Ma Calais Quartz Diorite 3.40 881 Ma Calais Quartz Diorite 1.03 1184 Ma Raring Granite -0.41 1250 Ma Gabbro dyke(?) 1.52 1086 Ma Notes: Analyses by Alain Potrel, Memorial University of Newfoundland. Sm and Nd contents and Nd isotopic composition were analyzed using a multicollector Finnigan Mat 262 mass spectrometer in static mode. Nd isotopic ratio are normalized to [sup.146]Nd/[sup.144]Nd = 0.7219. The reported values were adjusted to La Jolla Nd standard ([sup.143]Nd/[sup.144]Nd = 0.511860). During the course of data acquisition replicates of the standard gave a mean value of [sup.143]Nd/[sup.144]Nd = 0.511886 [+ or -] 26 (2[sigma], n=18). The in-run precisions on Nd isotopic ratio are given at 95% confidence level. Error on Nd isotopic compositions are <0.002% and errors on the [sup.147]Sm/[sup.144]Nd ratio are estimated to be less than 0.1%. The [[epsilon].sub.Nd] values are calculated using a [sup.147]Sm/[sup.144]Nd = 0.1967 and [sup.143]Nd/[sup.144]Nd = 0.512638 values for the present day chondrite uniform reservoir (CHUR). [sup.147]Sm decay constant is 6.54 [10.sup.-12][y.sup.-1] (Steiger and Jager, 1977). The depleted mantle model ages, TDM, were calculated both with respect to a D.M. with a [[epsilon].sub.Nd0] value of +10 isolated from the CHUR since 4.55 Ga and following a linear evolution with respect to the De Paolo (1988) mantle model.
We thank L.R. Fyffe (NB Department of Natural Resources Many sub-national governments have a Department of Natural Resources or similarly-named organization:
UNB Universidade de Brasília (University of Brasilia)
UNB United News of Bangladesh (news agency)
UNB Unclassified News Board
UNB Unbuffered , for providing the thin sections and sample powders from the thesis collection. Kay Thorne and Dave Lentz kindly allowed us to include their unpublished chemical data in our Table 4 (samples Fyffe 13, 38, 42, 43). Owen Gaskill permitted us to use some photographs from his B.Sc. honours thesis in Fig. 3. Field work by M. Hill was supported by the Maine Geological Survey The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information.
A geological survey . Comments by journal reviewers Spike Berry and Malcolm McLeod were helpful in improving the manuscript and especially in motivating the authors to change the name to Moosehorn Plutonic Suite.
ABBOTT, R.N. 197Z Petrology of the Red Beach granite near Calais, Maine. Unpublished PhD thesis, Harvard University Harvard University, mainly at Cambridge, Mass., including Harvard College, the oldest American college. Harvard College
Harvard College, originally for men, was founded in 1636 with a grant from the General Court of the Massachusetts Bay Colony. , Cambridge, Massachusetts This article is about the city of Cambridge in Massachusetts. For the English university town, see Cambridge, England. For other places, see Cambridge (disambiguation).
Cambridge, Massachusetts is a city in the Greater Boston area of Massachusetts, United States. , 223 p.
ABBOTT, R.N. 1986. Bedrock geology of the Red Beach, Robbinson, and Devil's Head 7.5' quadrangles, Maine. Maine Geological Survey, Open--File Report 86-73, 36 p.
AMOS, D.H. 1963. Petrography and age of plutonic rocks, extreme southeastern Maine. Geological Society of America The Geological Society of America (or GSA) is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in New York in 1888 by James Hall, James D. , Bulletin, 74, pp. 169-194.
BARR, S.M., WHITE, C.E., & MILLER, B.V. 2002. The Kingston terrane, southern New Brunswick, Canada: Evidence for a Silurian volcanic arc. Geological Society of America Bulletin 114, pp. 964-982.
COUGHLIN, S. 1986. Geology of the Staples Mountain Complex, Calais quadrangle quadrangle
Rectangular open space completely or partially enclosed by buildings of an academic or civic character. The grounds of a quadrangle are often grassy or landscaped. , eastern Maine. M.Sc. thesis, Queens College, Flushing, New York New York, state, United States
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of , 138 p.
DEPAOLO, DJ. 1988. Neodymium isotope geochemistry Isotope geochemistry is an aspect of geology based upon study of the relative and absolute concentrations of the elements and their isotopes in the Earth. Broadly, the field is divided into two branches: stable and radiogenic isotope geochemistry. . New York, Springer-Verlag, 187 p.
EL BOUSEILY, A.M., & EL SOKKARY, A.A. 1975. The relation between Rb, Ba, and Sr in granitic rocks. Chemical Geology, 16, pp. 207-219.
FYFFE, L.R. 1971. Petrogenesis of the adamellite--diorite transition, southwestern New Brunswick. MSc thesis, University of New Brunswick The University of New Brunswick (UNB) is a Canadian university located in the province of New Brunswick. The university has two main campuses: the principal campus founded in 1785 in Fredericton and a smaller campus which was opened in Saint John in 1964. , Fredericton, New Brunswick, 131 p.
FYFFE, L.R. 1990. Geology of the Potters Lake area (NTS NTS National Technical Systems
NTS National Trust for Scotland
NTS Nevada Test Site
NTS NT Server (Microsoft Windows)
nts Not the Same
NTS National Traffic System (amateur radio) 21G/ 03f), Charlotte County, New Brunswick. New Brunswick Department of Natural Resources and Energy, Minerals and Energy Division, Plate 90-150.
FYFFE, L.R., & FRICKER, A. 198Z Tectonostratigraphic terrane analysis of New Brunswick. Atlantic Geology, 23, pp. 113-122.
FYFFE, L.R., PICKERILL, R.K., & STRINGER, P. 1999. Stratigraphy stratigraphy, branch of geology specifically concerned with the arrangement of layered rocks (see stratification). Stratigraphy is based on the law of superposition, which states that in a normal sequence of rock layers the youngest is on top and the oldest on the , sedimentology sedimentology
Scientific discipline concerned with the physical and chemical properties of sedimentary rocks and the processes involved in their formation, including transportation, deposition, and lithification of sediments. and structure of the Oak Bay and Waweig formations, Mascarene Basin: implications for the paleotectonic evolution of southwestern New Brunswick. Atlantic Geology, 35, pp. 59-84.
GASKILL, O.D. 1999. Petrology of the St. Stephen Pluton and associated sulphide deposits, southern New Brunswick. B.Sc. Honours thesis, Acadia University Acadia University, at Wolfville, N.S., Canada; founded 1838; became Acadia Univ. 1891. It has faculties of arts, pure and applied sciences, management and education, and theology. Acadia Divinity College is associated with the university. , Wolfville, Nova Scotia Wolfville is a small town in the rural Annapolis Valley, Kings County, Nova Scotia, Canada, located about 100 km (62 mi) northwest of the provincial capital, Halifax. As of 2001, the population was 3,658. , 88 p.
HILL, M. 1991. Rocks of the Calais area, southeastern Maine. In New England New England, name applied to the region comprising six states of the NE United States—Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut. The region is thought to have been so named by Capt. Intercollegiate Geological Conference Guidebook. Edited by A. Ludman. pp. 266-285.
HILL, M., & ABBOTT, R.N. 1989. Commingled gabbroic and granitic magmas in the northern Bays-of-Maine Igneous Complex, Calais area, Maine. In Studies in Maine Geology--Igneous and metamorphic geology. Edited by R.D. Tucker and R.G. Marvinney. 4, pp. 35-43.
HOGAN, J.P., & SINHA, A.K. 1989. Compositional variation of plutonism Plu´to`nism
n. 1. The theory, early advanced in geology, that the successive rocks of the earth`s crust were formed by igneous fusion; - opposed to the Neptunian theory. in the Coastal Maine Magmatic Province: mode of origin and tectonic setting. In Studies in Maine Geology--Igneous and metamorphic geology. Edited by R.D. Tucker and R.G. Marvinney. 4, pp. 1-33.
HOUSTON, R.S. 1956. Genetic study of some pyrrhotite pyrrhotite (pĭr`ətīt) or magnetic pyrites, bronze-yellow to bronze-red mineral, a sulfide of iron sometimes containing nickel. It tarnishes easily and is somewhat magnetic. deposits of Maine and New Brunswick: Maine Geological Survey, Bulletin, 7, 112 p.
HUSSEY, A.M., II, CHAPMAN, C.A., DOYLE, R.G., OSBERG, P.H., PAVLIDES, L., & WARNER, J., (COMPILERS). 1967. Preliminary geologic map A geologic map or geological map is a special-purpose map made to show geological features.
The stratigraphic contour lines are drawn on the surface of a selected deep stratum, so that they can show the topographic trends of the strata under the ground. of Maine: Maine Geological Survey, scale 1:500 000.
HUTCHINSON, C.S. 1974. Laboratory Handbook of Petrographic Techniques. Wiley Interscience, New York, 527 p.
IRVINE, T.N., & BARAGAR, W.R.A. 1971. A guide to chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8, pp. 523-548.
JURINSKI, J.B. 1987. The Baring pluton: contaminated granite of the Moosehorn Plutonic Suite. B.Sc. thesis, Virginia Polytechnic institute and State University Virginia Polytechnic Institute and State University, at Blacksburg; land-grant and state supported; coeducational; chartered and opened 1872 as an agricultural and mechanical college. , Blacksburg, Virginia Blacksburg is an incorporated town located in Montgomery County, Virginia. As of the 2000 census, the town had a total population of 39,573, making it one of Virginia's larger towns. , 48 p.
JURINSKI, J.B. 1990. Petrogenesis of the Moosehorn Plutonic Suite, Maine. M.Sc. thesis, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 125 p.
KOOIMAN, G.J. 1996. St. Stephen nickel deposits, Charlotte County, New Brunswick--A compilation. New Brunswick Department of Natural Resources and Energy, Minerals and Energy division, Open File 96-19, 39 p.
LONGERICH, H., JENNER, G.A., FRYER, B.J., & JACKSON, S.E. 1990. Inductively coupled plasma- mass spectrometric analysis of geochemical samples. A critical evaluation based on case studies: Chemical Geology, 83, pp. 105-118.
LUDMAN, A., & HILL, M. 1986. Bedrock geology of the Calais 15' Quadrangle, eastern Maine. Maine Geological Survey, Open File 86-72.
LUDMAN, A., & HILL, M. 1990. Bedrock geology of the Calais 15' Quadrangle, eastern Maine. Maine Geological Survey, Open File 90-27, 32 p.
MCDOUGALL, I. AND HARRISON, T.M. 1999. Geochronology and Thermochronology by the [sup.40]Ar/[sup.39]Ar Method (Second Edition). Oxford University Press, New York, 269.
MCLAUGHLIN, K.J. 2003. The Moosehorn Plutonic Suite of southwestern New Brunswick and southeastern Maine: Petrology, geochemistry, and tectonic setting. Unpublished MSc thesis, Acadia University, Wolfville, Nova Scotia, 307 p.
MCLEOD, M.J. 1990. Geology, Geochemistry, and Related Mineral Deposits of the Saint George Batholith; Charlotte, Queens, and Kings Counties, New Brunswick. New Brunswick Department of Natural Resources and Energy, Mineral Resources, Mineral Resource Report 5.
MCLEOD, M.J., JOHNSON, S.C., & RUITENBERG, A.A. 1994. Geological map of southwestern New Brunswick. New Brunswick Department of Natural Resources and Energy, Mineral Resources Map NR-5.
MIYASHIRO, A., & SHIDO, F. 1975. Tholeiitic and calc-alkaline series in relation to the behaviours of titanium, vanadium, chromium, and nickel. American Journal of Science, 274, pp. 265-277.
PAKTUNC, A.D. 1989. Petrology of the St. Stephen intrusion and the genesis of related nickel-copper sulfide deposits, Economic Geology economic geology
Scientific discipline concerned with the distribution of mineral deposits, the economic considerations involved in their recovery, and assessment of the reserves available. , 84, pp. 817-840.
PEARCE, J.A. AND CANN CANN Canadian Association of Neuroscience Nurses , J.R. 1973. Tectonic setting of basic volcanic rocks determined using trace element analysis. Earth and Planetary Science planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, chemistry, and mathematics to the study of Letters, 19, pp. 290-300.
PEARCE, J.A., & NORRY, M.J. 1979. Petrogenetic implications of Ti, Zr, Y, and Nb variations in volcanic rocks. Contributions to Mineralogy and Petrology, 69, pp. 33-47.
PEARCE, J.A., HARRIS, N.B.W., & TINDLE, A.G. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25, pp. 956-983.
ROBINSON, P., TUCKER, R.D., BRADLEY, BERRY, H.N., & OSBERG, P.H. 1998. Paleozoic orogens in New England, USA. GFF GFF Gain Flattening Filter (used in Erbium Doped Fiber Amplifier)
GFF Glass Fiber Filter
GFF Grain Foods Foundation
GFF Generic File Format (application data)
GFF Government Furnished Facility , 120, pp. 119-148.
RUITENBERG, A.A., & MCCUTCHEON, S.R. 1978. Field guide to lower Paleozoic sedimentary and volcanic rocks of southwestern New Brunswick. In Ludman, A., editor, New England Intercollegiate Geological Conference Guidebook, 70th Annual Meeting, pp. 133-144.
SAMSON, S.D., & ALEXANDER JR., E.C. 198Z Calibration of the inter-laboratory [sup.40]Ar/[sup.39]Ar dating standard, MMhb-1. Chemical Geology, 66, pp. 27-34.
SAMSON, S.D., BARR, S.M., WHITE, C.E. 2000. Nd isotopic characteristics of terranes within the Avalon Zone, southern New Brunswick. Canadian Journal of Earth Sciences, 37, pp. 1039-1052.
SCHMITZ, M.D. & BOWRING, S.A. 2003. Constraints on the thermal evolution of continental lithosphere lithosphere (lĭth`əsfēr '), brittle uppermost shell of the earth, broken into a number of tectonic plates. The lithosphere consists of the heavy oceanic and lighter continental crusts, and the uppermost portion of the mantle. from U-Pb accessory mineral accessory mineral
A mineral that is present in a minor amount in rocks and is not considered an essential constituent of the rock.
accessory mineral thermochronometry of lower crustal xenoliths, southern Africa. Contributions to Mineralogy and Petrology, 144, pp. 592-618.
SEAMAN, S.J., WOBUS, R.A., WIEBE, R.A., LUBICK, N.., & BOWRING, S.A. 1995. Volcanic expression of bimodal magmatism: The Cranberry cranberry, low creeping evergreen bog plant of the genus Oxycoccus of the family Ericaceae (heath family). Cranberries are considered by some botanists to belong to the blueberry genus Vaccinium. Island--Cadillac Mountain Complex, coastal Maine. Journal of Geology, 100, pp. 395-409.
SEAMAN, S.J., SCHERER, E.E., WOBUS, R.A., ZIMMER, J.H., & SALES, J.G. 1999. Late Silurian volcanism volcanism
Any of various processes and phenomena associated with the surface discharge of molten rock or hot water and steam, including volcanoes, geysers, and fumaroles. in coastal Maine: The Cranberry Island series: Geological Society of America Bulletin, 111, pp. 686-708.
SHERVAIS, J.W. 1982. Ti-V plots and the petrogenesis of modern and ophiolitic magmas. Earth and Planetary Sciences Letters, 59, pp. 101-118.
STACEY, J.S., & KRAMERS, J.D. 1975. Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and Planetary Science Letters 26, pp. 207-221.
STEIGER, R.H., & JAGER, H. 1977. Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth and Planetary Science Letters, 36, pp. 359-362.
STEWART, D.B., TUCKER, R.D., AYUSO, R.A., & LUX A unit of measurement of the intensity of light. It is equal to the illumination of a surface one meter away from a single candle. See candela. , D.R. 2001. Minimum age of the Neoproterozoic Seven Hundred Acre island Formation and the tectonic setting of the Islesboro Formation, Islesboro Block, Maine. Atlantic Geology, 37, pp. 41-59.
SUN, S.S., & MCDONOUGH, W.F. 1989, Chemical and isotopic systematics systematics: see classification. of oceanic basalts: implications for mantle composition and processes. In Magmatism in the ocean basins. Edited by A.D. Saunders and M.J. Norry. Geological Society Special Publication, 42, pp. 313-345.
THORNE, K.G., & LENTZ, D.R. 2001. Geochemistry and petrogenesis of the East Branch Brook metagabbroic dykes in the Sawyer Brook fault zone, Clarence Stream gold prospect, southwestern New Brunswick. Atlantic Geology, 37, pp. 175-190.
TUCKER, R.D., OSBERG, P.H., a BERRY, H.N. 2001. The geology of a part of Acadia and the nature of the Acadian orogeny across central and eastern Maine. American Journal of Science, 301, pp. 205-260.
VAN STAAL, C.R., DEWEY, J.F., NIOCAILL, C.M., & MCKERROW, W.S. 1998. The Cambrian-Silurian tectonic evolution of the northern Appalachians and British Caledonides: history of a complex, west and southwest Pacific-type segment of lapetus. In Lyell: the Past is the Key to the Present. Edited by D.J. Blundell and A.C. Scott. Geological Society, London, Special Publications, 143, pp. 199-242.
WANLESS, R.K., STEVENS, R.D., LACHANCE, G.R., & DELABIO, R.D. 1973. Age determinations and geological studies (K-Ar isotopic ages report 11). Geological Survey of Canada Paper 73-2, pp. 84-87.
WEST, D.P., LUDMAN, A., LUX, D.R. 1992. Silurian age for the Pocomoonshine gabbro-diorite, southeastern Maine and its regional tectonic implications. American Journal of Science, 292, pp. 253-273.
WESTERMAN, D.S. 1972. Petrology of the Pocomoonshine Gabbro-Diorite, Big Lake, Quadrangle, Maine. Ph.D. dissertation, Lehigh University Lehigh University, at Bethlehem, Pa.; coeducational; chartered and opened 1866 by Asa Packer. It has undergraduate colleges of arts and science, business and economics, and engineering and applied science, as well as several graduate programs. , 175 p.
WHALEN, J.B., CURRIE, K., & CHAPPELL, B.W. 1987. A-type granites: geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology, 95, pp. 407-419.
WHALEN, J.B., JENNER, G.A., CURRIE, K.L., BARR, S.M., LONGSTAFFE, F,J, HEGNER, E. 1994. Geochemical and isotopic characteristics of granitoids of the Avalon Zone, southern New Brunswick: possible evidence for repeated delamination delamination /de·lam·i·na·tion/ (de-lam?i-na´shun) separation into layers, as of the blastoderm.
1. A splitting or separation into layers.
2. events. The Journal of Geology, 102, pp. 269-282.
WIEBE, R.A., HOLDEN, J.B., COOMBS Coombs can refer to:
WINCHESTER, J.A., & FLOYD, P.A. 1977. Geochemical discrimination of different magma series and their differentiation products using immobile im·mo·bile
1. Immovable; fixed.
2. Not moving; motionless.
immo·bil elements. Chemical Geology, 20, pp. 325-343.
Editorial responsibility: David Gibson
David Gibson, (March 9 1804 – January 25 1864), was a surveyor, farmer and political figure in Upper Canada.
K.J. McLAUGHLIN (1), S.M. BARR (1) *, M.D. HILL (2), M.D. THOMPSON (3), J. RAMEZANI (4), AND P.H. REYNOLDS (5)
(1.) Department of Geology, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6
(2.) Northeastern University Northeastern University, at Boston, Mass.; coeducational; founded 1898 as a program within the Boston YMCA, inc. 1916, university status 1922, fully independent of the YMCA 1948. , Boston, Massachusetts “Boston” redirects here. For other uses, see Boston (disambiguation).
Boston is the capital and most populous city of Massachusetts. The largest city in New England, Boston is considered the unofficial economic and cultural center of the entire New 02115 USA
(3.) Geology Department, Wellesley College, Wellesley, Massachusetts 02481 USA
(4.) Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 USA
(5.) Department of Earth Sciences, Dalhousie University Dalhousie University (dălhou`zē), at Halifax, N.S., Canada; nonsectarian; coeducational; founded 1818 by the 9th earl of Dalhousie. Except for a few years between 1838 and 1845, Dalhousie did not function as a university until 1863. , Halifax, Nova Scotia For other uses, see Halifax.
Halifax, Nova Scotia may refer to any of the following:
* Corresponding author: <email@example.com>
Date received: September 12, 2003 & Date accepted: March 3, 2004