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Age and petrology of the Machias Seal Island quartz monzodiorite, the southernmost rocks in New Brunswick, Canada.

ABSTRACT

Machias Seal Island in the northern Gulf of Maine consists of fine- to medium-grained weakly foliated quartz monzodiorite. Although previously inferred to be as young as Devonian, the quartz monzodiorite yielded an Ediacaran-Early Cambrian U-Pb (zircon) age of 542.0 [+ 9 Ma. Typical Machias Seal Island quartz monzodiorite contains strongly zoned plagioclase (50%), about 30% mafic minerals (biotite and amphibole with relict cores of both orthoand clinopyroxene, and 20% interstitial quartz and orthoclase. The average chemical composition (5 samples) has 60.6% Si[O.sub.2], with relatively high [Al.sub.2][O.sub.3] (over 16%) and low [K.sub.2]O (2.8%). Overall, the chemical characteristics, including low Rb, Y, and Nb, are consistent with emplacement in a continental margin subduction zone. The quartz monzodiorite contains abundant ovoid metadioritic enclaves, likely of cognate origin. Age and compositional similarities strongly suggest correlation of Machias Seal Island quartz monzodiorite with the abundant ca. 550-525 Ma gabbroic to granitic plutons of the Brookville terrane on the mainland of southern New Brunswick. Its age is similar also to the ages of volcanic and some plutonic rocks on Grand Manan Island and in the New River terrane in mainland southern New Brunswick, strengthening the interpretation that all of these areas are part of Ganderia. Hence the Fundy Fault southeast of Machias Seal Island likely marks the boundary between Ganderia and Avalonia in the Gulf of Maine.

RESUME

L'ile Machias Seal, dans la partie nord du golfe du Maine, se compose de monzodiorite quartzique a grains fins a moyens faiblement feuilletee. Meme si on deja presume que son origine remonterait au Devonien, une datation de la monzodiorite quartzique par la methode U-Pb sur zircon a indique un age d'Ediacara et du debut du Cambrien, soit de 542,0 [+ 9 Ma. Les mineralisations caracteristiques de monzodiorite quartzique de l'ile Machias Seal renferment un plagioclase fortement zone (50 p. 100), environ 30 p. 100 de mineraux mafiques (biotite et amphibole accompagnees de noyaux residuels d'orthopyroxene et de clinopyroxene), ainsi que 20 p. 100 de quartz et d'orthoclase interstitiels. La composition chimique moyenne (5 echantillons) est de 60,6 p. 100 de 8i[O.sub.2], une teneur relativement elevee de [Al.sub.2][O.sub.3] (plus de 16 p. 100) et une faible teneur en [K.sub.2]O (2,8 p. 100). Dans l'ensemble, les caracteristiques chimiques de ces mineralisations, y compris la faible teneur en Rb, Y et Nb, sont generalement associees a un emplacement dans une zone de subduction de la marge continentale. La monzodiorite quartzique contient d'abondantes quantites d'enclaves de metadiorite ovoides, vraisemblablement de la meme origine. L'age et les similitudes de composition de ces roches portent a croire qu'une correlation pourrait s'etablir entre la monzodiorite quartzique de l'ile Machias Seal et la grande quantite de plutons gabbroique a granitique de 550-525 Ma observee dans le socle de Brookville, dans la partie continentale du Sud du Nouveau-Brunswick. Par ailleurs, ces roches ont le meme age que celui des roches volcaniques et de certains plutons de l'ile Grand Manan et du socle de New River dans la partie continentale du Sud de la province, ce qui viendrait confirmer l'interpretation voulant que toutes ces zones fassent partie de Ganderia. La faille de Fundy au sud-est de l'ile Machias Seal marque donc la limite entre Ganderia et Avalon dans le golfe du Mairie.

[Traduit par la redaction]

INTRODUCTION

Machias Seal Island is located at the mouth of the Bay of Fundy, about 20 km southwest of Grand Manan Island and 30 km southeast of Machias, Maine (Fig. 1). The small rocky island is barren except for a lighthouse and dwellings maintained by the Government of Canada, although ownership of the island is disputed between Canada and the United States of America (e.g., Schmidt 2002). The island has the last occupied lighthouse in the Maritime Provinces, and is well known among bird-watchers as a nesting site for puffin, auk, and other seabirds. In addition to its political significance, Machias Seal Island is important geologically because of its location in an area through which it is difficult to trace terranes from Nova Scotia and New Brunswick into the New England states (Fig. 1). Geological studies on nearby Grand Manan Island (Fig. 1) have not resolved that problem, as rocks there have equivocal terrane affinity (e.g., Miller et al. 2007; Fyffe et al. 2009). However, they most resemble those of the New River terrane of southern New Brunswick, suggesting that the Ganderian Kingston and Brookville belts, as well as Avalonia and Meguma, all lie outboard of Grand Manan Island (Fig. 1).

Because of its small size, most regional geological maps (e.g., Hibbard et al. 2006) do not show Machias Seal Island. More detailed local maps have shown the island as Precambrian granite (e.g., Potter et al. 1979) or Silurian-Devonian granite (e.g., McLeod et al. 1994; New Brunswick Department of Natural Resources 2010). The purpose of this paper is to describe the petrology of a suite of granitoid samples collected from the island, present a new U-Pb zircon age for the suite, and use these results to interpret the most likely correlative units in the region.

[FIGURE 1 OMITTED]

GEOLOGY OF MACHIAS SEAL ISLAND

With the exception of grassy areas in the central part of the island, outcrop is continuous on Machias Seal Island (Fig. 2). The rocks are grey to locally pink, fine- to medium-grained, weakly foliated quartz monzodiorite with abundant dioritic enclaves, generally less than 20 cm in diameter. The quartz monzodiorite is cut by two steeply dipping mafic dykes, each about 1 m in width, which trend at about 015[degrees] across the island (Fig. 2). The eastern dyke is alkalic, and contains pseudomorphs of olivine phenocrysts in a fine-grained groundmass of plagioclase, brown amphibole, and pyroxene. The other dyke is more altered and consists mainly of plagioclase, pyroxene, and their alteration products. The age of these dykes is unknown, other than being younger than the quartz monzodiorite.

Typical Machias Seal Island quartz monzodiorite contains 50% strongly zoned plagioclase, 30% mafic minerals and about 20% interstitial quartz and K-feldspar (Figs. 3a, b). Plagioclase is strongly zoned from labradorite to oligoclase, based on petrographic determinations using extinction angles and on electron microprobe analyses in 3 samples (Fig. 4a). The most abundant mafic Mineral is green amphibole of magnesio-hornblende composition (Fig. 4b). The larger amphibole grains typically contain relict cores of both orthopyroxene and clinopyroxene, with the clinopyroxene rimming the orthopyroxene. The orthopyroxene is somewhat less magnesian than the coexisting clinopyroxene (Fig. 4c). Brown biotite occurs in association with amphibole and as separate grains. In both modes of occurrence, its composition is intermediate between phlogopite and annite, with relatively low aluminum content, and it plots in the field for calc-alkalic orogenic suites in the ternary MgO-Fe[O.sup.t]-[Al.sub.2][O.sub.3] discrimination diagram (Fig. 4d) of Abdel-Rahman (1992). Apatite, zircon (see description below), and magnetite are the most abundant accessory phases.

The enclaves are finer grained than their host rocks and of more mafic (dioritic) composition. They consist of plagioclase laths, orthopyroxene, clinopyroxene, amphibole, and biotite in a groundmass of plagioclase and K-feldspar (Figs. 3c, d). In contrast to the host monzodiorite, quartz is minor or absent in the enclaves. The compositions of the mafic minerals in the enclaves are similar to those in the host quartz monzodiorite (Fig. 4b, c, d), although the plagioclase is generally more calcic, up to [An.sub.90] (Fig. 4a).

GEOCHRONOLOGY

A sample of quartz monzodiorite (#182) from the eastern side of the island (Fig. 2) was collected for dating at the Pacific Centre for Isotopic and Geochemical Research (PCIGR). Zircons were separated using conventional crushing, grinding and wet shaking table methods, followed by heavy liquid and magnetic separation. The sample yielded abundant zircons, comprising clear, colorless to pale yellow, stubby square prisms (length:width ratios of 1-2) with simple terminations. Some of the grains were fractured; however, no internal zoning or inherited cores were observed under a binocular microscope or in transmitted light.

Methods used for U-Pb zircon analysis using ID-TIMS techniques at the PCIGR are described by Mortensen et al. (1995). Individual zircon fractions for analysis comprised 1 to 11 grains. U-Pb analytical data are listed in Table A5, and are shown on a conventional concordia plot in Figure 5. Four multigrain fractions of zircon (fractions B, C, D, E) were analyzed initially. The outer portions of these zircon grains had been strongly air abraded prior to dissolution in an attempt to minimize the effects of post-crystallization Pb-loss. The four analyses defined a short linear array that suggested an upper intercept age of approximately 542 Ma; however, there is significant scatter in the data and only analysis C is concordant (Fig. 5). In an attempt to obtain replicate concordant analyses and thus more confidently constrain the age of the rock, three additional zircon fractions were analyzed (B2, D2, E2). These analyses are of single zircon grains that were "chemically abraded" prior to dissolution. The chemical abrasion process involves thermally annealing the grains and then subjecting them to a strong leaching step in concentrated hydrofluoric acid; this procedure has been shown to remove most portions of zircon grains that have been altered or otherwise disturbed, and in many cases produces more concordant and reproducible analyses (see discussion of the chemical abrasion technique as used in the PCIGR in Scoates and Friedman 2008). Two analyses of the chemically abraded zircons still show minor discordance, suggesting that in those cases not all of the altered and disturbed portions of the grains were removed by the process. One of the analyses (B2), however, yields a concordant analysis that completely overlaps with air-abraded fraction C (Fig. 5). A regression of all of the data gives calculated upper and lower intercept ages of 541.9 [+ or -] 3.5 Ma and -125 [+ or -] 680 Ma, respectively (MSWD = 0.61; probability of fit = 0.69). A regression of all seven analyses forced through the origin yields an upper intercept age of 542.5 [+ or -] 2.9 Ma (MSWD = 0.53; probability of fit = 0.79). We consider the best estimate for the crystallization age of the sample, however, to be given by a weighted average of [sup.206]Pb/[sup.238]U ages for the two concordant analyses (C and B2), at 542.0 [+ or -] 0.9 Ma.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

This age coincides closely with the Ediacaran-Cambrian boundary (Walker and Geissman 2009) and is much older than the Early Devonian age previously inferred for intrusive rocks on the island on current maps (e.g., New Brunswick Department of Natural Resources 2010). Regionally, it falls within the range of U-Pb (zircon) ages obtained from numerous plutons in the Brookville terrane of southern New Brunswick (Fig. 6; e.g., White et al. 2002). It is also similar to the ages of some units in the New River terrane (Fig. 6) and three units on nearby Grand Manan Island: High Duck Island Granite (547.3 [+ or -] 1.1 Ma; Miller et al. 2007), tuff in the Priest Cove Formation (539 [+ or -] 3.3 Ma; Miller et al. 2007), and the Stanley Brook granite (535 [+ or -] 2.5 Ma; P. Valverde-Vaquero, unpublished written report to L.R. Fyffe, 2003). The similarity between Grand Manan Island and the New River terrane in rock types, Sm-Nd isotopic characteristics, and ages has been used to infer a link between those two areas, and for including both of them, as well as the Brookville terrane, in Ganderia (Barr et al. 2003; Miller et al. 2007; Fyffe et al. 2009). As documented in detail by Barr et al. (2003) and also discussed in subsequent papers (e.g., Miller et al. 2007; Fyffe et al. 2009), differences in rock types and ages indicate that none of these areas is likely to be related to the Avalonian Caledonia terrane.

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

GEOCHEMISTRY

Chemical analyses were obtained for 5 samples of the Machias Seal Island quartz monzodiorite and 2 samples from its dioritic enclaves. The quartz monzodiorite samples range in Si[O.sub.2] content from 59% to 63%, whereas the enclaves have lower Si[O.sub.2] (56% and 54%) (Fig. 7). A plot of CIPW normative compositions (Fig. 8a) is consistent with the names assigned on the basis of modal estimates (diagram hot shown). The enclaves and their host rocks tend to lie on linear trends in major element compositions (Fig. 7, 8b), suggesting that they are linked by crystal fractionation processes. Chondrite-normalized rare-earth element (REE) patterns are also similar in enclave samples and quartz monzodiorite sample NB04-176a, the most mafic of the analyzed quartz monzodiorite samples. The most felsic sample, NB04-182, shows higher REE, especially light REE, and a larger negative Eu anomaly consistent with feldspar fractionation (Fig. 9a). A multi-element comparison diagram also shows similarity between enclaves and host quartz monzodiorite samples, and a trend toward increasing incompatible element abundance with increasing silica content in the samples (Fig. 9b).

Because the age obtained for the quartz monzodiorite falls within the range of ages reported for Brookville terrane plutons (Fig. 6), and some of those plutons include similar monzodioritic rock types (e.g., White et al. 2002), fields are shown on the geochemical diagrams for those plutons (Figs. 7-9). In most cases the Machias Seal Island samples plot within the fields defined by the Brookville terrane plutons, and display similar trends, consistent with magma evolution dominated by crystal fractionation of plagioclase and mafic minerals. The REE patterns are also similar, although the Machias Seal Island enclave samples plot at the uppermost part of the range for plutons of the Brookville terrane, and the dated sample lies well above the range. The cause of this difference is not apparent in the mineralogy of the samples.

The Machias Seal Island samples have chemical features consistent with origin in a continental margin subduction zone (Fig. 10), an interpretation also made for the Brookville terrane plutons in earlier studies (White et al. 2002).

The epsilon Nd value of-l, calculated at 540 Ma (Table A8), is similar to that of many samples in the Brookville and New River terranes (Fig. 11). The tendency for igneous units to have negative epsilon Nd values is considered to be one of the characteristic features of Ganderia (Kerr et al. 1995; Samson et al. 2000; Barr et al. 2003).

REGIONAL IMPLICATIONS

The similarity in both age and petrology of the Machias Seal Island quartz monzodiorite to plutons of the Brookville terrane supports the interpretation that Machias Seal Island is part of the Brookville terrane. Although it is the closest land area to Machias Seal Island, none of the rocks on Grand Manan Island is similar in age and petrological characteristics to the Machias Seal Island quartz monzodiorite. Much of Grand Manan Island is composed of Mesozoic basalt, and the remaining third of the island is dominated by volcanic and sedimentary rocks (Fyffe and Grant 2005; Black 2005; Miller et al. 2007). The Three Islands Granite forms islands south of the main island, but it has been dated at 611 Ma, much older than the ca. 540 Ma Machias Seal Island quartz monzodiorite. Two small plutons on Grand Manan Island have yielded Ediacaran-Early Cambrian ages of 547.3 [+ or -] 1.1 Ma (Miller et al.

2007) and 535 [+ or -] 2.5 Ma (P. Valverde-Vaquero, unpublished written report to L.R. Fyffe, 2003), similar to the age of the Machias Seal Island quartz monzodiorite, but both are granitic in composition and hence petrologically unlike the quartz monzodiorite (Black 2005).

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

[FIGURE 10 OMITTED]

The assemblage of pre-Mesozoic rocks on Grand Manan Island and their ages led to tentative correlation with the New River terrane in mainland New Brunswick (Miller et al. 2007; Fyffe et al. 2009). The relationship between the New River and Brookville terranes is uncertain, although both are interpreted to be part of Ganderia. The position of Machias Seal Island so close to Grand Manan Island supports the interpretation that both Brookville and New River terranes are part of Ganderia, whereas Avalonia is located farther offshore (Fig. 1). Geophysical data from the area (e.g., Hutchinson et al. 1988; Keen et al. 1991) are not sufficiently detailed to enable resolution of these details, but the results of this study are consistent with the interpretation that the Fundy Fault, previously identified to the southeast on the basis of geophysical data, marks the boundary between Ganderia and Avalonia (Fig. 1).

[FIGURE 11 OMITTED]

Overall, the results of this study show that the geology of Machias Seal Island is closely linked to that of mainland New Brunswick, not adjacent parts of Maine. The latter area is dominated by Silurian-Devonian granitoid rocks of the Coastal Maine magmatic province (e.g., Hogan and Sinha 1989).

CONCLUSIONS

Machias Seal Island is composed of plutonic rocks of similar age and petrological features to those of the Brookville terrane in mainland southern New Brunswick. They are more than 100 million years older than the granitoid rocks that characterize the Coastal Maine magmatic province, with which they had previously been correlated. Although direct links with rock units exposed on nearby Grand Manan Island cannot be made, some units there are of similar age, supporting Ganderian affinity for both areas.

ACKNOWLEDGMENTS

Sandra Barr's research in New Brunswick is funded mainly by discovery grants from the Natural Sciences and Engineering Research Council of Canada. Funding for the dating component of this study was provided by the New Brunswick Department of Natural Resources. We thank the staff of the PCIGR at UBC for assistance in producing the U-Pb results reported in this contribution.

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Editorial responsibility: Simon K. Haslett

SANDRA M. BARR (1) *, JAMES K. MORTENSEN (2), CHRIS E. WHITE (3), RICHARD M. FRIEDMAN (2)

(1.) Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada

(2.) Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

(3.) Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia B3J 2T9, Canada

* Corresponding author <sandra.barr@acadiau.ca>

Date received: 08 June 2010 [paragraph] Date accepted: 08 September 2010

Doi: 10.4138/atlgeol.2010.009
Table A1a. Potassium feldspar compositions * from Machias
Seal Island quartz monzodiorite and enclaves.

                             weight %

Sample       Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

NB04-176a       64.55         0.04              18.85
NB04-176a       64.41         0.00              18.36
NB04-179        64.48         0.01              18.72
NB04-179        63.71         0.00              18.72
NB04-179        64.53         0.04              19.34
NB04-179        65.03         0.07              18.41
NB04-179        65.27         0.00              18.78
NB04-179        64.89         0.00              18.49
NB04-182        63.51         0.04              18.50
NB04-182        64.62         0.01              18.57
NB04-182        65.11         0.05              18.50
NB04-182        64.99         0.03              18.55
NB04-183a       65.19         0.04              18.69
N1304-183a      64.86         0.11              18.48
N1304-183a      65.16         0.05              18.57
NB04-183d       65.21         0.03              18.54
NB04-183d       65.29         0.03              18.58
NB04-183d       65.08         0.04              18.67
NB04-183d       65.59         0.00              18.79
NB04-183d       64.73         0.05              18.48
NB04-183d       64.63         0.00              18.54

                          weight %

Sample       Fe[O.sup.t]   MnO    MgO    CaO

NB04-176a       0.16       0.00   0.00   0.13
NB04-176a       0.01       0.01   0.00   0.05
NB04-179        0.00       0.00   0.00   0.00
NB04-179        0.00       0.00   0.00   0.16
NB04-179        0.16       0.00   0.00   0.26
NB04-179        0.04       0.03   0.01   0.12
NB04-179        0.03       0.00   0.00   0.04
NB04-179        0.01       0.00   0.00   0.00
NB04-182        0.04       0.02   0.00   0.05
NB04-182        0.05       0.04   0.00   0.06
NB04-182        0.08       0.02   0.00   0.04
NB04-182        0.11       0.02   0.00   0.08
NB04-183a       0.14       0.00   0.00   0.07
N1304-183a      0.18       0.01   0.00   0.14
N1304-183a      0.17       0.01   0.01   0.10
NB04-183d       0.12       0.00   0.00   0.09
NB04-183d       0.15       0.00   0.00   0.08
NB04-183d       0.17       0.00   0.01   0.10
NB04-183d       0.21       0.00   0.00   0.09
NB04-183d       0.09       0.01   0.01   0.10
NB04-183d       0.10       0.00   0.00   0.15

                          weight %

Sample       [Na.sub.2]O   [K.sub.2]O   Total

NB04-176a       1.23         14.57      99.53
NB04-176a       0.50         14.79      98.13
NB04-179        0.32         16.06      99.59
NB04-179        0.39         15.67      98.66
NB04-179        3.13         11.53      98.98
NB04-179        0.89         14.24      98.84
NB04-179        1.58         13.15      98.85
NB04-179        0.47         15.07      98.93
NB04-182        0.30         15.78      98.22
NB04-182        0.39         15.08      98.82
NB04-182        0.62         14.83      99.25
NB04-182        0.66         14.60      99.04
NB04-183a       1.36         13.85      99.34
N1304-183a      2.26         12.42      98.46
N1304-183a      1.80         13.14      99.01
NB04-183d       1.45         13.51      98.95
NB04-183d       1.67         13.22      99.02
NB04-183d       2.39         12.21      98.67
NB04-183d       2.28         12.37      99.33
NB04-183d       2.15         12.49      98.11
NB04-183d       2.79         11.43      97.64

             cations calculated on the basis of 32 oxygen

Sample        Si      Al    [Fe.sup.3+]    Ti    [Fe.sup.2+]

NB04-176a    11.92   4.10      0.00       0.01      0.02
NB04-176a    12.03   4.04      0.00       0.00      0.00
NB04-179     11.95   4.09      0.00       0.00      0.00
NB04-179     11.92   4.12      0.00       0.00      0.00
NB04-179     11.86   4.19      0.00       0.01      0.03
NB04-179     12.04   4.01      0.00       0.01      0.01
NB04-179     12.02   4.07      0.00       0.00      0.01
NB04-179     12.03   4.04      0.00       0.00      0.00
NB04-182     11.94   4.10      0.00       0.01      0.01
NB04-182     12.01   4.06      0.00       0.00      0.01
NB04-182     12.03   4.03      0.00       0.01      0.01
NB04-182     12.02   4.04      0.00       0.00      0.02
NB04-183a    12.00   4.05      0.00       0.01      0.02
N1304-183a   12.00   4.03      0.00       0.02      0.03
N1304-183a   12.01   4.03      0.00       0.01      0.03
NB04-183d    12.03   4.03      0.00       0.00      0.02
NB04-183d    12.03   4.03      0.00       0.00      0.02
NB04-183d    12.00   4.05      0.00       0.01      0.03
NB04-183d    12.01   4.05      0.00       0.00      0.03
NB04-183d    12.01   4.04      0.00       0.01      0.01
NB04-183d    12.00   4.06      0.00       0.00      0.02

             cations calculated on the basis
                      of 32 oxygen

Sample        Mn     Mg     Ca     Na     K

NB04-176a    0.00   0.00   0.03   0.44   3.43
NB04-176a    0.00   0.00   0.01   0.18   3.53
NB04-179     0.00   0.00   0.00   0.12   3.80
NB04-179     0.00   0.00   0.03   0.14   3.74
NB04-179     0.00   0.00   0.05   1.12   2.70
NB04-179     0.01   0.00   0.02   0.32   3.36
NB04-179     0.00   0.00   0.01   0.56   3.09
NB04-179     0.00   0.00   0.00   0.17   3.87
NB04-182     0.00   0.00   0.01   0.11   3.78
NB04-182     0.01   0.00   0.01   0.14   3.57
NB04-182     0.00   0.00   0.01   0.22   3.80
NB04-182     0.00   0.00   0.02   0.24   3.45
NB04-183a    0.00   0.00   0.01   0.49   3.25
N1304-183a   0.00   0.00   0.03   0.81   2.93
N1304-183a   0.00   0.00   0.02   0.64   3.09
NB04-183d    0.00   0.00   0.02   0.52   3.18
NB04-183d    0.00   0.00   0.02   0.60   3.11
NB04-183d    0.00   0.00   0.02   0.85   2.87
NB04-183d    0.00   0.00   0.02   0.81   2.89
NB04-183d    0.00   0.00   0.02   0.77   2.96
NB04-183d    0.00   0.00   0.03   1.01   2.71

             end member components

Sample        %Ab    %An     %Or

NB04-176a    11.30   0.70   88.00
NB04-176a     4.90   0.30   94.90
NB04-179      2.90   0.00   97.10
NB04-179      3.60   0.80   95.60
NB04-179     28.80   1.30   69.80
NB04-179      8.60   0.60   90.70
NB04-179     15.40   0.20   84.40
NB04-179      4.50   0.00   95.50
NB04-182      2.80   0.20   97.00
NB04-182      3.80   0.30   95.90
NB04-182      6.00   0.20   93.80
NB04-182      6.40   0.40   93.20
NB04-183a    12.90   0.40   86.70
N1304-183a   21.50   0.70   77.70
N1304-183a   17.10   0.50   82.30
NB04-183d    14.00   0.50   85.50
NB04-183d    16.00   0.40   83.50
NB04-183d    22.80   0.50   76.70
NB04-183d    21.80   0.50   77.70
NB04-183d    20.60   0.50   78.80
NB04-183d    26.90   0.80   72.30

* Analyses by JEOL 8200 electron microprobe in the Dalhousie
University Regional Electron Microprobe Laboratory.

Table A1b. Plagioclase feldspar compositions * from Machias Seal
Island quartz monzodiorite and enclaves.

                              weight %

Sample        Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

NB04-182         62.90         0.01              23.68
N1304-176a       55.46         0.05              28.67
NB04-176a-r      58.46         0.03              25.66
NB04-176a-c      54.14         0.05              29.05
NB04-176a-r      57.15         0.02              27.36
NB04-176a        59.80         0.00              25.42
NB04-176a        46.40         0.00              34.63
NB04-179-c       55.24         0.00              28.33
NB04-179-r       60.21         0.00              25.16
NB04-179-c       55.67         0.00              28.45
NB04-179-c       54.52         0.01              29.46
NB04-179-r       61.26         0.00              24.92
NB04-179         60.99         0.00              25.22
NB04-179         60.04         0.02              25.47
NB04-179         59.63         0.00              25.79
NB04-179         61.44         0.00              24.47
NB04-192         55.09         0.03              28.86
NB04-182         55.25         0.03              28.04
NB04-182         62.22         0.00              24.49
NB04-183a-c      50.94         0.05              32.32
NB04-183a-c      44.45         0.00              35.78
NB04-183d        55.79         0.02              27.82
NB04-183a        59.53         0.02              25.32
NB04-183a        58.54         0.02              26.24
NB04-183a        55.32         0.02              28.10
NB04-183a        54.14         0.05              28.98
NB04-183a        58.07         0.04              26.62
NB04-183d        56.15         0.00              27.47
NB04-183d        57.14         0.00              27.50
NB04-183d        46.38         0.01              34.05
NB04-183d        54.50         0.03              28.85
NB04-183d        59.64         0.01              25.34
NB04-183d        56.50         0.00              27.85
NB04-183d        60.67         0.01              24.70
NB04-183d        60.66         0.01              24.86
NB04-183d        58.80         0.00              26.43
NB04-183d        54.11         0.00              28.60
NB04-183d        54.09         0.00              28.65
NB04-183d        45.85         0.00              33.49
NB04-183d        55.56         0.00              27.80
NB04-183d        53.98         0.00              29.48
NB04-183d        53.91         0.00              28.71
NB04-183d        52.16         0.00              30.01
NB04-183d        54.88         0.05              28.64
N1304-183d       60.58         0.06              24.93
NB04-183d        53.13         0.00              29.40

                            weight %

Sample        Fe[O.sup.t]   MnO    MgO     CaO

NB04-182         0.17       0.00   0.00    4.45
N1304-176a       0.21       0.00   0.00   10.60
NB04-176a-r      0.22       0.00   0.00    7.31
NB04-176a-c      0.32       0.01   0.00   11.35
NB04-176a-r      0.17       0.00   0.00    8.77
NB04-176a        0.16       0.00   0.00    6.86
NB04-176a        0.17       0.00   0.00   16.87
NB04-179-c       0.18       0.00   0.00   10.10
NB04-179-r       0.18       0.00   0.00    6.27
NB04-179-c       0.26       0.00   0.00   10.32
NB04-179-c       0.31       0.00   0.00   11.11
NB04-179-r       0.18       0.00   0.00    5.87
NB04-179         0.17       0.00   0.00    6.35
NB04-179         0.15       0.02   0.00    6.63
NB04-179         0.23       0.00   0.00    7.01
NB04-179         0.12       0.00   0.00    5.51
NB04-192         0.24       0.02   0.01   10.10
NB04-182         0.29       0.01   0.19    9.63
NB04-182         0.16       0.03   0.00    5.38
NB04-183a-c      0.26       0.00   0.00   14.56
NB04-183a-c      0.29       0.00   0.00   19.02
NB04-183d        0.28       0.00   0.02    9.54
NB04-183a        0.20       0.01   0.00    6.77
NB04-183a        0.12       0.03   0.00    7.64
NB04-183a        0.27       0.02   0.00    9.78
NB04-183a        0.19       0.02   0.01   10.70
NB04-183a        0.20       0.03   0.00    7.83
NB04-183d        0.26       0.00   0.00    9.62
NB04-183d        0.27       0.00   0.01    8.86
NB04-183d        0.39       0.01   0.02   16.28
NB04-183d        0.26       0.01   0.01   10.26
NB04-183d        0.15       0.00   0.01    6.69
NB04-183d        0.20       0.00   0.00    9.83
NB04-183d        0.25       0.00   0.01    6.05
NB04-183d        0.16       0.00   0.00    6.08
NB04-183d        0.07       0.00   0.00    7.97
NB04-183d        0.27       0.00   0.01   10.80
NB04-183d        0.16       0.00   0.00   10.61
NB04-183d        0.18       0.00   0.00   16.43
NB04-183d        0.13       0.00   0.00    9.30
NB04-183d        0.28       0.00   0.01   11.85
NB04-183d        0.12       0.00   0.00   10.67
NB04-183d        0.31       0.00   0.01   12.10
NB04-183d        0.20       0.00   0.01   10.61
N1304-183d       0.25       0.00   0.00    6.06
NB04-183d        0.18       0.00   0.00   11.79

                             weight %

Sample        [Na.sub.2]O   [K.sub.2]O   Total

NB04-182         8.96          0.47      100.63
N1304-176a       5.71          0.21      100.92
NB04-176a-r      7.57          0.26       99.50
NB04-176a-c      5.34          0.21      100.49
NB04-176a-r      6.71          0.20      100.38
NB04-176a        7.77          0.23      100.24
NB04-176a        1.48          0.03       99.58
NB04-179-c       5.83          0.17       99.85
NB04-179-r       7.90          0.29      100.00
NB04-179-c       5.75          0.22      100.67
NB04-179-c       5.31          0.21      100.92
NB04-179-r       8.32          0.37      100.93
NB04-179         8.02          0.38      101.13
NB04-179         7.98          0.28      100.59
NB04-179         7.50          0.29      100.45
NB04-179         8.48          0.40      100.42
NB04-192         5.57          0.21      100.13
NB04-182         5.93          0.19       99.56
NB04-182         8.72          0.29      101.29
NB04-183a-c      3.58          0.10      101.80
NB04-183a-c      0.92          0.00      100.46
NB04-183d        6.02          0.26       99.75
NB04-183a        7.91          0.29      100.05
NB04-183a        7.37          0.19      100.15
NB04-183a        5.92          0.23       99.66
NB04-183a        5.28          0.21       99.58
NB04-183a        7.15          0.28      100.22
NB04-183d        6.29          0.27      100.06
NB04-183d        6.47          0.32      100.57
NB04-183d        1.62          0.05       98.81
NB04-183d        5.54          0.19       99.65
NB04-183d        7.73          0.34       99.91
NB04-183d        6.37          0.26      101.01
NB04-183d        8.09          0.34      100.12
NB04-183d        8.13          0.38      100.28
NB04-183d        7.41          0.19      100.87
NB04-183d        5.31          0.20       99.30
NB04-183d        5.47          0.19       99.17
NB04-183d        2.20          0.03       98.18
NB04-183d        6.13          0.22       99.14
NB04-183d        5.01          0.20      100.81
NB04-183d        5.49          0.18       99.08
NB04-183d        4.68          0.16       99.44
NB04-183d        5.63          0.19      100.21
N1304-183d       8.22          0.36      100.47
NB04-183d        4.97          0.14       99.61

              cations calculated on the basis of 32 oxygen

Sample         Si      Al    [Fe.sup.3]    Ti    [Fe.sup.2]

NB04-182      11.09   4.92      0.00      0.00      0.02
N1304-176a     9.92   6.04      0.00      0.01      0.03
NB04-176a-r   10.52   5.44      0.00      0.00      0.03
NB04-176a-c    9.76   6.17      0.00      0.01      0.05
NB04-176a-r   10.22   5.76      0.00      0.00      0.03
NB04-176a     10.65   5.33      0.00      0.00      0.02
NB04-176a      8.55   7.51      0.00      0.00      0.03
NB04-179-c     9.97   6.02      0.00      0.00      0.03
NB04-179-r    10.73   5.28      0.00      0.00      0.03
NB04-179-c     9.97   6.00      0.00      0.00      0.04
NB04-179-c     9.77   6.22      0.00      0.00      0.05
NB04-179-r    10.81   5.18      0.00      0.00      0.03
NB04-179      10.75   5.24      0.00      0.00      0.03
NB04-179      10.66   5.32      0.00      0.00      0.02
NB04-179      10.60   5.40      0.00      0.00      0.03
NB04-179      10.89   5.11      0.00      0.00      0.02
NB04-192       9.91   6.12      0.00      0.00      0.04
NB04-182      10.00   5.98      0.00      0.00      0.04
NB04-182      10.92   5.06      0.00      0.00      0.02
NB04-183a-c    9.14   6.83      0.00      0.01      0.04
NB04-183a-c    8.19   7.76      0.00      0.00      0.04
NB04-183d     10.07   5.91      0.00      0.00      0.04
NB04-183a     10.63   5.33      0.00      0.00      0.03
NB04-183a     10.46   5.52      0.00      0.00      0.02
NB04-183a     10.00   5.98      0.00      0.00      0.04
NB04-183a      9.82   6.19      0.00      0.01      0.03
NB04-183a     10.38   5.61      0.00      0.01      0.03
NB04-183d     10.11   5.83      0.00      0.00      0.04
NB04-183d     10.21   5.79      0.00      0.00      0.04
NB04-183d      8.61   7.44      0.00      0.00      0.06
NB04-183d      9.87   6.15      0.00      0.00      0.04
NB04-183d     10.66   5.33      0.00      0.00      0.02
NB04-183d     10.08   5.85      0.00      0.00      0.03
NB04-183d     10.80   5.18      0.00      0.00      0.04
NB04-183d     10.78   5.20      0.00      0.00      0.02
NB04-183d     10.44   5.53      0.00      0.00      0.01
NB04-183d      9.85   6.13      0.00      0.00      0.04
NB04-183d      9.85   6.14      0.00      0.00      0.02
NB04-183d      8.59   7.39      0.00      0.00      0.03
NB04-183d     10.08   5.94      0.00      0.00      0.02
NB04-183d      9.70   6.24      0.00      0.00      0.04
NB04-183d      9.83   6.16      0.00      0.00      0.02
NB04-183d      9.52   6.45      0.00      0.00      0.05
NB04-183d      9.89   6.08      0.00      0.01      0.03
N1304-183d    10.76   5.21      0.00      0.01      0.04
NB04-183d      9.66   6.30      0.00      0.00      0.03

              cations calculated on the basis of 32 oxygen

Sample         Mn     Mg     Ca     Na     K

NB04-182      0.00   0.00   0.84   3.06   0.11
N1304-176a    0.00   0.00   2.03   1.98   0.05
NB04-176a-r   0.00   0.00   1.41   2.64   0.06
NB04-176a-c   0.00   0.00   2.19   1.87   0.05
NB04-176a-r   0.00   0.00   1.68   2.33   0.05
NB04-176a     0.00   0.00   1.31   2.68   0.05
NB04-176a     0.00   0.00   3.33   0.53   0.01
NB04-179-c    0.00   0.00   1.95   2.04   0.04
NB04-179-r    0.00   0.00   1.20   2.73   0.07
NB04-179-c    0.00   0.00   1.98   2.00   0.05
NB04-179-c    0.00   0.00   2.13   1.85   0.05
NB04-179-r    0.00   0.00   1.11   2.85   0.08
NB04-179      0.00   0.00   1.20   2.74   0.09
NB04-179      0.00   0.00   1.26   2.75   0.06
NB04-179      0.00   0.00   1.34   2.59   0.07
NB04-179      0.00   0.00   1.05   2.91   0.09
NB04-192      0.00   0.00   1.95   1.94   0.05
NB04-182      0.00   0.05   1.87   2.08   0.04
NB04-182      0.00   0.00   1.01   2.97   0.07
NB04-183a-c   0.00   0.00   2.80   1.24   0.02
NB04-183a-c   0.00   0.00   3.75   0.33   0.00
NB04-183d     0.00   0.01   1.85   2.11   0.06
NB04-183a     0.00   0.00   1.30   2.74   0.07
NB04-183a     0.01   0.00   1.46   2.55   0.04
NB04-183a     0.00   0.00   1.90   2.08   0.05
NB04-183a     0.00   0.00   2.08   1.86   0.05
NB04-183a     0.01   0.00   1.50   2.48   0.06
NB04-183d     0.00   0.00   1.86   2.20   0.06
NB04-183d     0.00   0.00   1.70   2.24   0.07
NB04-183d     0.00   0.01   3.24   0.58   0.01
NB04-183d     0.00   0.00   1.99   1.94   0.04
NB04-183d     0.00   0.00   1.28   2.68   0.08
NB04-183d     0.00   0.00   1.88   2.21   0.06
NB04-183d     0.00   0.00   1.15   2.79   0.08
NB04-183d     0.00   0.00   1.16   2.80   0.09
NB04-183d     0.00   0.00   1.52   2.55   0.04
NB04-183d     0.00   0.00   2.11   1.87   0.05
NB04-183d     0.00   0.00   2.07   1.93   0.04
NB04-183d     0.00   0.00   3.30   0.80   0.01
NB04-183d     0.00   0.00   1.81   2.16   0.05
NB04-183d     0.00   0.00   2.28   1.75   0.05
NB04-183d     0.00   0.00   2.08   1.94   0.04
NB04-183d     0.00   0.00   2.37   1.66   0.04
NB04-183d     0.00   0.00   2.05   1.97   0.04
N1304-183d    0.00   0.00   1.15   2.83   0.08
NB04-183d     0.00   0.00   2.30   1.75   0.03

              end member components

Sample         %Ab     %An    %Or

NB04-182      76.40   21.00   2.60
N1304-176a    48.80   50.00   1.20
NB04-176a-r   64.30   34.30   1.50
NB04-176a-c   45.40   53.40   1.20
NB04-176a-r   57.40   41.50   1.10
NB04-176a     66.30   32.40   1.30
NB04-176a     13.70   86.10   0.20
NB04-179-c    50.60   48.40   1.00
NB04-179-r    68.40   30.00   1.60
NB04-179-c    49.60   49.20   1.20
NB04-179-c    45.80   53.00   1.20
NB04-179-r    70.50   27.50   2.10
NB04-179      68.10   29.80   2.10
NB04-179      67.50   31.00   1.50
NB04-179      64.90   33.50   1.70
NB04-179      71.90   25.80   2.20
NB04-192      49.30   49.40   1.20
NB04-182      52.10   46.80   1.10
NB04-182      73.40   25.00   1.60
NB04-183a-c   30.60   68.90   0.50
NB04-183a-c    8.10   91.90   0.00
NB04-183d     52.50   46.00   1.50
NB04-183a     66.80   31.60   1.60
NB04-183a     62.90   36.00   1.10
NB04-183a     51.60   47.10   1.30
NB04-183a     46.60   52.20   1.20
NB04-183a     61.30   37.10   1.60
NB04-183d     53.40   45.10   1.50
NB04-183d     55.90   42.30   1.80
NB04-183d      15.2   84.50   0.30
NB04-183d     48.90   50.00   1.10
NB04-183d     66.40   31.70   1.90
NB04-183d     53.20   45.40   1.40
NB04-183d     69.40   28.70   1.90
NB04-183d     69.20   28.60   2.10
NB04-183d     62.10   36.90   1.00
NB04-183d     46.50   52.30   1.20
NB04-183d     47.80   51.10   1.10
NB04-183d     19.50   80.40   0.20
NB04-183d     53.70   45.00   1.20
NB04-183d     42.90   56.00   1.10
NB04-183d     47.70   51.30   1.00
NB04-183d     40.80   58.30   0.90
NB04-183d     48.40   50.50   1.10
N1304-183d    69.60   28.40   2.00
NB04-183d     42.90   56.30   0.80

* Analyses by JEOL 8200 electron microprobe in the Dalhousie
University Regional Electron Microprobe Laboratory

Table A2. Amphibole compositions * from Machias Seal Island
quartz monzodiorite and enclaves.

                             weight %

Sample       Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

N1304-176a      48.13         0.81              5.85
NB04-176a       47.58         0.76              5.88
NB04-176a       47.68         0.84              5.93
NB04-179        47.86         1.19              5.78
NB04-179        46.89         1.38              6.54
NB04-179        47.16         1.25              6.40
NB04-182        46.49         1.41              6.52
NB04-182        46.29         1.50              6.79
NB04-182        49.51         0.60              4.84
NB04-183a       47.85         1.01              5.87
NB04-183d       48.41         0.28              5.64
NB04-183d       47.90         0.83              5.67
NB04-183d       47.04         1.01              6.37

                                weight %

Sample       Fe[O.sup.t]   [Cr.sub.2][O.sub.3]   MnO     MgO     CaO

N1304-176a      17.16             0.08           0.48   12.84   11.43
NB04-176a       17.61             0.00           0.42   11.81   10.24
NB04-176a       16.78             0.02           0.36   12.50   10.37
NB04-179        17.78             0.06           0.57   11.79   11.31
NB04-179        17.70             0.00           0.46   11.34   10.17
NB04-179        17.70             0.00           0.48   11.37   10.20
NB04-182        17.83             0.07           0.46   11.50   11.42
NB04-182        18.14             0.09           0.55   11.33   11.45
NB04-182        16.71             0.12           0.56   12.72   10.72
NB04-183a       17.78             0.05           0.37   12.22   11.28
NB04-183d       18.18             0.05           0.45   11.93   10.53
NB04-183d       17.19             0.08           0.31   12.32   10.08
NB04-183d       18.55             0.16           0.37   11.90   11.11

Sample       [Na.sub.2]O   [K.sub.2]O   Total

N1304-176a      0.94          0.56      98.20
NB04-176a       1.19          0.54      96.03
NB04-176a       1.19          0.57      96.22
NB04-179        1.32          0.59      98.19
NB04-179        1.48          0.66      96.62
NB04-179        1.59          0.66      96.81
NB04-182        1.36          0.71      97.69
NB04-182        1.44          0.76      98.25
NB04-182        1.07          0.44      97.17
NB04-183a       1.05          0.56      97.99
NB04-183d       0.94          0.53      96.89
NB04-183d       1.13          0.55      95.98
NB04-183d       1.23          0.68      98.25

             cations calculated on the basis of 23 oxygen

Sample       TSi    TAl    T[Fe.sup.3+]   CAl    CCr    C[Fe.sup.3+]

N1304-176a   7.04   0.96       0.01       0.05   0.01       0.58
NB04-176a    7.14   0.86       0.00       0.18   0.00       0.51
NB04-176a    7.11   0.89       0.00       0.15   0.00       0.51
NB04-179     7.08   0.92       0.00       0.09   0.01       0.32
NB04-179     7.04   0.96       0.00       0.20   0.00       0.44
NB04-179     7.07   0.93       0.00       0.21   0.00       0.41
NB04-182     6.93   1.07       0.00       0.08   0.01       0.33
NB04-182     6.88   1.12       0.00       0.07   0.01       0.33
NB04-182     7.30   0.70       0.00       0.14   0.01       0.43
NB04-183a    7.05   0.95       0.00       0.07   0.01       0.49
NB04-183d    7.18   0.82       0.00       0.17   0.01       0.56
NB04-183d    7.15   0.85       0.00       0.15   0.01       0.55
NB04-183d    6.93   1.05       0.02       0.06   0.02       0.55

             cations calculated on the basis of 23 oxygen

Sample       CTi     CMg    C[Fe.sup.2+]   CMn    B[Fe.sup.2+]   BMn

N1304-176a   0.09    2.80       1.45       0.03       0.07       0.03
NB04-176a    0.09    2.64       1.56       0.03       0.14       0.03
NB04-176a    0.09    2.78       1.44       0.02       0.14       0.02
NB04-179     0.13    2.60       1.82       0.04       0.06       0.04
NB04-179     0.16    2.54       1.64       0.03       0.14       0.03
NB04-179     0.14    2.54       1.67       0.03       0.14       0.03
NB04-182     0.16    2.56       1.85       0.03       0.05       0.03
NB04-182     0.17    2.51       1.88       0.03       0.05       0.04
NB04-182     0.07    2.80       1.52       0.04       0.11       0.04
NB04-183a    0.11    2.68       1.62       0.02       0.08       0.02
NB04-183d    0.03    2.64       1.57       0.03       0.13       0.03
NB04-183d    0.09    2.74       1.43       0.02       0.16       0.02
NB04-183d    0.11    2.61       1.63       0.02       0.09       0.02

             cations calculated on the
                basis of 23 oxygen

Sample       BCa    BNa    ANa     AK

N1304-176a   1.79   0.11   0.16   0.10
NB04-176a    1.65   0.17   0.18   0.10
NB04-176a    1.66   0.17   0.17   0.11
NB04-179     1.79   0.11   0.27   0.11
NB04-179     1.64   0.19   0.24   0.13
NB04-179     1.64   0.19   0.27   0.13
NB04-182     1.82   0.09   0.30   0.13
NB04-182     1.82   0.09   0.32   0.14
NB04-182     1.69   0.15   0.16   0.08
NB04-183a    1.78   0.12   0.18   0.11
NB04-183d    1.67   0.13   0.14   0.10
NB04-183d    1.61   0.16   0.17   0.11
NB04-183d    1.75   0.13   0.22   0.13

* Analyses by JEOL 8200 electron microprobe in the Dalhousie
University Regional Electron Microprobe Laboratory.

Table A3. Pyroxene compositions * from Machias Seal Island
quartz monzodiorite and enclaves.

                             weight %

Sample       Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

NB04-176a       51.26         0.44              2.73
NB04-176a       52.32         0.14              0.47
NB04-179        52.09         0.47              1.36
NB04-179        52.34         0.29              1.04
NB04-179        53.18         0.03              0.12
NB04-183a       50.67         0.59              2.05
NB04-183a       52.29         0.24              0.79
NB04-183a       52.07         0.36              0.94
N1304-183a      50.18         0.50              4.17
N1304-183d      51.61         0.36              1.63
NB04-183d       52.45         0.28              0.80
N1304-183d      51.99         0.45              1.09
NB04-183d       51.68         0.47              1.23
NB04-183d       52.10         0.35              1.03
NB04-183d       5l.59         0.32              1.20
NB04-183d       51.91         0.33              1.17
N1304-176a      51.36         0.26              0.79
NB04-176a       51.71         0.33              0.60
NB04-176a       52.67         0.19              1.06
NB04-176a       51.79         0.28              0.66
NB04-183a       51.80         0.27              0.36
NB04-183a       52.33         0.31              0.70
NB04-183a       52.29         0.22              1.23
NB04-183a       51.82         0.32              0.53
NB04-183d       53.76         0.13              0.27
N1304-183d      51.83         0.19              0.93
NB04-183d       51.35         0.36              0.54
NB04-183d       51.37         0.21              0.84
N1304-183d      51.87         0.29              0.61
NB04-183d       51.69         0.37              0.61

                                     weight %

Sample       Fe[O.sup.t]   [Cr.sub.2][O.sub.3]   MnO     MgO     CaO

NB04-176a       8.61              0.00           0.25   13.71   21.18
NB04-176a       11.66             0.10           0.42   13.04   22.40
NB04-179        14.69             0.10           0.47   14.00   17.86
NB04-179        9.35              0.01           0.41   14.00   22.72
NB04-179        9.06              0.03           0.56   13.53   24.02
NB04-183a       12.36             0.19           0.49   11.57   19.64
NB04-183a       12.22             0.08           0.54   12.00   20.00
NB04-183a       12.42             0.08           0.42   12.79   21.66
N1304-183a       8.79             0.71           0.25   13.69   21.80
N1304-183d      11.71             0.00           0.42   13.32   19.26
NB04-183d       11.63             0.09           0.40   13.02   19.32
N1304-183d      11.77             0.07           0.37   12.76   19.55
NB04-183d       11.87             0.08           0.37   12.56   19.82
NB04-183d       11.94             0.09           0.51   11.96   20.01
NB04-183d       1l.51             0.00           0.43   12.30   21.05
NB04-183d       11.53             0.00           0.43   12.28   21.32
N1304-176a      27.84             0.02           0.99   17.04    1.48
NB04-176a       25.96             0.08           0.86   19.56    1.56
NB04-176a       22.21             0.00           0.57   21.18    1.58
NB04-176a       25.44             0.11           0.76   18.72    2.51
NB04-183a       27.06             0.10           0.83   18.62    0.88
NB04-183a       25.53             0.08           0.70   19.33    1.36
NB04-183a       23.34             0.09           0.66   21.42    1.56
NB04-183a       27.10             0.09           0.77   18.40    1.71
NB04-183d       25.53             0.06           1.06   15.55    0.81
N1304-183d      23.94             0.00           0.69   19.51    1.01
NB04-183d       28.27             0.10           0.78   16.95    1.32
NB04-183d       26.86             0.09           0.79   17.63    1.41
N1304-183d      25.95             0.10           0.72   18.85    1.46
NB04-183d       26.87             0.08           0.73   17.61    1.50

                            weight %

Sample       [Na.sub.2]O   [K.sub.2]O   Total

NB04-176a       0.26          0.01       98.45
NB04-176a       0.24          0.00      100.80
NB04-179        0.30          0.00      101.34
NB04-179        0.23          0.19      100.58
NB04-179        0.19          0.00      100.73
NB04-183a       0.41          0.05       98.02
NB04-183a       0.31          0.04       98.51
NB04-183a       0.33          0.03      101.08
N1304-183a      0.38          0.01      100.47
N1304-183d      0.30          0.02       98.63
NB04-183d       0.27          0.04       98.30
N1304-183d      0.34          0.05       98.44
NB04-183d       0.34          0.04       98.46
NB04-183d       0.33          0.03       98.35
NB04-183d       0.30          0.01       98.81
NB04-183d       0.32          0.02       99.31
N1304-176a      0.01          0.03       99.82
NB04-176a       0.01          0.01      100.67
NB04-176a       0.00          0.00       99.46
NB04-176a       0.02          0.01      100.29
NB04-183a       0.00          0.04       99.96
NB04-183a       0.02          0.03      100.39
NB04-183a       0.00          0.00      100.81
NB04-183a       0.01          0.01      100.77
NB04-183d       0.06          0.04       97.27
N1304-183d      0.01          0.03       98.14
NB04-183d       0.03          0.03       99.73
NB04-183d       0.02          0.03       99.25
N1304-183d      0.01          0.04       99.90
NB04-183d       0.01          0.03       99.50

                          numbers of cations calculated

Sample       TSi    TAl    T[Fe.sup.3+]   M1Al   M1Ti   M1[Fe.sup.3+]

NB04-176a    1.94   0.06       0.00       0.06   0.01       0.00
NB04-176a    1.95   0.02       0.03       0.00   0.00       0.05
NB04-179     1.94   0.06       0.00       0.00   0.01       0.05
NB04-179     1.94   0.05       0.01       0.00   0.01       0.07
NB04-179     1.98   0.01       0.02       0.00   0.00       0.04
NB04-183a    1.96   0.04       0.00       0.05   0.02       0.00
NB04-183a    2.01   0.00       0.00       0.04   0.01       0.00
NB04-183a    1.94   0.04       0.02       0.00   0.01       0.06
N1304-183a   1.86   0.14       0.00       0.04   0.01       0.08
N1304-183d   1.97   0.04       0.00       0.04   0.01       0.00
NB04-183d    2.01   0.00       0.00       0.04   0.01       0.00
N1304-183d   1.99   0.01       0.00       0.04   0.01       0.00
NB04-183d    1.98   0.02       0.00       0.03   0.01       0.00
NB04-183d    2.00   0.00       0.00       0.05   0.01       0.00
NB04-183d    1.97   0.03       0.00       0.02   0.01       0.01
NB04-183d    1.97   0.03       0.00       0.02   0.01       0.01
N1304-176a   1.98   0.02       0.00       0.02   0.01       0.00
NB04-176a    1.95   0.03       0.02       0.00   0.01       0.03
NB04-176a    1.98   0.02       0.00       0.03   0.01       0.00
NB04-176a    1.97   0.03       0.01       0.00   0.01       0.02
NB04-183a    1.98   0.02       0.00       0.00   0.01       0.00
NB04-183a    1.98   0.02       0.00       0.01   0.01       0.00
NB04-183a    1.94   0.05       0.00       0.00   0.01       0.04
NB04-183a    1.97   0.02       0.01       0.00   0.01       0.01
NB04-183d    2.14   0.00       0.00       0.01   0.00       0.00
N1304-183d   2.00   0.01       0.00       0.04   0.01       0.00
NB04-183d    1.99   0.01       0.00       0.01   0.01       0.00
NB04-183d    1.98   0.02       0.00       0.02   0.01       0.00
N1304-183d   1.98   0.02       0.00       0.01   0.01       0.00
NB04-183d    1.99   0.01       0.00       0.02   0.01       0.00

             numbers of cations calculated

Sample       M1[Fe.sup.2+]     M1Cr   M

NB04-176a        0.16          0.00
NB04-176a        0.22          0.00
NB04-179         0.15          0.00
NB04-179         0.15          0.00
NB04-179         0.21          0.00
NB04-183a        0.26          0.01
NB04-183a        0.27          0.00
NB04-183a        0.22          0.00
N1304-183a       0.09          0.02
N1304-183d       0.20          0.00
NB04-183d        0.21          0.00
N1304-183d       0.22          0.00
NB04-183d        0.23          0.00
NB04-183d        0.26          0.00
NB04-183d        0.26          0.00
NB04-183d        0.26          0.00
N1304-176a       0.00          0.00
NB04-176a        0.00          0.00
NB04-176a        0.00          0.00
NB04-176a        0.00          0.00
NB04-183a        0.00          0.00
NB04-183a        0.00          0.00
NB04-183a        0.00          0.00
NB04-183a        0.00          0.00
NB04-183d        0.06          0.00
N1304-183d       0.00          0.00
NB04-183d        0.00          0.00
NB04-183d        0.00          0.00
N1304-183d       0.00          0.00
NB04-183d        0.00          0.00

* Analyses by JEOL 8200 electron microprobe in the Dalhousie
University Regional Electron Microprobe Laboratory. T, M1, and M2
are sites in the pyroxene crystal structure

Table A4. Biotite compositions * from Machias Seal Island
quartz monzodiorite and enclaves,

                             weight %

Sample      Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

NB04-176a      37.05         3.98              13.08
NB04-179       36.76         4.98              13.54
NB04-179       37.30         5.16              13.13
NB04-179       36.55         4.72              12.84
NB04-179       36.80         4.79              12.81
NB04-179       37.26         4.34              12.89
NB04-179       37.39         4.66              12.86
NB04-182       36.89         5.06              12.77
NB04-182       37.11         4.70              12.68
NB04-182       38.21         4.58              12.48
NB04-182       37.01         4.75              12.75
NB04-183a      37.39         4.42              13.24
NB04-183a      37.20         4.62              13.30
NB04-183a      37.52         4.36              12.92
NB04-183a      37.19         3.93              13.26
NB04-183a      37.05         3.86              13.39
NB04-183d      37.03         4.26              13.18
NB04-183d      36.96         3.80              12.81
NB04-183d      37.31         3.88              12.88
NB04-183d      36.75         4.57              13.63
NB04-183d      37.42         3.83              13.08
NB04-183d      36.45         3.99              13.53
NB04-183d      36.49         3.89              13.30

                                    weight %

Sample      [Cr.sub.2][O.sub.3]   Fe[O.sub.t]   MnO     MgO    CaO

NB04-176a          0.00              20.70      0.19   10.59   0.00
NB04-179           0.06              21.54      0.25   10.23   0.01
NB04-179           0.10              20.64      0.22   10.65   0.01
NB04-179           0.11              21.33      0.26    9.74   0.02
NB04-179           0.11              20.56      0.27   10.48   0.01
NB04-179           0.00              20.76      0.23   10.54   0.04
NB04-179           0.00              20.50      0.20   10.98   0.01
NB04-182           0.11              21.28      0.25   10.40   0.02
NB04-182           0.11              20.47      0.27   10.70   0.03
NB04-182           0.07              19.91      0.26   11.24   0.01
NB04-182           0.08              20.99      0.26   10.41   0.01
NB04-183a          0.14              21.17      0.16   11.31   0.04
NB04-183a          0.10              21.25      0.18   11.33   0.02
NB04-183a          0.08              20.40      0.17   11.36   0.04
NB04-183a          0.09              20.04      0.17   11.33   0.03
NB04-183a          0.10              19.69      0.18   11.06   0.08
NB04-183d          0.01              20.08      0.16   10.87   0.07
NB04-183d          0.00              19.99      0.16   10.91   0.09
NB04-183d          0.11              20.37      0.17   11.22   0.07
NB04-183d          0.11              21.26      0.14   10.26   0.03
NB04-183d          0.09              20.07      0.16   11.43   0.05
NB04-183d          0.10              21.21      0.12   11.38   0.03
NB04-183d          0.19              21.73      0.16   10.92   0.05

                           weight %

Sample      [Na.sub.2]O   [K.sub.2]0   Total

NB04-176a      0.11          8.49      94.19
NB04-179       0.15          9.45      96.96
NB04-179       0.14          9.03      96.37
NB04-179       0.07          8.67      94.31
NB04-179       0.12          8.59      94.54
NB04-179       0.08          8.44      94.58
NB04-179       0.11          8.66      95.37
NB04-182       0.09          9.15      96.01
NB04-182       0.18          8.73      94.98
NB04-182       0.18          8.74      95.68
NB04-182       0.15          8.77      95.18
NB04-183a      0.06          9.17      97.10
NB04-183a      0.07          9.16      97.22
NB04-183a      0.08          8.62      95.55
NB04-183a      0.07          8.68      94.79
NB04-183a      0.07          8.48      94.06
NB04-183d      0.07          8.48      94.21
NB04-183d      0.08          8.31      93.11
NB04-183d      0.07          8.27      94.35
NB04-183d      0.05          8.78      95.58
NB04-183d      0.06          8.80      94.99
NB04-183d      0.07          9.47      96.34
NB04-183d      0.12          9.29      96.13

            cations calculated on the basis of 24 oxygen

Sample       Si    [Al.sup.IV]   [Al.sup.VI]    Ti    [Fe.sup.2+]

NB04-176a   6.00      2.00          0.50       0.49      2.80
NB04-179    5.84      2.16          0.38       0.60      2.86
NB04-179    5.92      2.08          0.37       0.62      2.74
NB04-179    5.95      2.05          0.41       0.58      2.91
NB04-179    5.95      2.05          0.39       0.58      2.78
NB04-179    6.01      2.00          0.46       0.53      2.80
NB04-179    5.98      2.02          0.40       0.56      2.74
NB04-182    5.91      2.09          0.32       0.61      2.85
NB04-182    5.97      2.03          0.38       0.57      2.76
NB04-182    6.07      2.00          0.40       0.55      2.64
NB04-182    5.96      2.04          0.38       0.58      2.83
NB04-183a   5.90      2.10          0.37       0.53      2.80
NB04-183a   5.87      2.13          0.34       0.55      2.81
NB04-183a   5.98      2.02          0.41       0.52      2.72
NB04-183a   5.97      2.03          0.48       0.48      2.69
NB04-183a   5.99      2.01          0.54       0.47      2.66
NB04-183d   5.98      2.02          0.48       0.52      2.71
NB04-183d   6.03      2.00          0.50       0.47      2.73
NB04-183d   6.01      2.00          0.46       0.47      2.75
NB04-183d   5.89      2.11          0.46       0.55      2.85
NB04-183d   6.00      2.00          0.47       0.46      2.69
NB04-183d   5.83      2.17          0.38       0.48      2.84
NB04-183d   5.86      2.14          0.37       0.47      2.92

                cations calculated on the
                    basis of 24 oxygen

Sample       Cr     Mn     Mg     Ca     Na      K    Fe/Fe+Mg

NB04-176a   0.00   0.03   2.56   0.00   0.04   1.75     0.52
NB04-179    0.01   0.03   2.42   0.00   0.05   1.92     0.54
NB04-179    0.01   0.03   2.52   0.00   0.04   1.83     0.52
NB04-179    0.01   0.04   2.37   0.00   0.02   1.80     0.55
NB04-179    0.01   0.04   2.53   0.00   0.04   1.77     0.52
NB04-179    0.00   0.03   2.53   0.01   0.03   1.74     0.52
NB04-179    0.00   0.03   2.62   0.00   0.03   1.77     0.51
NB04-182    0.01   0.03   2.48   0.00   0.03   1.87     0.53
NB04-182    0.01   0.04   2.57   0.01   0.06   1.79     0.52
NB04-182    0.01   0.04   2.66   0.00   0.06   1.77     0.50
NB04-182    0.01   0.04   2.50   0.00   0.05   1.80     0.53
NB04-183a   0.02   0.02   2.66   0.01   0.02   1.85     0.51
NB04-183a   0.01   0.02   2.67   0.00   0.02   1.84     0.51
NB04-183a   0.01   0.02   2.70   0.01   0.03   1.75     0.50
NB04-183a   0.01   0.02   2.71   0.01   0.02   1.78     0.50
NB04-183a   0.01   0.03   2.66   0.01   0.02   1.75     0.50
NB04-183d   0.00   0.02   2.62   0.01   0.02   1.75     0.51
NB04-183d   0.00   0.02   2.66   0.02   0.03   1.73     0.51
NB04-183d   0.01   0.02   2.70   0.01   0.02   1.70     0.50
NB04-183d   0.01   0.02   2.45   0.01   0.02   1.80     0.54
NB04-183d   0.01   0.02   2.73   0.01   0.02   1.80     0.50
NB04-183d   0.01   0.02   2.71   0.01   0.02   1.93     0.51
NB04-183d   0.02   0.02   2.61   0.01   0.04   1.90     0.53

* Analyses by JEOL 8200 electron microprobe in the Dalhousie
University Regional Electron Microprobe Laboratory.

Table A5. U-Pb TIMS analytical data for Machias Seal Island
quartz monzodiorite sample NB04-182.

                        Wt (mg)     U      pb (2)
Sample description (1)            (pp) m   (PP) m

B: N2,+134,5,a           0.014      339     34.6
B2: N2,+134,1,ca         0.002      412     43.7
C: N2,+134,5,a           0.018      423      43
D: N2,+134,5,a           0.016      416     41.8
D2: N2,+134,1,ca         0.002     1422     148
E: N2,+134,5,a           0.013      294      30
E2: N2,+134,1,ca         0.010       57      6

                                                 total
                        [sup.206]pb/[sup.204]U   common   [sup.208]
Sample description (1)          (meas)            (pg)     Ph (%)

B: N2,+134,5,a                   4340              6        22.5
B2: N2,+134,1,ca                 1161              4        24.6
C: N2,+134,5,a                   4468              9        21.4
D: N2,+134,5,a                   5031              7        21.1
D2: N2,+134,1,ca                 5901              3        24.1
E: N2,+134,5,a                   3291              6        22.8
E2: N2,+134,1,ca                 1286              11       24.8

                               Isotopic Ratios (3)

Sample description (1)  [sup.206]pb/[sup.238]p   error

B: N2,+134,5,a                 0.08681           0.15
B2: N2,+134,1,ca               0.08773           0.14
C: N2,+134,5,a                 0.08772           0.11
D: N2,+134,5,a                 0.08698           0.11
D2: N2,+134,1,ca               0.08687           0.09
E: N2,+134,5,a                 0.08635           0.15
E2: N2,+134,1,ca               0.08725           0.40

                               Isotopic Ratios (3)

Sample description (1)  [sup.207]pb/[sup.235]p   error

B: N2,+134,5,a                  0.6976           0.31
B2: N2,+134,1,ca                0.7062           0.69
C: N2,+134,5,a                  0.7051           0.17
D: N2,+134,5,a                  0.7003           0.24
D2: N2,+134,1,ca                0.6999           0.18
E: N2,+134,5,a                  0.6932           0.27
E2: N2,+134,1,ca                0.7022           0.89

                               Isotopic Ratios (3)

Sample description (1)  [sup.207]pb/[sup.206]p   error

B: N2,+134,5,a                 0.05829           0.25
B2: N2,+134,1,ca               0.05839           0.65
C: N2,+134,5,a                  0.0583           0.11
D: N2,+134,5,a                 0.05839           0.28
D2: N2,+134,1,ca               0.05843           0.13
E: N2,+134,5,a                 0.05823           0.21
E2: N2,+134,1,ca               0.05837           0.81

                                            Isotopic Ages (Ma) (4)
                        Correlation
Sample description (1)  coefficient   [sup.206]pb/[sup.238]p   error

B: N2,+134,5,a             0.60               536.6             1.5
B2: N2,+134,1,ca           0.44               542.1             1.5
C: N2,+134,5,a             0.80               542.0             1.2
D: N2,+134,5,a             0.73               537.7             1.1
D2: N2,+134,1,ca           0.67               537.0             0.9
E: N2,+134,5,a             0.62               533.9             1.5
E2: N2,+134,1,ca           0.42               539.3             4.1

                             Isotopic Ages (Ma) (4)

Sample description (1)  [sup.207]pb/[sup.206]p   error

B: N2,+134,5,a                  540.5            11.1
B2: N2,+134,1,ca                544.3            28.2
C: N2,+134,5,a                  540.9             4.6
D: N2,+134,5,a                  544.6             7.7
D2: N2,+134,1,ca                546.0             5.8
E: N2,+134,5,a                  538.4             9.3
E2: N2,+134,1,ca                543.8            35.3

(1) N2 = nonmagnetic at 2 degree side slope on Frantz magnetic
separator; grain size given in microns; number of grains; a=
physically abraded; ca =chemically abraded; (2) radiogenic Pb,
corrected for blank, spike, and initial common Ph; (3) corrected for
blank Pb and U, and common Ph; errors Given at 1 standard deviation;
(4) corrected for blank Pb and U, and common Ph; errors given at 2
sigma level.

Table A6. Whole-rock chemical analyses * of samples from the
Machias Seal Island quartz monzodiorite and enclaves.

                       major oxides (wt %)

Sample      Si[O.sub.2]   Ti[O.sub.2]   [Al.sub.2][O.sub.3]

NB04-176A      59.33         0.78              16.76
NB04-178       59.79         0.76              16.72
NB04-179       62.22         0.661             15.54
NB04-180       62.29         0.629             15.7
NB04-182       63.17         0.637             15.38
NB04-183b      56.44         0.75              16.7
NB04-183c      53.74         0.83              16.66

                          major oxides (wt %)

Sample      [Fe.sub.2][O.sub.3.sup.t]    MnO    MgO    CaO

NB04-176A             7.25              0.12    3.06   6.45
NB04-178              6.93              0.11    2.77   6.15
NB04-179              5.72              0.094   2.33   4.98
NB04-180              5.32              0.087   2.06   4.19
NB04-182              5.29              0.088   2.11   4.38
NB04-183b             8.28              0.13    3.76   7.44
NB04-183c             9.48              0.15    4.59   8.85

                        major oxides (wt %)

Sample      [Na.sub.2]O   [K.sub.2]O   [P.sub.2][O.sub.5]

NB04-176A       3.2          2.41             0.21
NB04-178       3.28          2.41             0.2
NB04-179       3.19          3.21             0.17
NB04-180       3.28          3.43            0.178
NB04-182       3.17          3.41             0.15
NB04-183b      3.59          1.64             0.25
NB04-183c      3.86          0.92             0.24

            major oxides (wt %)

Sample      LOI    Total

NB04-176A   0.49   100.06
NB04-178    0.79   99.91
NB04-179    0.47   98.59
NB04-180    1.53   98.69
NB04-182    1.18   98.97
NB04-183b   0.70   99.73
NB04-183c   0.40   99.74

                         trace elements (ppm)

Sample      Ba     Rb     Sr      Y      Zr     Nb     U    Th

NB04-176A   290    69     228     24     156     9     2    10
NB04-178    271    70     227     27     190     9     2    13
NB04-179    270   103     182     29     200    10     3    10
NB04-180    282   111     217     28     204    10     3    10
NB04-182    331   110     174     28     205    11     2    10
NB04-183b   264   59.2   253.2   25.4   160.6   6.2   1.3   6.9
NB04-183c   138   31.6   276.4   24.3   86.2    5.5   1.1   3.9

                         trace elements (ppm)

Sample      Ni    Cr   Co     V     Cu    Zn    Ga    Pb

NB04-176A    3    14   52    122    35    77    18     9
NB04-178    <3    13   52    118    33    72    17    11
NB04-179    11    8    53    99     38    64    16    12
NB04-180    <3    6    46    75     33    63    16     9
NB04-182     3    7    52    93     22    68    15    19
NB04-183b   7.1   nd  69.4   198   17.7   27    16    7.4
NB04-183c   5.5   nd  75.4   230   13.7   17   15.7   6.1

            trace elements (ppm)

Sample       La     Nd

NB04-176A    37     29
NB04-178     42     31
NB04-179     45     34
NB04-180     47     34
NB04-182     42     29
NB04-183b    21    24.6
NB04-183c   19.9    26

* Analysed (except samples NB04-1836 and c) by X-ray Fluorescence at
the Regional Geochemical Centre, Saint Mary's University, Halifax,
Nova Scotia. Major elements and some trace elements were measured
using fused glass disks and other trace elements were measured
using pressed powder pellets. Analytical error is generally less
than 5% for major elements and 2-10% for trace elements.
[Fe.sub.2][O.sub.3.sup.t] is total Fe as [Fe.sub.2][O.sub.3]. LOI is
loss on ignition at 1000[degrees]C; nd--not determined. Samples
NB04-183b and c were analysed at ACME, Vancouver, by ICP-Ms.

Table A7. REE, Hf, and Ta data * from the Machias Seal
Island quartz monzodiorite and enclaves.

Sample        La       Ce        Pr       Nd      Sm      Eu

NB04-176a   24.937    54.129    6.633   27.506   5.311   1.182
NB04-182    70.193   141.730   16.762   32.120   6.336   1.141
NB04-183B   21.000    48.300    6.030   24.600   4.550   1.140
NB04-183C   19.900    47.100    6.100   26.000   5.150   1.240

Sample       Gd      Tb      Dy      Ho      Er      Tm      Yb

NB04-176a   4.593   0.796   4.849   0.955   2.790   0.432   2.758
NB04-182    5.377   0.819   5.130   1.089   3.267   0.482   3.261
NB04-183B   4.430   0.710   4.430   0.830   2.600   0.340   2.480
NB04-183C   4.640   0.720   4.240   0.780   2.540   0.300   2.240

Sample       Lu      Hf      Ta

NB04-176a   0.443   3.948   0.723
NB04-182    0.503   5.648   1.723
NB04-183B   0.390   4.500   0.700
NB04-183C   0.350   2.700   0.800

* Samples NB04-176a and 182 were analyzed at Memorial University of
Newfoundland by ICP-MS, using the [Na.sub.2][O.sub.2] sinter method
(Longerich et al. 1990). Samples NB04-183b, c were analysed by
ICP-MS (aqua regia disgestion) at ACME Analytical Laboratories Ltd.,
Vancouver, BC.

Table A8. Sm-Nd data * for sample NB04-182.

Sample     Age (t)   Nd (ppm)   Sm (ppm)   [sup.147]Sm/[sup.144]Nd

NB04-182     440      29.84      5.950             0.1205

Sample     [sup.143]Nd/[sup.144]Nd   2 sigma   Epsilon Nd(0)

NB04-182          0.512328              4          -6.1

Sample     Epsilon Nd(t)   T(DM) DeP

NB04-182       -0.8          1170

* Sm and Nd concentrations and Nd isotopic compositions were
analyzed at Memorial University of Newfoundland. The in-run
precisions on the Nd isotopic ratio are given at 95% confidence
level. Errors on Nd isotopic compositions are <0.002% and errors on
the [sup.147]Sm-[sup.144]Nd ratio are estimated to be lower than
0.1%. The epsilon Nd values are calculated using [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). The
[sup.147]Sm decay constant is 6.54 [10.sup.-12] [y.sup.-1] (Steiger
and Jager 1977). T(DM) was calculated following the DePaolo
(1988) mantle model.
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Author:Barr, Sandra M.; Mortensen, James K.; White, Chris E.; Friedman, Richard M.
Publication:Atlantic Geology
Article Type:Report
Geographic Code:1CANA
Date:Jan 1, 2010
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