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Zircon U-Pb and Hf isotopic constraints on the genesis of a post-kinematic S-type Variscan tin granite: the Logrosan cupola (Central Iberian Zone).

1. Introduction

The Variscan Orogeny generated a huge volume of granitic melts. The Iberian Belt shows the largest concentration of felsic magmatism within western Europe, mainly in its inner parts. The Central Iberian Zone (CIZ) is composed by vast granite batholiths drawing sub-concordant major linear arrays (Fig. 1a) (e.g., Lopez Plaza and Martinez Catalan, 1987). During the last two decades, U-Pb zircon geochronology has been applied to different granite plutons of these batholiths (e.g., Fernandez-Suarez et al., 2000; Dias et al., 1998). Much more recently, combined U-Pb and Lu-Hf isotope systematics on zircon grains have been used to identify source components and to constrain the age of heterogeneous inheritances incorporated in the granite genesis. This integrated isotope information contributed significantly to the discussions on the origin of the Central Iberian granites (e.g., Villaseca et al., 2012; Teixera et al., 2011).

In this work we have studied a small felsic cupola of the southern part of the CIZ related to two types of mineralizations: i) an intra-granitic D cassiterite-bearing vein-complex, usually related to greisen-like alteration, ii) an exo-granitic Prich ore of hydrothermal apatite (dahlite)-quartz veins (Vindel et al, 2014; Locutura et al., 2007). Other batholiths of this southern part of the CIZ have been dated by U-Pb zircon geochronology (Castelo Branco: Antunes et al., 2008; Cabeza de Araya: Gutierrez-Alonso et al., 2011; Nisa-Alburquerque: Sola et al., 2009; Montes de Toledo: Orejana et al., 2012), but none of them have been studied by the combined U-Pb and Hf-isotope approach. Therefore, we have used a combination of zircon U-Pb CA-ID-TIMS and LA-ICP-MS geochronology to better constrain the age of the granite emplacement and of the inherited zircons.

2. Geological Setting

The Logrosan pluton is located in the Central Iberian Zone (CIZ) (Julivert et al., 1972) of the Iberian Massif, at the southeast of the Caceres province (Spain) (Fig. 1a). Large volumes of granitoids were emplaced during the post-collisional stage of the Variscan Orogeny, mostly late- to postkinematically to the D3 event (e.g., Dias et al., 1998). The Logrosan granite is one of the post-kinematic bodies of the Central Extremadura Batholith (Castro, 1985) that intrudes into epizonal domains of the CIZ. The Logrosan granite is a small body that represents a typical felsic cupola related to complex hydrothermal mineralizations. Tin-tungsten deposits associated with granites in the Iberian Variscan Belt occur mainly in the Central Iberian Zone and constitute one of the most important Sn-W metallogenic provinces of the European Variscan Belt. Sn mineralization befalls as cassiterite-quartz stockwork and greisen type ore in the Logrosan granite. The Logrosan granite intruded the Neoproterozoic metasedimentary series of the Schist Greywacke Complex (SGC) which is characterized in this area by a monotonous decimetric to centimetric alternation of greywackes and shales with minor presence of sandstones and conglomerates (Fig. 1b). A Variscan low-grade regional metamorphism (Chl-Bt zone) has affected these Neoproterozoic country rocks. Moreover, the emplacement of the Logrosan granite has produced a superimposed contact metamorphism characterized by an inner biotite-tourmaline hornfel zone, an intermediate zone of micaceous spotted slates, and a transition zone of recrystallized slates and some metaquartzite levels (Fig. 1c).

The dominant regional structural pattern in the area is Variscan in age. The main Variscan deformation phases defined in the CIZ are also recognized in the area. D1 and D2 deformation phases correspond to the collisional stage of the Variscan orogeny and the crustal thickening which is associated with partial melting and a restricted production of peraluminous granitoids (Dias et al., 1998). The metasediments were folded during the first Variscan phase (D1) which started at 360 Ma in the CIZ (Abalos et al., 2002; Dallmeyer et al., 1997). D1 compressional structures are constituted by large, subvertical folds oriented N100/110E and associated with a schistosity (S1) parallel or transverse to the axial plane (Quesada et al., 1987). The emplacement of the Logrosan granite produced some deviations in the S1 orientation until it reaches E-W directions. A greenschist facies metamorphic grade is reached in the area. The second deformation phase occurred during Lower-Middle Carboniferous (330-310 Ma) (Martinez Catalan, 2011; and references therein). D2 event has an extensional character (Diez Balda et al., 1995) and it is characterized by recumbent folds associated with dextral shear zones (N40-N60) with an axial plane crenulation cleavage or schistosity (S2). The S2 schistosity is occasionally recognized in the studied area. The D3 phase took place between 320 and 312 Ma (Lopez-Moro et al., 2012; Valle Aguado et al., 2005; Dias et al., 2002) and constitutes the last ductile regional deformation phase. It is characterized by the generation of open to tight vertical folds with subhorizontal axes and subvertical shear zones with sinistral (NW-SE) or dextral (NE-SW) wrench movement (Dias et al., 1998). In the studied area shear zones are dextral with an ENE-WSW direction. On a regional scale, it has been assumed that such D3 structures were developed in a distensive context related to gravitational collapse and generalized extension across the belt (Diez Balda et al., 1995; Rodriguez-Pevida et al., 1990). Granite plutons, such as the Logrosan granite, were intruded later or post-kinematically to the D3 phase. Finally, the D4 fragile deformation phase corresponds to extension tectonics that took place from Middle Carboniferous to Permian times (Dias et al., 1998). In the studied area, D4 structures are characterized by the reactivation of old D3 faults in the opposite direction. These faults provided active channels for the flow of mineralized fluids and are almost certainly related to the tin ore vein system of the Logrosan granite.

3. Field relations and petrography

The Logrosan granite is an evolved leucogranitic apophysis with an outcropping area of about 4 km2 (Fig. 1c). This body shows a sub-ellipsoidal shape elongated in the NE-SW direction, and a hidden larger volume of granite rocks may be assumed by the extent of the contact-metamorphic area. The Logrosan pluton is mainly composed of a coarse- to medium-grained two-mica leucogranite (Main Unit) (Fig. 2a) which grades to fine-grained or porphyritic varieties (Fig. 2b). Where K-feldspar megacrysts appear, flow textures are visible with a N130 main trend, following the contact of the granitic pluton in the most external areas. The two summits of the hill defined by the Logrosan granite (the San Cristobal hill) are composed of a microporphyritic (two-texture) granite and an aplitic granite (Evolved Units) (Fig. 2c). No sharp contacts between the Evolved Units and the Main Unit could be observed. Pegmatitic and fine-grained leucocratic bodies of variable size are frequent and usually showing sharp contacts with the Main Unit. Micaceous, mostly biotitic enclaves are occasionally found, as well as schlieren structures. The bulk of the stock is composed of quartz, plagioclase, K-feldspar, muscovite, biotite and accessory minerals (tourmaline, apatite, zircon, monazite, ilmenite, Nb-rich rutile).

Tourmaline appears as an accessory phase within most of the Logrosan granite units, even in some pegmatitic miaroles. Tourmaline is also associated with all types of quartz-veining systems that cross-cut the granite body and occurs within the granite-metasediment contact. The Logrosan granite was triggered by complex hydrothermal events which are identified by the presence of sectors with a dense network of quartzrich veining (cm-scale in thickness of barren-, tourmaline-, cassiterite- rich varieties). Therefore, greisen-type alteration zones are found in the areas with a high proportion of mineralized veins and veinlets (Chicharro et al, 2011). Greisen alteration is not only restricted to the selvages but also affects some parts of the granitic body (Fig. 2d). This alteration is characterized by high contents of muscovite and the presence of disseminated cassiterite. A "sandy granite" is very common adjacent to the Sn-(W) veins and greisen alteration and in most cases is a result of old mining activity (processing/ panning for mineral recovery).

4. Analytical methods

A total of 9 representative samples weighted between 3-5 kg were collected for whole-rock geochemistry (6 medium to coarse-grained granites from the Main Unit and 3 fine-grained or microporphyritic granites from the Evolved Units) (Table 1). Fresh and less altered fractions of each sample were selected for crushing and powdering. Each sample was fused using a lithium metaborate-tetraborate mixture. The melt produced by this process was completely dissolved with 5% HN[O.sub.3]. Major analyses were carried out using fusion-inductively coupled plasma mass spectrometer (FUS-ICPMS) while trace elements were analyzed by fusion-inductively mass spectrometer (FUS-MS) at Activation Laboratories (ACTLABS, Canada). Uncertainties in major elements are bracketed between 1 and 3% relative, except for MnO (5 10%). The precision for Rb, Sr, Zr, Y, V, Hf and most of the REE range from 1 to 5%, and between 5 and 10% for the rest of trace elements. Some granite samples have concentrations in transition metals below detection limits (V: 5 ppm, Cr: 20 ppm, Sc: 1 ppm, Co: 10 ppm) and almost all the granites have Ni < 20 ppm and Mo < 2 ppm. More information on the procedure, precision and accuracy of ACTLABS ICP-MS analyses can be found at www.actlabs.com.

Fluorine and Lithium were determined in selected samples in the laboratory of the Spanish Geological and Mining Institute (IGME), where F was determined by spectrophotometric methods after its extraction by pyrohydrolysis and Li was extracted by digestion with HF-HN[O.sub.3]-HCl[O.sub.4] and determined by atomic absorption spectrophotometry. An analytical error of [+ or -] 10% has been estimated.

Stable isotope data were obtained at the Stable Isotope Laboratories of the Salamanca University (Spain). Whole rock samples of unaltered granite were analyzed for oxygen and hydrogen isotope composition (Table 2). [sup.18]O/[sup.16]O determinations for whole rock samples were carried out by laser fluorination using a conventional vacuum extraction line employing ClF3 as the reagent (Borthwick and Harmon, 1982; Clayton and Mayeda, 1963). H2 and H2O extraction for D/H isotopic analysis for whole rock samples were carried out by the uranium technique described by Godfrey (1962) with modifications introduced by Jenkin (1988) heating the samples at temperatures up to 1500 [degrees]C. Oxygen and hydrogen isotope ratios were measured in a SIRA-II mass spectrometer and data are reported in the normal denotation relative to VSMOW.

Sr-Nd isotopic compositions were measured on six representative granites (Table 2) at the Centro de Asistencia a la Investigacion (CAI) of Geochronology and Isotope Geochemistry (Complutense University of Madrid, Spain). Whole-rock samples were dissolved in ultra-pure reagents and the isotopes were subsequently isolated by exchange chromatography. Isotope analyses were carried out using a Sector 54 VG Multicollector Thermal Ionization Mass Spectrometer with data acquired in multidynamic mode. Repeated analyses on the NBS-987 standard gave [sup.87]Sr/[sup.86]Sr = 0.710240 [+ or -] 0.00005 (2a, n = 8) and for the La Jolla standard, values of [sup.143]Nd/[sup.144]Nd = 0.511847 [+ or -] 0.000003 (2[sigma], n = 14) were obtained.

Individual zircon and monazite crystals were separated for geochronology and Lu-Hf isotopic studies from a mixture of two representative granite samples (AQ1 and AQ2, see Table 1). About 5 kg granite of each sample were crushed and sieved with a steel jaw-crusher and a disk mill at the Complutense University of Madrid. Zircon and monazite were preconcentrated with a Wifley table using a modified version of the "water-based" separation technique of Soderlund and Johansson (2002) at the Spanish Geological Survey laboratories (IGME, Tres Cantos, Spain). Further separation based on paramagnetic properties was done using a Franz isodynamic separator. Finally the zircon and monazite selected for analyses were hand-picked under a microscope. Several monazite and zircon crystals were carefully selected by picking the most idiomorphic crystals to avoid all possibility of inheritance for ID-TIMS. A representative selection of zircons were strewn and mounted on epoxy resin for LA-ICPMS microanalysis. The mount was polished to expose the zircon central portions and studied with transmitted and reflected light on a petrographic microscope. The internal structure, inclusions, fractures and physical defects were analyzed using back scattered electron (BSE) imaging.

The zircon fractions selected for ID-TIMS were pre-treated with the chemical abrasion (CA) method of Mattinson (2005). Zircon annealing was carried at 900oC for 48 hours and the chemical attack was done in Parrish-type minibombs inside Parr bombs at 180oC for 12 hours. Final zircon dissolution was achieved after placing the bomb at 240oC for 72 hours. The procedure for extraction and purification of Pb and U is a scale-down version of that of Krogh (1973). A [sup.208]Pb-[sup.23]5U spike was used to obtain the U/Pb ratios by isotope dilution (ID). Isotopic ratios were measured with a Triton TIMS multi-collector mass spectrometer equipped with an axial secondary electron multiplier (SEM) ion counter. The instrument is set up to do measurements both in static and peak-jumping mode using the SEM. For static measurements the [sup.204]Pb was measured with the calibrated SEM (92-93% Yield calibration). The Pb measurements were done in the 1300-1460oC range, and U was measured in the 1420-1500 [degrees]C interval (for further analytical details see Rubio-Ordonez et al., 2012). Data reduction was done using the PbMacDat spreadsheet (Isacksen et al., 2007; www.earth-time.org). All isotopic ratios are corrected for mass fractionation, blank and initial common Pb after the model of Stacey and Kramers (1975). Ages and uncertainties were calculated with the decay constants of Jaffey et al. (1971), and are reported at the 2a level. The concordia age was calculated and the data were plotted with Isoplot 3.0 (Ludwig, 2003).

U-Pb in situ age determinations were carried out on 37 polished zircons using a New Wave Research LUV213 laserablation microprobe, attached to an Agillent 7500 quadrupole ICP-MS at the ARC GEMOC Centre of the Macquarie University, Sydney (Australia). A laser beam of 30 [micro]m diameter with energies of 60-100 mJ/pulse and 5 Hz repetition rate was shot during 100-120 s resulting in pits of about 30 [micro]m deep. Real-time data were processed using the GLITTER[R] software package. The correction factors were then checked using the GEMOC-GJ-1 with a TIMS age of 608.5 Ma, the Mud Tank zircon (734 [+ or -] 32 Ma, Black and Gulson, 1978) and the 91500 international zircon standard (1064 Ma, Wiedenbeck et al., 1995). Concordia diagrams (2[sigma] error ellipses), concordia ages and upper intercept ages were calculated using the Isoplot/Ex software (Ludwig, 2003).

In situ Hf isotopic measurements were performed on 28 previously dated zircon spots at the ARC GEMOC Centre of the Macquarie University. Analyses were carried out using a New Wave Research LUV213 laser-ablation microprobe, attached to a Nu Plasma multi-collector (MC) inductively coupled plasma mass spectrometer (ICPMS). The laser system delivers a beam of 213 nm UV light from a frequency-quintupled Nd:YAG laser. The laser was fired with energy of 5-7 J/ cm2, laser beam diameter was 30 gm and repetition rate was 5 Hz. The laser beam ablated the zircon surface during 100-120 s resulting in pits 30gm deep. The analytical methods are the same as described in detail by Griffin et al. (2002; 2004). To evaluate the accuracy and precision of the laser ablation results we have repeatedly analyzed two zircon standards: 91500 and Mud Tank (MT). These reference zircons gave [sup.176]Hf/[sup.177]Hf = 0.282310 [+ or -] 0.000049 (2[sigma]) and 0.282502 [+ or -] 0.000044 (2[sigma]), respectively, which are identical to average published values of 0.282306 [+ or -] 0.000008 for 91500 and 0.282507 [+ or -] 0.000006 for MT (Woodhead and Hergt, 2005). The 2[sigma] uncertainty on a single analysis of [sup.176]Lu/[sup.177]Hf is [+ or -] 0.001-0.002% (about 1 epsilon unit), reflecting both analytical uncertainties and the spatial variation of Lu/Hf across many zircons. The [sup.176]Lu decay constant value of 1.865 x [10.sup.-11][a.sup.-1] was used in all calculations (Scherer et al., 2001). Chondritic [sup.176]Hf/[sup.177]Hf = 0.282772 and [sup.176]Lu/[sup.177]Hf = 0.0332 (Bouvier et al., 2008) and the depleted mantle [sup.176]Hf/[sup.177]Hf = 0.28325 ([epsilon]Hf = +16.4) and [sup.176]Lu/[sup.177]Hf = 0.0384 were applied to calculate eHf values and model ages used in this work.

The trace element zircon composition was obtained by laser ablation (LA-ICPMS) at the Natural History Museum of London (NHM, London, UK) using an Agilent 7500CS ICP MS coupled to a New Wave UP213 laser source (213 nm frequencyquadrupled Nd-YAG laser). The diameter of the laser beam was 10 [micro]m. A 40 s gas blank was analyzed first to establish the background, followed by 50 s measurements for the remainder of the analysis. Each analysis was normalized to Si using concentrations determined by electron microprobe. Relative element sensitivities were calibrated with a NIST 612 glass standard.

5. Results

5.1. Whole-rock geochemistry

The results of major, minor and trace element analyses of nine granite samples are presented in Table 1. The Logrosan granite shows high Si[O.sub.2] (63.59-74.03 wt.%), [P.sub.2][O.sub.5] (0.420.78 wt.%) and [Al.sub.2][O.sub.3] (14.42-15.38 wt.%), but very low CaO (0.25-0.69 wt.%) contents (Table 1). The Logrosan granite has a strong peraluminous character, with an alumina-saturation index ranging from 1.22 to 2 and high normative corundum contents (3.55-8.42%).

In variation diagrams using Ti[O.sub.2], Logrosan samples do not define clear fractional crystallization trends, except for the MgO, which markedly decreases towards the more evolved samples (Fig. 3). Although there is some scatter in the, generally the [Al.sub.2][O.sub.3], FeOt, MgO, CaO and [K.sub.2]O contents decrease while the Si[O.sub.2], [Na.sub.2]O and [P.sub.2][O.sub.5] contents increase. Scatter is mainly found in a slightled albitized sample which behaves discordantly to other samples of the Main Unit (e.g. AQ6, see Table 1 and Figs 3 and 4). However, more evolved granites (Evolved Units) seem to form discrete trends for certain major elements such as CaO and [K.sub.2]O. Their depletion would be consistent with plagioclase and alkali feldspar fractionation, but they show different evolution trends for the Main and Evolved Units.

Granite REE patterns show a variable fractionation ([La.sub.N]/ [Yb.sub.N] = 8.37-33.6) but are generally highly fractionated, with a negative Eu anomaly for granites of the Main Unit (Eu/ Eu* = 0.32-0.42) and slightly more negative towards granites of the Evolved Units (Eu/Eu*=0.37-0.45) (Fig. 4). In trace-element chondrite normalized diagrams, the Logrosan samples show negative anomalies in Ba, Nb, Sr and Ti (Fig. 4). The negative Eu anomaly and the low Sr contents of the granite suggest that plagioclase fractionation has occurred for both Main Unit and Evolved Units. In variation diagrams Ba, Rb, Sr, Eu, Cs, Y, Th, HREE and LREE become depleted with increasing degree of fractionation (Fig. 3). As with major elements, Evolved granite Units show different trends for some elements (e.g., Rb, Fig. 3) compared to the Main Unit set of samples.

The HFSE show no clear trend with granite differentiation. A slight tendency of increasing Nb and Ta can be recognized, while Sn exhibits a wider scatter (Fig. 3). High Sn contents found in this granite with respect to the crustal average (i.e. granites with Sn contents higher than 10 ppm, as defined by Flinter, 1971) allow classifying it as stanniferous granite. Ga and Hf data display trends where more fractionated samples show the lowest contents. The overall range for Ga and Hf concentration is quite restricted (Ga: 20-25 ppm and Hf: 1.53.0).

5.2. Oxygen isotopes

Whole rock and quartz 518O results on Logrosan samples gave a narrow range between 14.1 and 15.0%o (vs. SMOW) showing a positive correlation with Si[O.sub.2] of the rock (Table 2). [[delta].sup.18]O values higher than 10 % have been observed in many Variscan granites from western Europe (Tartese and Boulvais, 2010; Hoefs and Emmermann, 1983) and are typical for high-Si[O.sub.2] peraluminous granites (Taylor, 1978). Similar [[delta].sup.18]O values have been found in other granites from the southern CIZ (e.g., Castelo Branco Batholith: 12.2-13.7%, Antunes et al., 2008). Nevertheless, these values are significantly higher than those found in the peraluminous S-type granites of the Spanish Central System, which mostly range from 8.3 to 10.2% (Villaseca and Herreros, 2000; Recio et al., 1992).

5.3. Sr-Nd isotopes

The measured Sr and Nd isotope ratios were recalculated back to 300 Ma based on the intrusion age determined in the section 5.5 (U-Pb geochronology). The Logrosan granite is characterized by a large variation in initial [sup.87]Sr/[sup.86]Sr ratios (from 0.7125 to 0.7286) whereas eNd is much less variable (between -4.3 and -4.0) (Table 2). The Sm-Nd model ages were calculated using the equation of Liew and Hofmann (1988) (Table 2) (Fig. 5). The obtained model ages (1.31-1.67 Ga) are similar to those given for other peraluminous monzogranites and leucogranites from the Central Extremadura Batholith (e.g., Antunes et al., 2008; Castro et al., 1999).

5.4. Zircon description and composition

A total of 68 zircon grains were selected. 37 grains were dated by U-Pb and 28 were analyzed for their Hf-isotope composition. Based on the morphology, we have distinguished two groups of zircon grains: (1) euhedral elongated bipyramidal prisms and (2) stubby prisms. Most of the analyzed grains (about 67%) belong to the first group. This population is characterized by sizes ranging from 100 to 200 [micro]m and aspect ratios ranging from 1:6 to 1:2, being dominantly 1:2 (Fig. 6, e.g., L24-20 and L30-31). The second zircon type comprises stubby prisms (1:1 aspect ratio) of usually smaller grain size (average size of 100 [micro]m) (Fig. 6, e.g., L24-12). The BSE images show that most zircon grains have homogeneous or sector-zoned inner cores with dark thin rims (Fig. 6, e.g. L24-01). Stubby zircons sometimes present texturally discordant dark cores and/or fine euhedral oscillatory zoning (Fig. 6, L30-22).

Logrosan zircons show negative Eu anomalies (Eu/ Eu*<0.3) and relatively high REE (647-2435 ppm), Nb (1.17-5.24 ppm), Ta (0.31-3.92 ppm), Sc (157-939 ppm) and Hf (7631-11800 ppm) contents, characteristic of zircon from granitoid rocks (Hoskin and Schaltegger, 2003; Belousova et al., 2002) (Table 3). Zircon REE abundances normalized to chondrite values (McDonough and Sun, 1995) show steeplyrising slopes from the LREE to the HREE. Euhedral elongated bipyramidal primatic crystals (type-1) are generally Variscan-age zircons and usually richer in Hf than inherited zircons, which are mainly stubby (type-2) (Fig. 6). This is in accordance with the fact that the abundance of Hf in igneous zircons is considered as a marker of the degree of magma differentiation (Hoskin and Schaltegger, 2003). Hf correlates positively with P, Y, Th, U, Nb, Ta, HREE and LREE, whilst it shows a negative correlation with Zr/Hf (Fig. 7). The positive correlation of P, Y and HREE with Hf reveals that "xenotime" substitution mechanism is the dominant substitution in the Logrosan zircon (Speer, 1982). Experiments on Zr/Hf fractionation in zircon-crystallizing melts unravel a decrease of the Zr/Hf ratio of the residual melt related to an increase of the abundance of Hf[O.sub.2] in zircon for fractional crystallization of peraluminous granitic melts (Linnen and Keppler, 2002). Then, the decrease in Zr/Hf with increasing Hf observed in the Logrosan zircon can be explained by crystal fractionation. Likewise, the behavior of incompatible elements, such as Th, U, Nb and Ta, which increase correlatively with Hf in zircon, denotes an enrichment of these elements in the melt as the magma evolves.

5.5. U-Pb geochronology

Seven zircon fractions and one monazite fraction were analyzed by ID-TIMS. All zircon fractions were pre-treated to remove Pb loss, before final dissolution, with the chemical abrasion (CA) method of Mattison (2005). Only one zircon fraction (Z7), a single grain, plots in a discordant position which could be attributed to partial secondary Pb-loss (see Krogh, 1982). The remaining data are either concordant or scattered due to the presence of older xenocrystic zircon.

Five fractions (zircon fractions Z3, Z5, Z8, Z6 and monazite fraction M1) are concordant and plot between 307 and 310 Ma. The remaining zircon fractions (Z1, Z2 and Z4) are discordant due to the presence of inherited zircons. These are multigrain (made up of 25 crystals) to some single crystal fractions (Table 4). The concordant fractions Z3 and Z5 and the discordant fractions Z2 and Z4 define a mixing line (Line 1; Fig 8a) which has an upper intercept of ca. 1.1 Ga suggesting a Mesoproterozoic inheritance. The concordant fractions Z3 and Z5 and the discordant fraction Z1 also define a mixing line (Line 2; Fig 8a) which has an upper intercept of ca. 550-560 Ma pointing to an additional Late Neoproterozoic inherited component. These are very long projections, so the validity of the age of the inherited component has been constrained by in-situ U-Pb ages (see LA-ICPMS data below).

The age of the intrusion of the Logrosan granite is constrained by the cluster of analyses on the Concordia curve between 307 and 310 Ma (fractions Z3, Z5, Z8, Z6 and M1; Table 4). Fraction Z6, a single zircon, is slightly older suggesting the possible presence of an inherited component. Zircon fractions Z3, Z8 and Z5 and the monazite fraction M1 overlap at 307-308 Ma (Fig 8a). These four fractions provide a combined "Concordia" age of 307.88[+ or -]0.86 Ma with an MSWD of 1.8 (decay constant errors included). This age is considered the age of zircon and monazite crystallization, and therefore our most accurate estimate for the age of the granite intrusion.

The LA-ICPMS data set is listed in Table 4 and plotted in a concordia diagram (Fig. 8b). Ages younger than 1,000 Ma are 204-corrected [sup.206]Pb/[sup.238]U, whereas older ages are 204-corrected [sup.207]Pb/[sup.206]Pb. Thirty seven analyses were performed, 32 of which yielded concordant ages ranging from 294 to 1975 Ma. Five analyses were rejected due to high common-Pb or degree of discordance. Nineteen analyses yielded Variscan ages and 13 analyses yielded older-than-Variscan ages. A total set of 19 Variscan zircons provide a weighted average [sup.206]Pb/[sup.238]U age of 303.0 [+ or -] 2.3 Ma (Fig. 8b). This weighted mean age is similar to that calculated using ID-TIMS data (307.88 [+ or -] 0.86 Ma) within uncertainty. We consider the IDTIMS age of 307.88 [+ or -] 0.86 Ma as the most accurate estimate for the age of the intrusion.

The thirteen older--than-Variscan ages represent 40% of inheritances. These ages are mostly Upper Neoproterozoic (from 550 to 847 Ma) (n = 8) and have been obtained on dark anhedral to subhedral cores of stubby zircon (type-2) crystals; one of them was measured in a homogeneous dark core overgrown by a Variscan-age rim (L24-4, Table 5). Two youngest inherited zircon crystals show Cambrian (518 Ma) and Ordovician (447 Ma) ages (spots L24-18 and L30-30, Table 5) and are homogeneous stubby crystals. One Mesoproterozoic age of 1068 Ma was obtained on a homogenous dark core of a stubby zircon crystal (spot L30-28, Table 5 and Fig 6). The two oldest inherited zircons are Paleoproterozoic, 1950 and 1975 Ma (spot L24-5 and L20-35, respectively; Table 5), and correspond to stubby zircon crystals.

5.6. Hf isotope zircon composition

The zircon Lu-Hf isotopic data collected during this study are summarized in Table 6 and plotted as a function of their crystallization ages in figure 9. This figure also includes published data for zircon from the Spanish Central System Batholith (Villaseca et al., 2012) and the Schist Greywacke Complex (Teixeira et al., 2011). Depleted-mantle model ages (Tdm) are useful to estimate the crustal residence age for the granite protolith (Andersen et al., 2002). [T.sub.DM] were calculated using the measured [sup.176]Lu/[sup.177]Hf ratios, referred to a model depleted mantle with a present-day [sup.176]Hf/[sup.177]Hf = 0.28325 and [sup.176]Lu/[sup.177]Hf = 0.0384 (Griffin et al., 2000; 2002). These [T.sub.DM] ages represent only a minimum age for the source of the host magma. Thus, a more realistic two-stage model ([T.sub.DM2]) has been used to estimate model ages of the source of the Logrosan granite. [T.sub.DM2] were calculated assuming a [sup.176]Lu/[sup.177]Hf ratio of 0.015 for the average continental crust (Griffin et al., 2000).

The Variscan zircon population yields initial [sup.176]Hf/[sup.177]Hf ratios of 0.282299-0.282758 which correspond to [epsilon][Hf.sub.(t)] varying from +5.7 to -10.5, a range well outside of analytical uncertainties. The [T.sub.DM2] range for Variscan zircon is accordingly wide and ranges from 928 to 1957 Ma but mostly between 1179 and 1594 Ma with a mean value of 1368 Ma which encompasses the values given by the whole rock Nd depleted model age (1.31-1.67 Ga). Neoproterozoic inherited zircons show initial [sup.176]Hf/[sup.177]Hf ratios of 0.281549 to 0.282735 which corresponds to eHf(t) of +14.7 to -29.7, with more frequent eHf(t) between +6.0 and -3.2. Meso to Paleoproterozoic zircons have [sup.176]Hf/[sup.177]Hf initial ratios of 0.281326-0.282007 and eHf(t) between -3.4 and -7.6.

5.7. Zircon saturation and Ti-in-zircon thermometries

Zircon saturation thermometry has been calculated based on the relationship between zircon solubility, temperature, and major element composition of the melt (Watson and Harrison, 1983). Zircon saturation thermometry of the Logrosan granite ranges from 699[degrees]C to 777[degrees]C and yields an average temperature of 742[degrees]C (Table 1). Apparent temperatures for zircon crystallization have been also estimated using the Tiin-zircon thermometer (Ferry and Watson, 2007). The Logrosan granite petrography suggests simultaneous crystallization of quartz, zircon and ilmenite, and thus aSi[O.sub.2] = 1 and aTi[O.sub.2] < 1. An a(Ti[O.sub.2]) value of 0.6 based on the presence of ilmenite has been assumed. This would lead to underestimation of zircon crystallization temperatures by [less than or equal to]50 [degrees]C (Watson and Harrison, 2005). Ti-in-zircon thermometry yields values from 744[degrees]C to 1024[degrees]C with an average temperature of 836[degrees]C (Table 3), these values are markedly higher than the ones obtained by zircon saturation thermometry.

6. Discussion

6.1. Granite fractional crystallization

The whole-rock geochemistry described above provides no evidence for a unique fractional crystallization trend to link the Main granite suite with the Evolved leucogranite Units. Hence, the Main and the Evolved Units are not related by simple crystal fractionation. Sequential restite fractionation can be dismissed as mafic xenoliths are absent in the Logrosan granite and most elements do not vary linearly with Si[O.sub.2] contents (Chappell et al., 1987). The low Ba and Sr contents together with high Rb concentrations found in the granites suggest that they have undergone some fractional crystallization (Breaks and Moore, 1992), which is consistent with a cupola stockwork scenario. Source-rock heterogeneities could explain the compositional evolution of the Logrosan granite since a significant number of major and trace elements do not show any linear correlations (Fig. 3). Moreover, the great variability in the whole-rock initial Sr isotopic ratios ([sup.87]Sr/[sup.86]Sr: 0.7125-0.7286) and the Hf-isotope composition of the Variscan-age zircons from the Logrosan granite (from +5.7 to -10.5) indicates a heterogeneous magmatic system. The variation of more than 15 eHf units (Table 6) is the maximum range obtained in zircons from the Iberian Variscan granites (Villaseca et al., 2012; Teixeira et al., 2011). Besides, the lack of a single evolutionary path in terms of Sr, Ba, Rb, Eu and CaO between the Main and Evolved Units indicates that fractional crystallization of plagioclase and K-feldspar did not occur in a simple closed magmatic system. Magmatic recharge from a deeper and chemically heterogeneous magma reservoir could produce the more residual and evolved granites of the Logrosan cupola. Thus a complex multi-pulse granite system inefficiently mixed, formed by isotopically heterogeneous fractionated magmas that episodically replenish the Logrosan cupola is more likely than a single magma batch following closed in situ fractional crystallization processes.

6.2. Zircon saturation and Ti-in-zircon thermometries

The average temperatures obtained for the Logrosan Variscan-age zircon crystallization is 836 [degrees]C, similar to other temperature estimates on S-type granites of the Central Iberian Zone (788 to 844[degrees]C after Orejana et al., 2012). Lower temperature estimates (699-777 [degrees]C, Table 1) have been obtained based on whole-rock zircon saturation. The average wholerock zircon saturation temperature (742[degrees]C) is below the average Ti-in zircon temperature (836[degrees]C) for the Logrosan granite. Granitoids rich in zircon inheritances are probably undersaturated with respect to zircon at the source and consequently their calculated zircon saturation temperatures are most likely underestimations of the actual temperature of crystallization (Miller et al., 2003). The zircon inheritances of the Logrosan granite may yield unrealistic zircon saturation temperatures. Hence, the average Ti-in-zircon temperature (836[degrees]C) provides a better estimation of the temperature of the magma from which the zircon crystallized.

6.3. Inheritances and source constraints

Mineralogical and geochemical features of the Logrosan granite (e.g., high peraluminosity and low CaO contents) and the absence of mafic microgranular enclaves suggest a crustal-derived melt origin with a major contribution of aluminous metasedimentary sources (Dias et al., 2002; Chappell et al., 1991). Likewise, high whole rock [[delta].sup.18]O values point to an [sup.18]O-enriched sedimentary or metasedimentary protolith. Perphosphorous character may be inherited from a P-rich source (Villaseca et al., 2008; Rodriguez-Alonso et al., 2004) as indicated in other P-rich granites of the area (Antunes et al., 2008; Villaseca et al., 2008; Ramirez and Menendez, 1999). This P-rich character is also consistent with the presence of phosphate mineralizations surrounding the granite and with dispersed phosphate mineralizations in the regional Schist Greywacke Complex (Vindel et al., 2014).

Zircons from the Logrosan granite have Zr/Hf ratios ranging 41-55 with an average value of 48. According to Pupin (2000), the estimated signature of zircon from the continental crust is 36-45. However, Perez-Soba et al. (2007) estimated the Zr/Hf ratios of zircons from migmatites and augen orthogneisses of the Spanish Central System and suggested a slightly higher range (Zr/Hf = 36-56) for pure crustal signatures. Hence Zr/Hf ratios of the Logrosan zircon fit well with crustal signatures. It is expected that the Zr/Hf ratio in a single magma series should be approximately constant (Wang et al., 2010). Therefore, the wide range of Zr/Hf values for such a small granitic body may indicate not only a different degree of differentiation but also a participation of several magma inputs.

The high initial [sup.87]Sr/[sup.86]Sr ratios of the Logrosan samples are attributed to a significant participation of the Sr derived from crustal material as established for similar granitoids of the CIZ (Ruiz et al., 2008; Castro et al., 1999; Villaseca et al., 1998). Variability in [sup.87]Sr/[sup.86]Sr data for the Logrosan granite (Fig. 5) may well indicate an origin by partial melting of a compositionally heterogeneous continental crust. The [sup.87]Sr/[sup.86]Sr ratios of the Logrosan granite plot in an intermediate space in the Sr-Nd isotopic field drawn by other monzogranites and leucogranites from the Central Extremadura Batholith. The large variability in [sup.87]Sr/[sup.86]Sr data at almost constant eNd values can hardly indicate mixing of different proportions of mantlederived magmas with crustal sources (Castro et al., 1999). The low negative initial Nd isotope ratios of the Logrosan granite (around -4.2), typical of other Central Extremadura Batholith granites (e.g., Castelo Branco, Antunes et al., 2008; Alburquerque, Gonzalez Menendez and Bea, 2004; Montes de Toledo, Villaseca et al., 2008), contrasts with other S-type granites from northern areas of the CIZ (Fig. 5). The metasediments of the SGC also show low Nd isotope signatures (at Variscan times) and might be the most appropriate protolith of the Logrosan granite (Fig. 5).

Inherited zircons in the Logrosan granite define an age range of ca. 447-1975 Ma displaying predominant Neoproterozoic populations (Table 5). Despite the limited dataset (13 inherited zircons), it is still possible to distinguish two main groups: (1) Cambro-Ordovician and Neoproterozoic ages and (2) Meso- and Paleoproterozoic ages (Fig. 10). The first group of inheritance (Early Paleozoic and Neoproterozoic) is the most abundant and fits well with materials derived from the Cadomian orogeny. The minor amount of Mesoproterozoic zircon inheritances and the distribution of Nd and Hf model ages around 1.45 [+ or -] 0.2 Ga, either in Variscan granites and Neoproterozoic metasediments, have been attributed to the Saharan and Arabian-Nubian shields as possible supplying provinces for the Central Iberian Zone (e.g., Pereira et al., 2012; Villaseca et al., 2011; Bea et al, 2010; Henry et al., 2009). The only Ordovician age (ca. 447 Ma) could be related to the Ordovician magmatism described along the Central Iberian Zone (e.g., Rubio-Ordonez et al., 2012; Neiva et al., 2009; Sola et al., 2008; Bea et al., 2007). In general, the probability density curve of the Logrosan granite inheritances shows a broad overlap with the zircon U-Pb age distribution previously reported for the Schist Greywacke Complex ages (Talavera et al., 2012; Teixeira et al., 2011; Gutierrez-Alonso et al., 2003) (Fig. 10). This comparison again points to the Schist Greywacke Complex as the most probable protolith of the Logrosan granite.

Magmatic zircons from the Logrosan granite have a significant wide range of [epsilon][Hf.sub.(t)] values showing variations up to 15 eHf units, similar to those observed in samples of Variscan S-type granites from northern Portugal (Teixeira et al., 2011). The large range of negative eHfffi values is in agreement with the S-type nature of the granite but there is also a significant proportion of positive [epsilon][Hf.sub.(t)] values (Fig. 9). The large range of negative [epsilon][Hf.sub.(t)] values denotes an origin by partial melting of heterogeneous crustal sources or by crustal contamination of a mantle-derived parental magma as proposed for other Variscan S-type granites from the Central Iberian Zone (Teixeira et al., 2011; Neiva et al., 2013). Although positive [epsilon][Hf.sub.(t)] values tend to be interpreted as mantle-derived, this cannot be easily applied to the Logrosan granite. The absence of coeval mafic magmatism and the clearly peraluminous and perphosphorous character of the Logrosan cupola is more in agreement with the involvement of recycled juvenile material in the genesis of this granite. From this prospective, [epsilon]Hf values of Neoproterozoic zircons from the SGC metasediments (sample from Sabugal area, spots 21 and 70 of Teixeira et al., 2011), recalculated at the age of the Logrosan granite emplacement, yield positive values (up to +4.5) that overlap with those found in Variscan-age zircons from the Logrosan granite. Moreover, some inherited Neoproterozoic zircons within the Logrosan granite show strong positive eHfffi values (up to +14.7, e.g. L24-33, Table 6) similar to zircon populations found in metasediments from the SGC (up to +11.7, spot Malcl-21 of Teixeira et al., 2011). Such correlation reinforces the genetic relationship with this probable protolith (Fig. 9) and is in agreement with the presence of a recycled mantle-derived component in the granite crustal source.

6.4. Geochronological comparison

Widespread granite generation occurred across the Central Iberian Zone over 325-300 Ma time interval (e.g., Dias et al., 1998; Fernandez Suarez et al., 2000; Bea et al., 2003; Orejana et al., 2012). Most of the felsic magmatism in the CIZ is synto post-tectonic with respect to the last ductile deformation phase (D3) (Dias et al., 1998) with three peaks at 320 (mainly syn-D3 leucogranites of Galicia and northern Portugal), 308306 and 301 Ma (Orejana et al., 2012; Teixeira et al., 2011; Fernandez-Suarez et al., 2000; Dias et al., 1998). The U-Pb results presented here indicate that the Logrosan intrusion occurred at ca. 308 Ma, thus in a post-tectonic Variscan stage.

The comparison of the ages of the granites from the southern CIZ (those of the Central Extremadura Batholith) and the Logrosan granite shows a good overlap: 310 Ma for Castelo Branco (Antunes et al., 2008), 308 Ma for Nisa-Alburquerque (Sola et al., 2009), 314-298 Ma for the Montes de Toledo (Orejana et al., 2011), and 309 Ma for the Cabeza de Araya and Trujillo plutons (Gutierrez-Alonso et al., 2011). They are also similar in age to the emplacement of the Los Pedroches batholith (314-304 Ma, Carracedo et al., 2009) located in the southern edge of the CIZ and to the age range of emplacement of the Spanish Central System batholith (311-298 Ma, Orejana et al., 2012; Diaz-Alvarado et al., 2011; Zeck et al., 2007; Bea et al., 2003). These similarities in age indicate that granite batholiths and plutons from the Spanish Central System and the southern CIZ are practically coeval.

7. Conclusions

The Logrosan cupola is a felsic, perphosphoric and strongly peraluminous (ASI=1.2-2) tin-granite (Sn=11-67ppm). Two distinct units can be distinguished using field, petrographic and geochemical evidences: (1) a coarse-grained monzogranite (Main Unit) and (2) highly fractionated leucogranite bodies mostly concentrated on the top of the pluton (Evolved Units). U-Pb zircon analyses yield a concordia age of 307.88 [+ or -] 0.86 Ma which is considered the age of the emplacement of the Logrosan granite, coeval with other post-Variscan granites of the Central Iberian Zone. The Ti-in-zircon thermometry provides an average estimated temperature of 836[degrees]C for the parental magma. The whole-rock geochemistry does not indicate that simple fractional

crystallization may produce both the Main and the Evolved granite suites. Complex Sr, Ba, Rb, Eu and CaO trends rather suggest inputs of different felsic magma batches from a deep magma reservoir. The integration of whole-rock geochemistry with O, Sr, Nd and Hf isotopic signatures suggests that the Logrosan granite is the result of partial melting of heterogeneous metasedimentary materials. And finally, zircon inheritance (mostly Neoproterozoic zircons) combined with the metasedimentary nature of the proposed protolith, allow to suggest that the Schist Greywacke Complex is the most appropriated source of the Logrosan granitic magma.

http://dx.doi.org/10.5209/rev_JIGE.2014.v40.n3.43928

Acknowledgments

This work was supported by the projects CGL2012-32822 (Economy and Competitivity Spanish Office) and 910492 (Complutense University), and the grant for C.Villaseca from Fundacion CajaMadrid. E. Chicharro would like to express her gratitude to Dr. Teresa E. Jeffries, from the Natural History Museum of London, for the provision of the analytical facilities and her assistance with the laser ablation technique. C. Villaseca also thanks the opportunity to undertake the analytical work in the Geochemical Analysis unit at GEMOC, at Macquarie University. We acknowledge Norman Pearson and Will Powell for their assistance with the LA-ICPMS analyses. PVV thanks funding from grant CGL2008-05952C[O.sub.2]-[O.sub.2]/BTE. Thanks are also given to Dr. Teresa Ubide, one anonymus reviewer and the editors whose thorough and helpful comments greatly improved the quality of the manuscript. Grateful thanks to Dr. Clemente Recio for carrying out the stable isotope analysis. This is contribution 464 from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au) and 941 in the GEMOC Key Centre (http://www.gemoc.mq.edu.au).

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E. Chicharro (1,2)*, C. Villaseca (2,3), P. Valverde-Vaquero (4), E. Belousova (5), J.A. Lopez-Garcia (1)

(1) Dpt. Cristalografia y Mineralogia, Facultad Ciencias Geologicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.

(2) Instituto de Geociencias (UCM, CSIC), c. Jose Antonio Novais, 12, 28040 Madrid, Spain

(3) Dpt. Petrologia y Geoquimica, Facultad Ciencias Geologicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.

(4) Instituto Geologico y Minero de Espana (IGME), Madrid, Spain.

(5) Dpt. Earth and Planetary Sciences, GEMOC, Macquarie University, Sydney, NSW 2109, Australia.

e-mail addresses:evachicharro@ucm.es (E.C., Corresponding author); granito@ucm.es (C.V.); p.valverde@igme.es(P. V-V); ebelouso@els.mq.edu.au (E.B.);

jangel@geo.ucm.es (J.A.L-G.)

Received: 10 January 2014 / Accepted: 10 June 2014 / Available online: 30 October 2014

Table 1.- Whole-rock major (wt. %), trace-element and REE (ppm)
compositions of the Logrosan granite

                                          Main granite

                       AQ1      AQ2      AQ4      AQ6      AQ13
                      111911   111912   111976   111978    L178

Si[O.sub.2]           72.46    72.26    72.53    73.93    73.12
[Al.sub.2][O.sub.3]   14.43    14.76    15.24    15.14    14.92
Fe[O.sub.t]            1.25     1.71     1.33     0.82     1.37
MnO                    0.02     0.02     0.02     0.02     0.02
MgO                    0.28     0.33     0.38     0.16     0.33
CaO                    0.59     0.45     0.69     0.50     0.54
[Na.sub.2]O            3.68     2.67     3.31     3.87     3.31
[K.sub.2]O             4.46     4.75     4.88     4.19     4.42
Ti[O.sub.2]            0.18     0.23     0.27     0.10     0.21
[P.sub.2][O.sub.5]     0.50     0.47     0.57     0.57     0.49
LOI                    1.33     2.55     1.62     1.51     1.47
Total                 99.16    100.20   100.80   100.80   100.20
Sc                     3.00     4.00     2.00     3.00     3.00
Be                    15.00    23.00    16.00    11.00    14.00
V                      7.00    12.00    10.00     < 5     13.00
Cr                     < 20     < 20     < 20     < 20     < 20
Co                     2.00     4.00     3.00     3.00     2.00
Ni                     < 20     < 20     < 20     < 20     < 20
Cu                     < 10    20.00     < 10     < 10    20.00
Zn                    30.00    50.00     60.0    30.00    40.00
Ga                    21.00    23.00    25.00    20.00    22.00
Ge                     2.20     2.10     1.70     2.30     2.30
As                     60.0     51.0     137      94.0     137
Rb                     288      301      338      317      311
Sr                    44.00    41.00     57.0    39.00    44.00
Y                      6.90     5.20     7.60     5.50     7.60
Zr                     76.0     80.0     118      43.0     82.0
Nb                     8.70    11.70    10.10    13.60    11.40
Mo                     < 2      < 2      < 2      < 2      < 2
Ag                    < 0.5     0.50    < 0.5    < 0.5    < 0.5
In                    < 0.1     0.10    < 0.1    < 0.1    < 0.1
Sn                     50.0     67.0     33.0     35.0     49.0
Sb                     0.50     0.40    < 0.2     0.70    < 0.2
Cs                     59.5     88.0     74.4     50.2     54.6
Ba                     224      241      290      138      226
La                    13.80    16.10    21.80     6.53    15.10
Ce                    31.40    35.60    50.20    14.80    33.10
Pr                     3.58     3.85     6.42     1.74     3.95
Nd                    13.30    14.50    25.80     6.40    15.60
Sm                     2.96     3.05     5.18     1.56     3.25
Eu                     0.32     0.32     0.47     0.21     0.33
Gd                     2.24     2.21     3.35     1.44     2.54
Tb                     0.33     0.29     0.46     0.25     0.36
Dy                     1.52     1.35     1.85     1.20     1.64
Ho                     0.24     0.21     0.26     0.19     0.25
Er                     0.60     0.52     0.60     0.51     0.66
Tm                     0.09     0.07     0.08     0.07     0.09
Yb                     0.56     0.49     0.44     0.53     0.52
Lu                     0.08     0.07     0.06     0.07     0.08
Hf                     2.20     2.40     3.00     1.50     2.60
Ta                     2.26     3.08     2.50     4.76     3.73
W                     24.60     82.1     74.2    36.00    23.90
Tl                     1.84     1.98     2.02     1.99     1.87
Pb                    28.00    22.00    29.00    21.00    24.00
Bi                     0.30    < 0.1     0.60     1.50     0.30
Th                     7.59     8.28    19.90     3.07     8.70
U                      7.91     7.25    10.90     8.49     7.04
F                               2003     1611     1150
Li                              290      303      141
T                      738      755      777      699      752
([degrees]C) *

                              Evolved granites

                       AQ14     AQ5     AQ11     AQ12
                       179     111979   L174     L177

Si[O.sub.2]           74.03    72.94    72.73   74.01
[Al.sub.2][O.sub.3]   14.94    15.30    14.42   14.83
Fe[O.sub.t]            1.14     0.78    1.45     1.17
MnO                    0.02     0.01    0.02     0.02
MgO                    0.24     0.22    0.22     0.26
CaO                    0.51     0.46    0.25     0.46
[Na.sub.2]O            3.42     3.27    2.95     2.95
[K.sub.2]O             4.53     4.83    4.35     4.63
Ti[O.sub.2]            0.17     0.17    0.13     0.15
[P.sub.2][O.sub.5]     0.46     0.54    0.51     0.55
LOI                    1.08     1.95    1.98     1.74
Total                 100.50   100.50   99.00   100.80
Sc                     2.00     2.00    2.00     3.00
Be                    18.00     7.00    19.00    9.00
V                     10.00     < 5     10.00    9.00
Cr                     < 20     < 20     280     180
Co                     2.00     2.00    2.00     2.00
Ni                     < 20     < 20    < 20     < 20
Cu                     < 10     < 10    < 10     < 10
Zn                     70.0     < 30    70.0     < 30
Ga                    21.00    20.00    24.00   20.00
Ge                     2.10     1.50    3.40     2.50
As                     64.0     123     44.0     103
Rb                     238      270      362     317
Sr                    38.00     52.0    32.00    57.0
Y                      9.60     5.40    3.30     6.60
Zr                     77.0     74.0    60.0     62.0
Nb                     9.00     9.60    15.90   11.10
Mo                     < 2      < 2      < 2     < 2
Ag                    < 0.5     0.70    < 0.5   < 0.5
In                    < 0.1    < 0.1    0.10    < 0.1
Sn                    11.00    37.00    29.00    53.0
Sb                     0.30     0.90    < 0.2    0.50
Cs                     26.7     70.3    51.6     145
Ba                     178      219      152     225
La                    13.00    11.40    8.81     9.67
Ce                    27.70    27.80    19.20   20.70
Pr                     3.34     3.25    2.17     2.48
Nd                    12.90    12.50    8.06    10.00
Sm                     2.94     2.92    1.73     2.47
Eu                     0.30     0.32    0.19     0.36
Gd                     2.52     2.22    1.26     2.24
Tb                     0.40     0.35    0.18     0.35
Dy                     1.87     1.50    0.84     1.75
Ho                     0.32     0.22    0.12     0.24
Er                     0.86     0.46    0.30     0.51
Tm                     0.12     0.06    0.05     0.06
Yb                     0.71     0.37    0.30     0.38
Lu                     0.11     0.05    0.05     0.06
Hf                     2.50     2.50    1.70     2.10
Ta                     1.97     1.98    4.00     2.30
W                      9.00     131     1.60     376
Tl                     1.40     1.77    1.56     1.79
Pb                    28.00    26.00    21.00   29.00
Bi                     2.60     0.40    < 0.1    0.60
Th                     6.65     8.67    5.30     4.45
U                     11.00    10.50    9.04     7.23
F                               1053
Li                              209
T                      746      744      734     733
([degrees]C) *

* Temperatures estimated using the saturation zircon
temperature of Watson and Harrison (1983)

Table 2.- Sr-Nd and O-D isotopic data of the Logrosan granite

Sample      Rock type      Age (Ma)   Rb    Sr   [sup.87]Rb/
                                                 [sup.86]Sr

AQ2       main granite       308      301   41     21.487
AQ6       main granite       308      317   39     23.806
AQ13      main granite       308      311   44     20.657
AQ3      altered granite     308      411   28     43.362
AQ10     altered granite     308      361   77     13.658
AQ5      evolved granite
AQ12     evolved granite     308      317   57     16.216

Sample   [sup.87]Sr/   [+ or -]   ([sup.87]Sr/   Sm (ppm)
         [sup.86]Sr    2[sigma]   [sup.86]Sr)
                                    .sub.t]

AQ2       0.822394        4         0.728213       3.05
AQ6       0.829387        6         0.725042       1.56
AQ13      0.807511        3         0.716966       3.25
AQ3       0.918694        6         0.728633       2.76
AQ10      0.774096        4         0.714232       4.90
AQ5
AQ12      0.783536        3         0.712459       2.47

Sample   Nd (ppm)   [sup.147]Sm/   [sup.143]Nd/   [+ or -]
                    [sup.144]Nd    [sup.144]Nd    2[sigma]

AQ2       14.50        0.1272        0.512294        2
AQ6        6.40        0.1474        0.512321        2
AQ13      15.60        0.1259        0.512290        1
AQ3       11.10        0.1503        0.512325        1
AQ10      19.50        0.1519        0.512343        1
AQ5
AQ12      10.00        0.1493        0.512327        2

Sample   [([sup.143]Nd/     [[epsilon]     TDM
          [sup.144]Nd)    .sup.t.sub.Nd]
            .sub.t]

AQ2         0.512037           -4.0        1.32
AQ6         0.512024           -4.2        1.62
AQ13        0.512036           -4.0        1.31
AQ3         0.512022           -4.3        1.67
AQ10        0.512036           -4.0        1.67
AQ5
AQ12        0.512026           -4.2        1.65

Sample    [[delta]      [delta]      [H.sub.2]O%
          .sup.18]    [D.sub.SMOW]
         .sub.SMOW]

AQ2         14.1         -84.7           1.4
AQ6
AQ13
AQ3
AQ10
AQ5         14.5         -77.9           1.3
AQ12        15.0         -77.0           1.2

Table 3.- LA-ICPMS trace element composition and REE (ppm)
of zircons from the Logrosan granite

Sample            L30-27   L24-17   L24-1    L24-20   L30-30

Age *               V        V        V        V        V

P                  409      274      516      409      430
Sc                 244      392      222      556      381
Ti                19.78    18.40    22.84     7.37    12.65
Y                  1780     1960     1560     3630     2280
Nb                 1.67     2.70     1.57     5.24     4.64
Ta                 0.52     0.88     0.50     1.60     1.53
Hf                 8490    10100     8680     9740    11800
Pb                 6.54     8.47     4.53     6.37    39.50
Th                 179      234      159      236      852
U                  601      1050     384      577      1530
La                 0.24     1.07     0.11    <0.06     2.21
Ce                 4.41     9.28     4.53     5.18     33.6
Pr                 0.51     1.44     0.65     0.22     8.37
Nd                 7.22     11.7     9.79     3.81     68.1
Sm                 14.7     16.0     15.6     12.0     46.3
Eu                 0.45     1.07     0.74     0.83     2.03
Gd                58.20    59.10    57.10    82.60    99.60
Tb                18.60    19.80    17.30    29.90    27.50
Dy                 206      209      179      366      262
Ho                 65.8     68.1     54.6     127      78.8
Er                 260      284      229      549      319
Tm                55.10    58.30    45.00    110.0    66.20
Yb                 531      568      413      1000     626
Lu                72.00    82.00    58.30    148.0    100.0
LREE              85.72    99.66    88.53    104.6    260.2
HREE               1209     1289     996      2330     1480
Zr/Hf             50.19    47.32    51.11    47.39    40.53
T                  872      863      889      766      821
([degrees]C) **

Sample            L24-19   L24-16   L24-6    L24-20   L30-31

Age *               V        V        V        V        V

P                  674      328      1233     692      613
Sc                 157      323      939      564      625
Ti                11.21    21.04     5.89    19.14    61.60
Y                  1440     1240     3612     1622     1082
Nb                 1.66     1.62     4.11     1.77     1.86
Ta                 0.55     0.44     1.34     0.57     0.49
Hf                 9150     8970    11524     9565    10633
Pb                21.50     5.94     5.30     5.64     8.32
Th                 750      202      149      185      236
U                  763      511      772      395      403
La                <0.06    <0.06    0.513    0.224     0.25
Ce                 7.12     3.06     5.18     4.79     3.70
Pr                 0.59     0.32     0.39     0.77     0.60
Nd                 9.26     5.74     4.36     11.1     7.6
Sm                 15.1     11.3     9.83     15.6     11.8
Eu                 0.43     0.39     0.62     0.77     0.34
Gd                55.80    40.00    61.93    59.12    41.23
Tb                15.80    12.20    23.48    16.34    11.17
Dy                 163      128      312      180      117
Ho                 53.2     42.7    113.6    55.65    37.58
Er                 218      186      505      222      156
Tm                44.60    40.50    104.2    43.72    31.43
Yb                 412      406      935      390      286
Lu                58.50    60.90    160.7    60.49    49.18
LREE              88.30    60.82    82.82    92.37    65.56
HREE               965      876      2154     968      688
Zr/Hf             49.98    49.35    42.74    47.86    45.18
T                  808      879      744      868      1024
([degrees]C) **

Sample            L24-10   L24-9    L30-28   L24-12

Age *               V       O-I      PO-I     PO-I

P                  585      322      430      942
Sc                 627      157      253      580
Ti                12.34    56.71    22.96    15.70
Y                  934      1060     1840     917
Nb                 1.75     1.61     1.17     4.21
Ta                 0.46     0.41     0.31     3.92
Hf                 7631     8370     9800     8471
Pb                 5.08     4.07     5.30    15.72
Th                 148      127      182      353
U                  568      179      243      740
La                 0.39    0.303    <0.06     2.37
Ce                 4.21     3.46     2.61     19.9
Pr                 0.68     0.43     0.49     4.68
Nd                 7.24     6.26     8.27     33.4
Sm                 8.92     9.21     15.8     21.8
Eu                 0.40     0.55     0.55     1.19
Gd                33.21    35.30    65.50    44.28
Tb                 9.32    10.40    18.80    11.66
Dy                 98.2     114      197      108
Ho                31.61     37.6     65.3     30.9
Er                 130      161      277      119
Tm                26.91    33.10    54.60    25.31
Yb                 254      315      485      236
Lu                41.88    50.50    79.60    36.53
LREE              55.05    55.52    93.22    127.6
HREE               592      722      1177     567
Zr/Hf             55.40    55.16    49.06    44.01
T                  818      1012     890      845
([degrees]C) **

* V Variscan-age zircon, PO-I pre-Ordovician inheritance,
O-I Ordovician inheritance. ** Temperatures estimated using
the Ti-in-zircon geothermometer recalibrated by Ferry and Watson
(2007). Temperatures uncertainty for each data is [+ or -] 4.5%

Table 4.- U-Pb ID-TIMS data of zircon and monazite fractions
from the Logrosan granite

                                   Concentration

Sample             Weight   U (ppm)   Pb (ppm)   Common
                    (mg)                         Pb (pg)

Z4 (A9)20smpr       120       101       8.0        231
Z1(A5)25smpr        100       81        4.4        33
Z2(A7)11medpr        80       125       6.6        38
Z3 (A8)3larpr        60       111       8.5        93
Z5(L1)3xtls          30       57        2.9         4
Z6(L4)Single         30       61        3.2         6
Z7(L2)2xtls+1fra     60       63        3.0         4
Z8(L3)Single         30       92        4.6         7
M1(X7)2xtls          20      5849       548        412

                                   Isotopic ratios

Sample              [sup.206]    [sup.206]Pb/   %(2s)   [sup.207]Pb/
                      Pb */       [sup.238]U             [sup.235]U
                   [sup.204]Pb

Z4 (A9)20smpr          134         0.05183      0.46       0.3895
Z1(A5)25smpr           583         0.05005      0.25       0.3651
Z2(A7)11medpr          617         0.04952      0.31       0.3602
Z3 (A8)3larpr          154         0.04889      0.44       0.3540
Z5(L1)3xtls           1063         0.04882      0.19       0.3540
Z6(L4)Single           724         0.04936      0.43       0.3586
Z7(L2)2xtls+1fra      1542         0.04771      0.43       0.3465
Z8(L3)Single           918         0.04907      0.42       0.3557
M1(X7)2xtls            784         0.04883      0.24       0.3540

                              Isotopic ratios

Sample             %(2s)   [sup.207]Pb/   % (2s)   Rho
                           [sup.206]Pb

Z4 (A9)20smpr      0.91      0.05451       0.76    0.56
Z1(A5)25smpr       0.44      0.05291       0.35    0.60
Z2(A7)11medpr      0.80      0.05276       0.73    0.40
Z3 (A8)3larpr      1.04      0.05251       0.90    0.52
Z5(L1)3xtls        0.75      0.05250       0.69    0.44
Z6(L4)Single       0.56      0.05269       0.35    0.78
Z7(L2)2xtls+1fra   0.60      0.05266       0.41    0.73
Z8(L3)Single       0.50      0.05257       0.27    0.85
M1(X7)2xtls        0.25      0.05258       0.08    0.95

                               Apparent ages (Ma)

Sample             [sup.206]Pb/   [sup.207]Pb/   [sup.207]Pb/
                    [sup.238]U     [sup.235]U    [sup.206]Pb

Z4 (A9)20smpr         325.7          334.0          392.0
Z1(A5)25smpr          314.8          316.0          324.7
Z2(A7)11medpr         311.6          312.4          318.4
Z3 (A8)3larpr         307.7          307.7          307.5
Z5(L1)3xtls           307.3          307.3          307.2
Z6(L4)Single          310.6          311.1          315.3
Z7(L2)2xtls+1fra      300.5          302.0          314.3
Z8(L3)Single          308.8          309.0          310.1
M1(X7)2xtls           307.3          307.7          310.9

Z, zircon, number of crystals; sm., small (ca. 80[micro]m); med.,
medium (100-120pm); lar., large (120-180pm); pr., euhedral
prisms (1:5 width/length ratio);el.; elongated (1:7 width/
length ratio); s.xtl., single crystal (>180[micro]m). All zircon
fractions were chemically abraded (CA technique after
Mattinson (2005). M, monazite. * Ratio corrected for mass
fractionation (0.11 [+ or -] 0.02 % AMU Pb; 0.10 [+ or -]
0.02 % AMU U), spike contribution and analytical blank
(6 pg Pb; 0.1 pg U). The other isotopic ratios are also
corrected for initial common Pb after the model of Stacey
and Kramers (1975). Rho, error OREJ correlation coefficient
of the [sup.207]Pb/[sup.235]U and [sup.206]Pb/[sup.238]U ratios.
Data reduced with PbMacDat (Isachsen et al 2007;
www.earth-time.org)

Table 5.- U-Pb LA-ICPMS data of zircons from the
Logrosan granite

Analysis    Common     U (ppm)   Th (ppm)   Th/U
           [sup.206]
            Pb (%)

L20-34       1.02       1590       330      0.207
L20-35       0.19        330       281      0.851
L20-36         0         245       141      0.577
L24-1          0         635       318      0.500
L24-2          0         291       226      0.777
L24-3          0        1088        50      0.046
L24-4C         0         339       174      0.513
L24-4R         0         281       166      0.593
L24-5        0.39        113        73      0.646
L24-6          0         490       165      0.336
L24-9          0         539       272      0.505
L24-10         0         154       136      0.879
L24-11       -0.16       328       209      0.637
L24-12         0         116        54      0.470
L24-13       0.43       2539       146      0.057
L24-16        0.1        485       241      0.497
L24-17         0         185       144      0.778
L24-19         0         233       212      0.910
L24-20         0         218       146      0.668
L24-32         0         320       159      0.496
L24-33         0         272       163      0.597
L30-21         0         306       240      0.784
L30-22         0         920        63      0.068
L30-23       -0.44       672       344      0.512
L30-24         0         925        99      0.107
L30-25         0        2028       2046     1.009
L30-26         0         542       166      0.307
L30-27         0         440       311      0.709
L30-28         0         176       342      1.944
L30-29       -0.38      2448       2228     0.910
L30-30       0.83       9542       250      0.026
L30-31         0         591       618      1.045

                           Radiogenic ratios

Analysis   [sup.207]Pb/   [sigma]   [sup.206]Pb/   [sigma]
            [sup.235]U               [sup.238]U

L20-34        0.3450      0.0117       0.0468      0.0007
L20-35        5.5353      0.1042       0.3311      0.0043
L20-36        0.3577      0.0082       0.0480      0.0007
L24-1         0.3596      0.0062       0.0483      0.0006
L24-2         0.3720      0.0091       0.0479      0.0007
L24-3         0.7040      0.0196       0.0837      0.0014
L24-4C        0.7413      0.0162       0.0891      0.0011
L24-4R        0.3788      0.0103       0.0499      0.0008
L24-5         5.2215      0.0922       0.3168      0.0038
L24-6         0.3510      0.0073       0.0481      0.0007
L24-9         0.7521      0.0117       0.0912      0.0011
L24-10        0.3634      0.0084       0.0494      0.0007
L24-11        0.9244      0.0140       0.1058      0.0013
L24-12        1.3287      0.0207       0.1405      0.0016
L24-13        0.3778      0.0116       0.0488      0.0008
L24-16        0.3776      0.0062       0.0489      0.0006
L24-17        0.3632      0.0156       0.0487      0.0009
L24-19        0.3538      0.0090       0.0477      0.0007
L24-20        0.3579      0.0110       0.0484      0.0008
L24-32        0.7701      0.0148       0.0935      0.0013
L24-33        1.0815      0.0183       0.1210      0.0015
L30-21        0.3597      0.0092       0.0481      0.0007
L30-22        0.8833      0.0264       0.1024      0.0018
L30-23        0.3666      0.0080       0.0481      0.0007
L30-24        0.5643      0.0081       0.0717      0.0009
L30-25        0.8096      0.0148       0.0962      0.0013
L30-26        0.3563      0.0080       0.0480      0.0007
L30-27        0.3534      0.0069       0.0479      0.0006
L30-28        1.8804      0.0465       0.1819      0.0024
L30-29        0.3715      0.0075       0.0479      0.0007
L30-30        0.3463      0.0078       0.0467      0.0006
L30-31        0.3494      0.0091       0.0475      0.0007

                 Radiogenic ratios            Age (Ma)

Analysis   [rho]   [sup.207]Pb/   [sigma]   [sup.206]Pb/
                   [sup.206]Pb               [sup.238]U

L20-34     0.38       0.0534      0.0020        295
L20-35     0.36       0.1213      0.0023        1844
L20-36     0.29       0.0540      0.0012        302
L24-1      0.44       0.0540      0.0009        304
L24-2      0.32       0.0563      0.0014        302
L24-3      0.33       0.0610      0.0017        518
L24-4C      0.2       0.0604      0.0014        550
L24-4R     0.31       0.0550      0.0015        314
L24-5      0.29       0.1196      0.0022        1774
L24-6      0.39       0.0529      0.0011        303
L24-9      0.44       0.0598      0.0009        563
L24-10     0.28       0.0534      0.0012        311
L24-11     0.42       0.0634      0.0009        648
L24-12     0.34       0.0686      0.0011        847
L24-13     0.26       0.0561      0.0019        307
L24-16     0.33       0.0560      0.0009        308
L24-17     0.16       0.0541      0.0024        306
L24-19     0.29       0.0538      0.0014        301
L24-20     0.22       0.0536      0.0017        305
L24-32     0.41       0.0598      0.0011        576
L24-33     0.38       0.0648      0.0011        736
L30-21      0.3       0.0542      0.0014        303
L30-22     0.29       0.0626      0.0019        629
L30-23     0.37       0.0553      0.0012        303
L30-24     0.48       0.0571      0.0008        447
L30-25     0.47       0.0610      0.0010        592
L30-26     0.34       0.0539      0.0012        302
L30-27     0.37       0.0535      0.0010        301
L30-28     0.15       0.0750      0.0020        1078
L30-29     0.41       0.0563      0.0011        301
L30-30     0.35       0.0538      0.0014        294
L30-31      0.3       0.0534      0.0014        299

                              Age (Ma)

Analysis   [sigma]   [sup.207]Pb/   [sigma]   Disc (%)
                     [sup.206]Pb

L20-34        4          347          85         18
L20-35       21          1975         34         7
L20-36        4          371          53         23
L24-1         4          372          38         22
L24-2         4          464          55         54
L24-3         8          641          60         24
L24-4C        7          618          50         12
L24-4R        5          414          62         32
L24-5        19          1950         33         10
L24-6         4          324          46         7
L24-9         7          597          33         6
L24-10        4          344          53         11
L24-11        7          721          32         11
L24-12        9          888          34         5
L24-13        5          457          78         49
L24-16        3          452          38         47
L24-17        6          376          101        23
L24-19        4          362          58         20
L24-20        5          355          72         16
L24-32        7          595          41         3
L24-33        8          769          36         4
L30-21        4          380          58         25
L30-22       10          694          65         10
L30-23        4          423          48         40
L30-24        5          494          30         11
L30-25        8          641          37         8
L30-26        4          366          51         21
L30-27        4          351          44         17
L30-28       13          1068         54         -1
L30-29        4          463          44         54
L30-30        4          361          61         23
L30-31        4          344          60         15

Table 6.- Lu-Hf LA-MC-ICPMS data of zircons from
the Logrosan granite

Sample    [sup.176]Hf/     1SE      [sup.176]Lu/   [sup.176]Yb/
          [sup.177]Hf               [sup.177]Hf    [sup.177]Hf

L24-1       0.282745     0.000039      0.0011         0.0295
L24-2       0.282761     0.000059      0.0006         0.0166
L24-6       0.282555     0.000057      0.0003         0.0087
L24-10      0.282466     0.000052      0.0008         0.0221
L24-16      0.282516     0.000041      0.0006         0.0171
L24-17      0.282496     0.000053      0.0005         0.0146
L24-19      0.282653     0.000029      0.0011         0.0318
L24-20      0.282601     0.000033      0.0013         0.0359
L24-21      0.282304     0.000140      0.0008         0.0219
L24-23      0.282488     0.000035      0.0008         0.0239
L24-26      0.282614     0.000032      0.0002         0.0059
L24-27      0.282591     0.000035      0.0011         0.0313
L24-31      0.282502     0.000160      0.0014         0.0378
L24-36      0.282651     0.000050      0.0010         0.0295
L24-24      0.282489     0.000110      0.0023         0.0654
L24-3       0.282557     0.000046      0.0009         0.0214
L24-7       0.281758     0.000052      0.0004         0.0103
L24-4       0.282528     0.000048      0.0010         0.0263
L24-9       0.282586     0.000036      0.0012         0.0299
L24-32      0.28261      0.000049      0.0016         0.0425
L24-25      0.282338     0.000032      0.0014         0.0400
L24-22      0.281564     0.000069      0.0013         0.0314
L24-11      0.282687     0.000034      0.0008         0.0217
L24-33      0.282749     0.000040      0.0010         0.0237
L24-12      0.282264     0.000057      0.0011         0.0330
L24-28      0.282034     0.000032      0.0013         0.0352
L24-05      0.28134      0.000051      0.0004         0.0097
L24-35      0.281449     0.000057      0.0005         0.0140

Sample    Age (Ma)   [Hf.sub.I]   [epsilon]Hf

L24-1       308       0.282739        5.0
L24-2       308       0.282758        5.7
L24-6       308       0.282553       -1.5
L24-10      308       0.282462       -4.8
L24-16      308       0.282512       -3.0
L24-17      308       0.282493       -3.7
L24-19      308       0.282647        1.8
L24-20      308       0.282594       -0.1
L24-21      308       0.282299       -10.5
L24-23      308       0.282483       -4.0
L24-26      308       0.282613        0.6
L24-27      308       0.282585       -0.4
L24-31      308       0.282494       -3.6
L24-36      308       0.282645        1.7
L24-24      447       0.282469       -1.2
L24-3       518       0.282549        3.2
L24-7       545       0.281753       -24.4
L24-4       550       0.282518        2.8
L24-9       563       0.282573        5.1
L24-32      576       0.282592        6.0
L24-25      592       0.282322       -3.2
L24-22      629       0.281549       -29.7
L24-11      648       0.282677       10.6
L24-33      736       0.282735       14.7
L24-12      847       0.282246       -0.2
L24-28      1068      0.282007       -3.6
L24-05      1950      0.281326       -7.6
L24-35      1975      0.281428       -3.4

Sample    1SE   [T.sub.DM]   [T.sub.DM2]
                   (Ga)         (Ga)

L24-1     1.4      0.72         0.98
L24-2     2.1      0.69         0.93
L24-6     2.0      0.97         1.39
L24-10    1.8      1.11         1.60
L24-16    1.5      1.03         1.49
L24-17    1.9      1.06         1.53
L24-19    1.0      0.85         1.18
L24-20    1.2      0.93         1.30
L24-21    5.0      1.33         1.96
L24-23    1.2      1.08         1.55
L24-26    1.1      0.88         1.26
L24-27    1.2      0.94         1.32
L24-31    5.7      1.07         1.53
L24-36    1.8      0.85         1.19
L24-24    3.9      1.12         1.49
L24-3     1.6      0.98         1.27
L24-7     1.8      2.07         3.02
L24-4     1.7      1.03         1.32
L24-9     1.3      0.95         1.18
L24-32    1.7      0.93         1.13
L24-25    1.1      1.31         1.73
L24-22    2.5      2.38         3.42
L24-11    1.2      0.80         0.89
L24-33    1.4      0.71         0.70
L24-12    2.0      1.40         1.74
L24-28    1.1      1.73         2.14
L24-05    1.8      2.63         3.09
L24-35    2.0      2.49         2.84
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Title Annotation:texto en ingles
Author:Chicharro, E.; Villaseca, C.; Valverde-Vaquero, P.; Belousova, E.; Lopez-Garcia, J.A.
Publication:Journal of Iberian Geology
Date:Dec 1, 2014
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