Genesis of the Gore Mountain garnet deposit, New York

Bartholomé, Paul

doi:10.2113/gsecongeo.55.2.255

Cited by 13 publications

(9 citation statements)

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“…These have all been characterised for δ 18 O in the University of Oregon laser fluorination stable isotope laboratory. Our primary SIMS RM is called ‘UAG’ (sample number S0068), a megacrystic pyrope garnet from the Gore Mountain Mine (Bartholomé ). Hundreds of ion microprobe analyses in our laboratory on dozens of randomly selected grains strongly suggest that this sample is homogeneous at better than 0.1‰ in 18 O/ 16 O.…”

Section: Experimental Set‐upmentioning

confidence: 99%

Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet

Ickert

Stern

2013

Geostandard Geoanalytic Res

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We report technical and data treatment methods for making accurate, high‐precision measurements of 18O/16O in Ca–Mg–Fe garnet utilising the Cameca IMS 1280 multi‐collector ion microprobe. Matrix effects were similar to those shown by previous work, whereby Ca abundance is correlated with instrumental mass fractionation (IMF). After correction for this effect, there appeared to be no significant secondary effect associated with Mg/Fe2+ for routine operational conditions. In contrast, investigation of the IMF associated with Mn‐ or Cr‐rich garnet showed that these substitutions are significant and require a more complex calibration scheme. The Ca‐related calibration applied to low‐Cr, low‐Mn garnet was reproducible across different sample mounts and under a range of instrument settings and therefore should be applicable to similar instruments of this type. The repeatability of the measurements was often better than ± 0.2‰ (2s), a precision that is similar to the repeatability of bulk techniques. At this precision, the uncertainties due to spot‐to‐spot repeatability were at the same magnitude as those associated with matrix corrections (± 0.1–0.3‰) and the uncertainties in reference materials (± 0.1–0.2‰). Therefore, it is necessary to accurately estimate and propagate uncertainties associated with these parameters – in some cases, uncertainties in reference materials or matrix corrections dominate the uncertainty budget.

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Section: Experimental Set‐upmentioning

confidence: 99%

Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet

Ickert

Stern

2013

Geostandard Geoanalytic Res

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“…Likewise, modal analyses demonstrate that the metagabbro and garnet-amphibolite contain the same percent garnet, i.e., ~13% (Luther, 1976;Sharga, 1986). Together these observations have led researchers to propose that the genesis of the garnet amphibolite was due to a copious infl ux of fl uid along and within ductile shear zones near the steep east-west border fault at temperatures of ~700-750 °C and mid-crustal pressures of 6-8 kbar (Buddington, 1939;Bartholomé, 1960;Luther, 1976;Sharga, 1986;Goldblum and Hill, 1992). Some observers have informally suggested that tonalitic partial melts of the amphibolite matrix were involved in garnet formation and enhanced the transfer of constituents, thus enabling the growth of unusually large crystals.…”

Section: Gore Mountainmentioning

confidence: 99%

“…5A, 6A, and 6B). As described by Bartholomé (1960), the hornblendite rims do not represent post-garnet reaction rims, but are properly understood as reaction products formed at the same time as the garnet. The presence of fl uids at high temperature facilitates the transport of chemical constituents and greatly favors growth over nucleation.…”

Section: Gore Mountainmentioning

confidence: 99%

Megacrystic Gore Mountain–type garnets in the Adirondack Highlands: Age, origin, and tectonic implications

McLelland

Selleck

2011

Geosphere

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“…Reported errors are a quadratic combination of the standard error of the analysis and the standard deviation of the reference materials analyzed together with the unknowns, and the uncertainties per analysis are typically ±0.2 ‰ (2σ). The primary reference material utilized in this study was UWG-2 (a megacrystic pyrope garnet from the Gore Mountain Mine, Bartholomé 1960), with a normalized δ 18 O VSMOW value of 5.72 ± 0.13 ‰ (2σ). The detailed analytical methods and precision and data reduction have been described by Ikert and Stern (2013).…”

Section: Garnet O Isotope Analysis With Simsmentioning

confidence: 99%

Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust

Wang

Collins²,

Weinberg

et al. 2016

Contrib Mineral Petrol

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juvenile character (εHf i +0.5 to +6.5) of Eocene Gangdese arc magmas. Together these two age groups indicate that a component of the xenolith was sourced from Gangdese arc rocks. The 35-20 Ma Miocene ages are derived from zircons with similar Hf-O isotopic composition as the Eocene Gangdese magmatic zircons. They also have similar steep REE curves, suggesting they grew in the absence of garnet. These zircons mark a period of early Miocene remelting of the Eocene Gangdese arc. By contrast, the youngest zircons (13.0 ± 4.9 Ma, MSWD = 1.3) are not zoned, have much lower HREE contents than the previous group, and flat HREE patterns. They also have distinctive high Th/U ratios, high zircon δ 18 O (+8.73-8.97 ‰) values, and extremely low εHf i (−12.7 to −9.4) values. Such evolved Hf-O isotopic compositions are similar to values of zircons from the UPV lavas that host the xenolith, and the flat REE pattern suggests that the 13 Ma zircons formed in equilibrium with garnet. Garnets from a strongly peraluminous metatonalite xenolith are weakly zoned or unzoned and fall into four groups, three of which are almandine-pyrope solid Abstract Felsic granulite xenoliths entrained in Miocene (~13 Ma) isotopically evolved, mantle-derived ultrapotassic volcanic (UPV) dykes in southern Tibet are refractory meta-granitoids with garnet and rutile in a near-anhydrous quartzo-feldspathic assemblage. High F-Ti (~4 wt.% TiO 2 and ~3 wt.% F) phlogopite occurs as small inclusions in garnet, except for one sample where it occurs as flakes in a quartz-plagioclase-rich rock. High Si (~3.45) phengite is found as flakes in another xenolith sample. The refractory mineralogy suggests that the xenoliths underwent high-T and high-P metamorphism (800-850 °C, >15 kbar). Zircons show four main age groupings: 1.0-0.5 Ga, 50-45, 35-20, and 16-13 Ma. The oldest group is similar to common inherited zircons in the Gangdese belt, whereas the 50-45 Ma zircons match the crystallization age and Communicated by Hans Keppler. Contrib Mineral Petrol (2016) 171:62 1 3 62 Page 2 of 19 solutions and have low δ 18 O (+6 to 7.5 ‰), intermediate (δ 18 O +8.5 to 9.0 ‰), and high δ 18 O (+11.0 to 12.0 ‰). The fourth is almost pure andradite with δ 18 O 10-12 ‰. Both the low and intermediate δ 18 O groups show significant variation in Fe content, whereas the two high δ 18 O groups are compositionally homogeneous. We interpret these features to indicate that the low and intermediate δ 18 O group garnets grew in separate fractionating magmas that were brought together through magma mixing, whereas the high δ 18 O groups formed under high-grade metamorphic conditions accompanied by metasomatic exchange. The garnets record complex, open-system magmatic and metamorphic processes in a single rock. Based on these features, we consider that ultrapotassic magmas interacted with juvenile 35-20 Ma crust after they intruded in the deep crust (>50 km) at ~13 Ma to form hybridized Miocene granitoid magmas, leaving a refractory residue. The ~13 Electronic supplementary material The onli...

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Genesis of the Gore Mountain garnet deposit, New York

Cited by 13 publications

References 0 publications

Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet

Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet

Megacrystic Gore Mountain–type garnets in the Adirondack Highlands: Age, origin, and tectonic implications

Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust

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Genesis of the Gore Mountain garnet deposit, New York

Cited by 13 publications

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Matrix Corrections and Error Analysis in High‐Precision SIMS18O/16O Measurements of Ca–Mg–Fe Garnet

Matrix Corrections and Error Analysis in High‐Precision SIMS18O/16O Measurements of Ca–Mg–Fe Garnet

Megacrystic Gore Mountain–type garnets in the Adirondack Highlands: Age, origin, and tectonic implications

Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust

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Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet

Matrix Corrections and Error Analysis in High‐Precision SIMS¹⁸O/¹⁶O Measurements of Ca–Mg–Fe Garnet