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Geosciences 2018, 8(5), 169; https://doi.org/10.3390/geosciences8050169

Columbite-Group Minerals from New York Pegmatites: Insights from Isotopic and Geochemical Analyses

1
New York State Museum, Research and Collections, Albany, NY 12230, USA
2
Department of Geology, St. Lawrence University, Canton, NY 13617, USA
3
Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA
4
Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
5
Eastern Geology and Paleoclimate Center, U.S. Geological Survey, P.O. Box 628, Montpelier, VT 05602, USA
*
Author to whom correspondence should be addressed.
Received: 11 April 2018 / Revised: 27 April 2018 / Accepted: 3 May 2018 / Published: 9 May 2018
(This article belongs to the Special Issue Geochronology Applied to Metallogeny and Deposit Studies)
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Abstract

Columbite crystals from niobium-yttrium-fluorine (NYF) pegmatites lacking zircon or containing metamict cyrtolite were analyzed for major and minor elements (Electron Microprobe (EMP)), trace elements (Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS)), and U-Pb geochronology (Laser AblationMulti-Collector-Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICP-MS)). All four pegmatite localities sampled are hosted by the Proterozoic Fordham gneiss and/or Paleozoic Bedford gneiss (Columbite-(Fe); Kinkel and Baylis localities) and the Manhattan Schist of Lower Paleozoic age (Columbite-(Mn); Fort George and Harlem River Drive localities) and yield Neoacadian ages. The weighted average U-Pb ages are 372.2 ± 8.2 Ma (Baylis Quarry), 371.3 ± 7.3 and 383.4 ± 8.9 Ma (Kinkel Quarry); 383 ± 15 Ma (185th St. and Harlem River Drive); and 372 ± 10 Ma (Fort George). A partial metamict zircon (“cyrtolite”) from the Kinkel Quarry yielded a weighted average U-Pb age of 376.9 ± 4.3 Ma. The Neoacadian ages obtained agree with those determined by thermal ionization mass spectrometry (TIMS) for zircon from Lithium-Cesium-Tantalum (LCT) pegmatites from Connecticut and Maine. No pegmatites temporally associated with the Taconic orogeny were found. The size, lack of common Pb, uniform U concentrations across crystal cross-sections, sufficient but moderate uranium concentrations, lack of metamictization, and consistency in U-Pb isotopic ratios for columbite samples BCB-COL, NYSM #25232, and NYSM #525.8 suggests they show promise as potential standards for oxide mineral LA-MC-ICP-MS geochronological analyses, however, additional characterization using ID-TIMS would be necessary to develop as such. View Full-Text
Keywords: NYF pegmatites; columbite-(Fe); columbite-(Mn); Bedford; Manhattan; Neoacadian; U-Pb columbite geochronology NYF pegmatites; columbite-(Fe); columbite-(Mn); Bedford; Manhattan; Neoacadian; U-Pb columbite geochronology
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Lupulescu, M.V.; Chiarenzelli, J.R.; Pecha, M.E.; Singer, J.W.; Regan, S.P. Columbite-Group Minerals from New York Pegmatites: Insights from Isotopic and Geochemical Analyses. Geosciences 2018, 8, 169.

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