02512nas a2200253   4500008004100000245010300041210006900144260001200213300000800225490000600233520174700239653002301986653001902009653001902028653001502047653001902062653003302081100002202114700002502136700001802161700001902179700001802198856004202216       2018                        eng d00aColumbite-Group Minerals from New York Pegmatites: Insights from Isotopic and Geochemical Analyses0 aColumbiteGroup Minerals from New York Pegmatites Insights from I  c05/2018  a1690 v83 a<p>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<br />
LA-MC-ICP-MS geochronological analyses, however, additional characterization using ID-TIMS would be necessary to develop as such.</p>
10aBedford; Manhattan10acolumbite-(Fe)10acolumbite-(Mn)10aNeoacadian10aNYF pegmatites10aU-Pb columbite geochronology1 aLupulescu, M., V.1 aChiarenzelli, J., R.1 aPecha, M., E.1 aSinger, J., W.1 aRegan, S., P.  uhttp://www.mdpi.com/2076-3263/8/5/169