02367nas a2200241 4500008004100000245011500041210006900156260001200225300000800237490000600245520158200251653002501833653001701858653002301875653004701898653002601945653003001971100002602001700002202027700001602049700001802065856004202083 2018 eng d00aAge and Origin of the Mesoproterozoic Iron Oxide-Apatite Mineralization, Cheever Mine, Eastern Adirondacks, NY0 aAge and Origin of the Mesoproterozoic Iron OxideApatite Minerali c09/2018 a3450 v83 a
At the Cheever Mine, located in the eastern Adirondack Mountains of the Mesoproterozoic Grenville Province, iron oxide-apatite ore forms a narrow (<3 m) sheet cross-cutting metasomatically altered, magnetite-bearing, albite-rich leucogranitic host rocks of the Lyon Mountain Granite suite. Zircon from the ore and five samples of country rock were dated by Laser Ablation-Multi-Collector-Inductively Coupled Plasma-Mass Spectrometry. The ore yielded a Concordia age of 1033.6 ± 2.9 Ma while three samples of host rock yielded ages of 1036.3 ± 2.9, 1040 ± 11, and 1043.9 ± 4.1 Ma. Two additional samples of host rock yielded older ages of 1059.6 ± 3.4 and 1066.0 ± 6.3 Ma and contain zircon xenocrystic cores with 207Pb/206Pb ages up to 1242 Ma. The zircons analyzed, including those separated from the ore, have characteristics typically associated with an igneous origin including size, shape, inclusions, oscillatory zoning, typical chondrite-normalized REE patterns, U contents, and U/Th ratios. This data establishes the age of the ore and alteration and a temporal, and likely genetic, connection between the ore and members of the Lyon Mountain Granite suite. A model invoking melting of Shawinigan country rocks, magmatic differentiation, and long-lived magmatic and metasomatic input along extensional fault conduits is proposed for the ore’s genesis. At the Cheever Mine, magmatic hydrothermal fluids and/or post-intrusion alteration appears not to have had a major impact on zircon, which preserves original U-Pb systematics.
10aAdirondack Mountains10aCheever Mine10aGrenville Province10airon oxide-apatite deposits (IOA deposits)10aLyon Mountain Granite10aU-Pb zircon geochronology1 aChiarenzelli, Jeffrey1 aLupulescu, M., V.1 aRegan, Sean1 aSinger, Jared uhttp://www.mdpi.com/2076-3263/8/9/345