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    SHRIMP U-Pb zircon Ages of Granitoids in the Wulasha Gold Deposit,Inner Mongolia,ChinaTiming of Mineralization and Tectonic Implications [查看] LAICHENGMIAO、YUMINQIU、NEALMCNAUCHTON、WEIMINGFAN、DAVIDI.GROVES、MINCUOZHAI
    Abstract:The wulashan gold deposit,situated along the northwestern margin of the North China Craton(NCC),is hosted by ductile-brittle faults with Archean metamophic volcano-sedimentary rocks of the Wulashan Group.This deposit is characterized by gold-bearing quartz-K feldspar and quartz veins.Both granitoid batholiths and pegmatite dikes intruded the metamorphic basement rocks,and are spatially associated with gold mineralization.Contrasting genetic medels have been proposed for the deposit due to lack of reliable age data.Our new SHRIMP U-Pb zircon ages for these intrusions now reveal important constraints on the mineraliztion time and tectonic evolution of this region.These intrusions contain inherited zircons of about 2.55Ga.probably from the Wulashan basement that was intruded by pegmatite dikes at about 1.84Ga:the latter probably are related to the major tectonic event leading to the final amalgamation for the NCC.The basement subsequently underwant at least three tectono-thermal events during Phanerozoic time(at353±7，169±7，and 132±2Ma）。 Combined with previous Ar-Ar and K-Ar ages,we suggest two gold mineralization episodes for the Wulashan gold deposit.The first episode occurred at about 350Ma .incicated by ages of a gold-related fuchsite and the Dahuabei granitoid batholith.This supports a previously proposed medel the relates gold mineralization to the Dahuabei granite the formed during collision of the Paleo-Mongolian block with the NCC.The second one occurred in the late Yanshannian period.as indicated by the mineralized K-feldspar-rich vein of 132±2Ma.This episode is simultaneous with those in the eastern NCC.indicative of a widespread late Yanshannian metallogenic event that was a response either to the subduction of lzanagi-Pacific plate beneath eastern China or to the removal of the Early Cretaceous lithosphere in the eastern NCC.
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