阿尔泰蒙库铁矿斜长角闪岩锆石SHRIMPU-Pb年龄及地质意义

Shrimp U-Pb Age of the Amphibolite from Mengku Iron Deposit and its Geological Implications in Altay,Xinjiang

蒙库大型铁矿位于阿尔泰南缘麦兹盆地,赋存于康布铁堡组变质火山-沉积岩系中,容矿岩石为石榴石矽卡岩、变粒岩、浅粒岩、斜长角闪岩和大理岩。矿体总体顺层分布,空间上与矽卡岩密切相关。对9号矿体围岩斜长角闪岩锆石SHRIMP U-Pb年龄进行了测定,12颗锆石的206Pb/238U加权平均年龄为(403.9±4.8)Ma(MSDW=1.3)。结合区域年代学资料,限定康布铁堡组形成时代为晚志留—早泥盆世,同时限定蒙库铁矿形成时代小于404 Ma。

The Mengku large-size iron deposit occurs in metavolcanic-sedimentary sequence of the Kangbutiebao Formation in the Maizi Basin of south Altay, with the host rocks being garnet skarn,granulitite,leucogranulitite,amphibolite and marble. Orebodies are largely concordant with the bedding of the strata,and the distribution of the orebodies is spatially related to skam.Precise SHRIMP U-Pb dating of zircon from the amphibolite in the No.9 orebody wall rock of the Mengku iron deposit has been carded out in this study.The results show that the weighted average 206pb/238U age of the 12 zircon grains is （403.9±4.8） Ma （MSDW=1.3）.A combination of the ages of Kangbutiebao Formation in the region limits the Kangbutiebao Formation is of Late Silurian-Early Devonian,and constraining the age of the Mengku iron deposit to〈404 Ma.