漠河盆地北部漠河组地层形成时代探讨--糜棱岩化微晶闪长岩LA-ICP-MS锆石U-Pb 年龄的制约

摘要

In the north area of the Mohe basin, there is mylonitized fine crystal biotite quartz diorite parallelly in-vading in the mylonitized sandstones. The research samples in this study are from the mylonitized fine crystal bio-tite quartz diorite. The weighted average age is 182.8±1.8 Ma by LA-ICP-MS of zircon U-Pb method. Combining with the characteristics of the fossil group of Phoenicopsis found in the Middle Jurassic, it is suggested that the Mohe formation is demarcated between the late period of early Jurassic to middle Jurassic. This result has impor-tant geological significance for the study on the tectonic genesis and evolution of the Mesozoic Mohe Basin from Mongolia Okhotsk orogenic belt.%通过对漠河盆地北部中侏罗统漠河组糜棱岩化砂岩内顺层侵入的糜棱岩化微晶黑云母石英闪长岩进行LA-ICP-MS锆石U-Pb年龄测试，获得的加权平均年龄为182.8±1.8 Ma，结合漠河组中的化石组合盛产Phoenicopsis属为特征，认为该组地层形成于（早侏罗世晚期-）中侏罗世。这一成果对研究蒙古-鄂霍茨克造山带中生代漠河盆地成因与构造演化具有重要的地质意义。