可可西里湖幅地质调查新成果及主要进展  

New results and major progress in regional geological survey of the Hoh Xil Lake Sheet

作　　者：朱迎堂[1,2] 郭通珍[3] 彭伟[3] 杨延兴[3] 陈海清[3] 史连昌[3] 王永文[3] 保光普[3] 陈建[3] 韩海臣[3] 

机构地区：[1]成都理工大学沉积地质研究所 [2]青海省地质调查院,青海西宁810012 [3]青海省地质调查院

出　　处：《地质通报》2004年第5期543-548,共6页Geological Bulletin of China

基　　金：中国地质调查局青藏高原1:25万可可西里湖幅(I46C001001)地调项目(编号:2000130009211)成果。

摘　　要：在西金乌兰构造带发现新元古代和泥盆纪地层。在巴颜喀拉山群中采获早三叠世和晚三叠世诺利期双壳化石,查明了测区三叠纪巴颜喀拉山群最高层位为诺利期陆棚—海陆交互相沉积。在移山湖及明镜湖一带发现大量泥盆纪基性岩墙群,获得了345.69Ma±0.91Ma的角闪石Ar-Ar法同位素年龄值。在湖东梁、太阳湖等地新发现钙碱性流纹岩、流纹英安岩及次火山岩,获得2.2Ma锆石U-Pb年龄和6.63Ma±0.07Ma透长石Ar-Ar年龄,为测区最新一期火山活动。在西金乌兰湖及蛇形沟等地发现倾向向南的构造面;根据三叠纪前陆盆地、火山岩浆弧及蛇绿岩等空间配置,结合深部地球物理特征,提出西金乌兰构造混杂岩带构造极性向南俯冲的认识。Neoproterozoic and Devonian strata are found in the Xijir Ulan tectonic belt and Early and Late Triassic Noric valve fossils are taken from the Bayan Har Mountain Group. It is ascertained that the highest horizon of the Triassic Bayan Har Mountain Group in the survey area is Noric shelf-paralic deposits. Many Devonian basic dike swarms are found in the vicinity of the Yishan Lake and Mingjing Lake and a hornblende Ar-Ar age of 345.69±0.91 Ma is obtained. Calc-alkaline rhyolite, rhyolitic dacite and subvolcanic rocks are found in Hudongliang and Taiyang Lake, which have a zircon U-Pb age of 2.2 Ma and a diopside Ar-Ar age of 6.63±0.07 Ma. They represent the latest phase of volcanic activity in the survey area. South-dipping tectonic surfaces are found in Xijir Ulan Lake and Shexinggou. According to the spatial distribution of the Triassic foreland basin, volcanic magma arc and ophiolites, combined with the deep geophysical characteristics, the authors put forward the idea of the southward subduction of the tectonic polarity of the Xijir Ulan tectonic mélange belt.

关 键 词：新元古界 巴颜喀拉山群 诺利期 喜马拉雅期火山岩 西金乌兰构造带 

分 类 号：P623.12[天文地球—地质矿产勘探]