皋兰岩群时代厘定及地质意义  

Age Determination of Gaolan Terrain and Its Geological Significance

作　　者：闫海卿[1] 汤桦[2] 钱壮志[1] 徐刚[1] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]西安地质矿产研究所,陕西西安710054

出　　处：《西北地质》2011年第4期1-7,共7页Northwestern Geology

基　　金：中国地质大调查研究项目J48C004002(兰州市幅)项目(199913000218)

摘　　要：由于缺乏化石依据以及区域岩浆事件扰动,中祁连东段褶皱基底(一套变质岩系)———皋兰岩群的成岩时代始终悬而未决。在1∶25万兰州市幅区域地质调查中,获得大量野外地质证据,剔除了岩浆事件干扰的年龄数据,取得较可靠的皋兰岩群成岩事件的Sm-Nd同位素等时线年龄为1180.3Ma,依据采获的蓟县纪微古植物化石佐证,将中祁连东段褶皱基底皋兰岩群成岩时代厘定为中元古代蓟县纪。该资料对探讨中祁连地块构造属性及区域构造演化具有重要意义。As lack of fossil evidence and the influence of regional magma events on isotopic age determination,the geological age of the Gaolan terrain,a group of grade metamorphic rocks as the fold basement of the central Qilian block,has not been determined for a long time.During the work of the regional geologi-cal surveying of 1/250000 Lanzhou city,the authors got a large number of field geological evidence and obtained the dependable Sm-Nd isotope age of 1180.3 Ma,which is consistent with the micro-fossils of the ancient plants from the Jixianian.The age of Gaolan terrain that is in the eastern section of central Qilian block fold basement belongs to mesoproterozoic Jixianian.It is significant to study the Central Qilian block structural properties and regional tectonic evolution.

关 键 词：中祁连 皋兰岩群 SM-ND年龄 时代厘定 

分 类 号：P534.1[天文地球—古生物学与地层学]