| 摘要: |
| 对测区岩石地层系统进行了重新划分厘定,正式填图单元33个、非正式填图单元20个;在南羌塘板片内首次发现晚三叠世磨拉石建造,并新建亭共拉组;将班公湖-怒江结合带南侧的接奴群解体为多仁组和日松组;证实竟柱山组与江巴组应为不同的岩石地层单位,江巴组应恢复其岩石地层单位,并在竟柱山组之上;发现木嘎岗日岩群复理石-硅质岩建造被沙木罗组陆源碎屑岩角度不整合覆盖,从而揭示班公湖-怒江结合带的关闭上限为晚侏罗世—早白垩世;证实郎山组与下伏地层之间存在一大型海侵超覆界面;在古昌蛇绿混杂岩带内首次发现斜长花岗岩,获128 Ma(Ar-Ar法)年龄。证实拉布错一带有一条蛇绿岩带存在,并在蛇绿岩中获141 Ma(Ar-Ar法)年龄,表明其构造侵位时期为侏罗系。 |
| 关键词: 1:25万 地质调查 物玛幅 成果与进展 西藏 |
| DOI： |
| 附件 |
| 投稿时间：2004-12-10 |
| 基金项目: |
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| 1:250 000 Oma Sheet in Xizang |
| Sichuan Institute of Geological Survey |
| (Sichuan Institute of Geological Survey, Chengdu 610213, Sichuan, China) |
| Abstract: |
| The stratagraphic systems in the Oma Sheet are redivided into thirty-three formal and twenty informal mappable units. The Late Triassic molasse formations are identified for the first time in the South Qiangtang landmass, and the Tinggongla Formation is established. The Jienu Group on the southern flank of the Bangong-Nujiang suture zone is redivided into the Duoren and Risum Formations. It is demonstrated that the Qangba Formation should overlie the Jingzhushan Formation, and the flysch-silicalite formations in the Muggar Kangri Group Complex are overlain with an angular unconformity by terrigenous clastic rocks of the Shamuluo Formation, implying that the Bangong-Nujiang suture zone was closed during the Late Jurassic to the Early Cretaceous. There exists a large-scale transgressive onlap boundary between the Langshan Formation and its underlying strata. The plagiogranites with an Ar-Ar age of 128 Ma are recognized for the first time in the Goicang ophiolitic mélange zone. The Ar-Ar age of 141 Ma for the ophiolite zone in the Lhabu Lake area shows that the tectonic emplacement of the ophiolites took place during the Jurassic. |
| Key words: 1:250 000 geological survey Oma Sheet development Xizang |
