摘要
藏东新元古代—寒武纪波密群由一套浅变质的活动大陆边缘浊积岩和碰撞型岛弧中酸性火山岩组成,化石稀少,缺乏时代依据。1∶20万区调和新一轮1∶25万区调修测专题研究在波密、察隅、贡山一带共采获微古植物化石21属50种,均为青、皖、浙、赣及滇中地区新元古代青白口纪、震旦纪及部分寒武纪早期较原始类型的常见分子。区域上可与高喜马拉雅的肉切村群,滇西的勐统群、公养河群和缅甸的Chaung Magyi群相对比。上述波密群活动大陆边缘浊积岩、碰撞型岛弧火山岩在经历了泛非末期壳源重熔花岗岩侵位(500～600Ma)和褶皱变质作用(644～664Ma)之后,成为冈瓦纳大陆北缘增生褶皱变质基底的一部分。
The Neoproterozoic to Cambrian Bomi Group in eastern Tibet consists of a suite of active continental-margin low-grade metamorphic turbidites and collision-type island-arc intermediate-acid volcanic rocks. In these rocks fossils are rare, so it is very difficult to determine their geological age. The authors collected 21 genera and 50 species of microflora fossils from these rocks in the Bomi-Zayü-Gongshan area, Tibet, during the previous 1：200000 regional geological surveys and a new-round 1：250000 regional geological survey and special-subject research. All those fossils are Upper Proterozoic Qingbaikouan, Sinian and partly Early Cambrian common elements of relatively primitive types occurring in Qinghai, Zhejiang, Jiangxi and central Yunnan, China and can be regionally correlated with those in the Rouqiecun Group in the Higher Himalayas, Mengtong and Gongyanghe groups in western Yunnan and Chaung Magyi Group in Burma. These above-mentioned active continental-margin turbidites and collision-type island-arc volcanic rocks became the folded and metamorphosed accredonary basement on the northern margin of Gondwana after undergoing emplacement of crustal anatectic granite （500-600Ma） and folding and metamorphism （644-664Ma） during the last stage of the pan-African orogeny.
出处
《地质通报》
CAS
CSCD
北大核心
2007年第1期81-87,共7页
Geological Bulletin of China
基金
中国地质调查局项目<青藏高原南部空白区基础地质调查与研究>(任务书编号:基[2005]002-14
工作项目编号:121010510214)的阶段性研究成果
关键词
藏东
新元古代-寒武纪
波密群
冈瓦纳大陆
增生基底
eastern Tibet
Neoproterozoic to Cambrian
Bomi Group
Gondwana
accretionary basement
