摘要
运用Dickinson三角图解、地球化学和阴极发光方法,对西藏山南琼结和贡嘎地区上三叠统深海—半深海郎杰学群砂岩和板岩进行了研究。碎屑成分和地球化学分析结果显示,物源总体来自再旋回造山带,含有大陆基块和混合区(切割弧)成分。阴极发光照射结果反映,物源区石英主要为变质成因(棕色光),次为深成/火山成因(浅紫兰色—绿色光),在一定程度上表明,母源区结晶基底可能已经抬升暴露,并且粘附在大陆块上。这些结果暗示,在拉萨地块与印度次大陆之间的新特提斯洋中可能存在一个含造山带的未名地块。
Provenance of the flysch Langjiexue Group of Upper Triassic in Qiongjie and Gongga area of southern Tibet, China, is analyzed in the paper. By clastic component, most of sands fall in recycled and mixed orogenic provenances. REE and trace element data show a mixture of parent source in recycled orogen tectonics by comparison with those proposed by Bhatia (1995). Either brown, or pale violet and blue, or green light of Quartz under cathode luminescence proves possibilities of metamorphic, volcanic and plutonic sources. Therefore, it is proposed that terrigenous sediments in the Langjiexue Group are derived from a parent source where had ever been in control of recycled orogen, during which crystalline basement could be exposed under air and attached on to a continent with some complexes of mélange. The provenance of the Langjiexue Group is of mixture. On the basis of discussion of provenance above, we disputably suppose that: (1) the Langjiexue Group could be a product generated in submarine fan under a rift or remnant sea, even in a foredeep of foreland basin; (2) there might be a block or microplate placed between Indian Subcontinent and Lhasa Block during Late Triassic, where a coeval orogenic belt should be accessory.
出处
《沉积学报》
CAS
CSCD
北大核心
2004年第4期553-559,共7页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目‘西藏拉孜-仁布地区的"修康群"与特提斯演化’(批准号:40272101)
西藏区调队<曲得贡幅>和<琼果幅>1:5万区调项目联合资助.
关键词
上三叠统
造山带
物源分析
西藏南部
阴极发光
结晶基底
特提斯
光照射
绿色光
深海
provenance analysis, clastic triangle plot, geochemistry, cathode luminescence, Langjiexue Group, Upper Triassic, Qiongjie-Gongga area, southern Tibet
