摘要
班公湖—怒江位于西藏中部 ,西起班公湖日土 (33.5°N ,79°E) ,向东经由措勤、尼玛、那曲至东部怒江带 ,走向近东西、其中部大致平行于北纬 32°线 ,延长大于 15 0 0km。该带蛇绿岩发育 ,是中生代板块缝合线 ,是南部拉萨地块与北部羌塘地块的分界线。其中段班戈地区白垩系地层发育 ,包括下白垩统底部川巴组 (K1c)、多巴组 (K1d)、郎山组 (K1l)和上白垩统江巴组 (K2 j)。川巴组为浅海相黑色页岩、泥岩、粉砂岩、砂岩、煤层和火山岩 ;多巴组为含有海侵夹层的陆相碎屑岩建造 ,海侵层为含园笠虫 (Orbitolinasp .)钙质砂岩 ;郎山组为浅海相—泻湖相台地型碳酸盐岩沉积 ;江巴组以陆相、厚层块状的砂砾岩红层为特征。本区白垩系层序的总体特征 ,是以海相火山岩—细碎屑岩为先导、经海陆过渡相碎屑岩和海相碳酸盐岩到陆相红层 ,形成于与B型俯冲作用有关的活动大陆边缘构造背景.
The ophiolite--bearing Bangong--Nujiang zone (BNZ) traversing central Tibet from east to west separates the Qiangtang block in the north from the Lhasa block in the south. The Cretaceous of the area includes Chuanba Formation (K 1c), Duoba Formation (K 1d), Langshan Formation (K 1l) and Jiangba Formation (K 2j). The K 1c is composed of black shale, sandy pelite, siltstone, sandstone, coal beds and volcanic rocks, mostly of shallow marine facies. The K 1d consists of terrestrial siliciclastics intercalated with some calcareous sandstone beds bearing Orbitolina sp. indicating marine influence. The K 1l is carbonate platform deposits of shallow marine and lagoon. The K 2j is characterized by terrestrial thick massive red conglomerate. An active margin related to B--subduction zone is considered to be the geological setting of the Cretaceous sedimentation.
出处
《世界地质》
CAS
CSCD
2003年第2期105-110,118,共7页
World Geology
基金
德国科学基金会 (DFG)西藏项目 (SCHN 2 0 2 / 14-1)资助
洪堡基金部分资助 .
