西藏措勤地区石炭纪—早二叠世古地理演化

EVOLUTION THE LITHOFACIES AND PALEOGEOGRAPHY IN THE COQEN AREA OF TIBET DURING THE CARBONIFERIOUS TO EARLIER PERMIAN

措勤地区在泥盆纪浅海碳酸盐台地的背景基础上,在石炭纪—早二叠世发育了一套陆源碎屑为主的海相沉积,古地理呈北部以陆棚海为主、南部发育斜坡-深海相的特征。早石炭世永珠组陆棚浅海限于北部的甲龙到阿布勒一带,其南侧至格嘎一措勤一线发育较宽的斜坡相沉积,晚石炭世时发生海侵,并随着冰期气候的盛行在边缘斜坡海环境内沉积了多套冰海砾岩,随着冰期气候的结束和海退,早二叠世昂杰组陆棚海沉积范围向南扩展到格嘎-达雄南部,陆棚海地边缘发育了生物礁或生物滩。古地理演化反映了研究区在早石炭世受南北向拉张的构造背景下形成了不同于泥盆纪碳酸盐台地的陆棚海—斜坡—深海盆地的古地理格局,晚石炭世拉张达到鼎盛,其后的早二叠世主要发育了稳定陆棚海沉积。

The Carboniferous to earlier Permian deposits in the Coqen area consist mainly of marine terrigenous clastie sediments with upon the Devonian carbonate platform setting. The character of the paleogeography takes on shelf-sea at the north part and slop and deep-sea at the south part. The marine terrigenous distribute at the north part, Jialong to Abule, and at the south part of that is expanse sloping grand slop deposit. Transgression occurred in Later Carboniferous and the outwash glaciofluvial deposits wid...