青藏高原内部三条磨拉石带的确定及其构造意义  

THREE MOLASSE BELTS WITHIN THE QINGHAI-TIBET PLATEAU AND THEIR TECTONIC IMPLICATIONS

作　　者：夏邦栋[1] 张开均[1] 孔庆友[1] 林鹤鸣[1] 

机构地区：[1]南京大学地球科学系,南京210093

出　　处：《地学前缘》1999年第3期173-180,共8页Earth Science Frontiers

摘　　要：青藏高原内部自北而南沿羌北－昌都、班公湖－怒江、雅鲁藏布江分别发育了3条磨拉石带。各磨拉石带的长度均超过1000km，宽度一般仅数十km，沉积物具有碎屑性、粗粒性、再旋回性，沉积体厚3000～8000m，具有在挤压造山背景下形成的磨拉石建造的基本特征。各磨拉石带都位于各自的地体缝合带并跨越其两侧的部分地带。北边的为金沙江缝合带及其西延部分，中部的为班公湖－怒江缝合带，南边的为雅鲁藏布江缝合带。3条磨拉石带标志着有3条雄伟的造山带与之毗邻。北边的是可可西里－巴颜喀拉造山带，中部和南部的两条造山带一直不为人们所注意，文中建议分别称之为藏中造山带和藏南造山带。此外，造山作用发生的时间明显滞后于地体缝合的时间，其间有后继的浅海盆地发育。磨拉石带的发育历史勾绘出青藏高原构造演化遵循一个程式，即"地体拼接－后继性盆地发育－造山作用发生－山脉消亡"，这是很有意义的构造现象。Three molasse belts, longer than 1000 km and wider than 10 km, exist within theQinghai - Tibet Plateau along northern Qiangtang - Changdu, Bangonghu - Nujiang, andYarlung Zangbo areas respectively. These molasses consist of 3000 ~ 8000 m thick, coarse,clastic and recyclic sediments, so they can be believed to be formed under compressive orogenicmovement. They situate in or across the Jinshajiang suture, the Bangonghu - Nujiang suture,and the Yarlung Zandbo suture respectively, which implies that these three orogens could haveekisted near these three molasse belts. These three orogens are the Kokoxili - Barkala orogen,the central Tibetan orogen, and the southern Tibetan orogen from north to south. The orogenswere generally formed somewhat later than the amalgamation between the terranes, while theshallow sea basins are commonly developed during the internal period.

关 键 词：磨拉石带 青藏高原 造山带 藏中造山带 构造意义 

分 类 号：P542.2[天文地球—构造地质学] P588.21[天文地球—地质学]