青海南部治多-杂多一带二叠系尕笛考组

青海南部二叠系尕笛考组厚度变化大,分布广,空间上呈链状展布。通过在该区地质调查对该组进行厘定,尕笛考组岩性组合为玄武岩、火山集块岩、火山角砾岩夹灰岩、砂岩和泥岩,与上覆九十道班组呈整合或假整合接触,为火山—沉积体系。尕笛考组产类Misellina-Schwagerina组合、非有孔虫、珊瑚Wentzellophyllum-Szechuanophyllum组合和腕足类等,表明地质时代为早二叠世罗甸期,与华南、西秦岭、藏东等地同期生物群可很好地对比,揭示出昌都地块在二叠纪时生物古地理区系属于特提斯大区华夏区,在构造古地理上为泛华夏大陆群或扬子板块的一个组成部分。

ON THE GADIKAO FORMATION IN ZHIDOI AND ZADOI AREAS,SOUTHERN QINGHAI

The Gadikao Formation was emended during 1/25000 geological mapping in the Zhidoi and Zadoi areas, southern Qinghai, where this formation is widely distributed and variable in thickness. It consists mainly of basalt, agglomerate, and volcanic breccia, interbedded with limestone, sandstone and mudstone, The Gadikao Formation is overlain conformably or disconformably by the Jiushidaoban Formation, and it represents a volcanic island deposition system. Some fossils including the fusulinid Misellina-Schwagerina assemblage, non-fusulinid foraminifers, the coral Wentzellophyllum-Szechuanophyllum assemblage and various brachiopods, occur in limestone units of the Gadikao Formation, indicating that the Gadikao Formation is of middle Early Permian Chihsian Stage, The Gadikao Formation can be easily correlated with equivalent strata in South China, western Qinling and eastern Tibet, further suggesting that the Qamdo Block was a part of the Pan-Cathaysian Continental Group or Yangtze Block and biogeographically belong to the Cathaysian Region of the greater Tethyan Realm.