对巴颜喀拉区三叠纪地层系统的认识

沿可可西里山、巴颜喀拉山、大雪山和邓崃山分布的王叠系，发育下、中、上三统，昔以西康群和巴颜喀拉山群称之，并划分了组或岩组，但区域对比和划分很不一致。本文从整个沉积盆地分析，提出地层系统和地层名称意见：下三叠统，沉积盆地东及东南部依附于杨子古陆之上，基底稳定，以板岩为主，夹砂岩灰岩，厚约２００ｍ，昔以菠茨沟组命名，宜沿用。中部及西部依附于华力西褶皱基底之上，活动性强，沉积厚度达３０００～６０００ｍ，且具两分性。该统建议用昌马河组命名。中三叠统，以稳定的砂岩层为特征，厚度从东南部６００ｍ到西北增至２０００～３５００ｍ，名称建议用杂谷脑组。上三叠统，全区由两个连续岩组组成，下部因砂岩层段多次出现，原地层单位名称多，对比混乱，笔者认为选用新都组一名作代表性名称较适宜；上部研究程度低，可暂以砂岩组称之。

SOME OPINIONS ABOUT THE TRIASSiC STRATIGRAPHYIN THE BAYAN HARA AREA

The upper ,middle and lower series may be recognized in the Triassic System in the BayanHara area distributed along the Hoh Xil ,Bayan Hara ,Daxue and Qionglai mountains. Formerlythey were called the Xikang Group and Bayan Hara Group ,Which were subdivided into forma-tions and subformations ,but their regional strategraphic correlation and devision are quite in-consistent. On the basis of the basin analysis ,this paper fut forward opinions about the strati-graphic system and nomenclature. For the Lower Triassic , lying on the Yangtze oldland, theeastern and southeastern parts of the sedimentary basin have a stable basement and the rockstherein consist mainly of slate with sandstone and limestone,about 200m thick. Forrnerly thisseries was named the Pochigou Formation,and it is advisable to continue to use this name. Thecentral and western parts rest on the basement of the Variscan folal ,so are rather active ,with asedimentary thickness as much as 3000- 6000m. It is advisable to name the lower series therethe Changmahe Formation. The Mlddle Teiassic is characterized by occurrcnce of sandstonebeds and its thickness increases from 600m in the southeastern part to 2000 3b00m in thenorthwestern part.It is advisabe to name it the Zhagunao Formation. The Upper "Triassic iscomposed of two contineuous rock formations in the whole area. For the lower part ias sanus-tone bdes occur repeatedly ,the original stratigraphic unit has many names , which are difficult tocorrelate. The author considers that it is right to use the Xindu Formation as the representativename for the upper series there. The upper part may be named the Sandstone formation for thetime being as it is less studed.