CAJ | 학술논문

对于青藏高原北部羌塘盆地中央隆起带晚古生代的构造演化历史，学术界目前仍存在不同观点。位于盆地中央隆起带角木日地区的羌资5井揭示出的下二叠统展金组细碎屑岩，对于该地区古地理研究和构造背景约束具有重要意义。通过对该井中17个展金组粉砂质泥岩和泥质粉砂岩样品的稀土元素地球化学研究表明：样品ω（ΣREE）整体较高，ω（ΣLREE）／ω（ΣHREE）及（La ／Yb）N 等比值显示其具有较弱的轻、重稀土元素分异；Ce anom ，Ce ／Ce *，Eu ／Eu *等参数反映样品主要形成于具有一定深度的浅海还原环境；（La ／Yb）N 值自下而上呈降低趋势，表明下部的沉积速率低于上部。稀土元素组合及其比值特征指示展金组物源以玄武岩和沉积岩混合为主。根据 La－Th－Sc 构造背景判别图解分析，并与不同构造背景下的杂砂岩稀土元素特征比较，认为展金组沉积岩的物源可能来自于具有类似岛弧构造特征的环境。
대우청장고원북부강당분지중앙륭기대만고생대적구조연화역사，학술계목전잉존재불동관점。위우분지중앙륭기대각목일지구적강자5정게시출적하이첩통전금조세쇄설암，대우해지구고지리연구화구조배경약속구유중요의의。통과대해정중17개전금조분사질니암화니질분사암양품적희토원소지구화학연구표명：양품ω（ΣREE）정체교고，ω（ΣLREE）／ω（ΣHREE）급（La ／Yb）N 등비치현시기구유교약적경、중희토원소분이；Ce anom ，Ce ／Ce *，Eu ／Eu *등삼수반영양품주요형성우구유일정심도적천해환원배경；（La ／Yb）N 치자하이상정강저추세，표명하부적침적속솔저우상부。희토원소조합급기비치특정지시전금조물원이현무암화침적암혼합위주。근거 La－Th－Sc 구조배경판별도해분석，병여불동구조배경하적잡사암희토원소특정비교，인위전금조침적암적물원가능래자우구유유사도호구조특정적배경。
There is a hot debate on the Neopaleozoic tectonic evolution history of central uplift zone of Qiangtang Basin,northern Tibet Plateau.The clastic sedimentary strata,with great geological significance for the research on palaeogeography and tectonic setting of study area,were discovered in the Lower Per-mian Zhanjin Formation of the Well Qiangzi 5 in Jiaomuri area of central uplift zone.Based on the rare earth element (REE) geochemical analysis of 17 samples of silty mudstone and muddy siltstone,the data show that the ΣREE is entirely high,and the ratios of ΣLREE /ΣHREE and LaN /Yb N indicate that the differentiation is slight.The Ce anom , Ce /Ce * and Eu /Eu * ratios suggest that the sedimentary rocks of Zhanjin Formation formed in a certain depth of shallow water.The Lan /Yb n values decrease gradually from bottom to top in the Well Qiangzi 5,which reflects that the sedimentary rate at the bottom sequence is low-er than at the upper sequence.The REE geochemical characteristics and relative parameters imply that the sedimentary rocks of Zhanjin Formation were mainly derived from the basalt and sedimentary rocks.The critical characteristic parameters,as well as the La-Th-Sc tectonic discrimination diagram imply an arc-like tectonic setting for the depositional basin of Zhanjin Formation.