柴东北缘上古生界砂砾岩碎屑组分特征及其物源构造属性

基于柴东北缘德令哈地区上古生界126件碎屑岩样品的镜下鉴定, 结合对牦牛山组、城墙沟组、怀头他拉组、克鲁克组及扎布萨尕秀组砂砾岩岩石学特征、沉积特征的野外调查, 研究柴达木东北部地区晚古生代碎屑岩物源区, 并在此基础上进一步讨论该地区晚古生代盆山格局。研究结果表明, 柴东北缘德令哈地区晚古生代主要发育扇三角洲-障壁海岸沉积体系, 砂砾岩碎屑颗粒结构成熟度较低, 重力流证据普遍存在; 各层段砂砾岩碎屑颗粒中Q/(R+F)值在1.89~3.74之间, 呈现低成分成熟度特点。碎屑颗粒组成及近物源沉积证据一致表明, 研究区晚古生代以鱼卡-沙柳河加里东期造山带为主要物源区。该造山带至少存在了195 Ma, 包括距今465~430 Ma的山体隆升与距今430~270 Ma的山体剥蚀阶段。柴达木海盆与德令哈海盆是两个独立的海盆, 发育展布方向完全相反的沉积体系。同时, 德令哈地区上古生界含油气系统勘探应将鱼卡河-沙柳河高压-超高压变质带视为勘探边界。 

THE CLASTIC COMPOSITION CHARACTERISTICS OF UPPER PALAEOZOIC GLUTENITE IN NORTHEAST QAIDAM EDGE AND THE STRUCTURAL ATTRIBUTES OF SOURCE AREA

Combining the microscopic analysis of one hundred and twenty-six clastic rock samples from the Upper Paleozoic in Delingha region with the petrology and sedimentology features of Maoniushan formation, Chengqianggou formation, Huaitoutala formation, Keruk formation and Zhabugaxiu formation, we concluded the provenance of the Upper Palaeozoic clastic rocks in Northeast Qaidam edge and made further discussion on the basin-mountain framework in this area. The resluts showed that fan dalta-beach barrier sedimentary system widely developed in Delingha region, the northeastern margin of Qaidam basin. The texture maturity sandstone of glutenite was low and the gravity flow was widespread with obvious evidence. The value of Q/(R+F) in each gravel layer was between 1.89 and 3.74,reflecting the low texture maturity. The clastic composition and the near-source sedimentary evidence consistently showed that the Yuka-Shaliuhe Caledonian orogenic belt was the provenance of the study area in Late Paleozoic which existed at least 195 Ma, including the uplift stage from 465 Ma to 430 Ma ago and the denudation stage between 430 Ma and 270 Ma ago. Qaidam basin and Delingha basin are two independent basin, with depositional system of opposite direction distribution. The Yuka-Shaliuhe HP-UHP metamorphic belt should be the exploration border of the Upper Paleozoic petroleum system in Delingha region.