四川盆地东北部镇巴地区二叠系C-O-Sr同位素组成及沉积演化特征  

Characteristics of C-O-Sr Isotope Composition of Permian and Their Sedimentary Evolution in Zhenba Area of the Northeastern Sichuan Basin,China

作　　者：姚升阳 牟传龙[2] 周刚 王启宇 王秀平[2] YAO Sheng-yang;MOU Chuan-long;ZHOU Gang;WANG Qi-yu;WANG Xiu-ping(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,Shandong,China;Chengdu Center,China Geological Survey,Chengdu 610081,Sichuan,China;Exploration and Development Research Institute,Southwest Oil and Gasfield Company,PetroChina,Chengdu 610041,Sichuan,China)

机构地区：[1]山东科技大学地球科学与工程学院,山东青岛266590 [2]中国地质调查局成都地质调查中心,四川成都610081 [3]中国石油西南油气田公司勘探开发研究院,四川成都610041

出　　处：《地球科学与环境学报》2020年第5期637-653,共17页Journal of Earth Sciences and Environment

基　　金：国家科技重大专项项目(2016ZX05004-005);中国石油天然气股份有限公司市场项目(XNS14JS2018-075)。

摘　　要：为认识四川盆地东北部镇巴地区二叠系海平面变化及沉积演化特征,选取陕西省镇巴县杨家湾典型剖面,以岩石学特征研究为基础,结合C-O-Sr同位素组成所反映的古海平面、古盐度、古温度变化来综合分析四川盆地东北部镇巴地区二叠系的沉积演化特征。C-O-Sr同位素分析结果显示:δ^13C值为-1.67‰~5.85‰,平均值为2.76‰;δ^18O值为-7.26‰^-3.44‰,平均值为-6.24‰;87Sr/86Sr值为0.707147~0.708133。C-O-Sr同位素组成所反映的古海平面、古温度(12.0℃~25.2℃,平均值约为21.0℃)、古盐度(盐度指示剂为120.88~135.90,平均值为129.84)特征表明:研究区处于水体流通较好的温暖—炎热的高盐度区,且全球海平面升降事件对研究区碳酸盐同位素组成起到良好的控制作用;研究区与全球海平面变化具有一致性,即栖霞初期的快速海侵后进入相对平稳、缓慢下降阶段,茅口初期经历大规模海侵与茅口末期海平面大幅度下降,吴家坪初期经历大规模海侵及中期海退,长兴初期海平面上升。综合分析沉积特征可知,研究区经历了由古海平面变化及构造运动控制的开阔台地→台地边缘→陆棚→缓坡环境的沉积演化过程。In order to understand the change of sea level and sedimentary evolution characteristics of Permian carbonate rocks in Zhenba area of the northeastern Sichuan Basin,the Yangjiawan section in Zhenba county of Shaanxi province was selected.Based on the field characteristics of rock formations and indoor petrology characteristics,and combined with the changes of paleosea level,paleosalinity and paleotemperature reflected by C-O-Sr isotopic composition,the sedimentary evolution characteristics of Permian in Zhenba area of the northeastern Sichuan Basin were comprehensively analyzed.The analysis results of C-O-Sr isotopes show that δ^13C is -1.67‰-5.85‰ with an average of 2.76‰;δ^18O is-7.26‰--3.44‰ with an average of -6.24‰;the ratio of 87Sr/86Sr is 0.707147-0.708133.The changes of paleosea level,paleotemperature(12.0℃-25.2℃ with an average of about 21.0℃),and paleosalinity(salinity indicator is 120.88-135.90 with an average of 129.84)reflected by C-O-Sr isotope compostions,indicate that Zhenba area is warm-hot high-salinity with good water circulation,and the global sea level eustatic events have a good control on the composition of carbonate isotopes;the sea level changes in Zhenba area are basically consistent with global sea level changes,that is,entering a relatively stable and slow decline stage after rapid transgression in early Qixia period,experiencing large-scale transgression in the early Maokou period and sea level decline significantly in the late Maokou period,experiencing large-scale transgression in the early Wujiaping period and regression in the middle Wujiaping period,and experiencing sea level rise in early Changxing period.Based on the comprehensive analysis of sedimentary characteristics,the sedimentary evolution process is open platform→platform edge→shelf→gentle slope in Zhenba area of the northeastern Sichuan Basin.

关 键 词：C-O-Sr同位素 碳酸盐岩 同位素分析 二叠系 古海平面 岩性特征 沉积演化 四川盆地 

分 类 号：P588.245[天文地球—岩石学]