内蒙古东部中二叠世吴家屯组海平面相对变化的泥岩地球化学证据  

Sea-Level Relative Movement of Middle Permian Wujiatun Formation in Eastern Inner Mongolia: Evidence from Mudstones Geochemistry

作　　者：明承栋[1] 侯读杰[2] 赵省民[3] 宋健[4] 邓坚[3] 吴赛赛[3] 

机构地区：[1]中海油能源发展股份有限公司工程技术分公司,广东深圳518067 [2]中国地质大学(北京)能源学院,北京100083 [3]中国地质调查局油气资源调查中心,北京100029 [4]中国石油大学(北京)地球科学学院,北京102249

出　　处：《现代地质》2015年第3期623-632,共10页Geoscience

基　　金：中国地质调查局项目"天山-兴蒙构造带石炭-二叠系对比研究"(1212011120966);国土资源部公益性行业科研专项项目(201311022)

摘　　要：对内蒙古东部中二叠统吴家屯组泥岩进行了微量元素和有机地球化学研究,显示研究区吴家屯组水体的古盐度范围为16.6‰~28.7‰,主要为半咸水沉积。微量元素及其比值可以反映古盐度和古水深的变化,两者受海平面相对变化的影响;且古盐度、海平面相对升降在沉积相上有较好的响应。利用定量计算的古盐度和反映古盐度的Sr/Ba、B/Ga值等编制了海平面相对变化曲线,显示研究区吴家屯组发生了2次海侵海退旋回,海侵发生在吴家屯组底部和中部。根据沉积相分析,结合地球化学指标V/（V＋Ni）值、稀土元素Ceanom及饱和烃气相色谱,表明区内吴家屯组主体为缺氧、还原的浅海陆棚环境,该环境有利于有机质的保存和烃源岩的发育。Through studying the ICP- MS trace elements and organic geochemistry of the Middle Permian Wujiatun Formation mudstones in eastern Inner Mongolia,it indicates that Wujiatun Formation mainly belongs to semi-salt water sedimentary environment; the range of palaeosalnity is 16. 6‰ to 28. 7‰. The paleosalinity and the change of water depth are showed by the trace elements and their ratios,which are impacted by the relative change of sea- level. Palaeosalinity and relative change of sea-level have a good correlation with sedimentary facies evolution. Using the quantitative calculation palaeosalinity and the values of Sr / Ba and B / Ga which reflect the paleosalinity and the water depth,the curve of relative change of sea-level of Wujiatun Formation was established. The Wujiatun Formation had undergone two transgression-regression cycles and the transgressions took place in the bottom and middle part of Wujiatun Formation. According to the geochemical index of V /（ V ＋ Ni）values,rare earth element Ceanomand saturated hydrocarbon gas chromatogram,combined with sedimentary faci-es analysis,showed that main body of Wujiatun Formation was formed in a neritic shelf environment characterized by reductive conditions,which is conducive to the preservation of organic matter and development of hydrocarbon source rock.

关 键 词：吴家屯组 泥岩 地球化学 古盐度 海平面变化 内蒙古东部 

分 类 号：TE122.1[石油与天然气工程—油气勘探]