黔南坳陷下奥陶统油苗与沥青特征及其成藏史

Characteristics of Oil Seepages and Bitumen of Lower Ordovician and Its Hydrocarbon Accumulation History in Southern Guizhou Depression

应用GC-MS和IRMS测试技术,对黔南坳陷下奥陶统红花园组油苗及沥青进行分析,对其成熟度及油源进行了分析对比,并探讨油气成藏史。研究表明,红花园组沥青为氧化成因,主要分布于研究区南部的丹寨—麻江地区;研究区北部的凯里地区以油苗显示为主,以下寒武统牛蹄塘组为主力烃源岩,以中下志留统翁项群页岩为次要烃源岩,具混源特征。受多期次构造活动的影响,研究区内的成藏史较为复杂,具多旋回的成藏-破坏特点,其中以晚燕山运动期的破坏活动最为强烈。

Using GC-MS and IRMS testing technologies, the paper analyzes oil seepages and bitumen, correlates their maturity and oil sources,and discusses hydrocarbon accumulation history in Lower Ordovician Honghuayuan formation in southern Guizhou depression. The result shows that the oxidized bitumen in Honghuayuan formation is mainly found in Danzhai-Majiang area in the southern study area; while the Kaili area in the northern study area with oil shows occuing widely, oil shows occur widely, and is of mixture source characteristics by the fact that the major source rocks appear in Niutitang formation of the Lower Cambrian, the secondary hydrocarbon source rocks are found in Wengxiang shale of the Middel-Lower Silurian. Under the influence of multi-stage tectonic activities, the hydrocarbon accumulation history is relatively complex and featured with accumulation-destruction of multicycles, among which the destruction is the strongest during the late Yanshan Movement period .