低可容空间河流三角洲沉积层序与聚煤模式  被引量:22

Sequence stratigraphy and coal accumulation of fluvial delta under low accommodation conditions

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作  者:鲁静[1] 邵龙义[1] 汪浩[1] 孙斌[2] 杨敏芳[2] 

机构地区:[1]中国矿业大学煤炭资源与安全开采国家重点实验室,北京100083 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出  处:《中国矿业大学学报》2012年第2期268-275,共8页Journal of China University of Mining & Technology

基  金:国家自然科学基金项目(41002049);国家重大科技专项(2011ZX05009-002);中央高校基本科研业务费专项资金项目(2009QD12)

摘  要:为了揭示低可容空间河流三角洲沉积背景下层序发育及聚煤特征,以鲁西南二叠系山西组为例进行了层序地层和聚煤作用研究.识别出强制海退(BFSR)造成的陆表侵蚀不整合面(SU)及其对应的整合面(CC*)、河流侵蚀面(RES)、古土壤层(PSS)、最大海退面(MRS)、海泛面(FS)、最大海泛面(MFS)7种层序界面,将煤系划分为12个准层序(2种准层序类型)、2个四级层序、1个三级层序,提出了低可容空间沉积背景下河流三角洲沉积体系聚煤模式.结果表明:低可容空间河流三角洲沉积背景下基准面与沉积界面基本一致,准层序以侵蚀面和海泛面为界并主要沉积于基准面上升半旋回;绝对海平面下降速率超过基底沉降速率是层序边界形成的主要驱动力;平面上聚煤中心位于下三角洲平原和间湾湖泊环境,指出剩余可容空间大小及新增可容空间产生速率是泥炭沉积的关键因素.The Permian of Shanxi formation in southwestern Shandong province was studied to unveil the accumulation pattern of coal in the fluvial delta under low accommodation. Key stra- tigraphic surfaces, i.e. terrestrial unconformity caused by forced regression (BFSR) and its correlative conformity (CC*), fluvial erosional surface (RES), paleosol seam (PSS), maxi- mum regression surface (MRS), flooding surface (FS) as well as maximum flooding surface (MFS) were recognized. The target coal measures was delineated into one 3rd sequence, two 4th order sequences, and twelve parasequences (two parasequences types). Subsequently, a coal accumulation model of fluvial delta in sequence stratigraphic framework under low accom- modation conditions was proposed. The result shows that, in low accommodation settings, the base level coincides with the sedimentary boundaries of fluvial delta; the parasequences are dominantly formed during the semi-cycle of the rising base level~ and the formation of the se- quence boundary is predominantly driven by the absolute sea level fall which is'faster than thefalling base level; The major coal seams were found to have been developed during transgress- ive system tracts, mainly in lower deltaic plain and interdistributary lacustrine, It is suggested that the size of residual accommodation during coal accumulation and the rate of accommodation increase are dominant controls of the peat accumulation.

关 键 词:低可容空间 河流三角洲 层序地层 聚煤 

分 类 号:P539.2[天文地球—古生物学与地层学]

 

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