Forming Mechanism of Continental Depression-lacustrine Large Delta of the 2-3 Members of Nenjiang Formation in Songliao Basin
Forming Mechanism of Continental Depression-lacustrine Large Delta of the 2-3 Members of Nenjiang Formation in Songliao Basin
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发表时间：
2012
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通讯作者：
Z. Shun
中科院分区：
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作者：
Z. Shun
为弄清松辽盆地嫩江组2-3段三角洲前积体的成因，进行了地震资料分析、构造演化和综合地质解释。认为三角洲大型前积体是在不同构造背景下不同倾角下形成的，断裂活动在嫩江组2-3段沉积期趋于休止，松辽盆地整体倾斜沉陷--东倾西沉，导致盆地古地理格局发生变化。沉积幅度和沉陷中心自东向西逐渐缩小。地层分布和湖泊面积呈南北条状伸展特征，物源方向由南北向向东西方向转变，沉积在盆地东部快速隆升的背景下迅速向前冲至湖泊，形成高角度的三角洲前积体，反映了明显的伸展较大、底隆明显、上覆不发育的福塞特格局，为嫩江组时期生油方向提供了直接证据，阐明了嫩江组2-3段凹陷-湖相大三角洲的形成机制，有助于松辽盆地油气勘探评价，为剩余资源勘探与配置评价提供指导。
In order to clarify the origin of foreset body of delta in the 2-3 members of Nenjiang Formation in the Songliao Basin,the analyses on seismic data,structural evolution and comprehensive geological interpretation were implemented.It was considered that the large foreset body of delta was generated under different tilts in different structural settings,the fault activities tended to be rested during sedimentary period of 2-3 members of Nenjiang Formation,the overall tilt and subsidence occurred in the Songliao Basin——tilting in the east and subsiding in the west,which lead to changes in the paleogeographic pattern of basin.The sedimentary range and subsidence center gradually reduced from east to west,the formation distribution and lake area showed the characters of north-southern strip-shaped extension.The source direction changed from the south-northern to the east-western.The sediments were rapidly carried forward to the lake in the background of eastern part of basin rapidly uplifting.It resulted in the high angle foreset body of delta,which illustrated obvious forset configuration of relatively large extension with obvious baselap and undeveloped toplap.It could provide a direct evidence of source direction of the period of Nenjiang Formation clarify the generation mechanism of Depression-lacustrine large delta of 2-3 member of Nenjiang Formation.It is helpful for the evaluation of oil and gas exploration in Songliao Basin and provides a guidance for the evaluation of residual resources exploration and deployment.