Sedimentary characteristics of the Cretaceous Denglouku Formation in the southeast uplift of the southern Songliao Basin

Li Zhandong; Li Yang; Liu Yunli; Hu Huiting; Ma Fengrong; Zhang Xiaogang

doi:10.11743/ogg20140315

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Sedimentary characteristics of the Cretaceous Denglouku Formation in the southeast uplift of the southern Songliao Basin
Vol. 35, Issue 3, Pages: 401-409(2014)
Online First：08 June 2014，

Published：2014
DOI： 10.11743/ogg20140315
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DOI：

Li Zhandong, Li Yang, Liu Yunli, et al. Sedimentary characteristics of the Cretaceous Denglouku Formation in the southeast uplift of the southern Songliao Basin[J]. 2014, 35(3): 401-409. DOI： 10.11743/ogg20140315.

摘要

为了查明松辽盆地南部东南隆起区登娄库组沉积特征及演化规律，开展了层序格架内的沉积相展布特征及演化研究。研究表明，登娄库组物源具有四周向中央汇聚的继承性特征，沉积相分布受盆地构造演化控制明显，主要发育了5种沉积相——冲积扇、扇三角洲、辫状河、辫状河三角洲和湖相。层序Ⅳ-d1为断-坳转换期的早期，沉积受断陷控制明显，致使沉积物快速卸载，各沉积体系向盆地内部进积的距离受到了限制，共发育了5个规模较大的分割式断陷和2个小型断陷。断陷周缘古凸起为冲积扇沉积体系的主要发育区，扇三角洲沉积分布于断陷的四周，扇三角洲前缘延伸到入湖处。沉积相主要以冲积扇、扇三角洲和湖相为主；层序Ⅳ-d2为断坳转换期的末期，研究区基本上形成了统一沉积物卸载区域，湖泊范围扩大，主要发育了冲积扇、扇三角洲、辫状河、辫状河三角洲和湖相沉积。以泛滥平原与滨浅湖的接触带为界，该界限以西主要发育来自西部和北部物源高地的冲积扇、辫状河沉积体系，该界限以东湖泊相大面积发育，伴随高地物源区碎屑沉积物陆续注入湖盆，构成了规模不等的退积式扇三角洲。其中，扇三角洲前缘和辫状河三角洲前缘亚相带是油气富集的主要储集体，是今后该区登娄库组油气勘探的有利相带。

Abstract

Sedimentary characteristics and evolution of the Denglouku Formation in the southeast uplift area of southern Songliao basin was studied based on analyses of sedimentary facies distribution and evolution in the context of sequence framework.The results show that the provenance of the Formation were distributed around the basin and supplied sediments from all directions to the center of the basin and the sedimentary facies distribution was controlled by basin tectonic evolution.Five major sedimentary facies were recognized in the area:alluvial fan

fan delta

braided river

braided delta

and lake.The sequence Ⅳ-d1 was formed during the early stage of transformation from a fault depression to a sag.The deposition was mostly controlled by the fault depression and the sediments were downloaded rapidly

restricting the distance of progradation to the inner basin.There developed five separated fault depressions and two small fault depression.Alluvial fan sedimentary systems were developed on the paleohighs around the fault depressions

fan delta systems were located around the fault depressions

while the fronts of the fan delta extended into the mouth of the lake.The sedimentary facies were dominated by alluvial fan

fan delta and lake.Sequence Ⅳ-d2 was formed during the late stage of transformation from fault depression to a sag when an unified sediment unloading area was developed

and the lake expanded.The sedimentary facies were dominated by alluvial fan

fan delta

braided river

braided river delta

littoral and lake.The contact zone of the flood plains and the shore-shallow lake can be regarded as a boundary

to the west of which formed allu-vial fan and braided river systems with sediments sourced from the western and the northern highland provenances;and to the east of which developed retrograded fan deltas of different scales with clastic sediments sourced from highlands.Among the facies

the fan delta front and braided river delta front are considered to be home to hydrocarbon reservoirs and therefore are the most promising exploration targets for oil and gas.