摘要
以高分辨率层序地层学和现代沉积学理论为指导,利用野外露头、岩心、测井与地震等资料,对鄂尔多斯盆地陇东地区三叠系延长组的层序地层格架和沉积环境进行了研究。将鄂尔多斯盆地陇东地区三叠系延长组长8_1—长6_3小层(LSC3)作为一个完整的长期基准面旋回,进一步细分为3个中期基准面旋回,即MSC3-1,MSC3-2和MSC3-3。其中,MSC3-1相当于长8_1小层,该沉积期湖盆强烈坳陷,砂体叠置样式以加积和退积为主;MSC3-2相当于长73—长72小层,该沉积期湖盆快速扩张,达到延长组沉积期的最大湖泛,主要发育欠补偿环境下的暗色泥页岩;MSC3-3相当于长7_2—长6_3小层,该沉积期湖盆开始收缩,砂体叠置样式以进积为主。陇东地区延长组沉积相可划分为辫状河三角洲、曲流河三角洲、湖泊以及浊积扇等4种类型。MSC3-1沉积期研究区以发育南西物源的辫状河三角洲为主;MSC3-2沉积期湖泊占据了主体地位,深湖中常见浊积砂体;MSC3-3沉积期湖泊萎缩,以来自南西物源的辫状河三角洲和来自北东物源的曲流河三角洲沉积为主。
Guided by the theories of high resolution sequence stratigraphy and modern sedimentology, sequence stratigraphic framework and depositional environment of Triassic Yanchang Formation in Longdong area of Ordos Basin were studied by making full use of outcrops, cores, logs and seismic data. Chang 8 1-Chang 63 sublayer （LSC3） was defined as an and MSC3-3, integral long-term base level cycle and then divided into three mid-term base level cycle： MSC3-1, MSC3-2 MSC3-1 equals to Chang 81 depositional period, when the basin was in strong depression with mainly aggradation and retrogradation stacking pattern. MSC3-2 equals to Chang 73-Chang 72 depositional period, when the basin expanded rapidly and reached the maximum flood surface, and deposited dark shale in under-compensa-tion status. MSC3-1 equals to Chang 72-Chang 63 depositional period, when the basin began to shrink with mainly progradation stacking pattern. Sedimentary facies of Yanchang Formation in Longdong area was identified as braided river delta, meandering river delta, turhidite fan and lacustrine environments. In MSC3-1, there was mainly braided river delta with provenance of southwest. In MSC3-2, lacustrine environment occupied dominant position and there were turbidite deposits in deep lake. In MSC3-3, lake began to decrease, so both braided river delta from southwest and meandering river delta from northeast prograded strongly.
出处
《岩性油气藏》
CSCD
北大核心
2016年第1期77-87,共11页
Lithologic Reservoirs
基金
国家重点基础研究发展计划(973)项目子课题"中国西部叠合盆地深部有效碎屑岩储层成因机制与发育模式"(编号:2011CB201104)
中国石油大学(北京)科研基金"不同类型盆地内砂岩孔隙与物性演化研究"(编号:KYJJ2012-01-18)联合资助
关键词
高分辨率
层序地层学
基准面旋回
沉积相
延长组
鄂尔多斯盆地
high resolution
sequence stratigraphy
base level cycle
sedimentary facies
Yanchang Formation
Ordos Basin
