混积层系沉积、层序特征——以鄂尔多斯盆地高桥地区本溪组为例

鄂尔多斯盆地高桥地区本溪组发育陆源碎屑岩和碳酸盐岩混合沉积.综合前人研究成果,根据野外露头、岩心、录井和测井等资料,分析了混积层系沉积、层序充填特征.结果 表明:本溪组发育陆源碎屑岩和碳酸盐岩相互叠加的混积层系,发育碎屑岩潮坪、混积潮坪和混积潟湖等沉积体系.根据层序地层原理,识别出1个区域不整合面、1个构造沉降转换面和...

Sedimentary characteristics and sequence stratigraphy in a mixed silicilastic-carbonate depositional system:Case study of Benxi Formation in Gaoqiao area,Ordos Basin

A mixed siliciclastic-carbonate succession is developed in Benxi Formation in the Gaoqiao area of Ordos Basin.On the basis of previous researches,sedimentary characteristics and sequence stratigraphy in a mixed silicilastic-carbonate depositional system of Benxi Formation were studied based on outcrop,core data,logging and well logs data in Gaoqiao area of Ordos Basin.It shows that the Benxi Formation is mainly composed of tidal flat depositional system which is subdivided into the siliciclastic tidal flat facies,the mixed tidal flat facies and mixed lagoon facies.According to the principle of sequence stratigraphy,one regional unconformity surface,one tectonic subsidence transition surface and one lithology and lithofacies transition surfaces are identified.The Benxi Formation is divided into SQ1-SQ2 of the 3rd-order sequences.Each sequence is mainly composed of transgressive system tract(TST)and highstand system tract(HST).The mixed siliciclastic-carbonate succession of Benxi Formation is developed under the circumstance of dominated silicicclastic sediments.Mixed sedimentation mainly occurred at the stage of TST of SQ2.The lithologic and lithofacies assemblages of mixed siliciclastic-carbonate succession are different in different sedimentary areas.The intertidal sandstone and mudstone are superimposed on the tidal channel facies sandstone and then to the limestone in the mixed tidal flat area.The lagoon mudstone is superimposed on the limestone in the mixed lagoon area.The limestone is superimposed on the subtidal sandstone and intertidal sandstone in the transitional area of the mixed tidal flat and the mixed lagoon.