摘要:
本文以高分辨率层序地层学为理论基础,将山西组划分为6个中期旋回层序,并以此为编图单元编制了相应的砂体等厚图、地层等厚图及砂地比等值线图。基于基准面和可容空间的变化,分析了研究区古地理演化特征。研究表明,山23期至山21期,沉积作用以进积-加积为主,发育较大规模三角洲,沉积砂体较厚;山13期至山11期,沉积作用以进积-加积-退积为主,湖岸线向北推进,湖泊具有扩大的趋势;山2期三角洲平原规模较三角洲前缘大,山1期三角洲前缘有缩小的趋势。
Abstract:
Six medium-term cyclic sequences have been distinguished for the Shanxi Formation in the light of high-resolution sequence stratigraphy,and associated maps are constructed,including the isopach map of sandstones,isopach map of strata and isogram of total sandstone thickness to stratigraphic thickness ratios.The palaeogeographic interpretation of the Permian Shanxi Formation is presented on the basis of base levels and accommodation spaces.The deposition of progradation and aggradation resulted in the formation of larger deltas and thicker sandstones during the deposition of the third submember to the first submember of the second member of the Shanxi Formation,whereas the deposition of progradation,aggradation and retrogradation led to the northward migration of the lake strandline and the extension of the lake area during the deposition of the third submember to the first submember of the first member of the Shanxi Formation.The delta plain was larger in scale than the delta front during the deposition of the second member of the Shanxi Formation,and the delta front became progressively smaller during the deposition of the first member of the Shanxi Formation.
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