摘要:
本文根据岩芯、岩石薄片、钻井和地震等资料的研究成果,将川东北元坝地区飞仙关组划分为两个三级层序:SQ1相当于飞仙关组一段、二段,SQ2相当于飞仙关组三段、四段。SQ1、SQ2由海侵体系域和高位体系域构成,缺少低位体系域。SQ1-TST期,元坝地区主要位于浅水碳酸盐台地上,为开阔台地相沉积,靠近东部为陆棚斜坡相沉积,从西到东依次发育开阔台地-台地边缘-斜坡相沉积。SQ1层序沉积时期,全区呈现西薄东厚的楔形几何形体。SQ2层序沉积时期,由于SQ1期的填平补齐作用,致使研究区整体演变为浅水碳酸盐台地沉积,沉积格局差异不大,以海侵和高位体系域为特征,对应海侵期的开阔台地和高位期的蒸发台地沉积。
Abstract:
The Feixianguan Formation in the Yuanba gas field, northeastern Sichuan may be divided, on the basis of cores, thin sections, well logs and seismic data, into two third-order sequences:SQ1 representing the 1st and 2nd members, and SQ2 representing the 3rd and 4th members of the Feixianguan Formation. Grounded upon the carbonate platform, both SQ1 and SQ2 are made up of the transgressive and highstand systems tracts and lack of the lowstand systems tract. During the deposition of the transgressive systems tract of SQ1, the bulk of the Yuanba area is built up of the open platform deposits on the shallow-water carbonate platform, and continental shelf deposits near the east. During the deposition of the highstand systems tract of SQ2, there are gradations of the open platformplatform margin-slope deposits from west to east. Till the deposition of SQ2, the whole area graded into the shallowwater carbonate platform dominated by the transgressive and highstand systems tracts representing the open platform deposits in the transgressive phase and evaporate platform deposits in the highstand phase.
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