川西坳陷中段上侏罗统遂宁组岩相古地理及砂体展布

以高分辨率层序地层学理论为指导，以中期旋回为编图单元，对川西坳陷中段上侏罗统遂宁组的古地理和砂体展布特征进行了研究。 结果表明：川西坳陷中段上侏罗统遂宁组可划分为 1 个长期旋回（LSC1）与 3 个中期旋回（MSC1，MSC2 和 MSC3）。 其中，MSC1-MSC3 沉积期，龙门山前缘均发育有较大规模的冲积扇群，辫状河三角洲沉积表现为多个辫状河三角洲叠置的沿龙门山前缘分布的辫状河三角洲群；MSC1-MSC2 沉积期，川西坳陷中段发育的沉积体系类型以辫状河三角洲-湖泊沉积为主，冲积扇仅在规模及位置上有所变化，该时期砂体主要分布于龙门山前缘与中江-回龙地区；MSC3 沉积期，辫状河三角洲平原沉积发育于郫县-温江-大邑地区，砂体厚度以及规模均较大。

Lithofacies paleogeography and sand bodies distribution of the Upper Jurassic Suining Formation in the middle section of western Sichuan Depression

Guided by the high resolution sequence stratigraphy theory, and making the middle-term cyclic sequence as mapping unit, this paper studied the paleogeography and sand body distribution characteristics. The result shows that the Upper Jurassic Suining Formation in the middle section of western Sichuan Depression can be divided into one long- term sequence （LSC1） and three middle-term sequences （MSC1-MSC3）. The front of Longmen Mountain developed alluvial fan group, and braided river delta deposition is manifested in multiple braided river delta overlay during the period of the MSC 1-MSC3. The depositions are mainly of braided river delta-lacustrine deposition during the period of the MSC1-MSC2, alluvial fan only changed in the size and location, and sand bodies mainly distributed in the front of Longmen Mountain and Zhongjiang-Huilong area. During the period of M3, the deposition changed into thick and large-scale braided river delta plain deposition, and sand bodies mainly distributed in Pixian-Wenjiang-Dayi area.