【摘要】 晚三叠世是四川盆地演化的重要时期。根据野外露头、钻井和地震资料,运用构造层序地层学的思路和方法,对四川盆地上三叠统层序界面、层序划分和层序特征进行深入研究,并建立层序地层格架。研究表明,四川盆地上三叠统可识别出4个层序界面:1)上三叠统与中、下三叠统之间的区域性构造不整合面;2)须二段与小塘子组的分界面;3)须三段与须四段之间的次级构造不整合面;4)三叠系与侏罗系之间的区域性构造不整合面。根据层序界面的发育情况,将研究区划分为3个构造层序,每个层序以最大湖泛面为界,划分为盆地扩张体系域(BE)和盆地收缩体系域(BW)2个体系域。晚三叠世四川盆地的演化主要是川西前陆盆地的演化,其中TS1为边缘前陆盆地演化阶段;TS2为川西前陆盆地形成阶段,龙门山逆冲推覆体开始逆冲推覆;TS3为川西前陆盆地发展阶段,受安县运动的影响,龙门山逆冲褶皱成山,使得整个四川盆地进入了陆相沉积环境。构造运动是控制晚三叠世四川盆地演化的重要因素。更多还原

【Abstract】 The Upper Triassic in the Sichuan Basin is a key to understand the evolutionary history of this basin. Using bore hole, outcrop, and seismostratigraphic data, the authors studied the tectonic sequence of the Upper Triassic in the Sichuan Basin. Four sequence boundaries were recognized, including 1) the tectonic unconformity between the Upper Triassic and Middle or Lower Triassic, 2) the lithostratigraphic boundary between the second member of the Xujiahe Formation and the Xiaotangzi Formation, 3) the tectonic unconformity between the third and fourth members of the Xujiahe Formation, 4) the Jurassic-Triassic tectonic unconformity.Therefore, the Upper Triassic is divided into three tectonic sequences, which can be correlated across the entire basin. Each sequence is divided into two system tracts using the largest lake flooding surface, and these represent the basin-expansion system tract and basin-reduction system tract. On the basis of tectonic sequence data,the evolution history of the Sichuan Basin is discussed. The Late Triassic in the Sichuan Basin are divided into three stages, which are the marginal foreland basin evolution stage (TS1), the western Sichuan Foreland Basin formation stage (TS2), and the western Sichuan Foreland Basin development stage (TS3). Because of influence by the An’xian Movement in TS2, the Longmenshan Thrust Belt was uplifted and became a mountain, which changed the Sichuan Basin into a terrestrial sedimentary environment. The most important factor controlling the basin evolution of the Late Triassic in the Sichuan Basin is tectonic activity.更多还原