Abstract:

The evolution of sedimentary facies，X-rays fluorescence analysis of sandstone and mudstone，and petrographic thin section were used in the research on Fankuai and Xiaotangzi sections in Sichuan foreland basin. We found that the sedimentary environment，palaeoclimate，palaeo-salinity and clastic compositions are relevant to the Indosinian movement of the Late Triassic.The tidal sedimentary environment is developed in the early stage of late-Indosinian movement.The warm palaeoclimate and high palaeosalinity are appeared at the same time. During the depositional period of Member 2 of Xujiahe Formation，the depth of sedimentary water is shallow，and the salinity is high，and the climate changes cool.But during the depositional period of Member 3 of Xujiahe Formation，the climate changes warm again and the salinity reduces.After the Anxian tectonic movement, during the depositional period of member 4 of Xujiahe Formation,the salinity is lower than before，and the continental deposits occur in Sichuan foreland basin.The depth of the sedimentary water is shallow and the climate changes cool.The composition of sandstone,controlled by the late-Indosinian movement, shows the evolution of the provenance in front of Dabashan and Longmen Mountains.

Key words: Dabashan Mountain, Longmen Mountain, Late Triassic, sedimentary environment, tectonic movement

摘要：

通过对大巴山前樊哙剖面与龙门山前小塘子村剖面上三叠统沉积相垂向演化分析、砂泥岩X射线荧光光谱分析、储集层微观薄片研究，认为川东北与川西北地区上三叠统的沉积环境、沉积水体的深度和盐度及砂岩碎屑组分与印支晚幕构造运动有紧密的关系。印支晚幕运动早期，大巴山与龙门山前的小塘子组沉积水体盐度较高，属温暖潮湿气候下的潮坪沉积；须家河组二段沉积时期，随着大巴山与龙门山的低幅隆升，古气候由温暖潮湿逐渐变为较干冷，沉积水体变浅且盐度高，属辫状河三角洲沉积。须三段沉积时期，大巴山与龙门山前古气候又演变为温暖潮湿，沉积水体加深，湖泊沉积较发育，水体盐度逐渐降低。印支晚幕安县运动发生后，大巴山前与龙门山前的古气候变得干冷，沉积水体变浅，盐度降低，沉积物属典型的陆相淡水沉积。同时，小塘子组—须家河组砂岩碎屑成分也随着构造运动的演化具有显著的不同。

CLC Number: 

• P512.2