泸州古隆起对贵州赤水地区早、中三叠世沉积环境和相带展布的控制

Controls of Luzhou Uplift on Sedimentary Environment and Facies Distribution in Early and Middle Triassic,Chishui,Guizhou Province

在地质历史中,区域大地构造和区域古地貌单元的不同特征是控制沉积相带展布及发育的主要因素之一。东吴运动形成的泸州古隆起是影响本区沉积相带展布的重要因素。早、中三叠世时,泸州古隆起的高部位向南延伸到太和场以南,宝元以北一带。宝元、龙爪等构造处于泸州古隆起东南部斜坡上,而宝元构造处于古隆起东南部斜坡上部,龙爪构造处于古隆起东南部斜坡中部。此古地貌格局,与区域海平面升降一起,控制了早三叠世沉积相带展布和地层厚度。在古地貌高的隆起区域,由于水体开阔、水动力条件相对较强,沉积了有利于形成储集体的滩相沉积物(生屑滩、砂屑滩、鲕粒滩等)。从泸州古隆起的高部位向古隆起的斜坡区,地层厚度逐渐增大,沉积物向粒度变细、颜色加深的特征相变。

In the geological history, the distribution and the development of sedimentary facies was controlled by the regional tectonics and the regional relief. The Luzhou Uplift, which under the influence of Dongwu Movement, was one of the important controlling factors for the distribution of the Mesozoic sedimentary environment and the sedimentary facies in the area of southern Sichuan basin. During the Early and the Middle Triassic, the Luzhou Uplift developed and stretched to the south, the regional topography characteristic influenced the local sedimentary environment change and sea-level controlled the sedimentary facies distribution and the thickness of strata. For example, the Baoyuan and the Longzhao are two gas-beating structures, in which the reservoirs distribute in lower Triassic. Both of these two gasbearing structures are located at the south slope of the Luzhou Uplift, but the position of the Baoyua structure is on the upper part of the slope, and the Longzhao structure is on the lower slope. The position of the Baoyuan structure is higher than that of the Longzhao. At the high slope of the Uplift, the open sea environment had the stronger hydro-energy, the different banks such as oncolite and bioclastic could be deposited in this area. This sedimentary environment is better for reservoirs formation. From the higher part to the lower part of the Luzhou Uplift, along with the depth of water increased, the thickness of the strata increased, and the grain of the sediments decreased which was the representative of deeper water deposition.