关键词: 四川盆地, 泸州古隆起, 地层不整合, 盆山耦合, 成因机制

Abstract: Increased understanding of the geological structure of large paleo-uplift within a basin is often accompanied by great oil and gas discovery. The exploratory findings of abundant oil and gas in the Luzhou paleo-uplift demonstrate that it is one of the most important oil and gas structural units in the Sichuan Basin. Many geological factors influenced the formation and evolution of the Luzhou paleo-uplift from joint response of the intra-plate deformation of the Yangtze Block and the Indosinian Orogeny of the peripheral block, making the paleo-uplift a natural laboratory for studying basin-mountain coupling and basin evolution. In this study, we carried out a detailed determination of the Indosinian Luzhou paleo-uplift in southeastern Sichuan by using a large number of seismic reflection profiles and drilling data. We also determined the loss of Triassic strata in the uplift area by stratigraphic correlation analysis of different regions. Based on the detailed seismic interpretation, we analyzed the developmental characteristic of the unconformities and subsequently revealed the periodic evolutionary characteristic of the Luzhou paleo-uplift. Meanwhile, by combining drilling and seismic data, we tracked the distribution range of pinch out of different periods and described in detail the distribution characteristic of Luzhou paleo-uplift. We further investigated the dynamic characteristics of the Luzhou paleo-uplift formation and evolution by taking into account the tectonic background of the study area and proposed the genetic mechanism model of the Luzhou paleo-uplift. It is believed that the Luzhou paleo-uplift in the southeastern Sichuan Basin has undergone three significant evolutionary stages, i.e. budding stage of the sedimentary period of the Early Triassic Jialingjiang Formation, developmental stage of the Middle Triassic Leikoupo Formation, and extinction stage of the Late Triassic Xujiahe Formation. The formation of the Luzhou paleo-uplift is controlled by the Indosinian Orogeny in the peripheral block. The peleo-uplift can be regarded as crustal uplifted zones in the front of the piedmont depression, during the period of westward migration and extrusion of the Jiangnan Xuefeng Orogen, on the southeastern margin of the Yangtze Block.

Key words: Sichuan Basin, Luzhou paleo-uplift, stratigraphic unconformity, basin-mountain coupling, formation mechanism