黔中隆起及周缘下组合主要不整合分布特征及其对盖层的影响

DISTRIBUTION OF UNCONFORMITIES AND THEIR IMPACTS ON CAP ROCKS IN LOWER ASSEMBLAGE IN CENTRAL GUIZHOU UPLIFT AND PERIPHERAL REGIONS,SOUTHWEST CHINA

以沉积盆地沉积波动过程分析方法为理论指导,对黔中隆起及其周缘地区7个典型野外地质观测剖面震旦—石炭系沉积-剥蚀过程进行了系统分析和预测,对地层因不整合所造成的剥蚀厚度进行恢复,研究表明区内不同构造单元的沉积-剥蚀过程35Ma,20Ma的高频波动周期,定量恢复了下中奥陶统顶部、下中志留统顶部不整合剥蚀量分别为100m^540m和100m^390m。黔中隆起及周缘地区2个主要不整合呈现近西向-近北东方向和近南北向的剥蚀叠加,再现了关键时期沉降沉积区和隆起剥蚀区区域分布规律。综合分析认为不整合对盖层的影响是该区油气成藏的主要控制因素,预测盖层有利区域主要分布于黔中隆起西北部和滇黔北部坳陷。

Based on sedimentary wave process method, the process of sedimentary-erosion of 7 field geologic sections were analyzed in the Central Guizhou Uplift and peripheral regions, south- west China. The thickness of the uncomformity from Sinian to Carboniferous is resumed. Decom- posed from high-frequency wave periods containing the 35 Ma and 20 Ma reflected the deposition- erosion process in different structural units. The curves of high-frequency wave periods corre- spond to the uplift-erosion process. The erosion quantity of the main unconformities in the top Lower and Middle Ordovician and the top Lower and Middle Silurian were calculated with the thickness between 100 m and 540 m and between 100 m and 390 m, respectively. The two uncon- formities were superimposed in the west to northeast and south to north in the Central Guizhou Uplift and peripheral regions. Meanwhile, the thickness of the horizontal distribution in uncon- formities was resumed. The cap rocks were influenced by the unconformities which was the key controlling factor in the studied area. The most favorable belts of the cap rocks were predicted in the northwestern Central Guizhou Uplift and Dianqian North Depression.