Abstract: Several groups of strike-slip faults are developed in the central Sichuan Basin. Due to the small vertical displacement of strike-slip faults and the superposition of multi-period activities, it is difficult to identify the fault formation time. Comprehensively based on the U-Pb dating of multi-stage carbonate cements near the fault zone, in combination with the analyses of mineral diagenetic sequence and fluid inclusions as well as dating results of other minerals, the paper confirms the multi-stage activity time of strike-slip faults in the central Sichuan Basin, and also analyzes the controlling effect of strike-slip faults on hydrocarbon accumulation. The research results indicate that the strike-slip faults underwent multiple stages of activities, and mainly occurred from the Early Caledonian period to Yanshan period. The tensional strike-slip faults, which formed during the Late Hercynian period and were affected by the Emei taphrogenic movement, vertically connected with multiple layers and facilitated the formation of high-quality reservoirs near the fault zone, thus providing transportation conditions for the formation of large-scale paleo-oil reservoirs during the Indosinian period. Moreover, a significant amount of oil was generated in the source rocks of the rifting trough during the Indosinian period. The oil was then transported vertically and horizontally along the NWW-trending strike-slip fault over long distances, resulting in the three-dimensional differential enrichment of paleo-oil reservoirs. The paleo-oil reservoir underwent quasi-in-situ cracking in the Yanshanian period, leading to the formation of paleo-gas reservoirs. Subsequently, these paleo-gas reservoirs underwent adjustment, reconstruction and re-migration during the period from the Late Yanshanian to the Himalayan epoch. At that time, the NWW-trending strike-slip faults primarily played a role in sealing and transverse shielding, thus controlling the local gas enrichment and preservation. In conclusion, the NWW-trending strike-slip faults played a significant role in controlling the formation, migration, and accumulation of hydrocarbons in the study area.

Key words: deeply buried reservoir, U-Pb dating of carbonate, fluid inclusion, strike-slip fault, fault activity time, Sichuan Basin

摘要： 四川盆地中部(川中地区)深层海相地层发育多组走滑断裂,其垂向位移小且存在多期活动,断裂的形成时期难以判识。通过对断裂带附近发育的多期碳酸盐胶结物进行U-Pb定年,结合矿物的成岩序次分析、流体包裹体分析及其他矿物的定年结果,综合厘定了川中地区走滑断裂多期流体活动的时限,剖析了走滑断裂对油气成藏的控制作用。研究结果表明:川中地区的走滑断裂经历了多期活动,主要活动时间为早加里东期—燕山期,与峨眉地裂运动有关的晚海西期走滑拉张断裂在垂向上沟通了多个层系,有利于在断裂带附近形成优质储层,并为印支期大规模古油藏的形成提供输导条件;印支期,裂陷槽内烃源岩大量生油,原油沿着NWW向走滑断裂在纵向和横向上进行长距离输导,在川中地区形成了多层系、立体、差异化富集的古油藏;燕山期,古油藏发生准原位裂解而形成古气藏;晚燕山期—喜马拉雅期,古气藏发生调整改造和再运移,此时,NWW向走滑断裂主要起到封闭和横向遮挡的作用,控制了天然气的局部富集和保存。NWW向走滑断裂对川中地区油气的运移成藏与富集起到了重要的控制作用。

关键词: 深层储层, 碳酸盐U-Pb定年, 流体包裹体, 走滑断裂, 断裂活动时间, 四川盆地