四川盆地新元古代裂谷体系发育的大地构造背景OA

As the successive discovery of large Sinian gas fields such as Weiyuan,Anyue and Penglai in the Sichuan Basin,deep to ultra-deep strata have demonstrated attractive prospects of petroleum exploration.The primary task of deep to ultra-deep petroleum exploration in this basin is to determine the distribution and characteristics of the prototype basin,thereby revealing its early stage tectonic background.Based on the latest data such as gravity,magnetic,electrical methods,seismic surveys,drilling,paleomagnetism,magmatic rock ages,and geochemistry,the basement structure and tectonic position of the Sichun basin were clarified.This study reveals the peripheral tectonic processes and deep geological background,systematically analyzing the tectonic setting of the Upper Yangtze Block during different periods of the Neoproterozoic.The study suggests that the Yangtze Block may have formed through the amalgamation of the Shennong terrane in the northwest and an oceanic plateau in the southeast.The Yangtze Block and the Cathaysia Block collided between 820 and 810 Ma to form the South China Block.The Sichuan Basin exhibits a dual-basement configuration,comprising the Late Archean to Paleoproterozoic crystalline basement and the Mesoproterozoic folded basement.During the Neoproterozoic to Early Paleozoic,the Yangtze Block was located on the northwestern margin of the Rodinia supercontinent,close to the Australian or Indian continent.The Yangtze Block experienced three tectonic-magmatic events in the Neoproterozoic,reflecting the entire process of subduction and back-arc extension of the Proto-Tethys Ocean.After approximately 810 Ma,the Upper Yangtze Block entered an extensional tectonic regime,developing a series of"wide rift"basins in a back-arc setting.The Yangtze Block underwent a complete convergence-extension cycle during the Neoproterozoic,with the extensional rift basins being the primary target for deep to ultra-deep exploration studies.