【摘要】 四川盆地是典型的经历了多期构造演化过程的克拉通盆地,在其多套沉积层序中富含天然气,天然气的开发利用历史悠久。近年来连续发现了普光、龙岗、合川、新场、九龙山和元坝等多个大气田。揭示四川盆地的形成演化过程,不仅为探讨克拉通盆地的成因机制奠立重要基础,而且为探索强烈构造活动环境之下油气有效聚集与保存机制提供重要线索。本文利用盆地内部最新的地面地质调查、钻探、重磁与地震等油气勘探资料,将周缘板块构造演化、造山带的发展与盆地的沉积充填密切结合,探讨四川盆地及邻区的盆地发展历史及其多旋回叠加过程。研究认为,四川盆地位于中上扬子克拉通之上,在显生宙期间,表现为板块构造围限下的陆内变形与盆地发育过程,即北侧为秦岭洋盆（早古生代为北秦岭洋,晚古生代—三叠纪为南秦岭洋）,西南侧为昌宁—孟连洋盆、金沙江—墨江洋盆、甘孜—理塘洋盆（主要为古特提斯洋盆）,东南侧为江南—雪峰陆内裂陷带（主要为早古生代裂陷）和西北侧龙门山陆内裂陷带（主要为晚古生代裂陷）,这些洋盆或裂陷带的开启与关闭使得四川盆地及邻区经历了原特提斯洋（Z—S）、古特提斯洋（D—T）与新特提斯洋（J—Q）3个演化阶段,每一阶段包括与洋盆打开有关的伸展阶段和与洋盆闭合有关的聚敛挤压阶段,这些构造作用在克拉通内部表现为伸展期(Z—O、D—P—T₃χ³、J_1-2)盆地与挤压期(S、T₃χ^4-6、J₃—K₁)盆地交替发育的特点,体现出盆地发展的旋回性。不同性质的旋回/盆地发生横向复合与垂向叠加形成多旋回盆地相叠加的"层、块"地质结构,受周缘盆—山体系多期构造作用的影响,这种"垂向分层、横向分块"的结构遭受了强烈改造,对油气聚集产生了深远的影响。更多还原

【Abstract】 The Sichuan Basin is a kind of classic cratonic basin having undergone multi-stage evolution,and is rich of gas resources in the different sets of sedimentary sequences.It boasts its long history of gas development and utilization,and a number of recently discovered giant gas fields such as Puguang,Longgang,Hechuan,Xinchang,Jiulongshan,and Yuanba.To explore the processes of formation and evolution of Sichuan Basin is not only an important aspects for addressing the genetic mechanism of cratonic basins,but also a key clue for recognizing the critical conditions of oil and gas accumulation and preserve under the strongly modified tectonic settings.Considering the adjacent plate tectonic evolution,and combing the basin depositional filling with the developing of the peripheral orogenic belts,the paper takes advantage of using the newly released data on surface geology,drilling,gravitational and magnetic,and seismic profiles to address the basin evolution history and its superposed processes of Sichuan Basin and around area.The Sichuan Basin is founded upon the Middle and Upper Yangtze Craton, exhibiting characteristics of the intra-continental deformation and basin development under the adjacent plate tectonic circumstances in the Phanerozoic Eon.With the Qingling Ocean to the north,which was the North Qingling Ocean in Early Paleozoic and the South Qinling Ocean in Late Paleozoic to Triassic respectively,the paleo-Tethyan oceans such as the Changning-Menglian Ocean,Jinshajing-Mojiang Ocean,and Gantze-Litang Ocean to the southwest,the Early Paleozoic Jiangnan-Xuefeng rift-sag to the southeast and the Late Paleozoic Longmenshan rift-sag to the northwest,the Sichuan Basin and its adjacent area had undergone three stages of proto-Tethyan,paleo-Tethyan,and neo-Tethyan evolution controlled by the opening and closing of these oceans and rift-sags.Each stage includes the extension relating to the opening of oceans and the amalgamation and compression relating to the closing of oceans,giving rise to the extensional basins during the Sinian to Ordovician,Devonian to the sedimentary period of the third member of Xujiahe Formation,and Early and Middle Jurassic alternating with the compression basins during the Silurian,the sedimentary period of the fourth to sixth member of Xujiahe Formation,and the Late Jurassic to Quaternary respectively.The basin cycles had resulted in the horizontally combination and vertically superimposition of proto-type basins, producing a distinct kind of geological structures called as stratified and blocked.Influenced by the multi-periods of interaction between the basin and the orogenic belts,the stratified and blocked basin structure has been intensively modified,and played a great role in the oil and gas accumulation in the basin.更多还原