准噶尔盆地的类型和构造演化

准噶尔盆地的早二叠世属于裂谷还是前陆盆地 ,存在意见分歧 ;晚二叠世—老第三纪盆地的性质也不确定。文中通过对盆地构造几何学、沉降史、热史及火山岩的综合分析研究 ,对盆地类型和构造演化获得了一些新的认识 :( 1)准噶尔盆地在早二叠世为裂谷 ,晚二叠世为热冷却伸展坳陷 ,三叠纪—老第三纪为克拉通内盆地 ,新第三纪至今 ,由于印度板块与亚洲大陆碰撞才形成陆内前陆盆地。 ( 2 )对石炭纪—早二叠世的岩浆活动结合区域构造资料的研究表明 ,准噶尔地区古生代的板块运动和造山作用具软碰撞特点 ,早二叠世的裂谷盆地是在软碰撞背景下造山带伸展塌陷的产物。 ( 3)地幔热对流作用可能是软碰撞造山后伸展塌陷的主要深部动力学机制。

TYPES AND TECTONIC EVOLUTION OF JUNGER BASIN

Junggar basin is a large continental interior basin in western China, which has been developing since Early Permian Controversy focuses on the type of basin in Early Permian and its origin Also the attributions of the basin from Triassic to Early Tertiary is unknown Evidences about basin fill architecture, tectonic subsidence, geo thermal histories, petrological and geochemical characteristics of Early Permo carboniferous volcanic rocks can provide the following new recognition (1) The basin was initially rifted in Early Permian followed by thermal cooling subsidence during Late Permian, thence went through the cratonic basin stage from Triassic to Paleogene, and finally through the foreland basin developing (2)A large number of calc alkaline suite volcanic rocks erupted in early Permo Carboniferous accompanied by type A granites intrusion suggest that the rift in Early Permian was related to postorogenic extension collapse Furthermore soft collision was a tectonic background for postorogenic extension collapse during Paleozoic in Northern Xinjiang (3) The driving mechanism of postorogenic extension collapse was a mantle thermal convection