攀西裂谷存在吗?  

Does the Panzhihua-Xichang Rift Exist?

作　　者：何斌[1] 徐义刚[1] 肖龙[1] 王雅玫[2] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]中国地质大学,武汉430030

出　　处：《地质论评》2003年第6期572-582,共11页Geological Review

基　　金：国家自然科学基金重点项目(编号40234046);中国科学院知识创新工程项目(编号KZCX2-101);国家973项目(编号G1999043205)的成果

摘　　要：大陆裂谷以地幔上隆、岩石圈伸展、减薄、断陷和沉降为特征,伸展构造环境是大陆裂谷形成的必要条件和本质特征。中国学者以前所认为攀枝花—西昌裂谷的主要标志是海西期层状堆晶杂岩、晚二叠世峨眉山玄武岩、印支期环状碱性杂岩和晚三叠世裂谷盆地沉积。最近一系列研究成果表明攀西地区海西期—印支期构造岩浆热事件是地幔柱和岩石圈相互作用的结果,不是裂谷作用的产物。进一步对上扬子西缘二叠纪—三叠纪的沉积作用和构造特征综合分析表明攀西地区不存在裂谷盆地沉积。该区晚二叠世—中三叠世为古陆隆起遭受剥蚀,晚三叠世断陷型类磨拉石建造是前陆走滑复合盆地的产物。本文根据对攀西地区二叠纪—三叠纪的岩浆活动、沉积作用、构造特征和地球物理资料等方面综合研究对攀西裂谷的存在提出质疑,并以峨眉山地幔柱活动为主线探讨了攀西地区古生代和中生代的地质构造演化历史。The main features of continental rift are mantle upwelling, extension, thinning, faulting and subsidence of lithosphere. The extensional environment is necessary and key to form a continental rift. It has been considered by the Chinese geologists in the past that the Panxi (Panzhihua-Xichang) rift is marked mainly by layer complexes, Emeishan basalts,ring alkalic complexes and sedimentation of the rift basins in the late Triassic. Recently, a series of studies have shown that this huge magmatic event from the Variscan to the Indosinian is a product of mantle plume-lithosphere interaction. Analysis of sedimentation and structures on the western margin of the upper Yangtze block demonstrates that the Panxi area is an old land and was eroded from late Permian to middle Triassic. The late Triassic molasses formation in faulted basins is caused by foreland loading and strike-slip exerted by the Tethys closure, and no narrow rift basin existed. This paper presents questions about the existence of the Panxi rift based on magmatic activities, sedimentary processes, structural features and geophysical data, and proposes a geological evolution history of the Panxi area from Paleozoic to Mesozoic.

关 键 词：攀西裂谷 峨眉山玄武岩 她帽样 大陆裂谷 伸展构造 

分 类 号：P542.3[天文地球—构造地质学]