摘要
通过对扬子地块西北缘后龙门山构造带南华纪—早古生代沉积地层的分析研究,综合运用岩石学、沉积特征分析的手段,结合与前龙门山构造带、碧口地块、米仓山构造带和汉南地块的沉积特征对比,探讨后龙门山构造带南华纪—早古生代的沉积环境,查明其形成环境。结果表明:在南华纪—早古生代后龙门山构造带沉积环境可分为南华纪—震旦纪裂解-稳定沉积和早古生代伸展裂陷沉积两个阶段,其中在早古生代伸展裂陷阶段后龙门山构造带经历了裂解→抬升→局部裂解→抬升→裂解的反复过程,最终形成了志留系茂县群裂陷槽沉积,主要沉积了一套代表伸展裂陷环境的沉积岩系,并有少量的陆内火山岩系。研究结果进一步证实,龙门山构造带在南华纪—早古生代总体是一个陆内裂谷带,不发育与古缝合线相关的构造混杂岩和蛇绿混杂岩带,是在陆内裂谷的基础上于印支期—燕山期形成的陆内造山带。
Through the research on sedimentary strata of Nanhuan Period-Early Paleozoic of Back-Longmenshan tectonic belt in the northwest margin of Yangtze Block with the methods of petrology and sedimentary strata,the sedimentary and forming environments of Nanhuan Period-Early Paleozoic of Back-Longmenshan tectonic belt were discussed based on the contrast of sedimentary characteristics of Fore-Longmenshan tectonic belt,Bikou Block,Micangshan tectonic belt and Hannan Block.The results indicated that the sedimentary environments of Nanhuan Period-Early Paleozoic of Back-Longmenshan tectonic belt could be divided into two stages,including the division-stable stage of Nanhuan-Sinian Period and the extension and division-collapse stage of Early Paleozoic;Back-Longmenshan tectonic belt had the repetitive process of divergence→lifting→partial divergence→lifting→divergence during the extension and division-collapse stage of Early Paleozoic;aulacogen sedimentary in Maoxian Group of Silurian System,which represented the extension and division-collapse environment,was eventually formed,and there was a little intra-continental volcanic rocks.The results further confirmed that Back-Longmenshan tectonic belt in general was an intra-continental rift belt during Nanhua Period-Early Paleozoic and an intra-continental orogenic belt based on the intra-continental aulacogen in Indosinian-Yanshanian Period,and did not develop tectonic and ophiolitic melange belts related with the ancient suture.
出处
《地球科学与环境学报》
CAS
2011年第2期117-124,共8页
Journal of Earth Sciences and Environment
基金
国家自然科学基金项目(40972136
40572121
40234041)
中央高校基本科研业务费专项资金项目(CHD2009JC046
CHD2009JC053
CHD2009JC070)
中国石油化工股份有限公司海相前瞻性研究项目(YPH08006)
关键词
扬子地块西北缘
后龙门山构造带
南华纪—早古生代
沉积环境
裂陷槽
northwest margin of Yangtze Block
Back-Longmenshan tectonic belt
Nanhuan Period-Early Paleozoic
sedimentary environment
aulacogen
