摘要
宁镇山脉处于西太平洋外带,郯城—庐江断裂带之东侧。中生代,由于太平洋板块与亚洲大陆的斜向俯冲和郯城—庐江断裂带的左行剪切活动,造成了沿江下扬子地区一系列的 NE 向剪切拉张盆地和剪切挤压褶皱山系。宁镇山脉正是在这种构造背景上形成的剪切挤压褶皱山系。
Since 1930s,many geologists have worked on the Ning-Zhen range and fixed the structu- re outline to be ′3-anticlinorium-2-synclinorium′.Up to now,this structure frame still remains correct.This paper mainly focuses on its formation and development basesd on the historical dynamic analysis of identified tectonic time and space. The Ning-Zhen fold belt,consists of the baeement of shallow metamorphosed flyschoid formation and the cover of sedimetary rock ranging from the Sinian to Triassic systems was formed in the craton environment.The folds appear to be reversed ′S′-shape on the horizontal plane trending from NE-EW-NNE.The folds belong to the parallel fold and compose ejective folds.The longitudinal reverse faults constitute overthrust imbricate fault.The statist- ical analysis on the joints in the whole area shows that there are two kinds of tectonic sttess fields-horizontal lateral stress and sinistral shear stress. In the Late Permian Epoch and Late Triassic Epoch,the North China Plate and Yangtze Plate were put togather and made the area become the margin of continental plate.In the Mesozoic Ear,owing to the subduction of the pacific plate under the Asian plate and the si- nistral shear of Tan-Lu fault system,the area was on the background of shear and tension. During the Middle and Late Jurassic Epoch,the uplifting of thermal expansion happened in the area.Upper mantle magma intruded along the faults and the alkatic volcanic series erupt- ed.The crust of the-area thinned.All these evidences confirmed that the lower Yangtze area was a graben in the Mesozoic Ear.After the Jurassic Period,with the southwards movement of the old continent,the Tan-Lu fault happened strong sinistral shear.This mechanism re- sulted in a series of transtensional basin and transpressional range along the Yangtze river.
出处
《江苏地质》
1990年第1期13-16,共4页
Jiangsu Geology
