论文部分内容阅读
晚中生代,中朝、扬子两地块的拼合带进一步受到强烈的陆内构造-岩浆活动改造,为揭示其规律性,以拼合带上北秦岭二郎坪群主体地块为研究对象,综合开展了中小构造解析、显微构造岩组学、电子探针、年代学等研究。研究发现,二郎坪群主体内部的小寨-二郎坪剪切带具右行韧性走滑特征,大庙-湾潭剪切带具右行韧性走滑兼后期脆-韧性逆掩叠加的特征;40Ar/39Ar构造-热年代学分析揭示出一期连续抬升-剥露过程,时间介于~121 Ma和~100 Ma之间。晚中生代二郎坪群地块经历了伸展-走滑-收缩背景依次控制下的构造改造过程,先是在区域伸展体制下,被内部的小寨-二郎坪剪切带、大庙-湾潭剪切带切割为抱树坪岩片、火神庙岩片、二进沟岩片等构造岩片;在其后的早白垩世早期区域走滑背景下,各构造岩片又发生了平移为主的右行走滑运动;最后,二郎坪岩体的侵入终止了内部小寨-二郎坪剪切带的活动,而大庙-湾潭剪切带也在区域收缩体制下终止活动,从而使二郎坪群重又焊接为一体。研究结果预示着北秦岭二郎坪群晚中生代同时期的构造体制可能与大别山是相反的。
In the Late Mesozoic, China-North Korea and Yangtze blocks were further subjected to intense intracontinental-magmatic activity transformation. To reveal the regularity, the main massif of Erlangping Group in North Qinling Mountains was taken as the study object, Analysis of small and medium structures, microstructures of rock group science, electronic probes, chronology and other studies. The study shows that the Xiaozhai - Erlangping shear zone inside the main body of Erlangping Group has the right ductile strike - slip characteristics, and the DaMiao - Wantan shear zone has the right ductile strike - slip and late brittle - ductile overtopping. The 40Ar / 39Ar tectono-thermal chronological analysis revealed a continuous uplift-debridement process with time between ~ 121 Ma and ~ 100 Ma. The Late Mesozoic Erlang Pont massif underwent the tectonic transformation process under the control of extensional-strike-slip-shrinkage background. Firstly, under the regional extensional system, it was cut by the internal Xiaozhai-Erlangping shear zone, Damingmiao-Wantan And the tectonic slices such as Baohuuping rock slice, Vulcanic rock slice, and Bijin ditch rock slice are cut with cutting; in the background of the early Early Cretaceous regional strike-slip, each of the tectonic slices undergo a translational right-lateral strike slip movement; Finally, the intrusion of Erlangping rock mass terminated the activity of the Inner Xiaozhai-Erlangping Shear Zone, while the Damiao-Wantan shear zone terminated its activity under the regional contractional regime, thereby re-welding the Erlangping Group into one . The results indicate that the tectonic regime of the same period of the Mesozoic Erdi Ping Group in the North Qinling Mountains may be the opposite of that of the Dabie Mountains.