Orogeny And Uplift In The Mesozoic-Cenozoic At Western Qin Ling

The research of orogene in Western Qinling, which is valuable for the research of evolutional history of orogenen in Western Qinling and provides credible background information for energy and mineral exploration, is increasingly concerned recently.This paper, which is based on fundamental geological theories such as sedimentation, quaternary geology, and structural geology, synthetically studies tectonic characteristics of orogenen in Western Qinling by detailed field on-the-spot investigation, indoor section construction. Certain technical methods such as micro tectonic analysis for relative litho and minerals, dating analysis, orientation analysis, testing of element in nappe and regional seismic information are applied in this paper.The tectonic style in orogenic uplift area is stratum entrapped thrust-fold model. In mid-Qinling it is represented as imbricate thrust pattern, and in Bailongjiang uplift area as back thrust rosette pattern. The tectonic style in depression area is caprock slipped thrust fold model, which tectonic style basically is tightening rupture and surge or fault propagation fold and low angle thrust abruption.With field investigation and actual measurement in Bailong River terrace and Min River, Bailong River can be divided into 7 terraces and Min River 3 terraces. This paper estimates magnitude and speed of crust uplifting in different era by analyzing the differences in pedestal depth and age and finds out that the terrace development in Western Qinling is characterized by multistage and inhomogeneity, and the uplift evidently accelerates since Late Pleistocene epoch.Having integrating a great deal of data such as latitude of planation surface, relative geologic time, stream terrace, thickness of sedimentation in Kainozoic era and some archaeological achievements, this paper studies tectonic uplifting characteristics in Western Qinling orogene in Cenozoic era and estimates uplifting speed in each stage. It has four obviously uplifting eras , K2~E1,N1~N2,Q1,Q4. Finally, it concludes that the tectonic uplift in Western Qinling orogene in Kainozoic era is staged. Compared to uplifting speed in Qinghai-Tibet Plateau, it is clear that since 3.6 Ma, Western Qinling, which is affected by the fast uplift of Qinghai-Tibet Plateau, has uplifted rapidly until now and gradually turns into one part of northeast of Qinghai-Tibet Plateau.