The relationship between the deep structure and quaternary tectonics of the pamir and Tien-Shan

Abstract

Abstract The Quaternary period in the Pamir and Tien-Shan is marked by a sharp increase in the intensity of uplift which followed a short tectonically calm period in the late Pliocene and the early Pleistocene. Rates of the upward movement increased from the early Pleistocene to Holocene. The structural pattern of the region was formed throughout the whole neotectonic stage but the present shape is mainly the result of the Quaternary movements. A number of large uplifts and relative depressions can be identified in the Tien-Shan and Pamir. Only some of the greatest depressions were subject to absolute downwarping in their central parts during the Quaternary time. Numerous new data on the thickness of the earth's crust of Central Asia obtained in the past few years have allowed construction of a new relief map of the Mohorovicic discontinuity in the Tien-Shan and Pamir and of the discontinuity in relationship to the character of the Quaternary tectonic movements. As a result, correspondences relating to the development of the earth's crust were established and a suggestion was made as to the current rejuvenation of the structural pattern, with both an anti-Tien-Shan and a meridional direction dominating in the Pamir. The comparison of the development of the earth's crust as a whole with the lateral heterogeneities of the upper mantle confirmed the assumption about the current rejuvenation. At the same time it made evident once again that there are significant differences in the deep processes taking place in the Pamir and Tien-Shan. Combining analyses of both the subsurface and the surface development in this part of Asia provided a better view of the characteristics of the deep fault zones. This has allowed the authors to outline the latent ruptures and establish individual blocks of the earth's crust that show different structure and development.