Quaternary Evolution of the Tectonic Geomorphology in the Jintanan Shan and Its Implications for the Northward Growth of the Qinghai-Tibetan Plateau
The Hexi Corridor is a key area for studying the uplift and expansion of the Qinghai-Tibetan Plateau since the Cenozoic.Jintanan Shan is a young uplifted mountain located in the north of the Hexi Corridor.The tectonic geomorphological evolution of this mountain could provide insights into the northward growth of the Qinghai-Tibetan Plateau.Here,we report the results of an integrative study,including detailed sedimentary observations and descriptions,chronological determination(Optically Stimulated Luminescence dating and Electron Spin Resonance dating),provenance,and structural deformation analyses,on a new Quaternary sedimentary section in the Jintanan Shan area.Our results reveal the existence of a disconformity in the Jintanan Shan section,which divides this section into two parts:the lower part of fluvial facies deposits with a provenance from the northern Qilian Shan to the south and sedimentary age of 0.64-0.60 Ma;the upper part of alluvial sediments from the Jintanan Shan,as a product of the proximal deposition in piedmont,with sedimentary age of 118-80 ka.This indicates that the Jintanan Shan experienced intensive uplift during the Mid Pleistocene(0.6-0.1 Ma),and its structural deformation controlled the regional landscape evolution.Before ca.0.6 Ma,the Jintanan Shan likely had not yet uplifted significantly,and the fluvial sediments from the northern Qilian Shan were widely deposited in this region,forming a large piedmont alluvial plain.Subsequently,the frontal fault zone of the northern Qilian Shan propagated northwards into the Jintanan Shan Fault(0.6-0.1 Ma),causing tectonic uplift of the Jintanan Shan,which blocked the deposition of fluvial sediments and formed a disconformity.In the Late Pleistocene(ca.0.1 Ma),the uplifted Jintanan Shan provided abundant proximal debris,which rapidly accumulated above the disconformity and formed a set of alluvial sediments.Combining previous research and our new data,we propose that the structural deformation of the northeastern Qinghai-Tibetan Plateau has progressively expanded northwards since the Late Cenozoic.Moreover,the Hexi Corridor experienced remarkable northward growth of the Qinghai-Tibetan Plateau during the Quaternary.
万方数据
维普
