Uplift and Expansion of the North Qilian Shan Recorded by Detrital Fission Tracks in the Jiudong Basin, NW China

Baotian Pan,Dianbao Chen,Jiaxin Zhang,Xiaofei Hu,Qiming Zhao

doi:10.3389/feart.2021.826104

Abstract

The North Qilian Shan, located in the northeastern front of the Tibetan Plateau, is an ideal region to study the expansion process of the plateau, which is not clearly revealed due to the lack of direct evidence and an accurate age control. In the Jiudong Basin (foreland basin of the North Qilian Shan), a continuous late Cenozoic sedimentary sequence and a reliable chronostratigraphic framework (post-7 Ma) provide us the material to study this process. In this study, we first analyzed the provenance changes of the sediment by detrital apatite fission track age distributions and apatite particle textures. The result shows that the first provenance change occurred at 4.6–3.6 Ma, when the sediment source changed from the southern to the northern parts of the North Qilian Shan, and it indicates that the North Qilian Shan Fault had propagated to its modern location. The second provenance change occurred at 3.0–2.4 Ma, at when the Yumu Shan and its south region began to provide sediments for the Jiudong Basin, and it indicates that the tectonic deformation in the North Qilian Shan had expanded to the North Yumu Shan Fault. Our finding suggests that two significant expansion events happened since the Pliocene for the North Qilian Shan.

Highlights

The collision of the Indian and Eurasian plates caused the uplift and expansion of the Tibetan Plateau, which has a profound impact on the geomorphic evolution of Asia and the global climate change (e.g., Molnar et al, 1993; An et al, 2001; Pan et al, 2004; Xu et al, 2011)
The lower section includes two samples from 5.9 to 4.6 Ma, and apatite fission track (AFT) ages are mostly distributed in 60–160 Ma; the middle section includes three samples from 3.6 to 3.0 Ma, and AFT ages are mostly distributed in 100–180 Ma; and the upper section includes five samples from 2.4 to 0 Ma, and AFT ages have a wider distribution in 60–300 Ma
The lag time inflection point suggested that the recycled sediments have appeared in MH core since 2.4 Ma, and it is consistent with the time of provenance change and the time of sedimentary facies change

Summary

Introduction

The collision of the Indian and Eurasian plates caused the uplift and expansion of the Tibetan Plateau, which has a profound impact on the geomorphic evolution of Asia and the global climate change (e.g., Molnar et al, 1993; An et al, 2001; Pan et al, 2004; Xu et al, 2011). From apatite fission track (AFT) age distribution across the main range, Pang et al (2019a) suggest a sequence of thrust faults prograde to the north since Late Miocene (~10 Ma). To the north of the main range, paleomagnetic studies on the exposed Cenozoic strata in the Jiuxi Basin suggest

Methods

Results

Discussion

Conclusion