Abstract
Syntectonic sediments record the growth process of active fold and fault belts. The Quaternary in the Chengdu plain are the syntectonic sediments formed during the structure deformation of the Longmen Shan in Late Cenozoic, which is of great significance for understanding the formation and evolution of the Longmen Shan. However, the geometry and formation of the Quaternary in the Chengdu plain are still unsettled. This paper determines the Quaternary thickness in the Chengdu plain with audio magnetotellurics (AMT), electrical resistivity tomography (ERT) and borehole, and discusses the formation of Quaternary in the Chengdu plain in combination with previous deep and surface data. It also predicts the Quaternary geometry in Chengdu plain by AMT, and concludes that the thickness in Huayuan may be larger than that in Zhuwapu (541 m). The borehole reveals that the Quaternary thickness in the Huayuan is upto 571.3 m, which is the thickest Quaternary so far. With the Longmen Shan piedmont wedging into the Sichuan basin, and under the intense erosion of Minjiang river, structure wedges of different scales are formed and result in salient and recess, which corresponds to the geometry of the Quaternary in the Chengdu plain. Therefore, the coupling between deep structures and surface processes controls the formation of the Quaternary in the Chengdu plain.
NSTL
Elsevier