Formation and evolution of Xianshuihe Fault Belt in the eastern margin of the Tibetan Plateau: Constraints from structural deformation and geochronology

Abstract

The Xianshuihe Fault Belt (XSF), along which the syntectonic Zheduoshan batholith was emplaced, has great significance for the reconstruction of the tectonic framework in the eastern margin of the Tibetan Plateau. In this contribution, formation process and evolution of the XSF are discussed based on the structural deformation in the field and the geochronology of Zheduoshan batholith. The results show that the XSF current arc‐shaped protrusion to the north‐east probably was formed by a fracture of the clockwise rotation compression that extended northward to the periphery with the eastern Himalayan tectonic syntaxis as the centre. It is a complex fault belt formed by the superposition of multi‐stage structures. In the early‐stage formation and evolution of the XSF, the Oligocene‐Miocene migmatite zone and Miocene granites of the Zheduoshan batholith were emplaced. Among them, the lower limit of the XSF's initial activity time was not less than 47 Ma that was limited by the Zircon U–Pb geochronology of migmatite zone formed under the compression system. During the emplacement of Miocene granites, the XSF underwent a process from compression to sinistral strike‐slip, and the geochronology indicates that the onset of the XSF sinistral strike slip should not be less than 14 Ma. After syntectic magmatism, the XSF also experienced the shear deformation (from ductile to brittle) with sinistral kinematics. 40Ar‐39Argeochronology results show that the ductile shear deformation mainly occurred around 5.5–3.2 Ma and accompanied a staged and differential uplift from north to south. It extended to the south along the weak crustal zone of Anninghe, Daliangshan, Xiaojiang, and other faults, forming the Xianshuihe–Anninghe–Xiaojiang sinistral strike‐slip fault system on the eastern margin of the Tibetan Plateau, and large‐scale sinistral strike slip began around 5 Ma. Our new insights lay a foundation for understanding and dissecting the formation and evolution of the Tibetan Plateau eastern margin.

Does Large‐Scale Crustal Flow Shape the Eastern Margin of the Tibetan Plateau? Insights From Episodic Magmatism of Gongga‐Zheduo Granitic Massif

“…The Cenozoic magmatism here reflected a complex deformation history related to the Xianshuihe Fault: compression during the Eocene, transition from compression to strike-slip during the Miocene, and large-scale shearing during the Pliocene (e.g., Y. Chen et al, 2020;Y.-Z. Zhang et al, 2017).…”

“…The Zheduo granites consist of mainly Miocene syenogranite with some Jurassic syenogranite (Lai & Zhao, 2018 ; H. Li, Zhang, et al., 2015 ; Roger et al., 1995 ), and newly discovered fine‐grained monzogranite and leucogranitic dike (Figures S2–S4 in Supporting Information S1 ). The Cenozoic magmatism here reflected a complex deformation history related to the Xianshuihe Fault: compression during the Eocene, transition from compression to strike‐slip during the Miocene, and large‐scale shearing during the Pliocene (e.g., Y. Chen et al., 2020 ; Y.‐Z. Zhang et al., 2017 ).…”

Structural analysis of the foreland basin of the southern Longmenshan tectonic belt: New insights from magnetic fabrics

“…The LMS extends south to the Sichuan-Yunnan N-S trending tectonic belt, forming a "Y-shaped" tectonic pattern. The Daliangshan fault system and the Xianshuihe fault belt are typical structural systems with a trend from NW to N-S on the eastern margin of the Tibetan Plateau (Figure 2b), which were formed in the Cenozoic (Y. T. Chen et al, 2015Chen et al, , 2020. Therefore, the NW-trending structures in the FBSL, including the Shuangshi Fault, are the result of superimposed deformations with the Sichuan-Yunnan N-S-trending tectonic belt, to a certain extent.…”

Fluvial geomorphic parameters of the Shuiluo River Catchment and their tectonic implications, SE Tibetan Plateau

“…The study of these fault zones can reveal the tectonic activity and orogenic belt information in the periphery of the Tibetan Plateau, and then we can further analyze the uplift mechanism of the plateau (Li et al 2016;Wu et al 2023a, b). These fault and orogenic belts have been studied by many scholars (Wang et al 2008(Wang et al , 2014Li et al 2015Li et al , 2021Yan et al 2017;Chen et al 2020;Yin and Luo 2021;Tian et al 2023;Shi et al 2023;Luo et al 2023), which further enriched the research base of the Tibetan Plateau. Understanding the activity mechanisms and differential activity of these active faults is beneficial for understanding the characteristics of the Cenozoic tectonic landforms around the Tibetan Plateau and even the tectonic movements of the entire it and theirs tectonically implications.…”