Depicting Permian to Triassic thickness variation of the Kunlun-Qaidam Continental Arc: Implication for tectonic evolution of the South Kunlun Ocean

IF 1.3 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Acta Geochimica Pub Date : 2024-10-28 DOI:10.1007/s11631-024-00744-9

Zhigang Wang, Jiaopeng Sun, Yukun Qi, Weidong He, Kai Ye, Zongli Li, Lei He, Junxiang Zhang, Teng Wang

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Abstract

Determining the evolutionary history of the Permian-Triassic Kunlun-Qaidam Continental Arc is essential to understanding the subduction and closure processes of the South Kunlun Ocean. In this paper, we utilize (La/Yb)_N ratios collected from a filtered geochemical dataset on Permian to Triassic calc-alkaline rocks (55 wt%–68 wt% SiO₂) and plutonic rocks within the Kunlun-Qaidam Continental Arc to reconstruct the spatiotemporal variation of the relative crustal thickness. Combined with known geologic observations, we discuss the subduction-accretionary tectonics of the South Kunlun Ocean and the topographic evolution of the Kunlun-Qaidam Continental Arc. Two episodes of crustal thickening and thinning were revealed. The reconstructed thickness reveals two crustal thickening and thinning events for the Kunlun-Qaidam Continental Arc from ca. 270 to 210 Ma. The southern sector of the Kunlun-Qaidam Continental Arc is about 7 km thicker than the northern portion, with a maximum thickness of about 55 km at ca. 270 and 230 Ma. The ca. 270 and 230 Ma crustal thickening events coincide with renewed northward subduction of the South Kunlun Ocean plate and ocean closure, respectively, whereas the ca. 270‒240 Ma and ca. 230‒210 Ma crustal thinning events may reflect slab break-off of the oceanic plate and lithospheric collapse during the post-collision extension, respectively.

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昆仑—柴达木大陆弧二叠系—三叠纪厚度变化及其对南昆仑洋构造演化的启示

确定二叠系—三叠系昆仑—柴达木大陆弧的演化历史，对认识南昆仑洋的俯冲和闭合过程具有重要意义。本文利用昆仑—柴达木大陆弧内二叠纪—三叠纪钙碱性岩（SiO2为55 wt% ~ 68 wt%）和深成岩的（La/Yb）N过滤地球化学数据，重建了地壳相对厚度的时空变化特征。结合已有的地质观测资料，讨论了南昆仑洋俯冲-增生构造和昆仑-柴达木大陆弧的地形演化。地壳增厚变薄两期。重建厚度揭示了约270 ~ 210 Ma期间昆仑-柴达木大陆弧两次地壳增厚减薄事件。昆仑-柴达木大陆弧南段比北段厚约7 km，约270 ~ 230 Ma时最厚约55 km。约270 Ma和230 Ma地壳增厚事件分别与南昆仑大洋板块重新向北俯冲和海洋闭合相吻合，而约270 ~ 240 Ma和230 ~ 210 Ma地壳减薄事件可能分别反映碰撞后伸展过程中大洋板块板块断裂和岩石圈崩塌。

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来源期刊

Acta Geochimica GEOCHEMISTRY & GEOPHYSICS-

CiteScore

2.80

自引率

6.20%

发文量

1134

期刊介绍： Acta Geochimica serves as the international forum for essential research on geochemistry, the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth‘s crust, its oceans and the entire Solar System, as well as a number of processes including mantle convection, the formation of planets and the origins of granite and basalt. The journal focuses on, but is not limited to the following aspects: • Cosmochemistry • Mantle Geochemistry • Ore-deposit Geochemistry • Organic Geochemistry • Environmental Geochemistry • Computational Geochemistry • Isotope Geochemistry • NanoGeochemistry All research articles published in this journal have undergone rigorous peer review. In addition to original research articles, Acta Geochimica publishes reviews and short communications, aiming to rapidly disseminate the research results of timely interest, and comprehensive reviews of emerging topics in all the areas of geochemistry.