Offshore-onshore tectonomagmatic correlations: Towards a Late Mesozoic non-Andean-type Cathaysian continental margin
Changhai Xu, Yuling Deng, Calvin G. Barnes, Hesheng Shi, Christophe Pascal, Yuanyuan Li, Shunli Gao, Donghui Jiang, Jianlei Xie, Changqian Ma
Abstract
Although much evidence points to a Late Mesozoic large silicic igneous province in SE South China (SESC), diverse Andean-type and non-Andean-type models have been proposed to explain its origins. New age, isotope, and trace element data on zircon from wells in East China Sea (ECS) and offshore-onshore tectonomagmatic comparisons allow reassessment of the geodynamic interactions (ca. 200–86 Ma) between the Cathaysia-based arc and intraplate activity from a large mantle wedge framework. In region, remnants of the West ECS arc, Ryukyu-Taiwan mélange, and SESC intraplate define a trench–arc–intraplate architecture. Changes in arc magmatic states (flare-ups and lulls; high U/Yb, low T, variable εHf(t)) permit identification of a cycle of arc initiation, thickening, decline, arc-root removal, and arc migration, highly correlating with changes of Izanagi subduction beneath East Asia. Voluminous intraplate silicic magmatism operated in response to the slab stagnation dynamics: slab dehydration, lithospheric delamination, fluid-fluxed crustal anataxis, and crustal–mantle melt hybridization in crustal hot zones. Such geodynamic scenarios, unlike an Andean-type continental margin, instead result in the construction of a Late Mesozoic Cathaysian-type active continental margin.