Late Paleozoic–early Mesozoic southward subduction-closure of the Paleo-Asian Ocean: Proof from geochemistry and geochronology of early Permian–late Triassic felsic intrusive rocks from North Liaoning, NE China
Late Paleozoic–early Mesozoic southward subduction-closure of the Paleo-Asian Ocean: Proof from geochemistry and geochronology of early Permian–late Triassic felsic intrusive rocks from North Liaoning, NE China
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晚古生代—早中生代古亚洲洋向南俯冲-闭合——辽北早二叠世—晚三叠世长英质侵入岩的地球化学和年代学证据
DOI：
10.1016/j.lithos.2019.105165
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发表时间：
2019
期刊：
影响因子：
3.5
通讯作者：
Tie Gao
中科院分区：
文献类型：
--
作者：
Yi Shi;Zhenghong Liu;Yongjiang Liu;Shaoshan Shi;Minghui Wei;Jiajia Yang;Tie Gao
许多研究证实索伦克-赛尔木伦-长春-延吉缝合带以南存在晚古生代-早中生代增生弧和俯冲杂岩带。但由于东部缝合带被松辽盆地所覆盖，迄今为止尚未有针对该地区晚古生代—早中生代侵入岩的完整报道。最近，在辽宁北部法库地区发现了一系列花岗岩侵入体。锆石（SHRIMP）U-Pb测年结果显示，研究区存在8组长英质侵入岩，形成时间为283~227Ma（早二叠世—晚三叠世）。结合区域事件研究，提出了法库地区二叠纪-三叠纪四阶段构造演化情景：活动大陆边缘背景下的早二叠世岩浆作用（293-274Ma）；中晚二叠世岩浆活动处于俯冲转化为碰撞的环境中（270-255Ma）；早中三叠世岩浆作用，碰撞转化为海洋板块的分离（255-242Ma）；中晚三叠世岩浆活动记录了碰撞后造山运动向伸展环境（241~215Ma）转变的过程。早二叠世-晚三叠世的长英质侵入记录了汇聚大陆边缘的伸展-碰撞和古亚洲洋的俯冲-灭绝。锆石Hf同位素分析得出εHf(t)值为-2.03~15.80，几乎全部为正值（有两点为负值），表明源区具有贫化特征。根据侵位时间和赋存位置，推测岩体是由华北克拉通（NCC）下方古亚洲洋壳俯冲碰撞生成的。该研究为华北克拉通北缘松辽盆地晚古生代—早中生代的构造演化和古亚洲洋最终闭合的特征提供了有力的证据。
Many studies have confirmed the existence of Late Paleozoic–Early Mesozoic accretionary arc and subduction complex belt to the south of the Solonker-Xar Moron-Changchun-Yanji Suture (SXCYS) zone. Nevertheless, since the suture from the east is covered by the Songliao Basin, until now there have been no completed reports focused on the Late Paleozoic–Early Mesozoic intrusive rocks of this area. Recently, a sequence of granitoid intrusions was identified in the Faku area, northern Liaoning. Zircon (SHRIMP) U-Pb dating results show that there are eight groups of felsic intrusions in the study area, and the intrusions formed at 283–227 Ma (Early Permian to Late Triassic). Together with study of regional events, A four-stage tectonic evolution scenario was recommended during Permian-Triassic in the Faku area: Early Permian magmatism in an activity continental margin setting (293–274 Ma); Middle-Late Permian magmatism in a setting where subduction is translated into collision (270–255 Ma); Early-Middle Triassic magmatism in a setting where collision is translated into detachment of the oceanic slab (255–242 Ma); and Middle to Late Triassic magmatism recorded procedure of post-collision orogeny transformed into extensional environment (241–215 Ma). The Early Permian–Late Triassic felsic intrusions documented the extension-collision of the convergent continental margin and the subduction-extinction of the Paleo-Asian Ocean. Zircon Hf isotopic analyses yield εHf(t) values of −2.03–15.80, almost all of which are positive (with two points being negative), indicating the depleted characteristics of the source area. According to emplacement time and occurrence location, the plutons are interpreted to have been generated by the subduction-collision of the Paleo-Asian oceanic crust beneath the North China Craton (NCC). This study provides strong evidence for Late Paleozoic–Early Mesozoic tectonic evolution and the characterization of the eventual closure of the Paleo-Asian Ocean in the Songliao Basin overlying the northern margin of the NCC.