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The middle permian to triassic tectono-magmatic system in the southern Korean Peninsula
Gondwana Research ( IF 6.1 ) Pub Date : 2020-12-30 , DOI: 10.1016/j.gr.2020.11.017
Sung Won Kim , Sanghoon Kwon , Youn-Joong Jeong , Weon Seo Kee , Byung Choon Lee , Uk Hwan Byun , Kyoungtae Ko , Deung-Lyong Cho , Paul S. Hong , Seung-Ik Park , M. Santosh

The Permo-Triassic adakitic magmatism in the southern Korean Peninsula preserves important tectonomagmatic records along the East Asian continental margin. In this study, we present SHRIMP/LA–MC–ICPMS U-Pb zircon ages and Hf isotope signature with whole-rock geochemical compositions of the Middle Permian to Middle Triassic granitoid gneiss-granitoid suites and the Middle to Late Triassic plutonic rocks in the southeastern Korean Peninsula. The former yield three age groups of ca. 272–263 Ma, ca. 258–251 Ma and ca. 243–240 Ma, respectively. The latter group yield ca. 237–216 Ma ages, indicating a long term magmatism that lasted from the Middle Permian to late Triassic. The granitoid gneiss-granitoid suites have chemical compositions similar to high silica adakitic rocks, showing high SiO2 (59.55–73.97 wt.%), Na2O (3.55–5.30 wt.%), Sr/Y (30–401), and La/YbN (11–173), and low MgO (0.18–1.82 wt.%), Y (2–14 ppm) and YbN (2–7). These rocks are peraluminous with high Ba and Sr, and show relatively high K2O contents and K2O/Na2O ratios (> 0.7), with positive correlation between La/YbN vs. Sr/Y ratios and high initial Sr ratios. These features reflect different contribution of the slab-derived adakite melts that interacted with peridotitic mantle in the metasomatized mantle wedge and the Middle Paleoproterozoic lower crustal basement of the Yeongnam Massif. On the contrary, the Triassic alkaline magmatism in the Yeongnam Massif is alternatively interpreted either by a tectonic switch to the extension-dominated arc system or by a delamination of an overthickened arc. The results from this study offer important evidence for a common subduction-accretion system existed between the North and South China Cratons and microcontinents between them along margins of the East Asian continental blocks, with different plate interaction in different locations generating distinct magmatic suites.



中文翻译:

朝鲜半岛中二叠纪至三叠纪构造岩浆系统

朝鲜半岛南部的Permo-Triassic岩浆作用岩浆保留了东亚大陆边缘的重要构造岩性记录。在这项研究中,我们介绍了SHRIMP / LA-MC-ICPMS U-Pb锆石年龄和Hf同位素特征,以及中二叠统至中三叠纪花岗岩类片麻片麻质-类质岩组合的全岩石地球化学成分以及中三叠世中晚期的三叠纪深成岩。朝鲜半岛东南部。前者分为三个年龄组。272–263 Ma,约。约258–251马。分别为243–240 Ma。后一组产量约。237-216 Ma年龄,表明从中二叠纪到三叠纪晚期一直存在着长期的岩浆作用。花岗岩型片麻岩-类质岩套件的化学成分类似于高硅质石质岩石,显示出高SiO 2(59.55-73.97 wt。%),Na2 O(3.55-5.30 wt。%),Sr / Y(30-401)和La / Yb N(11-173)和低MgO(0.18-1.82 wt。%),Y(2-14 ppm)和Yb N(2-7)。这些岩石具有高Ba和Sr的高铝酸盐含量,并且显示出相对较高的K 2 O含量和K 2 O / Na 2 O比(> 0.7),并且La / Yb N与正相关。与Sr / Y比和较高的初始Sr比。这些特征反映了板坯来源的玄武岩熔体的不同贡献,这些熔体与变质的地幔楔和影南地块的中古古生界下地壳基底中的橄榄岩地幔相互作用。相反,Yeongnam断层中的三叠纪碱性岩浆作用是通过构造转换到伸展为主的弧系或过厚弧的分层来解释的。这项研究的结果为华北和华南克拉通之间以及沿东亚大陆块边缘的它们之间的微大陆之间存在着一个共同的俯冲-增生系统提供了重要的证据,而且不同位置的板块相互作用产生了不同的岩浆组。

更新日期:2020-12-30
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