Age, petrogenesis, and tectonic implications of the late <scp>Permian</scp> magmatic rocks in the <scp>Middle Gobi</scp> volcanoplutonic <scp>Belt</scp> , <scp>Mongolia</scp>
Age, petrogenesis, and tectonic implications of the late <scp>Permian</scp> magmatic rocks in the <scp>Middle Gobi</scp> volcanoplutonic <scp>Belt</scp> , <scp>Mongolia</scp>
复制标题
<scp>中戈壁</scp>火山深成<scp>带</scp>晚<scp>二叠世</scp>岩浆岩的年龄、岩石成因和构造意义，<scp>蒙古</scp>
DOI：
10.1111/iar.12457
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发表时间：
2022
期刊：
影响因子：
1.5
通讯作者：
Chimedsuren Munkhnasan
中科院分区：
文献类型：
--
作者：
Ganbat Ariuntsetseg;Tsujimori Tatsuki;Miao Laicheng;Safonova Inna;Pastor‐Gal?n Daniel;Anaad Chimedtseren;Aoki Shogo;Aoki Kazumasa;Chimedsuren Munkhnasan
蒙古-鄂霍次克带是中亚造山带中最年轻的一段，是蒙古-鄂霍次克洋演化闭合的产物。大洋闭合形成了两个火山深成带：北部的色楞格带和南部的中戈壁带（在今天的坐标中）。然而，蒙古-鄂霍次克带的起源和构造演化，特别是中戈壁带的起源和形成时代仍然是个谜。为了更好地了解中部戈壁带岩浆活动的历史，我们对中部戈壁带的主要组成部分Mandalgovi火山深成岩套的样品进行了地球化学、U-Pb年代学、锆石Hf和全岩Nd同位素分析。结果表明，该深圳湾火山对应物以二叠纪Sahalyn gol流纹岩和~247 Ma Ikh khad安山岩为代表。黑云母-花岗岩和角闪石-花岗闪长岩的地球化学成分表明，它们的前身分别是变杂砂岩和角闪岩。它们的特征是全岩εNd（t）和锆石εHf（t）值为正值，表明为幼年原岩。辉长岩是由交代的岩石圈地幔源在超俯冲背景下部分熔融而形成的。黑云母花岗岩和Sahalyn gol流纹岩是由弧间伸展背景下的沉积物重熔形成的。后来，角闪岩花岗岩和Ikh khad火山位于蒙古-鄂霍次克洋俯冲形成的火山弧上。中戈壁带岩浆岩形成于活动大陆边缘环境。考虑到蒙古-鄂霍次克带南缘同时代弧源岩浆建造沿着的一致分布，洋盆以相对同步的方式闭合。
The Mongol–Okhotsk Belt, the youngest segment of Central Asian Orogenic Belt, was formed by the evolution and closure of the Mongol–Okhotsk Ocean. The oceanic closure formed two volcanoplutonic belts: Selenge Belt in the north and the Middle Gobi Belt in the south (in present day coordinates). However, the origin and tectonic evolution of the Mongol–Okhotsk Belt in general, and the origin and formation age of the Middle Gobi Belt in particular, remain enigmatic. To better understand the history of the magmatic activity in the Middle Gobi Belt, we conducted geochemical, U–Pb geochronological, zircon Hf, and whole‐rock Nd isotopic analyses of samples from the Mandalgovi volcanoplutonic suite, the major component of the Middle Gobi Belt. Our results show that the plutonic rock consists of ~285 Ma gabbro, ~265 Ma biotite‐granite and ~250 Ma hornblende‐granodiorite. The volcanic counterpart is represented by a Permian Sahalyn gol rhyolite and ~247 Ma Ikh khad andesite. The geochemical compositions of biotite‐granite and hornblende‐granodiorite indicate that their precursors were metagraywacke and amphibolite, respectively. They are characterized by positive whole‐rock εNd(t) and zircon εHf(t) values, indicating juvenile protoliths. The gabbro was derived by partial melting of a metasomatized lithospheric mantle source in a supra‐subduction setting. The biotite‐granite and Sahalyn gol rhyolite are formed by remelting of sediments in an inter‐arc extension setting. Later the hornblende‐granite and Ikh khad volcanic were emplaced at a volcanic arc formed by the subduction of the Mongol–Okhotsk Ocean. We conclude that the magmatic rocks of the Middle Gobi Belt formed in an active continental margin setting. Considering the consistent distribution of coeval arc‐derived magmatic formations along the southern margin of the Mongol–Okhotsk Belt, the oceanic basin was closed in a relatively simultaneous manner.