{"title":"蒙古中戈壁火山-成矿带晚二叠世岩浆岩的时代、成因及构造意义","authors":"Ariuntsetseg Ganbat, Tatsuki Tsujimori, Laicheng Miao, Inna Safonova, Daniel Pastor-Galán, Chimedtseren Anaad, Shogo Aoki, Kazumasa Aoki, Munkhnasan Chimedsuren","doi":"10.1111/iar.12457","DOIUrl":null,"url":null,"abstract":"<p>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 ε<sub>Nd</sub>(<i>t</i>) and zircon ε<sub>Hf</sub>(<i>t</i>) 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.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2022-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Age, petrogenesis, and tectonic implications of the late Permian magmatic rocks in the Middle Gobi volcanoplutonic Belt, Mongolia\",\"authors\":\"Ariuntsetseg Ganbat, Tatsuki Tsujimori, Laicheng Miao, Inna Safonova, Daniel Pastor-Galán, Chimedtseren Anaad, Shogo Aoki, Kazumasa Aoki, Munkhnasan Chimedsuren\",\"doi\":\"10.1111/iar.12457\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>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 ε<sub>Nd</sub>(<i>t</i>) and zircon ε<sub>Hf</sub>(<i>t</i>) 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.</p>\",\"PeriodicalId\":14791,\"journal\":{\"name\":\"Island Arc\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2022-08-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Island Arc\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/iar.12457\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Island Arc","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/iar.12457","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
蒙古-鄂霍次克带是中亚造山带最年轻的一段,是由蒙古-鄂霍次克洋的演化和闭合形成的。洋闭形成了北部的色楞格带和南部的中戈壁带两条火山-深成带(以今坐标)。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一个谜。为了更好地了解中戈壁带岩浆活动的历史,我们对中戈壁带的主要组成部分Mandalgovi火山-成岩套件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,深部岩体主要由~285 Ma辉长岩、~265 Ma黑云母花岗岩和~250 Ma角闪石花岗闪长岩组成。火山对应物为二叠纪萨哈林金流纹岩和~247 Ma Ikh khad安山岩。黑云母-花岗岩和角闪石-花岗闪长岩的地球化学组成表明,它们的前体分别为辉长岩和角闪岩。全岩εNd(t)和锆石εHf(t)值均为正,表明原岩发育较幼。辉长岩是在超俯冲环境下由交代岩石圈地幔源部分熔融形成的。黑云母花岗岩和萨哈林金流纹岩是在弧间伸展环境下由沉积物重熔形成的。后来角闪花岗岩和Ikh khad火山被安置在蒙古-鄂霍次克洋俯冲形成的火山弧上。认为中戈壁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期弧源岩浆构造的一致分布,洋盆闭合相对同步。
Age, petrogenesis, and tectonic implications of the late Permian magmatic rocks in the Middle Gobi volcanoplutonic Belt, Mongolia
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.
期刊介绍:
Island Arc is the official journal of the Geological Society of Japan. This journal focuses on the structure, dynamics and evolution of convergent plate boundaries, including trenches, volcanic arcs, subducting plates, and both accretionary and collisional orogens in modern and ancient settings. The Journal also opens to other key geological processes and features of broad interest such as oceanic basins, mid-ocean ridges, hot spots, continental cratons, and their surfaces and roots. Papers that discuss the interaction between solid earth, atmosphere, and bodies of water are also welcome. Articles of immediate importance to other researchers, either by virtue of their new data, results or ideas are given priority publication.
Island Arc publishes peer-reviewed articles and reviews. Original scientific articles, of a maximum length of 15 printed pages, are published promptly with a standard publication time from submission of 3 months. All articles are peer reviewed by at least two research experts in the field of the submitted paper.