{"title":"南秦岭三叠系广头山岩体强过铝质花岗岩成因的岩石地球化学制约","authors":"Q. Guan, Junlin Cao, Rixiang Wang, Peiling Xie, Wenyue Xia, Xiaowei Li","doi":"10.1111/1755-6724.15103","DOIUrl":null,"url":null,"abstract":"As an important part of the Early Mesozoic granites in the South Qinling tectonic belt (SQTB), the Guangtoushan pluton provides a material basis for research on the composition of magma sources and the effects of peritectic assemblage entrainment (PAE) on the changes in the granite composition. As shown by the results of LA‐ICP‐MS zircon U‐Pb dating, the Guangtoushan pluton was emplaced during the Late Triassic (214–212 Ma) and was formed in the post‐collision stage between the SQTB and the Yangtgze plate. The collected samples had high SiO2 content and low Cr and Ni contents, indicating that the magmas did not undergo significant crust‐mantle mixing during their evolution. The Guangtoushan granitoids were distributed along the trend line of magmatic fractional crystallization in the F‐An‐Or diagram. This result, combined with the relatively homogeneous Sr‐Nd isotopic composition, implies that the Guangtoushan pluton underwent slight assimilation and contamination. As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid‐absent experimental melts, the magma sources of the Guangtoushan granitoids contain a variety of materials, such as graywackes, pyroclastic graywackes, and pelites and are not derived from lower crustal mafic rocks. The correlation between the maficity and the major and trace elements further indicates that our strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite‐bearing crustal rocks and that its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals.","PeriodicalId":7095,"journal":{"name":"Acta Geologica Sinica ‐ English Edition","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Petrological and Geochemical Constraints on The Origin of Strongly Peraluminous Granitoids from The Triassic Guangtoushan Pluton in South Qinling\",\"authors\":\"Q. 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This result, combined with the relatively homogeneous Sr‐Nd isotopic composition, implies that the Guangtoushan pluton underwent slight assimilation and contamination. As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid‐absent experimental melts, the magma sources of the Guangtoushan granitoids contain a variety of materials, such as graywackes, pyroclastic graywackes, and pelites and are not derived from lower crustal mafic rocks. The correlation between the maficity and the major and trace elements further indicates that our strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite‐bearing crustal rocks and that its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals.\",\"PeriodicalId\":7095,\"journal\":{\"name\":\"Acta Geologica Sinica ‐ English Edition\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2023-08-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Acta Geologica Sinica ‐ English Edition\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1111/1755-6724.15103\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Geologica Sinica ‐ English Edition","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1111/1755-6724.15103","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
广头山岩体作为南秦岭构造带早中生代花岗岩的重要组成部分,为研究岩浆源组成及包岩组合夹带作用对花岗岩组成变化的影响提供了物质基础。LA‐ICP‐MS锆石U‐Pb测年结果表明,广头山岩体的侵位时间为晚三叠世(214-212 Ma),形成于扬子板块与SQTB板块碰撞后阶段。样品SiO2含量高,Cr和Ni含量低,表明岩浆在演化过程中没有发生明显的壳幔混合作用。在F - An - Or图上,广头山花岗岩类沿岩浆分异结晶趋势线分布。这一结果与相对均匀的Sr - Nd同位素组成相结合,表明广头山岩体经历了轻微的同化和污染。通过对比广头山花岗岩类与各种无流体的实验熔体的组成可以推断,广头山花岗岩类的岩浆来源包含多种物质,如灰屑岩、火山碎屑灰屑岩、泥质岩等,并非来源于下地壳基性岩。丰度与主微量元素对比进一步表明,广头山岩体强过铝质花岗岩是由含黑云母的地壳岩石部分熔融形成的,其岩浆演化伴随着斜辉石及其副矿物的夹带作用。
Petrological and Geochemical Constraints on The Origin of Strongly Peraluminous Granitoids from The Triassic Guangtoushan Pluton in South Qinling
As an important part of the Early Mesozoic granites in the South Qinling tectonic belt (SQTB), the Guangtoushan pluton provides a material basis for research on the composition of magma sources and the effects of peritectic assemblage entrainment (PAE) on the changes in the granite composition. As shown by the results of LA‐ICP‐MS zircon U‐Pb dating, the Guangtoushan pluton was emplaced during the Late Triassic (214–212 Ma) and was formed in the post‐collision stage between the SQTB and the Yangtgze plate. The collected samples had high SiO2 content and low Cr and Ni contents, indicating that the magmas did not undergo significant crust‐mantle mixing during their evolution. The Guangtoushan granitoids were distributed along the trend line of magmatic fractional crystallization in the F‐An‐Or diagram. This result, combined with the relatively homogeneous Sr‐Nd isotopic composition, implies that the Guangtoushan pluton underwent slight assimilation and contamination. As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid‐absent experimental melts, the magma sources of the Guangtoushan granitoids contain a variety of materials, such as graywackes, pyroclastic graywackes, and pelites and are not derived from lower crustal mafic rocks. The correlation between the maficity and the major and trace elements further indicates that our strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite‐bearing crustal rocks and that its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals.
期刊介绍:
Acta Geologica Sinica mainly reports the latest and most important achievements in the theoretical and basic research in geological sciences, together with new technologies, in China. Papers published involve various aspects of research concerning geosciences and related disciplines, such as stratigraphy, palaeontology, origin and history of the Earth, structural geology, tectonics, mineralogy, petrology, geochemistry, geophysics, geology of mineral deposits, hydrogeology, engineering geology, environmental geology, regional geology and new theories and technologies of geological exploration.