{"title":"中国松潘-甘孜造山带柯儿岭花岗伟晶岩及伴生锂矿化的成岩作用:磷灰石和块岩化学证据","authors":"Qing-Gao Yan, Jian-Kang Li, Deng-Hong Wang, Ze-Ying Zhu, Chao Li, Zhen-Yu Chen","doi":"10.1007/s00126-024-01316-w","DOIUrl":null,"url":null,"abstract":"<p>Li–Cs–Ta (LCT)-type granitic pegmatites commonly occur adjacent to granitic bodies. For many pegmatite fields, it is not obvious whether the pegmatitic melt originated from an evolved granitic magma or from low-degree partial melting of metasedimentary rocks. The Ke’eryin granitic pegmatites in the Songpan–Ganze orogenic belt, China, which hosts large Li<sub>2</sub>O reserves around large-volume granitic intrusions, including biotite granite (BG), two-mica granite (TG), and muscovite granite (MG), present an excellent location to investigate the petrogenesis of granitic pegmatites and associated Li mineralization. Our results suggest that these granites were generated from a common magma source and emplaced in pulses, coupled with fractional crystallization. These granites and associated pegmatites show discordant trends in the bulk-rock Zr/Hf and Nb/Ta ratios and apatite Y/Ho and Sr/Y ratios, which reflect an evolution from granitic magma to flux-rich pegmatite melts. Pegmatitic melts might have derived from TG magma during evolution from BG to TG and MG magma. Initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios of BG apatite (0.7161–0.7188) and low bulk-rock Fe<sub>2</sub>O<sub>3</sub>/FeO ratios (0.04–0.22) imply that the Xikang Group at depth might have undergone high-degree partial melting to produce the original granitic magma. This melting of metasedimentary rocks, resulting in a large-volume magma with low flux and rare-metal contents, was followed by protracted fractionation during multiple pulses of magma emplacement. This process resulted in the formation of flux- and rare metal-rich pegmatite melts from granitic magma. This mechanism may be applicable to many LCT-type pegmatites associated with large granitic complexes worldwide.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Petrogenesis of Ke’eryin granitic pegmatites and associated Li mineralization in the Songpan–Ganze orogenic belt, China: evidence from apatite and bulk-rock chemistry\",\"authors\":\"Qing-Gao Yan, Jian-Kang Li, Deng-Hong Wang, Ze-Ying Zhu, Chao Li, Zhen-Yu Chen\",\"doi\":\"10.1007/s00126-024-01316-w\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Li–Cs–Ta (LCT)-type granitic pegmatites commonly occur adjacent to granitic bodies. For many pegmatite fields, it is not obvious whether the pegmatitic melt originated from an evolved granitic magma or from low-degree partial melting of metasedimentary rocks. The Ke’eryin granitic pegmatites in the Songpan–Ganze orogenic belt, China, which hosts large Li<sub>2</sub>O reserves around large-volume granitic intrusions, including biotite granite (BG), two-mica granite (TG), and muscovite granite (MG), present an excellent location to investigate the petrogenesis of granitic pegmatites and associated Li mineralization. Our results suggest that these granites were generated from a common magma source and emplaced in pulses, coupled with fractional crystallization. These granites and associated pegmatites show discordant trends in the bulk-rock Zr/Hf and Nb/Ta ratios and apatite Y/Ho and Sr/Y ratios, which reflect an evolution from granitic magma to flux-rich pegmatite melts. Pegmatitic melts might have derived from TG magma during evolution from BG to TG and MG magma. Initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios of BG apatite (0.7161–0.7188) and low bulk-rock Fe<sub>2</sub>O<sub>3</sub>/FeO ratios (0.04–0.22) imply that the Xikang Group at depth might have undergone high-degree partial melting to produce the original granitic magma. This melting of metasedimentary rocks, resulting in a large-volume magma with low flux and rare-metal contents, was followed by protracted fractionation during multiple pulses of magma emplacement. This process resulted in the formation of flux- and rare metal-rich pegmatite melts from granitic magma. This mechanism may be applicable to many LCT-type pegmatites associated with large granitic complexes worldwide.</p>\",\"PeriodicalId\":18682,\"journal\":{\"name\":\"Mineralium Deposita\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.4000,\"publicationDate\":\"2024-09-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Mineralium Deposita\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1007/s00126-024-01316-w\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mineralium Deposita","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s00126-024-01316-w","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Petrogenesis of Ke’eryin granitic pegmatites and associated Li mineralization in the Songpan–Ganze orogenic belt, China: evidence from apatite and bulk-rock chemistry
Li–Cs–Ta (LCT)-type granitic pegmatites commonly occur adjacent to granitic bodies. For many pegmatite fields, it is not obvious whether the pegmatitic melt originated from an evolved granitic magma or from low-degree partial melting of metasedimentary rocks. The Ke’eryin granitic pegmatites in the Songpan–Ganze orogenic belt, China, which hosts large Li2O reserves around large-volume granitic intrusions, including biotite granite (BG), two-mica granite (TG), and muscovite granite (MG), present an excellent location to investigate the petrogenesis of granitic pegmatites and associated Li mineralization. Our results suggest that these granites were generated from a common magma source and emplaced in pulses, coupled with fractional crystallization. These granites and associated pegmatites show discordant trends in the bulk-rock Zr/Hf and Nb/Ta ratios and apatite Y/Ho and Sr/Y ratios, which reflect an evolution from granitic magma to flux-rich pegmatite melts. Pegmatitic melts might have derived from TG magma during evolution from BG to TG and MG magma. Initial 87Sr/86Sr ratios of BG apatite (0.7161–0.7188) and low bulk-rock Fe2O3/FeO ratios (0.04–0.22) imply that the Xikang Group at depth might have undergone high-degree partial melting to produce the original granitic magma. This melting of metasedimentary rocks, resulting in a large-volume magma with low flux and rare-metal contents, was followed by protracted fractionation during multiple pulses of magma emplacement. This process resulted in the formation of flux- and rare metal-rich pegmatite melts from granitic magma. This mechanism may be applicable to many LCT-type pegmatites associated with large granitic complexes worldwide.
期刊介绍:
The journal Mineralium Deposita introduces new observations, principles, and interpretations from the field of economic geology, including nonmetallic mineral deposits, experimental and applied geochemistry, with emphasis on mineral deposits. It offers short and comprehensive articles, review papers, brief original papers, scientific discussions and news, as well as reports on meetings of importance to mineral research. The emphasis is on high-quality content and form for all articles and on international coverage of subject matter.