Knowledge Management System Of Guangzhou Institute of Geochemistry，CAS
Zhang, Feng1,2,3; Guo, Feng1,2 ; Zhang, Xiaobing1,2; Zhao, Liang1,2
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| Magmatic degassing and fluid metasomatism promote compositional variation from I-type to peralkaline A-type granite in the late Cretaceous Fuzhou felsic complex, SE China | |
| Source Publication | AMERICAN MINERALOGIST
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| ISSN | 0003-004X |
| 2024-07-26 | |
| Volume | 109Issue:7Pages:1228-1247 |
| DOI | 10.2138/am-2023-8936 |
| Language | 英语 |
| WOS Research Area | Geochemistry & Geophysics ; Mineralogy |
| Abstract | A-type granites generally have much lower water, higher temperature, and incompatible element concentrations than I-type granitoids. Yet it remains unclear why I-A-type granitic complexes occur in convergent plate margins. Here we conduct geochemical analyses on apatite and mafic minerals from the late Cretaceous I-A-type granitic complex in Fuzhou area, SE China, aiming to decipher differentiation, fluid metasomatism, and degassing that primarily control the compositional diversity of felsic magmas. Apatites in both rock types are F-rich and show large H2O and delta D variations, i.e., 341-3892 ppm H2O and -325 to +336 parts per thousand delta D in I-type granitoids; 67-1366 ppm H2O and -251 to +1439 parts per thousand delta D in A-type granites. H2O in apatite is negatively correlated with La/Sm and Sr/Y in the I-type granitoids, whereas it is positively correlated with Ce and total rare earth element (REE) concentrations in the A-type granites. Once H2O increases up to hundreds of ppm, both rock types show a rapid decrease of H2O/Ce, an increase of F/Cl, and extensive H isotope fractionation. Arfvedsonite occurs as a late crystallizing mineral in the A-type granite and has much higher contents of Na2O, K2O, F, and high field strength elements (HFSE) than hornblende in the I-type granitoids, indicating the addition of F-HFSE-rich alkaline fluids during its magmatic evolution. The consumption of arfvedsonite and formation of aegirine further indicate the role of fluid metasomatism and H-2 degassing via a reaction of 3Na(3)Fe(5)Si(8)O(22)(OH)(2) + 2H(2)O = 9NaFeSi(2)O(6) + 2Fe(3)O(4) + 6SiO(2)+5H(2). The combined geochemical data demonstrate that the systematic differences in mineral assemblage, whole-rock composition, magma temperature, H2O content, and delta D of apatite between the I- and A-type granites are likely attributed to varying degrees of differentiation, fluid metasomatism and magmatic degassing. The I-type granitoids experienced hornblende, biotite, plagioclase, K-feldspar, and apatite fractionation and close-system degassing. The A-type granite was likely formed from the I-type monzogranitic magma that was metasomatized by the mantle-derived F-HFSE-rich alkaline fluids to produce the peralkaline magma, which further experienced K-feldspar + plagioclase + biotite + apatite fractionation and open-system degassing. Further numerical estimation indicates that the primary magma of Fuzhou granitic complex contained similar to 3.0 wt% H2O, and the lower water content of A-type granite was likely attributed to strong degassing during its emplacement. Our results indicate that some peralkaline A-type granites can be generated from relatively water-poor I-type granitic magmas by fluid metasomatism and degassing. |
| Keyword | Magmatic degassing fluid metasomatism water content and H isotopes apatite Fuzhou I-A-type granitic complex SE China |
| WOS ID | WOS:001265587400012 |
| Indexed By | SCI |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.gig.ac.cn/handle/344008/78307 |
| Collection | 同位素地球化学国家重点实验室 |
| Corresponding Author | Guo, Feng |
| Affiliation | 1.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Peoples R China 2.Chinese Acad Sci, Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 3.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China |
| Recommended Citation GB/T 7714 | Zhang, Feng,Guo, Feng,Zhang, Xiaobing,et al. Magmatic degassing and fluid metasomatism promote compositional variation from I-type to peralkaline A-type granite in the late Cretaceous Fuzhou felsic complex, SE China[J]. AMERICAN MINERALOGIST,2024,109(7):1228-1247. |
| APA | Zhang, Feng,Guo, Feng,Zhang, Xiaobing,&Zhao, Liang.(2024).Magmatic degassing and fluid metasomatism promote compositional variation from I-type to peralkaline A-type granite in the late Cretaceous Fuzhou felsic complex, SE China.AMERICAN MINERALOGIST,109(7),1228-1247. |
| MLA | Zhang, Feng,et al."Magmatic degassing and fluid metasomatism promote compositional variation from I-type to peralkaline A-type granite in the late Cretaceous Fuzhou felsic complex, SE China".AMERICAN MINERALOGIST 109.7(2024):1228-1247. |
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