IOCAS-IR  > 海洋地质与环境重点实验室
Amphibole perspective to unravel the rhyolite as a potential fertile source for the Yonaguni Knoll IV hydrothermal system in the southwestern Okinawa Trough
Chen, Zuxing1,3; Zeng, Zhigang1,2,3,4; Qi, Haiyan1; Wang, Xiaoyuan1,3,4; Yin, Xuebo1,3,4; Chen, Shuai1,3,4; Yang, Wenqiang5; Ma, Yao1; Zhang, Yuxiang1,3
2019-11-09
Source PublicationGEOLOGICAL JOURNAL
ISSN0072-1050
Pages23
Corresponding AuthorZeng, Zhigang(zgzeng@ms.qdio.ac.cn)
AbstractYonaguni Knoll IV is an active seafloor hydrothermal system containing massive Zn-Pb sulfides located in the southwestern Okinawa Trough. Previous research has suggested that the metal elements Zn and Pb were dominantly derived from the local volcanic rocks via water-rock interactions. However, it is not known whether or why the volcanic rocks are rich in these metals. Here, we performed a detailed in situ analysis of the major and trace elements in amphiboles in the rhyolite from the hydrothermal field to decipher the physical-chemical conditions of the silicic magma, including temperature (T), pressure (P), oxygen fugacity (fO(2)), volatile contents (Cl, H2O) and metal contents (Pb, Zn), and investigate the behavior of the metals (Zn and Pb) during melt evolution. Our results show that the amphiboles are euhedral calcic magnesio-hornblende and are in equilibrium with the hydrous and oxidized host rhyolitic melt characterized by high H2Omelt (similar to 5.8-6.5 wt.%), fO(2) (NNO +0.1 to +0.6) and SiO2melt (similar to 71.73-72.62 wt.%) values at 761-797 degrees C and 102-137 MPa, corresponding to an approximate depth of 3.9-5.2 km. In addition, the rare earth element (REE) patterns of the melt reconstructed from the amphiboles are analogous to those of cold-wet-oxidized rhyolites. Thus, the amphiboles crystallized in a cold-wet-oxidized shallow silicic magma chamber. The high oxygen fugacity is inferred to have favored sulfur and metal enrichment in the melt. The most abundant metal in the amphiboles is Zn (237-294 ppm), and the concentrations of Pb are much lower (0.86-3.32 ppm), suggesting that Zn preferentially entered the amphibole and that Pb was retained in the melt. The Cl content of the amphiboles ranges from 0.11 to 0.25 wt.%, and accordingly, the Cl-melt content estimated from the amphiboles varies from 0.15 to 0.28 wt.%. The low (Cl/H2O)(melt) ratios, which are <0.05 (i.e., similar to 0.02-0.04), suggest that the melt exsolved an H2O-rich vapor rather than a hydrosaline fluid with insufficient Cl to transport metals (e.g., Pb and Zn) into the vapor phase during degassing both in the magma chamber and during ascent. The lack of exsolved hydrosaline fluid and the high oxidation conditions resulted in the metal elements Pb and Zn remaining dissolved in the rhyolitic melt and/or partitioning into crystalline minerals upon eruption. Thus, the large volumes of rhyolitic magma that intruded into the upper crust of the Yonaguni Knoll IV hydrothermal field are a potential fertile source of these elements via leaching by heated seawater.
Keywordamphibole hydrosaline fluid magma chamber Yonaguni Knoll IV hydrothermal field Okinawa Trough
DOI10.1002/gj.3667
Indexed BySCI
Language英语
Funding ProjectNational Natural Science Foundation of China[41325021] ; National Natural Science Foundation of China[41706052] ; Shandong Provincial Natural Science Foundation, China[ZR2019BD010] ; Qingdao National Laboratory for Marine Science and Technology[2016ASKJ13] ; Qingdao National Laboratory for Marine Science and Technology[2015ASKJ03] ; Special Fund for the Taishan Scholar Program of Shandong Province[ts201511061] ; National Basic Research Program of China[2013CB429700] ; International Partnership Program of Chinese Academy of Sciences[133137KYSB20170003] ; National Program on Global Change and Air-Sea Interaction[GASI-GEOGE-02]
WOS Research AreaGeology
WOS SubjectGeosciences, Multidisciplinary
WOS IDWOS:000495351200001
PublisherWILEY
Citation statistics
Document Type期刊论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/165041
Collection海洋地质与环境重点实验室
Corresponding AuthorZeng, Zhigang
Affiliation1.Chinese Acad Sci, Inst Oceanol, CAS Key Lab Marine Geol & Environm, Seafloor Hydrothermal Act Lab, Qingdao 266071, Shandong, Peoples R China
2.Univ Chinese Acad Sci, Beijing, Peoples R China
3.Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao, Shandong, Peoples R China
4.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao, Shandong, Peoples R China
5.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian, Shaanxi, Peoples R China
First Author AffilicationInstitute of Oceanology, Chinese Academy of Sciences
Corresponding Author AffilicationInstitute of Oceanology, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
Chen, Zuxing,Zeng, Zhigang,Qi, Haiyan,et al. Amphibole perspective to unravel the rhyolite as a potential fertile source for the Yonaguni Knoll IV hydrothermal system in the southwestern Okinawa Trough[J]. GEOLOGICAL JOURNAL,2019:23.
APA Chen, Zuxing.,Zeng, Zhigang.,Qi, Haiyan.,Wang, Xiaoyuan.,Yin, Xuebo.,...&Zhang, Yuxiang.(2019).Amphibole perspective to unravel the rhyolite as a potential fertile source for the Yonaguni Knoll IV hydrothermal system in the southwestern Okinawa Trough.GEOLOGICAL JOURNAL,23.
MLA Chen, Zuxing,et al."Amphibole perspective to unravel the rhyolite as a potential fertile source for the Yonaguni Knoll IV hydrothermal system in the southwestern Okinawa Trough".GEOLOGICAL JOURNAL (2019):23.
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