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The dynamics of the southern Okinawa Trough magmatic system: New insights from the microanalysis of the An contents, trace element concentrations and Sr isotopic compositions of plagioclase hosted in basalts and silicic rocks
Guo, Kun1,2,3,5; Zhai, Shi-Kui4; Wang, Xiao-Yuan2,3; Yu, Zeng-Hui4; Lai, Zhi-Qing4; Chen, Shuai2,3; Song, Zhao-Jun1,2; Ma, Yao2,3; Chen, Zu-Xing3; Li, Xiao-Hui3; Zeng, Zhi-Gang2,3
2018-10-10
Source PublicationCHEMICAL GEOLOGY
ISSN0009-2541
Volume497Pages:146-161
Corresponding AuthorGuo, Kun(guokun1016@l63.com) ; Zhai, Shi-Kui(zhai2000@ouc.edu.cn)
AbstractThe Okinawa Trough (OT) is a back-arc, initial marginal sea basin located behind the Ryukyu arc-trench system. Analysis of the plagioclase phenocrysts from two basalts and two silicic rocks dredged from different locations in the southern Okinawa Trough (SOT) provides a detailed record of the nature and composition of and changes in the magma within the magmatic system. Plagioclase phenocrysts from the basalt record Sr-87/Sr-86 values of 0.704015-0.704360 and 0.704686-0.704863, respectively, which overlap with previously reported whole-rock values and suggest that the parent magma of the plagioclase represents upwelling mantle materials influenced by a subducted component. Plagioclase-melt thermobarometry records the crystallization of plagioclase phenocrysts in the basalt at the bottom of the lower crust near the Moho (depths of similar to 20 +/- 7.5 km and similar to 25 +/- 7.5 km). The temporal record of the Sr and Ba contents in the melt recorded by these crystals, which were calculated using partition coefficients and the Sr isotopic compositions of the plagioclases from the basalts, demonstrates the existence of two distinct mafic magmas within the SOT due to the presence of different subducted components (i.e., the subduction of the Gagua Ridge). Significant textural variations and wide ranges in the An(35-89) and trace element concentrations and in situ Sr isotopic compositions (0.705748-0.707520) are observed in plagioclase crystals from silicic rocks in the SOT. The barometry results for the plagioclases from silicic rocks yield a wide range of crystallization depths ranging from 6.6 to 17.8 km. The Sr isotopic compositions and trace element concentrations of high-An(80) plagioclases in basalt and silicic rocks indicate that there is no direct relationship between these two magma chambers. The negative correlation between the An contents and the Sr isotopic compositions in the plagioclases from silicic rocks indicates that more upper continental crust materials joined the magma source as its evolution proceeded. The presence of core-sieved plagioclase in the silicic rock indicates that decompression and/or magma mixing occurred. Thus, we propose a multilayer magma chamber system to explain the complex plagioclase crystals in silicic rocks. Two potential mush zones were recognized; their generation may have been controlled by the adiabatic decompression melting of lower crustal materials resulting from crustal extension or the post-collisional extension of the Northern Taiwan Mountain Belt. The two potential mush zones at greater depths are relatively basic, whereas the shallow magma reservoirs, which are the host magmas of the plagioclase, are relatively silicic.
KeywordSouthern Okinawa Trough Plagioclase Microanalysis Magmatic system Subduction
DOI10.1016/j.chemgeo.2018.09.002
Indexed BySCI
Language英语
Funding ProjectNational Natural Science Foundation of China[41476044] ; National Natural Science Foundation of China[41472155] ; National Natural Science Foundation of China[41706052] ; National Basic Research Program of China[2013CB429702] ; Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology grant[MGQNLM-KF201707] ; Shandong Provincial Natural Science Foundation, China[ZR2017PD002] ; China Ocean Mineral Resources RD Association[DY135-N2-1-04] ; Special Fund of Postdoctoral Innovation Project in Shandong Province
WOS Research AreaGeochemistry & Geophysics
WOS SubjectGeochemistry & Geophysics
WOS IDWOS:000445186400012
PublisherELSEVIER SCIENCE BV
Citation statistics
Cited Times:10[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/160239
Collection海洋地质与环境重点实验室
Corresponding AuthorGuo, Kun; Zhai, Shi-Kui
Affiliation1.Shandong Univ Sci & Technol, Coll Earth Sci & Engn, Qingdao 266590, Peoples R China
2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266061, Peoples R China
3.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China
4.Ocean Univ China, Coll Marine Geosci, Minist Educ, Key Lab Submarine Geosci & Prospecting Tech, Qingdao 266100, Peoples R China
5.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao 266071, 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
Guo, Kun,Zhai, Shi-Kui,Wang, Xiao-Yuan,et al. The dynamics of the southern Okinawa Trough magmatic system: New insights from the microanalysis of the An contents, trace element concentrations and Sr isotopic compositions of plagioclase hosted in basalts and silicic rocks[J]. CHEMICAL GEOLOGY,2018,497:146-161.
APA Guo, Kun.,Zhai, Shi-Kui.,Wang, Xiao-Yuan.,Yu, Zeng-Hui.,Lai, Zhi-Qing.,...&Zeng, Zhi-Gang.(2018).The dynamics of the southern Okinawa Trough magmatic system: New insights from the microanalysis of the An contents, trace element concentrations and Sr isotopic compositions of plagioclase hosted in basalts and silicic rocks.CHEMICAL GEOLOGY,497,146-161.
MLA Guo, Kun,et al."The dynamics of the southern Okinawa Trough magmatic system: New insights from the microanalysis of the An contents, trace element concentrations and Sr isotopic compositions of plagioclase hosted in basalts and silicic rocks".CHEMICAL GEOLOGY 497(2018):146-161.
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