TY - JOUR
T1 - Geochemical and Sr―Nd isotopic constraints on the origin of volcanic rocks from the northern Okinawa Trough
AU - Shu, Yunchao
AU - Zeng, Zhigang
AU - Yin, Xuebo
AU - Wang, Xiaoyuan
AU - Chen, Shuai
N1 - Funding Information:
We thank the captain and crew of the R/V Kexue Yihao for their assistance in recovering the samples. This work was supported by the National Programme on Global Change and Air-Sea Interaction (Grant No. GASI-GEOGE-02), International Partnership Program of Chinese Academy of Sciences (Grant No. 133137KYSB20170003), National Key Basic Research Program of China (Grant 2013CB429700), Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDA11030302), Special Fund for the Taishan Scholar Program of Shandong Province (Grant ts201511061), National Special Fund for the 13th Five Year Plan of COMRA (Grant DY135-G2-1-02), Aoshan Talent Program Supported by Qingdao National Laboratory for Marine Science and Technology (Grant 2015ASTP-0S17), Innovative Talent Promotion Program (Grant 2012RA2191), Science and Technology Development Program of Shandong Province (Grant 2013GRC31502), Scientific and Technological Innovation Project Financially Supported by Qingdao National Laboratory for Marine Science and Technology (Grant 2015ASKJ03), National High Level Talent Special Support Program, CAS/SAFEA International Partnership Program for Creative Research Teams, and Qingdao Collaborative Innovation Center of Marine Science and Technology.
Publisher Copyright:
© 2018 John Wiley & Sons, Ltd.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Okinawa Trough is an active back-arc basin behind the Ryukyu Arc in the western Pacific. We report the geochemical and isotopic (Sr, Nd) compositions of volcanic rocks, which are recovered as lavas and pumices, dredged from northern Okinawa Trough. The volcanic rocks are composed of basaltic andesite, andesite, dacite, and trachydacite. Both intermediate and felsic rocks are characterized by enrichments in large-ion lithophile elements (LILEs) and depletion in high-field strength elements (HFSEs). Three groups of volcanic rocks have been identified. Andesite D5-1 and trachydacite D10 display identical Sr and Nd isotopic ratios, together with strongly enriched in light-REE and incompatible elements, compared to previously published basalts from middle Okinawa Trough (MOT). Andesite D5-1 and trachydacite D10 are derived from basaltic magma modified by fractional crystallization. Andesites D5-2, D5-3, and D5-4 exhibit lower 87Sr/86Sr and higher 143Nd/144Nd ratios than MOT basalts, transitional REE patterns and trace element ratios between adakite rocks and MOT basalts. Features of these samples can be interpreted by further mixing of the interaction magma of mantle wedge and subducted-slab-melt, with evolved basaltic magma. Dacite D22, occurring as pumice, shows undistinguishable trace element, including REE, and Sr and Nd isotopic compositions with rhyolites from the southern Ryukyu volcanic front, which indicates that this pumice was not emplaced in situ and most likely drifted from southern Ryukyu volcanic front by Kuroshio Current.
AB - Okinawa Trough is an active back-arc basin behind the Ryukyu Arc in the western Pacific. We report the geochemical and isotopic (Sr, Nd) compositions of volcanic rocks, which are recovered as lavas and pumices, dredged from northern Okinawa Trough. The volcanic rocks are composed of basaltic andesite, andesite, dacite, and trachydacite. Both intermediate and felsic rocks are characterized by enrichments in large-ion lithophile elements (LILEs) and depletion in high-field strength elements (HFSEs). Three groups of volcanic rocks have been identified. Andesite D5-1 and trachydacite D10 display identical Sr and Nd isotopic ratios, together with strongly enriched in light-REE and incompatible elements, compared to previously published basalts from middle Okinawa Trough (MOT). Andesite D5-1 and trachydacite D10 are derived from basaltic magma modified by fractional crystallization. Andesites D5-2, D5-3, and D5-4 exhibit lower 87Sr/86Sr and higher 143Nd/144Nd ratios than MOT basalts, transitional REE patterns and trace element ratios between adakite rocks and MOT basalts. Features of these samples can be interpreted by further mixing of the interaction magma of mantle wedge and subducted-slab-melt, with evolved basaltic magma. Dacite D22, occurring as pumice, shows undistinguishable trace element, including REE, and Sr and Nd isotopic compositions with rhyolites from the southern Ryukyu volcanic front, which indicates that this pumice was not emplaced in situ and most likely drifted from southern Ryukyu volcanic front by Kuroshio Current.
KW - back-arc basin
KW - Okinawa Trough
KW - petrogenesis
KW - volcanic rocks
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U2 - 10.1002/gj.3332
DO - 10.1002/gj.3332
M3 - Article
AN - SCOPUS:85054183816
VL - 54
SP - 3304
EP - 3313
JO - Geological Journal
JF - Geological Journal
SN - 0072-1050
IS - 6
ER -