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dc.contributor.authorShao, Hebin  Concept link
dc.contributor.authorYang, Shouye  Concept link
dc.contributor.authorHumphris, Susan E.  Concept link
dc.contributor.authorCai, Di  Concept link
dc.contributor.authorCai, Feng  Concept link
dc.contributor.authorLi, Jiangtao  Concept link
dc.contributor.authorLi, Qing  Concept link
dc.date.accessioned2017-07-13T16:20:19Z
dc.date.issued2017-05-18
dc.identifier.urihttps://hdl.handle.net/1912/9094
dc.description© The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Chemical Geology 465 (2017): 35-51, doi:10.1016/j.chemgeo.2017.05.020.en_US
dc.description.abstractDuring the Integrated Ocean Drilling Program (IODP) Expedition 331, five sites were drilled into the Iheya North Knoll hydrothermal system in the Okinawa Trough (OT) — a back-arc basin characterized by thick terrigenous sediment. Following up on the previous study by Shao et al. (2015), we present new mineralogical, geochemical, and Sr-Nd isotope data to investigate the origin of the hydrothermal sediments and characterize the hydrothermal system. The substrate at the Iheya North Knoll is dominated by pumiceous sediment and other volcanoclastic materials interbedded with hemipelagic (terrigenous and biogenous) sediments. Impermeable layers separate the hydrothermal sediments into distinct units with depth that are characterized by various assemblages of alteration materials, including polymetallic sulfides, sulfates, chlorite- and kaolinite-rich sediments. The rare earth elements (REEs) and Nd isotope data suggest that the chlorite-rich and kaolinite-rich layers primarily resulted from the alteration of pumiceous materials in different chemical and physical conditions. Kaolinite-rich sediment likely reflects low pH and low Mg concentration fluids, while chlorite-rich sediment formed from fluids with high pH and increased Mg contents, likely at higher temperatures. The Sr isotopic compositions of subsurface anhydrite reflect high seawater/hydrothermal fluid ratios in the mid-OT hydrothermal area. Compared with chlorite-rich sediments from other sediment-covered or felsic-hosted hydrothermal systems, the chlorite-rich sediments in the mid-OT are characterized by lower concentrations of Al and Fe but much higher Y, Zr, Hf, Th and REEs, indicative of the distinct nature of the precursor rocks in this region.en_US
dc.description.sponsorshipThis work was supported by the National Natural Science Foundation of China (Grant Nos. 41376049 and 41225020), National Programme on Global Change and Air-Sea Interaction (GASI-GEOGE-03), AoShan Talents Program Supported by Qingdao National Laboratory for Marine Science and Technology (No. 2015ASTP-OS11), Program of Shanghai Subject Chief Scientist (No. 14XD1403600), and Continental Shelf Drilling Program (No. GZH201100202).en_US
dc.language.isoen_USen_US
dc.relation.urihttps://doi.org/10.1016/j.chemgeo.2017.05.020
dc.subjectHydrothermal alterationen_US
dc.subjectChlorite-rich sedimentsen_US
dc.subjectOkinawa Troughen_US
dc.subjectTerrigenousen_US
dc.subjectPumiceen_US
dc.subjectSr-Nd isotopesen_US
dc.subjectIntegrated Ocean Drilling Programen_US
dc.titleThe origin of hydrothermal chlorite- and anhydrite-rich sediments in the middle Okinawa Trough, East China Seaen_US
dc.typePreprinten_US


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