Helium isotopes in volcanic rocks from the Okinawa Trough-impact of volatile recycling and crustal contamination

2016 ◽  
Vol 51 ◽  
pp. 376-386 ◽  
Author(s):  
Zenghui Yu ◽  
Shikui Zhai ◽  
Kun Guo ◽  
Yonghua Zhou ◽  
Tong Zong
Keyword(s):  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Helium Isotopes ◽  
The Okinawa Trough

scholarly journals Origin of Pumice in Sediments from the Middle Okinawa Trough: Constraints from Whole-Rock Geochemical Compositions and Sr-Nd-Pb Isotopes

2019 ◽  
Vol 7 (12) ◽  
pp. 462
Author(s):  
Xue Fang ◽  
Zhigang Zeng ◽  
Siyi Hu ◽  
Xiaohui Li ◽  
Zuxing Chen ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Lower Crust ◽  
Late Quaternary ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
The Okinawa Trough ◽  
Primitive Magma ◽  
The Indian Ocean ◽  
Lower Crustal

Frequent volcanic activity has occurred in the Okinawa Trough (OT) during the late Quaternary, which attracted much attention to the origin of volcanic rocks. Pumice collected from the seafloor has been extensively investigated, whereas few studies paid attention to the pumice in the sediment. The geochemical compositions of pumice preserved in sediments generally provide insight into past volcanic activity and regional magmatism. Here, we present major and trace element compositions and Sr-Nd-Pb isotope data, together with the established age framework for pumice samples recovered from sediment core S9 in the middle OT (MOT) to investigate their possible formation. Compositionally, the S9 pumice samples are dacite and are characterized by relatively higher Sr (87Sr/86Sr = 0.70480–0.70502) and Pb (206Pb/204Pb = 18.321-18.436, 207Pb/204Pb = 15.622–15.624, and 208Pb/204Pb = 38.52–38.63) and lower Nd (143Nd/144Nd = 0.51272–0.51274) isotope compositions than basalts from the MOT. The geochemical compositions of pumice clasts from different layers of core S9 display no temporal variation trends and vary within narrow ranges. On the basis of the geochemical characteristics of S9 pumice samples, we infer that the parent magma of these samples might generate from hybrid magma through an extensive fractional crystallization process. The Indian Ocean MORB-type mantle was first metasomatized by the subducted Philippine Sea sediments to form the primitive magma; then, followed by assimilation of a small amount of lower crustal component occurred in the lower crust. The long-term magmatism and relatively consistent isotopic compositions indicate that a magma chamber might have existed in the lower crust of the MOT between 11.22 and 12.96 cal. ka BP.

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

2006 ◽  
Vol 49 (4) ◽  
pp. 375-383 ◽  
Author(s):  
Peng Huang ◽  
Anchun Li ◽  
Ningjing Hu ◽  
Yongtao Fu ◽  
Zhibang Ma
Keyword(s):  
Okinawa Trough ◽  
Volcanic Rocks ◽  
The Okinawa Trough

scholarly journals Zircon Record of Supercontinent Amalgamation in Back-arc Volcanic Rocks

2020 ◽  
Author(s):  
Zhigang Zeng ◽  
Zuxing Chen ◽  
Yuxiang Zhang
Keyword(s):  
Continental Crust ◽  
Detrital Zircon ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Crustal Thickening ◽  
The Okinawa Trough ◽  
Global Age ◽  
Back Arc

Abstract Episodic supercontinental amalgamation has profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere and biosphere. However, the timing of supercontinent formation has mainly been constrained by the global age spectra of detrital zircon. Here, we show that the zircons in back-arc volcanic rocks not only reflect the evolution of local magmatism but also contain a record of global continental amalgamation events. We found that the young (<100 ka) zircons in volcanic rocks from the Okinawa Trough have old (108 Ma to 2.7 Ga) inherited zircon, which were captured as the magma ascended through the rifting continental crust. Moreover, the ages of the inherited zircons correspond to five supercontinent amalgamation events. Specifically, the Archaean inherited zircons, which have positive ɛHf(t) and low δ18O values, correspond to the formation of juvenile global continental crust. In contrast, the negative ɛHf(t) and high δ18O values of post-Archaean inherited zircons indicate that their parental magma contained recycled, old crust due to the enhanced crustal thickening and crust-mantle interactions during supercontinent assembly. Therefore, inherited zircons in back-arc volcanic rocks not only reflect the evolution of local magmatism but also contain a record of global supercontinental amalgamation events.

scholarly journals Two Processes of Anglesite Formation and a Model of Secondary Supergene Enrichment of Bi and Ag in Seafloor Hydrothermal Sulfide Deposits

2021 ◽  
Vol 10 (1) ◽  
pp. 35
Author(s):  
Zhigang Zeng ◽  
Zuxing Chen ◽  
Haiyan Qi
Keyword(s):  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Hydrothermal Systems ◽  
Sulfide Deposits ◽  
The Okinawa Trough ◽  
Supergene Enrichment ◽  
Seawater Environment ◽  
Back Arc ◽  
Enrichment Process

The in situ element concentrations and the sulfur (S), and lead (Pb) isotopic compositions in anglesite were investigated for samples from seafloor hydrothermal fields in the Okinawa Trough (OT), Western Pacific. The anglesite grains are of two kinds: (1) low Pb/high S primary hydrothermal anglesite (PHA), which is formed by mixing of fluid and seawater, and (2) high Pb/low S secondary supergene anglesite (SSA), which is the product of low-temperature (<100 °C) alteration of galena in the seawater environment. The Ag and Bi in the SSA go through a second enrichment process during the formation of high Pb/low S anglesite by galena alteration, indicating that the SSA and galena, which may be the major minerals host for considerable quantities of Ag and Bi, are potentially Ag-Bi-enriched in the back-arc hydrothermal field. Moreover, REEs, S and Pb in the OT anglesite are likely to have been leached by fluids from local sub-seafloor volcanic rocks and/or sediments. A knowledge of the anglesite is useful for understanding the influence of volcanic rocks, sediments and altered subducted oceanic plate in hydrothermal systems, showing how trace metals behave during the formation of secondary minerals.

Geochemical and isotopic characteristics of volcanic rocks from the northern East China Sea shelf margin and the Okinawa Trough

2010 ◽  
Vol 29 (4) ◽  
pp. 48-61 ◽  
Author(s):  
Zhigang Zeng ◽  
Shaoxiong Yu ◽  
Xiaoyuan Wang ◽  
Yongtao Fu ◽  
Xuebo Yin ◽  
...  
Keyword(s):  
East China Sea ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
East China ◽  
China Sea ◽  
The Okinawa Trough ◽  
East China Sea Shelf ◽  
Shelf Margin

High-potassium volcanic rocks from the Okinawa Trough: Implications for a cryptic potassium-rich and DUPAL-like source

2017 ◽  
Vol 53 (5) ◽  
pp. 1755-1766 ◽  
Author(s):  
Yuxiang Zhang ◽  
Zhigang Zeng ◽  
Xiaohui Li ◽  
Xuebo Yin ◽  
Xiaoyuan Wang ◽  
...  
Keyword(s):  
Okinawa Trough ◽  
Volcanic Rocks ◽  
High Potassium ◽  
The Okinawa Trough

scholarly journals Zircon record of an Archaean crustal fragment and supercontinent amalgamation in quaternary back-arc volcanic rocks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhi-gang Zeng ◽  
Zu-xing Chen ◽  
Yu-xiang Zhang
Keyword(s):  
Continental Crust ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
The Okinawa Trough ◽  
O Isotopes ◽  
Back Arc ◽  
First Time ◽  
Integrated Study

AbstractMagmatism has profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere, and biosphere in back-arc basins. However, the timing of the magmatism in the Okinawa Trough (OT) is not well constrained by the age spectra of zircons. Here, for the first time, we carry out an integrated study combining in situ analysis of zircon U–Th–Pb and Hf–O isotopes, and trace element compositions of zircons from the volcanic rocks from the southernmost part of the OT. We found that the young (< 100 ka) zircons in these volcanic rocks have old (108 Ma to 2.7 Ga) inherited cores, which were captured as the magma ascended through the rifting continental crust. In particular, the inherited Archean zircons strongly suggest that remnants of the old East Asian continental blocks underlie the embryonic crustal rifting zone. Moreover, the ages of most of the inherited zircons correspond to five supercontinent amalgamation events. Specifically, the Archaean inherited zircons, which have positive εHf(t) and low δ18O values, correspond to the formation of juvenile continental crust. In contrast, the negative εHf(t) and high δ18O values of the post-Archaean inherited zircons indicate that their parental magma contained recycled older crust due to the enhanced crust-mantle interactions during the evolution of the early continental crust. Therefore, the inherited zircons in the back-arc volcanic rocks not only reflect the evolution of the local magmatism, but they also contain a record of the Archaean crustal fragment and of several global continental amalgamation events.

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