Okinawa trough: Hydrothermal activity in the okinawa trough back-arc basin: Geological background and hydrothermal mineralization

Jun Ichiro Ishibashi, Fumihiko Ikegami, Takeshi Tsuji, Tetsuro Urabe

Research output: Chapter in Book/Report/Conference proceedingChapter

56 Citations (Scopus)


The Okinawa Trough is a back-arc basin behind the Ryukyu trench-arc system and located along the eastern margin of the Eurasian continent. Sulfide and sulfate mineralization associated with hydrothermal activity has been recognized in ten hydrothermal fields in the Okinawa Trough. Hydrothermal mineralization recognized in these fields is commonly represented by coexisting occurrence of zinc- and lead-enriched polymetallic sulfides and abundant sulfate minerals. The mineralogy and geochemical signatures present has led researchers to suggest these areas may be a modern analogue for the formation of ancient Kuroko-type volcanogenic massive sulfide (VMS) deposits. Recent seafloor drilling during IODP (Integrated Ocean Drilling Program) Expedition 331 documented the subsea floor structure of a hydrothermal system at the Iheya North Knoll. Mineral textures and hydrothermal assemblages present in the drilled cores obtained from a hydrothermal mound in the proximal area are consistent with Kuroko-type mineralization. Based on geochemical studies, the intra-field diversity of mineralization commonly recognized in the Okinawa Trough can be explained by subsea floor phase separation of the hydrothermal fluid, which reflects shallow water depth (from 700 to 1,600 m). The sub seafloor phase separation may. play an important role to accumulate metal elements beneath the seafloor. Based on geophysical and geological studies, the Okinawa Trough is considered a back-arc basin in the rifting stage. Such a tectonic setting is characterized by development of normal faulting in brittle continental crust and frequent intrusion of a magma, which can be expected to provide favorable environment for development of a hydrothermal system.

Original languageEnglish
Title of host publicationSubseafloor Biosphere Linked to Hydrothermal Systems
Subtitle of host publicationTAIGA Concept
PublisherSpringer Japan
Number of pages24
ISBN (Electronic)9784431548652
ISBN (Print)9784431548645
Publication statusPublished - Jan 1 2015

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)


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