High-resolution magnetic signature of active hydrothermal systems in the back-arc spreading region of the southern Mariana Trough

Masakazu Fujii, Kyoko Okino, Chie Honsho, Jerome Dyment, Florent Szitkar, Nobutatsu Mochizuki, Miho Asada

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

High-resolution vector magnetic measurements were performed on five hydrothermal vent fields of the back-arc spreading region of the southern Mariana Trough using Shinkai 6500, a deep-sea manned submersible. A new 3-D forward scheme was applied that exploits the surrounding bathymetry and varying altitudes of the submersible to estimate absolute crustal magnetization. The results revealed that magnetic-anomaly-derived absolute magnetizations show a reasonable correlation with natural remanent magnetizations of rock samples collected from the seafloor of the same region. The distribution of magnetic-anomaly-derived absolute magnetization suggests that all five andesite-hosted hydrothermal fields are associated with a lack of magnetization, as is generally observed at basalt-hosted hydrothermal sites. Furthermore, both the Pika and Urashima sites were found to have their own distinct low-magnetization zones, which could not be distinguished in magnetic anomaly data collected at higher altitudes by autonomous underwater vehicle due to their limited extension. The spatial extent of the resulting low magnetization is approximately 10 times wider at off-axis sites than at on-axis sites, possibly reflecting larger accumulations of nonmagnetic sulfides, stockwork zones, and/or alteration zones at the off-axis sites

Original languageEnglish
Pages (from-to)2821-2837
Number of pages17
JournalJournal of Geophysical Research: Solid Earth
Volume120
Issue number5
DOIs
Publication statusPublished - 2015 May 1
Externally publishedYes

Keywords

  • back-arc spreading region
  • deep-sea magnetics
  • hydrothermal system
  • Mariana Trough

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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