Hot fluids, burial metamorphism and thermal histories in the underthrust sediments at IODP 370 site C0023, Nankai Accretionary Complex

Man Yin Tsang, Stephen A. Bowden, Zhibin Wang, Abdalla Mohammed, Satoshi Tonai, David Muirhead, Kiho Yang, Yuzuru Yamamoto, Nana Kamiya, Natsumi Okutsu, Takehiro Hirose, Myriam Kars, Florence Schubotz, Akira Ijiri, Yasuhiro Yamada, Yusuke Kubo, Yuki Morono, Fumio Inagaki, Verena B. Heuer, Kai Uwe Hinrichs

Research output: Contribution to journalArticlepeer-review

Abstract

Drilling during International Ocean Discovery Program (IODP) Expedition 370 at Site C0023 encountered instances of hydrothermal mineralization from 775 to 1121 m below seafloor. Fluid inclusion homogenization temperatures measured on barite veins within this interval indicate precipitation from fluids with temperatures up to 220 °C, and salinities ten times higher than interstitial water (16–25 c.f. 2.8–3.6 wt % NaCl). Patches of stratabound mineralization (rhodochrosite, calcite, barite and anhydride) are largely confined to the vicinity of veins and have vertical thicknesses and extents that can be explained by precipitation within the thermal aureoles of veins. Thermal maturities measured on petroleum biomarkers in underthrust sediments record a rise from pre-oil window to early oil window thermal maturities. Basin models show that increases in thermal maturity can be explained by burial metamorphism, and kinetic-based calculations suggest that hot fluids would only have had a minimal effect on hydrocarbon generation. However, the movement of hot fluids still has geochemical implications and creates a complex thermal history where both short-duration, localized heating within fracture zones at hot temperatures (~200 °C for less than 1 yr) and heating during burial over long durations (80–110 °C for 0.5–2 Myrs) need to be considered.

Original languageEnglish
Article number104080
JournalMarine and Petroleum Geology
Volume112
DOIs
Publication statusPublished - Feb 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Geophysics
  • Geology
  • Economic Geology
  • Stratigraphy

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