Geological framework of an active hydrothermal site in the North Fiji Basin: Starmer cruise of the submersible Nautile

Conference · Fri Jun 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6193053

Auzende, J ^[1]

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1. Ifremer, Plouzane (France)

During the summer of 1989 the French submersible Nautile carried out a diving cruise on the North Fiji Basin ridge axis in the frame of the Starmer French-Japanese joint project. The diving sites were selected using the Seapso 3, Kaiyo 87, and Kaiyo 88 cruises Seabeam surveys. They are located around 17{degree}S in the axial graben at the northern end of the N15 ridge. The axis consists of an 18 km wide, N15 elongated dome cut by a 2 km wide axial graben. The elevation of the dome with respect to adjacent oceanic floor is 500-600 m. It culminates at less than 1,900 m, which is higher than a normal oceanic ridge. The axial graben width (2 km) is also unusual compared to oceanic ridge with intermediate spreading rates such as the EPR at 21{degree}N. Six Nautile dives have been devoted to the detailed exploration of the axial graben between 16{degree}58'S and 17{degree}00'S in order to locate the hydrothermal vents in the inferred most active part of the axial graben. A structural map has been established on the basis of dive observation. Between 17{degree}S and 16{degree}58'S, the axis shows a succession of N15-trending horsts and grabens paralleling the main orientation of the ridge. Two main lateral grabens and a central graben can be recognized. The central graben shows remarkably constant width (200 m) and depth (2,000 m). It is bounded by two small horsts, few tens of meters wide. Observed tectonic features include N15 normal fault scarps and abundant open fissures with the same direction. The whole area is dusted with sediments indicating that volcanism was not active recently. Evidence of recent hydrothermal activity such as oxide staining, dead munch, dead chimney is abundant all along the central graben.

• OSTI ID: 6193053
• Report Number(s): CONF-900702-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:6; Conference: 5. Circum-Pacific energy and mineral resources conference, Honolulu, HI (USA), 29 Jul - 3 Aug 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
PACIFIC OCEAN
HYDROTHERMAL SYSTEMS
FIJI
GEOLOGIC FAULTS
MAPPING
SEA BED
SEDIMENTARY BASINS
TECTONICS
ENERGY SYSTEMS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOTHERMAL SYSTEMS
ISLANDS
SEAS
SURFACE WATERS
150200* - Geology & Hydrology of Geothermal Systems
580000 - Geosciences