Structural style and petroleum prospects of Tonga Ridge

Conference · Wed Mar 01 04:00:00 EST 1989 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:6132773

Pflueger, J; Havard, K; Gatliff, R; Helu, B

Recent reprocessing of seismic data from the Tonga Ridge has provided a clearer picture of the tectonic style of a forearc basin. Sediments along the ridge achieve a maximum thickness of more than 4000 m. Many faults have been observed, almost all of which are normal. The presence of scarps on the sea floor show that a significant percentage of the faults are active today. Although seismic transverses are not spaced closely enough to allow unambiguous definition of fault orientations, they believe that most of the tensional faults are parallel to the ridge axis. A second set of near-vertical faults with apparent transcurrent movement exists at a high angle to the ridge axis. Bathymetry has played a major role in defining the strikes of the second set of faults. The tensional failures are due to the flexing of the ridge as the leading edge of the Indo-Australian plate is pulled down and under by frictional attachment to the subducting Pacific plate. The development of major fault blocks is related to the subduction of Pacific plate seamounts. Fault-bounded closures and Eocene to Miocene reefs would form excellent traps for hydrocarbons. Oil seeps of biodegaded but thermally mature crude oil on the island of Tongatanu encouraged the drilling of five exploratory test wells, but the source rock feeding the seeps was not discovered. Burial history and geothermal modeling indicate that mature source rocks could occur deeper than depths penetrated by the test wells.

• OSTI ID: 6132773
• Report Number(s): CONF-890404-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 73:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
AUSTRALASIA
AUSTRALIA
CENOZOIC ERA
EXPLORATION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
MATURATION
MINERAL RESOURCES
MIOCENE EPOCH
PETROLEUM DEPOSITS
RESOURCES
TERTIARY PERIOD