Preliminary assessment of hydrocarbon potential of Larsen basin, Antarctica
The Larsen basin, on the northwest margin of the Weddell Sea, formed as a Mesozoic ensialic basin during Gondwana breakup. At the northern end of this basin, 5-6 km of sedimentary rock crop out on James Ross Island, exposing elements of a large hydrocarbon system. Aeromagnetic and outcrop data suggest that the basin history inferred from James Ross Island persists to 70/sup 0/S. Deposition was in half-grabens on the extending Weddell Sea margin or in restricted back-arc basins. Upper Jurassic anoxic marine strata, deposited prior to rifting, form a rich potential source (TOC up to 2.5%) with both marine and terrestrial kerogens. Arc-derived volcaniclastic sediments of Barremian-Oligocene age form a regressive megasequence. Basal strata represent slope apron and rudaceous submarine fan deposits proximal to the margin; fan conglomerates form lenticular bodies hundreds of meters thick and tens of kilometers across, enveloped in slope-apron mudstones. Late Cretaceous fault reactivation and uplift led to dramatic shallowing of the basin, with deposition of shelf facies. Although there are many attractive reservoir targets, there may be problems of pore occlusion due to the abundant labile volcanic grains. However, there is evidence of more quartzose sandstone toward the top of the section and toward the basin center. In the northern Weddell basin, there is moderate potential for oil generated from Upper Jurassic source rocks and reservoired in Cretaceous and Tertiary sandstones and conglomerates, in large stratigraphic or structural traps caused by partial basin inversion during deposition.
- Research Organization:
- British Antarctic Survey, Cambridge, England
- OSTI ID:
- 6185863
- Report Number(s):
- CONF-870606-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 71:5; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ANTARCTIC REGIONS
ANTARCTICA
CENOZOIC ERA
CRETACEOUS PERIOD
EXPLORATION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
JURASSIC PERIOD
MESOZOIC ERA
MINERAL RESOURCES
PETROLEUM DEPOSITS
POLAR REGIONS
RESERVOIR ROCK
RESOURCE POTENTIAL
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SOURCE ROCKS
TERTIARY PERIOD