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Geochemical characteristics of Tertiary Sagara oil from an active forearc basin, Shizuoka, Japan
Author(s) -
Yessalina Svetlana,
Suzuki Noriyuki,
Saito Hiroyuki
Publication year - 2006
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.2006.00529.x
Subject(s) - forearc , geology , pristane , phytane , source rock , structural basin , maturity (psychological) , siliciclastic , geochemistry , neogene , sedimentary rock , sterane , sedimentary basin analysis , sedimentary basin , oil field , paleontology , subduction , hopanoids , sedimentary depositional environment , tectonics , hydrocarbon , psychology , developmental psychology , chemistry , organic chemistry
The Sagara oil field is located in the Neogene Kakegawa Basin, close to the Izu collision zone at the junction between the main Japanese Islands and the Izu–Bonin Arc. The Sagara oil field is one of the few oil fields situated in a forearc basin on the Pacific side of Japan and is present in a sedimentary basin with poor oil‐generating potential. Several crude oils from Sagara oil field were investigated to infer their origin. Organic geochemical characteristics of Sagara oils showed the influences of light biodegradation, migration‐contamination, and migration‐fractionation. The maturity levels of Sagara oils evaluated based on abundant alkylnaphthalenes corresponded to 0.9–1.2% vitrinite reflectance. Sagara oils were characterized by significant amounts of higher plant biomarkers, a high pristane/phytane ratio and an absence of organic sulphur compounds, suggesting a siliciclastic source rock deposited under nearshore to fluvial–deltaic environments. Numerous faults and fractures in the active forearc basin provided excellent conduits and facilitated upward migration of light hydrocarbons generated at greater depth in the Kakegawa Basin.