Upper Permian lacustrine oil shales, southern Junggar basin, northwest China

Journal Article · Tue Dec 01 04:00:00 EST 1992 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6914242

Carroll, A R; Brassell, S C; Graham, S A ^[1]

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1. Stanford Univ., CA (United States)

Upper Permian organic-rich lacustrine mudstones (oil shales) that crop out in the southern Junggar basin rank among the richest and thickest petroleum source rock intervals in the world, with maximum TOC values reaching 34% and Rock-Eval pyrolytic yields (S[sub 2]) up to 200 kg HC/t rock. Lacustrine sedimentary facies define an overall transgressive-regressive cycle of approximately 2000 m gross thickness, which includes approximately 800 m of source rocks averaging 4.1% TOC and 26.2 kg HC/t rock. Basinal facies comprise silicic, organic-rich, laminated lacustrine mudstones and interbedded siltstones; organic matter contained in the mudstones ranges in composition from type I to type III. Basinal facies were deposited in a deep, oxygen-deficient, stratified lake. Lake-margin facies consist of nonlaminated siliciclastic mudstones, rippled dolomitic silstones and sandstones, and minor limestones. Maximum TOC values are approximately 6%. Desiccation cracks are common in the marginal facies, but evaporite minerals are rare or absent. Biomarker correlation parameters measured from rock extracts exhibit significant stratigraphic variability, but strongly support the hypothesis that Upper Permian lacustrine oil shales charge the giant Karamay field in the northwestern Junggar basin. Karamay oils are characterized by high relative abundances of [beta]-carotane. This characteristic is restricted to desiccated facies in the outcrop sections, however. We therefore propose that an abundance of [beta]-carotane indicates elevated environmental salinities during deposition of the oil shales. 16 figs., 9 tabs.

• OSTI ID: 6914242
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 76:12; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040200* -- Oil Shales & Tar Sands-- Reserves
Geology
& Exploration
ASIA
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHINA
DECOMPOSITION
ENERGY SOURCES
EXPLORATION
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
MATERIALS
MINERAL RESOURCES
OIL SHALE DEPOSITS
OIL SHALES
PALEOZOIC ERA
PERMIAN PERIOD
PYROLYSIS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SHALES
THERMOCHEMICAL PROCESSES