Depositional environment and distribution of Late Cretaceous [open quotes]source rocks[close quotes] from Costa Rica to West Africa

Conference · Mon Feb 01 00:00:00 EST 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6103003

Erlich, R N; Sofer, Z ^[1]; Pratt, L M ^[2]; Palmer, S E ^[3]

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1. Amoco Overseas Exploration Company, Houston, TX (United States)
2. Indiana Univ., Bloomington, IN (United States)
3. Amoco Research Company, Tulsa, OK (United States)

Late Cretaceous [open quotes]source rocks[close quotes] from Costa Rica, western and eastern Venezuela, and Trinidad were studied using organic and inorganic geochemistry, biostratigraphy, and sedimentology in order to determine their depositional environments. Bulk mineralogy and major element geochemistry for 304 samples were combined with Rock Eval data and extract biomaker analysis to infer the types and distributions of the various Late Cretaceous productivity systems represented in the dataset. When data from this study are combined with published and proprietary data from offshore West Africa, Guyana/Suriname, and the central Caribbean, they show that these Late Cretaceous units can be correlated by their biogeochemical characteristics to establish their temporal and spatial relationships. Paleogeographic maps constructed for the early to late Cenomanian, Turonian, Coniacian to middle Santonian, and late Santonian to latest Campanian show that upwelling and excessive fluvial runoff were probably the dominant sources of nutrient supply to the coastal productivity systems. The late Santonian to Maastrichtian rocks examined in this study indicate that organic material was poorly preserved after deposition, even though biologic productivity remained constant or changed only slightly. A rapid influx of oxygenated bottom water may have occurred following the opening of a deep water connection between the North and South Atlantic oceans, and/or separation of India from Africa and the establishment of an Antarctic oceanic connection. This study suggests that the most important factors that controlled source rock quality in northern South America were productivity, preservation, degree of clastic dilution, and subsurface diagenesis.

• OSTI ID: 6103003
• Report Number(s): CONF-930306-; CODEN: AABUD2
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:2; Conference: International congress of the American Association of Petroleum Geologists (AAPG), Caracas (Venezuela), 14-17 Mar 1993; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
AFRICA
SOURCE ROCKS
COSTA RICA
GUYANA
SEDIMENTARY ROCKS
MAPS
SEDIMENTS
DIAGENESIS
DEPOSITION
SURINAM
VENEZUELA
CARBON SOURCES
CRETACEOUS PERIOD
DISTRIBUTION
GEOCHEMISTRY
MINERALOGY
PALEONTOLOGY
PRODUCTIVITY
SEDIMENTATION
STRATIGRAPHY
CENTRAL AMERICA
CHEMISTRY
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGY
LATIN AMERICA
MESOZOIC ERA
ROCKS
SOUTH AMERICA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences