Evolution of reef and atoll margin carbonates, upper Eocene through lower Miocene, Enewetak, Marshall Islands

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6083344

Saller, A H; Schlanger, S O

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1,000 m of upper eocene, Oligocene, and lower Miocene carbonates. STrontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids(.), and minor planktonic forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic are abundant in fore-reef, reef, and some back-reef strata). Petrographic and geochemical data indicate arogonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates.

• OSTI ID: 6083344
• Report Number(s): CONF-880301-
• Resource Relation: Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20 Mar 1988
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
CARBONATE ROCKS
DEPOSITION
MARSHALL ISLANDS
PETROLEUM GEOLOGY
NATURAL GAS DEPOSITS
GEOLOGIC HISTORY
PETROLEUM DEPOSITS
REEFS
CALCITE
CEMENTING
CONTINENTAL MARGIN
DOLOMITE
EOCENE EPOCH
EXPLORATION
GEOCHEMISTRY
ISOTOPE DATING
MIOCENE EPOCH
PETROGRAPHY
SANDSTONES
STRATIGRAPHY
AGE ESTIMATION
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CENOZOIC ERA
CHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
ISLANDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MICRONESIA
MINERAL RESOURCES
MINERALS
OCEANIA
OXYGEN COMPOUNDS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
TERTIARY PERIOD
020200* - Petroleum- Reserves
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030200 - Natural Gas- Reserves
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& Exploration