Patterns of foraminiferal and nanoplankton abundance and diversity as a tool for sequence stratigraphy analysis of the Eocene in Western Venezuela

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

OSTI ID:6102453

Pittelli, R; Duran, I ^[1]

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1. Maraven S.A., Caracas (Venezuela)

Detailed micropaleontological and nanoplankton studies have been integrated with wireline logs and lithology to define middle to upper Eocene sequence stratigraphy for three wells in the Andes Foothills Area. An estimate of the relative abundance of each species was made for both foraminifera and calcareous nanoplankton, standard sample preparation included processing of a uniform volume of well cuttings. Data consists of 6 faunal/floral checklists recording the occurrence of forminiferal and calcareous nanoplankton species. The faunal/floral diversity, abundance and discontinuity, together with glauconite concentration, helped to define the Sequence Boundaries and the Maximum Flooding Surfaces. These discontinuities were calibrated for age, and were compared with the ages of the Sequence Boundaries of Hag et al. (version 1992). the Lutetian-Bartonian stage (middle Eocene) sediments consists of gluaconitic marls and limestones and shales, representing a sequence of transgressive, condensed and highstand regressive deposits are assigned to Planktonic Zones P10-P14 (Blow, 1979) and Nanoplankton Zones NP 15 - NP 17 (Martini, 1971). The Priabonian stage (upper Eocene) sediments assigned Planktonic Zones P15-P17 and Nanoplankton Zones NP18-NP19, contains mainly claystones and scattered quartzose silts and sand beds, consisting of slope fan deposits and lowstand regressive deposits, underlying a regional unconformity (SB 30). The position of biostratigraphic boundaries is influenced by the paleogeographic setting and paleoenvironmental conditions.

• OSTI ID: 6102453
• 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
BOUNDARY LAYERS
POSITIONING
FOSSILS
ABUNDANCE
VENEZUELA
STRATIGRAPHY
ANDES
DATA ANALYSIS
EOCENE EPOCH
FORAMINIFERA
LITHOLOGY
OIL WELLS
PALEONTOLOGY
PLANKTON
SEA LEVEL
WELL LOGGING
ANIMALS
AQUATIC ORGANISMS
CENOZOIC ERA
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGY
INVERTEBRATES
LATIN AMERICA
LAYERS
LEVELS
MICROORGANISMS
MOUNTAINS
PETROLOGY
PROTOZOA
SARCODINA
SOUTH AMERICA
TERTIARY PERIOD
WELLS
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences