Molecular and carbon isotopic analysis of specific biological markers: Evidence for distinguishing between marine and lacustrine depositional environments in sedimentary basins of Brazil

Conference · Mon Jan 01 00:00:00 EST 1996 · AAPG Bulletin

OSTI ID:6858289

Guthrie, J M; Trindade, L A.F.; Eckardt, C B; Takaki, T ^[1]

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1. Petrobras Research and Development Center, Rio de Janeiro (Brazil)

A suite of organic-rich, immature shales (TOC's ranging between 0.7 to 28.4 %) from various basins throughout Brazil were selected for carbon isotopic ([delta][sup 13]C) analysis of individual biological compounds in order to characterize marine and lacustrine depositional environments. Carbon isotopic compositions of pristane, phytane, n-heptadecane; 28, 30-bisnorhopane; 17[alpha](H), 21[beta](H)-hopane, and gammacerane, together with other commonly used biomarker parameters show variations that are related to sources of organic matter and to depositional processes in the paleoenvironment. Plots relating hopane/sterane ratios to the [delta][sup 13]C compositions pristane, phytane, n-heptadecane; 28, 30-bisnorhopane, and 17[alpha](H), 21[beta](H)-hopane show that these compounds in lacustrine shales are consistently more depleted in [sup 13]C than in marine shales. For example, the [delta][sup 13]C values of pristane and phytane in lacustrine shales vary from -28 to -32 %. and in marine shales from -22 to -24 [per thousand]. The correlation between high abundance of hopanes relative to steranes with depleted [sup 13]C compositions in these compounds is supporting evidence for a more abundant input of methanogenic bacteria in these lacustrine shales.

• OSTI ID: 6858289
• Report Number(s): CONF-960527-; CODEN: AABUD2
• Journal Information: AAPG Bulletin, Vol. 5; Conference: Annual convention of the American Association of Petroleum Geologists, Inc. and the Society for Sedimentary Geology: global exploration and geotechnology, San Diego, CA (United States), 19-22 May 1996; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
BRAZIL
SEDIMENTARY BASINS
OIL SHALES
GEOCHEMISTRY
CARBON ISOTOPES
METHANOGENIC BACTERIA
BACTERIA
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMISTRY
DEVELOPING COUNTRIES
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC STRUCTURES
ISOTOPES
LATIN AMERICA
MATERIALS
MICROORGANISMS
ROCKS
SEDIMENTARY ROCKS
SHALES
SOUTH AMERICA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences