Lack of enhanced preservation of organic matter in sediments under the oxygen minimum on the Oman Margin

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(92)90152-9· OSTI ID:7235576

Pedersen, T F ^[1]; Shimmield, G B; Price, N B ^[2]

---

1. Univ. of British Columbia, Vancouver (Canada)
2. Univ. of Edinburgh (United Kingdom)

The impingement of oxygen minima on continental margins is widely thought to promote the accumulation of sedimentary facies enriched in well-preserved organic matter. It is shown here, however, that such a relationship does not clearly apply to the productive Oman Margin in the Arabian Sea, which hosts one of the most severe oxygen minima in the oceans. Measurements made on the 0-1 cm depth interval from fourteen box cores collected from the outer shelf-upper continental slope area off Oman show that (1) deposited organic matter is overwhelmingly of marine origin, (2) there is no significant correlation between the abundance of sedimentary organic carbon (C{sub org}) and the bottom-water O{sub 2} concentration, (3) there is no relation between the sedimentary C{sub org}:N ratio and bottom-water O{sub 2}, and (4) there is no correlation between the hydrogen index (HI) of the organic matter and bottom water oxygen. There are, however, significant correlations between the C{sub org}:N ratio and the I:C{sub org}, Cr:Al, and Zr:Al ratios, as well as between the C{sub org}:N ratio and the hydrogen index. Overall, these data suggest that the bottom water oxygen concentration has little effect in governing either the distribution of the degree of preservation of organic matter on this margin. Thus, the generally high but spatially variable C{sub org} content of the sediments on the Oman Margin may not reflect the occurrence of an oxygen minimum but instead be the result of a high settling flux of organic matter, supported by monsoon-driven upwelling, and post-depositional redistribution of the organic material by hydrodynamic influences.

• OSTI ID: 7235576
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 56:1; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
CONTINENTAL MARGIN
GEOCHEMISTRY
OMAN
ORGANIC MATTER
PRESERVATION
SEAWATER
WATER CHEMISTRY
ALUMINIUM
ARABIAN SEA
CARBON
CHROMIUM
CORRELATIONS
DEPOSITION
DEPTH
EXPERIMENTAL DATA
NITROGEN
ORIGIN
OXYGEN
SAMPLING
ZIRCONIUM
ASIA
CHEMISTRY
DATA
DEVELOPING COUNTRIES
DIMENSIONS
ELEMENTS
HYDROGEN COMPOUNDS
INDIAN OCEAN
INFORMATION
MATTER
METALS
MIDDLE EAST
NONMETALS
NUMERICAL DATA
OXYGEN COMPOUNDS
SEAS
SURFACE WATERS
TRANSITION ELEMENTS
WATER
580000* - Geosciences
540310 - Environment
Aquatic- Basic Studies- (1990-)