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Schulte, Sonja; Mangelsdorf, Kai; Rullkötter, Jürgen (2000): Organic compounds in surface sediments from the Pakistan continental margin. PANGAEA,, Supplement to: Schulte, S et al. (2000): Organic matter preservation on the Pakistan continental margin as revealed by biomarker geochemistry. Organic Geochemistry, 31(10), 1005-1022,

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In order to assess whether the oxygen-minimum zone (OMZ) in the Arabian sea has an effect on the preservation and composition of organic matter in surface sediments we investigated samples from three different transects on the Pakistan continental margin across the OMZ. In addition to determining the total amount of organic carbon (TOC), we analyzed the extractable lipids by gas chromatography, combined gas chromatography/mass spectrometry, and compound-specific stable carbon isotope measurements. The extractable lipids are dominated by marine organic matter as indicated by the abundance of lipids typical of marine biota and by the bulk and molecular isotopic composition. Sediments from within the OMZ are enriched in organic carbon and in several extractable lipids (i.e. phytol, n-alcohols, total sterols, n-C35 alkane) relative to stations above and below this zone. Other lipid concentrations, such as those of total n-fatty acids and total n-alkanes fail to show any relation to the OMZ. Only a weak correlation of TOC with mineral surface area was found in sediments deposited within the OMZ. In contrast, sediments from outside the OMZ do not show any relationship between TOC and surface area. Among the extractable lipids, only the n-alkane concentration is highly correlated with surface area in sediments from the Hab and Makran transects. In sediments from outside the OMZ, the phytol and sterol concentrations are also weakly correlated with mineral surface area. The depositional environment of the Indus Fan offers the best conditions for an enhanced preservation of organic matter. The OMZ, together with the undisturbed sedimentation at moderate rates, seems to be mainly responsible for the high TOC values in this area. Overall, the type of organic matter and its lability toward oxic degradation, the mineral surface area, the mineral composition, and possibly the secondary productivity by (sedimentary) bacteria also appear to have an influence on organic matter accumulation and composition.
Median Latitude: 23.818194 * Median Longitude: 65.750097 * South-bound Latitude: 22.486000 * West-bound Longitude: 64.217000 * North-bound Latitude: 24.956000 * East-bound Longitude: 67.007000
Date/Time Start: 1993-09-03T00:00:00 * Date/Time End: 1993-09-29T00:00:00
Minimum DEPTH, sediment/rock: 0.01 m * Maximum DEPTH, sediment/rock: 0.01 m
SO90_103KG * Latitude: 23.020000 * Longitude: 66.401000 * Date/Time: 1993-09-18T00:00:00 * Elevation: -1206.0 m * Recovery: 0.37 m * Location: Arabian Sea * Campaign: SO90 (PAKOMIN) * Basis: Sonne * Method/Device: Box corer (Reineck) (BCR) * Comment: GPS,
SO90_107KG * Latitude: 23.060000 * Longitude: 66.505000 * Date/Time: 1993-09-19T00:00:00 * Elevation: -992.0 m * Recovery: 0.45 m * Location: Arabian Sea * Campaign: SO90 (PAKOMIN) * Basis: Sonne * Method/Device: Box corer (Reineck) (BCR) * Comment: GPS,
SO90_110KG * Latitude: 23.097000 * Longitude: 66.483000 * Date/Time: 1993-09-19T00:00:00 * Elevation: -776.0 m * Recovery: 0.55 m * Location: Arabian Sea * Campaign: SO90 (PAKOMIN) * Basis: Sonne * Method/Device: Box corer (Reineck) (BCR) * Comment: GPS,
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Latitude of eventLatitude
2Longitude of eventLongitude
3Event labelEvent
4Elevation of eventElevationm
5DEPTH, sediment/rockDepthmGeocode
6Carbon, organic, totalTOC%Schulte, SonjaElement analyser CHN
7Carbon in carbonateC (carb)%Schulte, SonjaCalculated
84alpha,23,24-Trimethyl-5alpha-cholest-22E-en-3beta-ol per unit mass total organic carbonDinosterol/TOCµg/gSchulte, SonjaGas chromatography - Mass spectrometry (GC-MS)
9n-Alkane, total per unit sediment massn-Alkane tot/sedµg/gSchulte, SonjaGas chromatography
103,7,11 Methyl, 15, Dimethyl, pentan-2dien-1ol, Phytol normalized to TOC per unit mass total organic carbonPhytol/TOCµg/gSchulte, SonjaGas chromatography - Mass spectrometry (GC-MS)
11n-Alcohol per unit mass total organic carbonn-Alco/TOCµg/gSchulte, SonjaGas chromatographyC24+C25+C26+C27+C28, total
12sum per unit mass fatty acids (C12...C33) of total organic carbonSum fatty acids/TOCµg/gSchulte, SonjaGas chromatography
13Sum sterols normalized to total organic carbon massSterols TOCµg/gSchulte, SonjaGas chromatography - Mass spectrometry (GC-MS)
14n-Pentatriacontane (C35H72) per unit mass total organic carbonC35/TOCµg/gSchulte, SonjaGas chromatography
15Sum n-Tetracosanoic acid+n-Hexacosanoic acid per unit mass total organic carboSum C24+C26 acid/TOCµg/gSchulte, SonjaGas chromatography
16iso-, antiso C15 and C17 acid per unit mass total organic carboni,aC15+C17/TOCµg/gSchulte, SonjaGas chromatography
17n-Hentriacontane normalized to total organic carbonC31 TOCµg/gSchulte, SonjaGas chromatography
270 data points

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