Publication Date:
2024-01-19
Description:
A series of core samples taken during Cruise 79 of Glomar Challenger, drilling offshore Morocco (Mazagan Plateau), is analyzed for their low-molecular-weight hydrocarbon contents. Fifty-four samples from DSDP Holes 544A, 545, 547A, and 547B, deep frozen on board immediately after recovery, are studied by a hydrogen-stripping/thermovaporization technique combined with capillary gas chromatography. Thirty-eight compounds in the C2-C8 molecular range, including saturated, olefinic, and aromatic hydrocarbons, are identified.
Because of large differences in organic carbon contents, the total C2-C8 hydrocarbon concentrations vary from about 20 to 1500 ng/g dry sediment weight in the whole sample series. Organic-carbon normalized values are about 3.2 x 10**4 ng/g Corg for Lithologic Subunits IIIA and IIIB at Site 545 (Cenomanian to Aptian) and 1.0 x 10**5 ng/g Corg for Unit V at Site 547 (Cenomanian to Albian) reflecting the slightly more advanced maturity stage at the latter site. Values exceeding 10**5 ng/g Corg (Site 545) and 2 x 10**5 ng/g Corg (Site 547) are associated with samples that are very lean in organic carbon and are generally rich in carbonate. These samples are enriched by small amounts of gaseous hydrocarbons.
A detailed study of individual hydrocarbon concentrations, plotted against depth, reveal additional indications for migration phenomena. At Site 547, for instance, the most mobile hydrocarbons studied (e.g., ethane) appear to migrate by diffusion or a related process from more than 700 m depth toward the surface.
Keywords:
1,cis-2-Dimethylcyclopentane per unit sediment mass; 1,cis-3-Dimethylcyclopentane per unit sediment mass; 1,trans-2,cis-3-trimethylcyclopentane per unit sediment mass; 1,trans-2,cis-4-trimethylcyclopentane per unit sediment mass; 1 trans-2-Dimethylcyclopentane per unit sediment mass; 1 trans-3-Dimethylcyclopentane per unit sediment mass; 2,2-Dimethylbutane per unit sediment mass; 2,2-Dimethylpropane per unit sediment mass; 2,3-Dimethylbutane per unit sediment mass; 2,3-Dimethylpentane per unit sediment mass; 2,4-Dimethylpentane per unit sediment mass; 2,5-Dimethylhexane per unit sediment mass; 2-Methylheptane per unit sediment mass; 2-Methylhexane per unit sediment mass; 2-Methylpentane per unit sediment mass; 3-Methylhexane per unit sediment mass; 3-Methylpentane per unit sediment mass; 79-544A; 79-545; 79-547A; 79-547B; Benzene per unit sediment mass; Carbon, organic, total; Cis-2-butene per unit sediment mass; Cyclohexane per unit sediment mass; Cyclopentane per unit sediment mass; Deep Sea Drilling Project; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Element analyser CHN, LECO; Elevation of event; Ethane per unit sediment mass; Ethene per unit sediment mass; Ethylcyclopentane per unit sediment mass; Event label; Glomar Challenger; Hydrogen index, mass HC, per unit mass total organic carbon; Isobutane per unit sediment mass; Isopentane per unit sediment mass; Latitude of event; Leg79; Lithology/composition/facies; Longitude of event; Methylcyclohexane per unit sediment mass; Methylcyclopentane per unit sediment mass; n-Butane per unit sediment mass; n-Heptane per unit sediment mass; n-Hexane per unit sediment mass; n-Octane per unit sediment mass; North Atlantic/PLATEAU; n-Pentane per unit sediment mass; Oxygen index, mass CO2, per unit mass total organic carbon; Propane per unit sediment mass; Propene per unit sediment mass; Pyrolysis temperature maximum; Rock eval pyrolysis (Espitalié et al. 1977); Sample code/label; see reference(s); Toluene per unit sediment mass; Trans-2-butene per unit sediment mass
Type:
Dataset
Format:
text/tab-separated-values, 2376 data points
