Publication Date:
2024-01-09
Description:
Sedimentological and organic geochemical investigations of sediments of Site 798 give important information about the paleoenvironmental and paleoceanographic conditions of the Japan Sea. Distinct dark/light cycles from the uppermost 37 m of the record (i.e. the last 200,000 years) were sampled in detail and analyzed for TOC content, C/N-ratios and hydrogen index values to characterize the organic material. A subdivision into three types of cycles was possible, representing different environmental conditions during formation of the dark/light rhythms. Additionally, the data were correlated with the global oxygen isotope curve and biogenic opal data to define the stratigraphic framework and stage boundaries. The results indicate that glacial intervals are generally dominated by a very distinctive cyclicity whereas interglacial sediments are more homogenous and cycles less pronounced. Glacial sea-level lowstands probably lead to a stratification of the water column and anoxic sedimentary conditions (and, thus, distinct dark/light cyclicity with an enrichment of marine organic carbon in the dark part) while the well-mixed Japan Sea of the interglacial periods barely reached oxygen-deficient levels although high productivity caused the enhanced oxygen demand due to the decay of marine organic material. Dilution by siliciclastic material and supply of terrigenous organic matter may occasionally control the organic carbon fluctuations.
Keywords:
128-798B; AWI_Paleo; Calcium carbonate; Calculated; Carbon, organic, total; Carbon/Nitrogen ratio; Carbon/sulfur ratio; Depth, composite; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Element analyser CHN, LECO; Hydrogen index, mass HC, per unit mass total organic carbon; Japan Sea; Joides Resolution; Leg128; Mass spectrometer Finnigan MAT 251; Ocean Drilling Program; ODP; Oxygen index, mass CO2, per unit mass total organic carbon; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Pyrolysis temperature maximum; Rock eval pyrolysis (Behar et al., 2001); Sample code/label; Sulfur, total; δ13C, organic carbon
Type:
Dataset
Format:
text/tab-separated-values, 1557 data points
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