Stable isotopic and carbonate cyclicity in deep sea sediments from different DSDP Holes

DOI

Oxygen and carbon isotopic variability of the dominant (<38 µm) carbonate fraction within bedded, organic-carbon rich Lower Cretaceous sediment intervals from various DSDP sites are closely correlated with preservational changes in the carbonates. Isotopic fluctuations are absent where carbonate contents vary little and where the carbonate fraction is dominated by biogenic phytoplankton remains. Within each of the studied intervals oxygen and carbon isotopic ratios become increasingly more negative in samples with carbonate contents higher than about 60% in which the proportion of diagenetic microcarbonate increases rapidly. Carbon isotopic ratios show a trend towards positive values in samples with carbonate contents of less than 40% and strong signs of dissolution. The taxonomic composition of nannofossil assemblages varies little within single intervals, despite significant differential diagenesis among individual beds; this points towards ecological stability of oceanic surface waters during the deposition of alternating beds. Bedding is, however, closely related to changing bioturbation intensity, indicating repeated fluctuations of the deep-water renewal rates and oxygen supply. Various microbial decomposition processes of organic matter leading to bed-specific differential carbonate diagenesis resulted in an amplification of primary bedding features and are considered responsible for most of the observed fluctuations in the stable isotopic ratios and carbonate contents.

Supplement to: Thierstein, Hans R; Roth, Peter H (1991): Stable isotopic and carbonate cyclicity in Lower Cretaceous deep-sea sediments: Dominance of diagenetic effects. Marine Geology, 97(1-2), 1-34

Identifier
DOI https://doi.org/10.1594/PANGAEA.760692
Related Identifier https://doi.org/10.1016/0025-3227(91)90017-X
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.760692
Provenance
Creator Thierstein, Hans R; Roth, Peter H
Publisher PANGAEA
Publication Year 1991
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 2 datasets
Discipline Earth System Research
Spatial Coverage (-69.173W, -50.871S, 179.256E, 47.382N); North Atlantic/HILL; South Atlantic/PLATEAU; South Atlantic/SYNCLINE; North Atlantic/BASIN; North Atlantic/CONT RISE; North Atlantic/SEAMOUNT; North Pacific/SEAMOUNT; North Pacific/CONT RISE
Temporal Coverage Begin 1970-05-13T00:00:00Z
Temporal Coverage End 1978-08-28T00:00:00Z