Pudsey, Carol J (1984): Minerals at DSDP Leg 78A Holes [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.808754, Supplement to: Pudsey, CJ (1984): X-ray mineralogy of Miocene and older sediments from Deep Sea Drilling Project Leg 78A. In: Biju-Duval, B; Moore, JC; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 78A, 325-342, https://doi.org/10.2973/dsdp.proc.78a.112.1984
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Abstract:
One hundred and fifty-three samples of Recent to Late Cretaceous sediments from Sites 541, 542, and 543 were analyzed by X-ray diffraction. The main constituents are quartz, feldspar, clinoptilolite, opal-CT, calcite, and clay minerals (kaolinite, illite, smectite, and palygorskite). Minor components (generally less than 10% of the total) include amphibole, dolomite, rhodochrosite, chlorite, and mixed-layer clays. Amorphous clays, volcanic glass, and biogenic silica are also present.
Calcite in the form of microfossils is a major component of the Cretaceous and post-Miocene sediment: during the Paleocene to Miocene the sites were below the calcite compensation depth (CCD). Detrital quartz and feldspar increase upsection, recording the passage of the area from ridge crest, through open ocean, to the vicinity of a volcanic arc. Authigenic clinoptilolite may be derived from silicic glass via a smectite intermediate. Opal-CT is present only in Eocene clays, occurring as lepispheres growing on radiolarians. Palygorskite and dolomite, found in the lowest sediments at Site 543, may be related to hydrothermal activity or alteration of basalt.
The smectite content of the sediments strongly affects their physical properties and their behavior during deformation. Clay mineralogy may therefore be important in the formation of décollement zones.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Median Latitude: 15.583100 * Median Longitude: -58.698433 * South-bound Latitude: 15.517000 * West-bound Longitude: -58.728300 * North-bound Latitude: 15.712300 * East-bound Longitude: -58.653700
Date/Time Start: 1981-02-13T00:00:00 * Date/Time End: 1981-02-28T00:00:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets
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Datasets listed in this publication series
- Pudsey, CJ (1984): (Table 2) Minerals at DSDP Hole 78-541. https://doi.org/10.1594/PANGAEA.808751
- Pudsey, CJ (1984): (Table 3) Minerals at DSDP Hole 78-542. https://doi.org/10.1594/PANGAEA.808752
- Pudsey, CJ (1984): (Table 4) Minerals at DSDP Hole 78-543. https://doi.org/10.1594/PANGAEA.808753