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Meyers, Philip A; Bernasconi, Stefano M; Forster, Astrid (2006): Geochemistry of Albian to Santonian black shale sequences on the Demerara Rise, South American margin [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.757127, Supplement to: Meyers, PA et al. (2006): Origins and accumulation of organic matter in expanded Albian to Santonian black shale sequences on the Demerara Rise, South American margin. Organic Geochemistry, 37(12), 1816-1830, https://doi.org/10.1016/j.orggeochem.2006.08.009

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Abstract:
Ocean Drilling Program Leg 207 recovered thick sequences of Albian to Santonian organic-carbon-rich claystones at five drill-sites on the Demerara Rise in the western equatorial Atlantic Ocean. Dark-colored, finely laminated, Cenomanian-Santonian black shale sequences contain between 2% and 15% organic carbon and encompass Oceanic Anoxic Events 2 and 3. High Rock-Eval hydrogen indices signify that the bulk of the organic matter in these sequences is marine in origin. However, d13Corg values lie mostly between -30 per mil and -27 per mil, and TOC/TN ratios range from 15 to 42, which both mimic the source signatures of modern C3 land plants. The contradictions in organic matter source indicators provide important implications about the depositional conditions leading to the black shale accumulations. The low d13Corg values, which are actually common in mid-Cretaceous marine organic matter, are consequences of the greenhouse climate prevailing at that time and an associated accelerated hydrologic cycle. The elevated C/N ratios, which are also typical of black shales, indicate depressed organic matter degradation associated with low-oxygen conditions in the water column that favored preservation of carbon-rich forms of marine organic matter over nitrogen-rich components. Underlying the laminated Cenomanian-Santonian sequences are homogeneous, dark-colored, lower to middle Albian siltstones that contain between 0.2% and 9% organic carbon. The organic matter in these rocks is mostly marine in origin, but it occasionally includes large proportions of land-derived material.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 9.300330 * Median Longitude: -54.427157 * South-bound Latitude: 9.048617 * West-bound Longitude: -54.733050 * North-bound Latitude: 9.453633 * East-bound Longitude: -54.199517
Date/Time Start: 2003-01-15T00:00:00 * Date/Time End: 2003-02-23T00:00:00
Event(s):
207-1257 * Latitude: 9.453633 * Longitude: -54.341783 * Date/Time Start: 2003-01-15T00:00:00 * Date/Time End: 2003-01-22T00:00:00 * Elevation: -2951.0 m * Penetration: 747.9 m * Recovery: 428.9 m * Location: South Atlantic Ocean * Campaign: Leg207 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 74 cores; 625.9 m cored; 122 m drilled; 68.5 % recovery
207-1258 * Latitude: 9.433333 * Longitude: -54.733050 * Date/Time Start: 2003-01-22T00:00:00 * Date/Time End: 2003-02-01T00:00:00 * Elevation: -3192.2 m * Penetration: 1393.4 m * Recovery: 882.7 m * Location: South Atlantic Ocean * Campaign: Leg207 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 141 cores; 1116.6 m cored; 276.8 m drilled; 79 % recovery
207-1259 * Latitude: 9.300400 * Longitude: -54.199517 * Date/Time Start: 2003-02-01T00:00:00 * Date/Time End: 2003-02-16T00:00:00 * Elevation: -2354.5 m * Penetration: 1668.7 m * Recovery: 644.9 m * Location: South Atlantic Ocean * Campaign: Leg207 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 104 cores; 929.6 m cored; 739.1 m drilled; 69.4 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
5 datasets

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Datasets listed in this publication series

  1. Meyers, PA; Bernasconi, SM; Forster, A (2006): (Appendix A) Carbon chemistry for Albian-Santonian black shale sequences at ODP Site 207-1257. https://doi.org/10.1594/PANGAEA.757124
  2. Meyers, PA; Bernasconi, SM; Forster, A (2006): (Appendix A) Carbon chemistry for Albian-Santonian black shale sequences at ODP Site 207-1258. https://doi.org/10.1594/PANGAEA.757126
  3. Meyers, PA; Bernasconi, SM; Forster, A (2006): (Appendix A) Carbon chemistry for Albian-Santonian black shale sequences at ODP Site 207-1259. https://doi.org/10.1594/PANGAEA.757120
  4. Meyers, PA; Bernasconi, SM; Forster, A (2006): (Appendix A) Carbon chemistry for Albian-Santonian black shale sequences at ODP Site 207-1260. https://doi.org/10.1594/PANGAEA.757121
  5. Meyers, PA; Bernasconi, SM; Forster, A (2006): (Appendix A) Carbon chemistry for Albian-Santonian black shale sequences at ODP Site 207-1261. https://doi.org/10.1594/PANGAEA.757122