Not logged in
PANGAEA.
Data Publisher for Earth & Environmental Science

Stein, Ruediger; ten Haven, H Lo; Littke, Ralf; Rullkötter, Jürgen; Welte, Dietrich Hugo (1989): Organic geochemistry of late Cenozoic sediments from the eastern subtropical Atlantic [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.746635, Supplement to: Stein, R et al. (1989): Accumulation of marine and terrigenous organic carbon at upwelling Site 658 and nonupwelling Sites 657 and 659: implications for the reconstruction of paleoenvironments in the eastern subtropical Atlantic through Late Cenozoic times. In: Ruddiman, W; Sarnthein, M; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 108, 361-385, https://doi.org/10.2973/odp.proc.sr.108.143.1989

Always quote citation above when using data! You can download the citation in several formats below.

RIS CitationBibTeX CitationShow MapGoogle Earth

Abstract:
Detailed organic geochemical investigations have been performed on sediment samples from upwelling Site 658 and nonupwelling Sites 657 and 659. The major objective of this study has been the relationship between organic carbon accumulation and paleoclimatic and paleoceanographic conditions in the upwelling area off northwest Africa during late Cenozoic times. The study is based on results from organic carbon, nitrogen, and hydrogen analyses, Rock-Eval pyrolysis, kerogen microscopy, gas chromatography, and gas chromatography/mass spectrometry.
In general, nonupwelling Sites 657 and 659 are characterized by low organic carbon values of less than 0.5%. At Site 657, four events of high organic carbon deposition (total organic carbon of 1%-3%) occur and represent turbidites and a slump interval.
The upper Pliocene to Pleistocene sediments of upwelling Site 658 display high organic carbon contents of 0.5%-4%, with higher contents concentrated in the upper Pliocene. Accumulation rates of organic carbon vary between 0.1 and 0.5 gC/cm-**2/1000 yr, with maximum values between 3.5 and 3.1 Ma. Short-term cyclic ("Milankovitch-type") variations in organic carbon accumulation suggest climate-controlled mechanisms causing these fluctuations.
The quality of organic matter at Site 658 is a mixture of kerogen type II and HI, with a dominance of the marine type. This is indicated by high hydrogen-index values of 200-400 mgHC/gC, low C/N ratios of 5-15, atomic H/C ratios of 1.0-1.5, and high amounts of marine macerals (alginite and liptodetrinite).
We have estimated paleoproductivity for Sites 658 and 659 based on the amount of marine organic carbon. At open-marine Site 659, mean paleoproductivity varies between 20 and 50 gC/m**2/yr. At Site 658, mean paleoproductivity reaches high values of 160 to 320 gC/m**2/yr, very similar to those recorded in modern upwelling areas. The changes in productivity off northwest Africa are linked to changes in nutrient supply caused by both upwelling and fluvial input.
The change from a dominantly humid climate to one characterized by fluctuations between humid and fully arid climates in northwest Africa occurs between 3.1 and 2.45 Ma.
Project(s):
Coverage:
Median Latitude: 19.878100 * Median Longitude: -19.792443 * South-bound Latitude: 18.077200 * West-bound Longitude: -21.026200 * North-bound Latitude: 21.331500 * East-bound Longitude: -18.580800
Date/Time Start: 1986-02-27T22:15:00 * Date/Time End: 1986-03-12T11:15:00
Event(s):
108-657A * Latitude: 21.331500 * Longitude: -20.948800 * Date/Time Start: 1986-02-27T22:15:00 * Date/Time End: 1986-03-01T22:00:00 * Elevation: -4232.0 m * Penetration: 178.2 m * Recovery: 127.57 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 19 cores; 178.2 m cored; 0 m drilled; 71.6 % recovery
108-658 * Latitude: 20.749200 * Longitude: -18.580800 * Date/Time Start: 1986-03-04T00:00:00 * Date/Time End: 1986-03-08T00:00:00 * Elevation: -2274.0 m * Penetration: 537.1 m * Recovery: 541.5 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 59 cores; 537.1 m cored; 0 m drilled; 100.8% recovery
108-658A * Latitude: 20.749200 * Longitude: -18.580800 * Date/Time Start: 1986-03-04T15:15:00 * Date/Time End: 1986-03-07T01:15:00 * Elevation: -2274.0 m * Penetration: 300.4 m * Recovery: 294.98 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 300.4 m cored; 0 m drilled; 98.2 % recovery
Size:
7 datasets

Download Data

Download ZIP file containing all datasets as tab-delimited text — use the following character encoding: