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| Bertrand, P; Pedersen, Tf; Schneider, R; Shimmield, G; Lallier-verges, E; Disnar, Jr; Massias, D; Villanueva, J; Tribovillard, N; Huc, Ay; Giraud, X; Pierre, C; Venec-peyre, Mt. |
| Sediments on the Namibian Margin in the SE Atlantic between water depths of similar to1000 and similar to3600 m are highly enriched in hydrocarbon-prone organic matter. Such sedimentation has occurred for more than 2 million years and is geographically distributed over hundreds of kilometers along the margin, so that the sediments of this region contain a huge concentrated stock of organic carbon. It is shown here that most of the variability in organic content is due to relative dilution by buried carbonates. This reflects both export productivity and diagenetic dissolution, not differences in either water column or bottom water anoxia and related enhanced preservation of organic matter. These observations offer a new mechanism for the formation of... |
| Tipo: Text |
Palavras-chave: Petroleum source rocks; Coastal upwelling; Deep-sea sediments; Quaternary climate; Southwestern African Margin. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/00224/33553/31977.pdf |
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| Hill, T. M.; Kennett, J. P.; Valentine, D. L.; Yang, Z.; Reddy, C. M.; Nelson, R. K.; Behl, R. J.; Robert, C.; Beaufort, L.. |
| Marine hydrocarbon seepage emits oil and gas, including methane (approximate to 30 Tg of CH4 per year), to the ocean and atmosphere. Sediments from the California margin contain preserved tar, primarily formed through hydrocarbon weathering at the sea surface. We present a record of variation in the abundance of tar in sediments for the past 32,000 years, providing evidence for increases in hydrocarbon emissions before and during Termination IA [16,000 years ago (16 ka) to 14 ka] and again over Termination IB (11-10 ka). Our study provides direct evidence for increased hydrocarbon seepage associated with deglacial warming through tar abundance in marine sediments, independent of previous geochemical proxies. Climate-sensitive gas hydrates may modulate... |
| Tipo: Text |
Palavras-chave: Methane; Paleoclimate; Quaternary climate; Hydrate; Tar. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34524/33432.pdf |
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