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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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| Beaufort, L.; Van Der Kaars, S.; Bassinot, F. C.; Moron, V.. |
| Past variations in the dynamics of the Australian monsoon have been estimated from multi-proxy analysis of a core retrieved in the Eastern Banda Sea. Records of coccolith and pollen assemblages, spanning the last 150 000 years, allow reconstruction of past primary production in the Banda Sea, summer moisture availability, and the length of the dry season in northern Australia and southeastern Indonesia. The amount of moisture available during the summer monsoon follows typical glacial/interglacial dynamics with a broad asymmetrical 100-kyr cycle. Primary production and length of the dry season appear to be closely related, given that they follow the precessional cycle with the same phase. This indicates their independence from ice-volume variations. The... |
| Tipo: Text |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34259/32630.pdf |
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| Ohkushi, K.; Kennett, J. P.; Zeleski, C. M.; Moffitt, S. E.; Hill, T. M.; Robert, Cyril; Beaufort, L.; Behl, R. J.. |
| The oxygen minimum zone (OMZ) of the late Quaternary California margin experienced abrupt and dramatic changes in strength and depth in response to changes in intermediate water ventilation, ocean productivity, and climate at orbital through millennial time scales. Expansion and contraction of the OMZ is exhibited at high temporal resolution (107-126 year) by quantitative benthic foraminiferal assemblage changes in two piston cores forming a vertical profile in Santa Barbara Basin (569 m, basin floor; 481 m, near sill depth) to 34 and 24 ka, respectively. Variation in the OMZ is quantified by new benthic foraminiferal groupings and new dissolved oxygen index based on documented relations between species and water-mass oxygen concentrations.... |
| Tipo: Text |
Palavras-chave: Oxygen minimum zone; Foraminifera; Ventilation; Oxygen index; Pacific; Hypoxia. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37489/35811.pdf |
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