| PALEOCEANOGRAPHY |
Late Paleocene Osmium Isotope Data
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Ravizza, G., R.N. Norris, J. Blusztajn, and M-P. Aubry. 2001. An osmium isotope excursion associated with the late Paleocene
thermal maximum: Evidence of intensified chemical weathering. Paleoceanography 16(2):155-163.
| Data Coverage |
North: 49.08 * South: -10.22 |
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West: -13.1 * East: 93.9 |
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Altitude: -5601 m |
Data: Please Cite Data Contributors!
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Summary: In the latest Paleocene an abrupt shift to more negative delta13C values has been documented at numerous marine and terrestrial
sites [Bralower et al., 1997; Cramer et al., 1999; Kaiho et al., 1996; Kennett and Stott, 1991; Koch et al., 1992; Stott et
al., 1996; Thomas and Shackleton, 1996; Zachos et al., 1993]. This carbon isotope event (CIE) is coincident with oxygen isotope
data that indicate warming of surface waters at high latitudes of nearly 4°--6 °C [Kennett and Stott, 1991] and more moderate
warming in the subtropics [Thomas et al., 1999]. Here we report 187Os/188Os isotope records from the North Atlantic and Indian
Oceans which demonstrate a >10% increase in the 187Os/188Os ratio of seawater coincident with the late Paleocene CIE. This
excursion to higher 187Os/188Os ratios is consistent with a global increase in weathering rates. The inference of increased
chemical weathering during this interval of unusual warmth is significant because it provides empirical evidence supporting
the operation of a feedback between chemical weathering rates and warm global climate, which acts to stabilize Earth's climate
[Walker et al., 1981]. Estimates of the duration of late Paleocene CIE [Bains et al., 1999; Bralower et al., 1997; Norris
and Röhl, 1999; Röhl et al., 2000] in conjunction with the Os isotope data imply that intensified chemical weathering in response
to warm, humid climates can occur on timescales of 104--105 years. This interpretation requires that the late Palcocene thermal
maximum Os isotope excursion be produced mainly by increased Os flux to the ocean rather than a transient excursion to higher
187Os/188Os ratios in river runoff. Although we argue that the former is more likelythan the latter, we cannot rule out significant
changes in the 187Os/188Os ratio of rivers.
More Info on Paleoceanography Data |
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Parameters: Os-187-Os-188 ratio of bulk sediment; delta O18 PDB (bulk carbonate); Osmium concentration (ppt) of bulk sediment measured by ICP-MS; Rhenium concentration (ppt) of bulk sediment measured by ICP-MS.; delta C13 PDB (bulk carbonate); Re-187/Os-188 ratio of bulk sediment
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Complete XML Record: noaa-ocean-2587
(Last Revised: 2007-12-21 )
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DOC/NOAA/NESDIS/NCDC (National Climatic Data Center, NESDIS, NOAA, U.S. Department of Commerce )
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| http://www.ncdc.noaa.gov/paleo/ |
| E-mail: bruce.a.bauer@noaa.gov |
| E-mail: paleo@noaa.gov |
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