Paleoceanography

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Marine core evidence for reduced deep water production during Termination II followed by a relatively stable substage 5e (Eemian)
Paleoceanography - Tập 12 Số 1 - Trang 51-63 - 1997
Delia W Oppo, Michael Horowitz, Scott J. Lehman
We present oxygen and carbon isotope records of benthic foraminifera from the glacial stage 6 through interglacial substage 5e (Eemian) sections of several cores from the subpolar North Atlantic. The cores range in water depth from 1451 to 2658 m. In one core, we generated estimates of sea surface temperature (SST) and of ice‐rafted detritus (IRD) delivery for all of stage 5. We reconstruc...... hiện toàn bộ
Zinc concentrations in benthic foraminifera reflect seawater chemistry
Paleoceanography - Tập 15 Số 3 - Trang 299-306 - 2000
Thomas M. Marchitto, William B Curry, Delia W Oppo
We have measured Zn/Ca ratios in two taxa of Holocene‐aged benthic foraminifera from throughout the world's oceans. Zn/Ca is controlled by bottom water dissolved Zn concentration and, like Cd/Ca and Ba/Ca, by bottom water saturation state with respect to calcite. Measurements on “live‐collected” foraminifera suggest that the saturation effect occurs during growth and is not a postdepositio...... hiện toàn bộ
High‐amplitude variations in North Atlantic sea surface temperature during the early Pliocene warm period
Paleoceanography - Tập 24 Số 2 - 2009
K. T. Lawrence, Timothy D. Herbert, Catherine Brown, Maureen E. Raymo, Alan M. Haywood
We provide the first continuous, orbital‐resolution sea surface temperature (SST) record from the high‐latitude North Atlantic, a region critical to understanding the origin of the Plio‐Pleistocene ice ages and proximal to regions that became frequently glaciated after ∼2.7 Ma. We analyzed sediments from Ocean Drilling Program Site 982 over the last 4 Ma for their alkenone unsaturation ind...... hiện toàn bộ
The 41 kyr world: Milankovitch's other unsolved mystery
Paleoceanography - Tập 18 Số 1 - 2003
Maureen E. Raymo, Kerim H. Nisancioglu
For most of the Northern Hemisphere Ice Ages, from ∼3.0 to 0.8 m.y., global ice volume varied predominantly at the 41,000 year period of Earth's orbital obliquity. However, summer (or summer caloric half year) insolation at high latitudes, which is widely believed to be the major influence on high‐latitude climate and ice volume, is dominated by the 23,000 year precessional period. Thus th...... hiện toàn bộ
Role of tropics in changing the response to Milankovich forcing some three million years ago
Paleoceanography - Tập 18 Số 2 - 2003
S. George Philander, Alexey V. Fedorov
Throughout the Cenozoic the Earth experienced global cooling that led to the appearance of continental glaciers in high northern latitudes around 3 Ma ago. At approximately the same time, cold surface waters first appeared in regions that today have intense oceanic upwelling: the eastern equatorial Pacific and the coastal zones of southwestern Africa and California. There was furthermore a...... hiện toàn bộ
The timing of major climate terminations
Paleoceanography - Tập 12 Số 4 - Trang 577-585 - 1997
Maureen E. Raymo
A simple, untuned “constant sedimentation rate” timescale developed using three radiometric age constraints and eleven δ18O records longer than 0.8 Myr provides strong support for the validity of the SPECMAP timescale of the late Quaternary [Imbrie et al., 1984]. In particular, the present study independently confirms the link between major d...... hiện toàn bộ
Ground‐truthing the boron isotope‐paleo‐pH proxy in planktonic foraminifera shells: Partial dissolution and shell size effects
Paleoceanography - Tập 19 Số 4 - 2004
Bärbel Hönisch, N. G. Hemming
Sediment samples from the Ontong‐Java Plateau in the Pacific and the 90° east ridge in the Indian Ocean were used to investigate whether shell size and early diagenesis affect δ11B of the symbiont‐bearing planktonic foraminifer Globigerinoides sacculifer. In pristine shells from both study locations we found a systematic increase of δ... hiện toàn bộ
A core top assessment of proxies for the ocean carbonate system in surface‐dwelling foraminifers
Paleoceanography - Tập 22 Số 3 - 2007
Yunyan Ni, Gavin L. Foster, T. R. Bailey, Tim Elliott, Daniela N. Schmidt, Paul N. Pearson, Brian A. Haley, Christopher D. Coath
We have assessed the reliability of several foraminifer‐hosted proxies of the ocean carbonate system (δ11B, B/Ca, and U/Ca) using Holocene samples from the Atlantic and Pacific oceans. We examined chemical variability over a range of test sizes for two surface‐dwelling foraminifers (Globigerinoides sacculifer and ... hiện toàn bộ
B/Ca in planktonic foraminifera as a proxy for surface seawater pH
Paleoceanography - Tập 22 Số 2 - 2007
Jimin Yu, Henry Elderfield, Bärbel Hönisch
Boron isotope systematics indicate that boron incorporation into foraminiferal CaCO3 is determined by the partition coefficient, KD (= hiện toàn bộ
Possible roles of pH, temperature, and partial dissolution in determining boron concentration and isotopic composition in planktonic foraminifera
Paleoceanography - Tập 18 Số 4 - 2003
Michael W. Wara, M. L. Delaney, Thomas D. Bullen, Ana Christina Ravelo
We present the first continuous records from 0 to 5 Ma (in 0.333 m.y. integrated time steps) of paired boron/calcium (B/Ca) ratios and boron isotopes (δ11B) in the planktonic foraminifera Globogerinoides sacculifer (without sacc) from a site in the western equatorial Pacific Ocean (Ocean Drilling Program Site 806). These measurements, the fir...... hiện toàn bộ
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