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
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 reconstruct
bathym...
Zinc concentrations in benthic foraminifera reflect seawater chemistry
Paleoceanography - Tập 15 Số 3 - Trang 299-306 - 2000
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
postdepositional arti...
High‐amplitude variations in North Atlantic sea surface temperature during the early Pliocene warm period
Paleoceanography - Tập 24 Số 2 - 2009
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 index and c...
The 41 kyr world: Milankovitch's other unsolved mystery
Paleoceanography - Tập 18 Số 1 - 2003
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 the geolog...
Role of tropics in changing the response to Milankovich forcing some three million years ago
Paleoceanography - Tập 18 Số 2 - 2003
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
signifi...
The timing of major climate terminations
Paleoceanography - Tập 12 Số 4 - Trang 577-585 - 1997
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 deglaciations (terminations) and increases in northern
he...
Ground‐truthing the boron isotope‐paleo‐pH proxy in planktonic foraminifera shells: Partial dissolution and shell size effects
Paleoceanography - Tập 19 Số 4 - 2004
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 δ11B and Mg/Ca with shell size. Shells in the
sieve size class 51...
A core top assessment of proxies for the ocean carbonate system in surface‐dwelling foraminifers
Paleoceanography - Tập 22 Số 3 - 2007
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
Globigerinoides ruber). Measurements of δ11B in G. ruber show no significant
relation...
Possible roles of pH, temperature, and partial dissolution in determining boron concentration and isotopic composition in planktonic foraminifera
Paleoceanography - Tập 18 Số 4 - 2003
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 first made in conjunction with calcification temperature
(m...
B/Ca in planktonic foraminifera as a proxy for surface seawater pH
Paleoceanography - Tập 22 Số 2 - 2007
Boron isotope systematics indicate that boron incorporation into foraminiferal
CaCO3 is determined by the partition coefficient, KD (= ), and
[B(OH)4−/HCO3−]seawater, providing, in principle, a method to estimate seawater
pH and PCO2. We have measured B/Ca ratios in Globigerina bulloides and
Globorotaliainflata for a series of core tops from the North Atlantic and the
Southern Ocean and in Globige...
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