Calculation of paleoproductivity during the Eocene-Oligocene transition of ODP Site 113-689

High-resolution records of carbon and oxygen isotopes and benthic foraminiferal accumulation rates for the Eocene-Oligocene section at Ocean Drilling Program Site 689 (Maud Rise, Weddell Sea; paleodepth about 1500 m) were used to infer variations in paleoproductivity in relation to changes in climate and ventilation of the deeper-water column. The benthic foraminiferal abundance and isotope records show short-term fluctuations at periodicities of 100 and 400 ka, implying orbitally driven climatic variations. Both records suggest that intermediate-depth water chemistry and primary productivity changed in response to climate. During the Eocene, productivity increased during cold periods and during cold-to-warm transitions, possibly as a result of increased upwelling of nutrient-rich waters. In the Oligocene, in contrast, productivity maxima occurred during intervals of low delta18O values (presumably warmer periods), when a proto-polar front moved to the south of the location of Site 689. This profound transition in climate-productivity patterns occurred around 37 Ma, coeval with rapid changes toward increasing variability of the oxygen and carbon isotope and benthic abundance records and toward larger-amplitude delta18O fluctuations. Therefore, we infer that, at this time, temperature fluctuations increased and a proto-polar front formed in conjunction with the first distinct pulsations in size of the Antarctic ice sheet. We speculate that this major change might have resulted from an initial opening of the Drake Passage at 37 Ma, at least for surface- and intermediate-water circulation.

Sea surface temperature calculation based on alkenones in sediments off northwest Africa

The molecular stratigraphy of Biogeochemical Oceanic Flux Study core 31K (19°N, 20°10'W) and Ocean Drilling Program Hole 658C (20°45'N, 18°35'W) has been studied for C37 alkenone abundances over the past 80 ka at high resolution (~circa 200-500 years). The derived Uk 37' sea surface temperature record for both cores shows a range of temperatures from about 18°C during the last glacial to 21.5°C during the early Holocene. Both records also reveal changes in sea surface temperature as much as 2°-4°C over a few hundred years, which correlate well with similar abrupt climatic changes observed in cores from elsewhere in the NE Atlantic, associated with 'Heinrich events'. Our results indicate that meltwater produced by these ice-rafting events was transmitted southward by the Canary Current, where it had considerable impact on sea surface temperatures in the subtropical eastern Atlantic.

Verification of the time-response method for heat load calculation.

"Office of the Assistant Secretary for Policy Development and Research, Dept. of Housing and Urban Development."

Gas producers and blast furnaces : theory and methods of calculation.

Mode of access: Internet.

The natural principles and analogy of the harmony of form.

Mode of access: Internet.

Calculation of water oscillation in coastal harbors : HARBS and HARBD user's manual /

"April 1987."

Back-calculation of layer parameters for LTPP test sections.

"October 2002."

Labor turnover : calculation and cost.

Includes bibliographical references.

Calculation of GFSR pseudorandom number binary starting matrix,

Mode of access: Internet.

Path integral calculation of the two-particle slater sum for He4 /

"August 20, 1965"

Path integral calculation of the three-particle direct and exchange contributions to the pair distribution function and of the third virial coefficient for He4 gas /

Thesis--Illinois.

Theory and calculation of the nonlinear energy transfer between sea waves in deep water /

"May 1982."

Development of a method for numerical calculation of wave refraction /

"October 1964."

Calculation of wave attenuation due to friction and shoaling : an evaluation /

"October 1980."

A guide to the calculation of criticality limits for enriched uranium /

"Contract No. AT 06-63380."