Stable isotope record of Cibicidoides wuellerstorfi from Pleistocene sediments of DSDP Site 86-502 in the Caribbean Sea

Variations in the stable isotopic composition of benthic foraminifera from Deep-Sea Drilling Project (DSDP) site 502B in the Caribbean Sea are used to reconstruct Atlantic intermediate water circulation variability over the last 1.2 m.y. Comparison of this record with other North Atlantic benthic isotope records indicates that Atlantic intermediate water circulation was relatively enhanced during glacial maxima when North Atlantic deep water (NADW) production was reduced. However, a simple, compensatory relationship between intermediate and deepwater circulation is not apparent. Geochemical models have shown that such changes in ocean circulation can affect atmospheric CO2 levels by changing vertical nutrient and alkalinity profiles. The Delta delta13C difference between Caribbean site 502B and deep equatorial Pacific site 677 is highly coherent and in phase with ice volume. Like the delta18O record, there is an increase in amplitude (40%) and a large increase in 100 kyr power after 0.7 Ma. The 1.2? Delta delta13C amplitude scales to 70 ppm V in atmospheric CO2 using Boyle's (1986) box model result. The implied increase in CO2 amplitude after 0.7 Ma may suggest a positive feedback role in effecting the higher-amplitude climatic fluctuations which characterize the last 0.7 m.y.

(Table 1) Sediment temperature and thermal conductivity at DSDP Leg 86 Holes

Using a new temperature recording instrument recently developed at the Woods Hole Oceanographic Institution, downhole temperature measurements were made at five sites during Deep Sea Drilling Project Leg 86. The instrument, which can be installed in the shoe of the hydraulic piston corer, allows measurements of sediment temperature to be made simultaneously with the collection of sediment cores. A numerical procedure was applied to correct the temperature disturbance caused by the corer's friction with the sediment. Detailed temperature profiles constructed from the data were combined with the measurement of thermal conductivity to calculate heat flow. Heat flow values were generally low at all sites of Leg 86, consistent with the age of the lithosphere (>100 m.y.) in the Northwestern Pacific Basin.

University of Michigan Women's Golf Team, 1985/86

Top Row (L-R): Noel Brisson, Donna Greenbury, Lisa DiMatteo, Val Madill, Head Coach Sue LeClair

Bottom Row (L-R): Terri Mage, Missy Bauer, Jan Idomir