Late Paleocene to Eocene stable isotope record od ODP Site 143-865

An expanded and largely complete upper Paleocene to upper Eocene section was recovered from the pelagic cap overlying Allison Guyot, Mid-Pacific Mountains at Ocean Drilling Program (ODP) Site 865 (18°26'N, 179°33'W; paleodepth 1300-1500 m). Reconstructions show that the site was within a few degrees of the equator during the Paleogene. Because no other Paleogene sections have been recovered in the Pacific Ocean at such a low latitude, Site 865 provides a unique record of equatorial Pacific paleoceanography. Detailed stable isotopic investigations were conducted on three planktonic foraminiferal taxa (species of Acarinina, Morozovella, and Subbotina). We studied benthic foraminiferal isotopes at much lower resolution on species of Cibicidoides and Lenticulina, Nuttallides truempyi and Gavelinella beccariiformis, because of their exceptional rarity. The d18O and d13C stratigraphies from Site 865 are generally similar to those derived from other Paleocene and Eocene sections. The planktonic foraminiferal records at Site 865, however, include significantly less short-term, single-sample variability than those from higher-latitude sites, indicating that this tropical, oligotrophic location had a comparatively stable water column structure with a deep mixed layer and less seasonal variability. Low-amplitude (0.1-0.8 per mil) oscillations on timescales of 250,000 to 300,000 years correlate between the d13C records of all planktonic taxa and may represent fluctuations in the mixing intensity of surface waters. Peak sea surface temperatures of 24°-25°C occurred in the earliest Eocene, followed by a rapid cooling of 3-6°C in the late early Eocene. Temperatures remained cool and stable through the middle Eocene. In the late Eocene, surface water temperatures decreased further. Vertical temperature gradients decreased dramatically in the late Paleocene and were relatively constant through much of the Eocene but increased markedly in the late Eocene. Intermediate waters warmed through the late Paleocene, reaching a maximum temperature of 10°C in the early Eocene. Cooling in the middle and late Eocene paralleled that of surface waters, with latest Eocene temperatures below 5°C. Extinction patterns of benthic foraminifera in the latest Paleocene were similar to those observed at other Pacific sites and were coeval with a short-term, very rapid negative excursion in d13C values in planktonic and benthic taxa as at other sites. During this excursion, benthic foraminiferal d18O values decreased markedly, indicating warming of 4 to 6°C for tropical intermediate waters, while planktonic taxa show slight warming (1°C) followed by 2°C of cooling. Convergence of d18O values of planktonic and benthic foraminifera suggests that thermal gradients in the water column in this tropical location collapsed during the excursion. These data are consistent with the hypothesis that equatorial Pacific surface waters were a potential source of warm, higher salinity waters which filled portions of the deep ocean in the latest Paleocene. Oxygen isotopic data indicate that equator to high southern latitude sea surface thermal gradients decreased to as little as 4°C at the peak of the excursion, suggesting some fundamental change in global heat transport.

Benthic foraminifera and phytodetritus species in sediments from DSDP Leg 85, and ODP Legs 113 and 143

From late middle Eocene through earliest Oligocene, high-latitude regions cooled, and by the end of the period, continental ice sheets existed in Antarctica. Diversity of planktonic microorganisms declined, and modern groups of terrestrial vertebrates originated. Coeval faunal changes in deep-sea benthic foraminifers have been related to cooling of deep waters and increased oxygenation. Cooling, however, occurred globally, whereas species richness declined at high latitudes and not in the tropics. The late Eocene and younger lower-diversity, high-latitude faunas typically contain common Epistominella exigua and Alabaminella weddellensis, opportunistic phytodetritus-exploiting species that indicate a seasonally fluctuating input of organic matter to the sea floor. We speculate that the species-richness gradient and increase in abundance of phytodetritus-exploiting species resulted largely from the onset of a more unpredictable and seasonally fluctuating food supply, especially at high latitudes.

Event no. 143

IMB (Irvine, Michigan, Brookline), a collaboration between the University of Michigan, the University of California at Irvine, and the U.S. Department of Energy, was an experiment designed to determine the ultimate stability of matter. One of nine interesting events from the IMB detector in its first 204 live days of running. Similar to proton decay but rejected.

Evaluation of LS-DYNA wood material model 143 /

"HRDI-04/08-05(1M)E"--P. [4] of cover.

Operator's and organizational maintenance manual : radio set AN/GRC-143, (NSN 5820-00-926-7355).

Includes index.

Organizational maintenance repair parts and special tools list for radio set AN/GRC-143 (NSN 5820-00-926-7355).

"June 1978."

Operator's manual, mask, chemical-biological : field, ABC-M17 (4240-00-542-4450-small) (4240-00-542-4451-medium) (4240-00-542-4452-large), M17A1 (4240-01-106-0485-X-small) (4240-00-926-4199-small) (4240-00-926-4201-medium) (4240-00-926-4200-large), and M17A2 (4240-01-143-2017-X-small) (4240-01-143-2018-small) (4240-01-143-2019-medium) (4240-01-143-2020-large).

"2 March 1983."

Operator's manual : generator, smoke, mechanical, pulse jet, M3A4 (1040-01-143-9506).

"September 1985."

Organizational and direct support maintenance repair parts and special tools lists for generator, smoke, mechanical, pulse jet, M3A4 (1040-01-143-9506).

"June 1989."

Organizational and direct support maintenance manual [microform] : generator, smoke, mechanical, pulse jet, M3A4 (1040-01-143-9506).

"October 1985."

Unit, direct support, and general support maintenance repair parts and special tools lists ... : distributor, water, self-propelled, 2500 gallon capacity, sectionalized and non-sectionalized models 613BWDS and 613BWDNS, NSN 3825-01-143-1213, NSN 3825-01-143-1212.

"March 1992."

Operator, organizational, direct and general support, and depot maintenance manual : compressor, reciprocating; air, 15 CFM, 175 psi; electric motor driven, (Ingersoll-Rand model 242D7-1/2) FSN 4310-143-9280.

"December 1969."