Planktonic Foraminiferal Assemblages and Pleistocene Temperatures: ABSTRACT

Abstract

The faunistic compositions of recent planktonic foraminiferal assemblages from the Atlantic Ocean between 0-46°N lat. correlate with average ocean temperatures at 50-m depth. The correlation between temperature and faunistic assemblages provides the basis for an independent method of reconstructing paleotemperatures during the Pleistocene. In this model, Parks' distance coefficient is used to construct a similarity matrix comparing every recent sample station with every other station based on the abundance of species and phenotypes. Relative to the station(s) of highest diversity there is a linear relation between the similarity of all stations and average ocean temperatures at 50-m depth. Pleistocene assemblages contain the same species and phenotypes as found in recent sediments. Comparison of the similarity of Pleistocene assemblages with recent assemblages in the manner suggested allows an estimate of the ocean temperatures at 50-m depth during deposition of the assemblages. The model, tested in an equatorial core suggests faunistic paleotemperatures which are ± 1° from isotopic paleotemperatures of G. sacculifer from the same core. The temperature range between glacial and interglacial periods in the equatorial Atlantic is 5-6°C. In the Caribbean, during the last 100,000 years, the faunistic paleotemperature ranged between 20 and 27.5°C, a somewhat larger variation than that found in the equatorial Atlantic. The results of this study provide an independent estimate of paleotemperatures during the Pleistocene Epoch. Comparison of faunistic and isotopic paleotemperatures for the cores examined are consistent with Emiliani's estimate of paleotemperature variations, whereby 70% of the isotopic variation is directly related to changes in ocean temperature. End_of_Article - Last_Page 625------------