Abstract
Abstract. Planktonic foraminiferal faunas have been studied from the Pleistocene of ODP Site 1073 (Leg 174A), New Jersey margin, NW Atlantic Ocean and their abundances have been compared in the >63 μm and >150 μm size-fractions from the same samples. Trends in the relative abundance of many species are similar in the two size-fractions, although the general level varies considerably. The mean abundance and ranges of Neogloboquadrina pachyderma (sinistral), N. pachyderma (dextral), Globorotalia inflata and Globigerina bulloides are greater in the >150 μm size-fraction compared with the >63 μm size-fraction. Turborotalita quinqueloba, Globigerinita uvula, G. glutinata, G. clarkei, and juvenile species are more abundant in the >63 μm size-fraction than the >150 μm size-fraction. Peaks (c. 60%) in abundance of G. uvula occur in the >63 μm size-fraction only, although the causes of these patterns are unclear. The data suggest that, in general, consistent palaeoclimatic/palaeoceanographic information is achieved by studying planktonic foraminiferal faunas from either size-fraction. However, because particular smaller species are either under-represented or even absent from the larger (>150 μm) size-fraction, the smaller (>63 μm) size-fraction must be included in studies of planktonic foraminifera. Furthermore, studies that involve planktonic foraminifera in the >63 μm size-fraction could provide different transfer function estimates for sea surface temperatures in areas where workers have only used larger (>125 μm and >150 μm) size-fractions.
Highlights
Planktonic foraminiferal faunas have been used extensively in reconstructing past oceanographic and climatic conditions
The CLIMAP (Climate, Long-Range Investigation, Mapping and Prediction) Project members (McIntyre et al, 1976; CLIMAP, 1981, 1984) recommended the use of the >149 μm size-fraction as a standard in palaeoceanographic and palaeoecological studies. This is because the smaller-sized planktonic foraminifera which are difficult to identify and time consuming to count are eliminated from the sample (Imbrie & Kipp, 1971)
A total of 53 sediment samples was studied for planktonic foraminifera from Ocean Drilling Program (ODP) Site 1073
Summary
Planktonic foraminiferal faunas have been used extensively in reconstructing past oceanographic and climatic conditions. The geographical and vertical distribution of planktonic foraminifera is principally related to their preferences for specific temperatures and food requirements (e.g. Bé & Tolderlund, 1971; Kipp, 1976; Bé, 1977) This relationship has been applied to fossil faunas to understand past distribution and abundance patterns. The CLIMAP (Climate, Long-Range Investigation, Mapping and Prediction) Project members (McIntyre et al, 1976; CLIMAP, 1981, 1984) recommended the use of the >149 μm size-fraction as a standard in palaeoceanographic and palaeoecological studies. This is because the smaller-sized planktonic foraminifera which are difficult to identify and time consuming to count are eliminated from the sample (Imbrie & Kipp, 1971). Whatever size-fraction is used, in order to achieve reliable comparisons between foraminiferal faunas of different workers only the same size-fraction should be considered
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
