(Appendix) Relative abundance of planktonic foraminifera in ODP Site 138-846 late Quaternary sediments

• Main Authors: Le, Jianning, Mix, Alan C, Shackleton, Nicholas J
• Format: Dataset
• Language: English
• Published: PANGAEA 1995
• Subjects: 138-846; COMPCORE; Composite Core; Counting >150 µm fraction; Depth; composite revised; sediment/rock; DSDP/ODP/IODP sample designation; Globigerina bulloides; Globigerina rubescens; Globigerinella aequilateralis; Globigerinella calida; Globigerinoides ruber; Globigerinoides sacculifer; Globigerinoides tenellus; Intercore correlation; Joides Resolution; Leg138; Neogloboquadrina dutertrei; Neogloboquadrina pachyderma dextral; Ocean Drilling Program; ODP; Orbulina universa; Sample code/label; South Pacific Ocean; Neogloboquadrina pachyderma; Planktonic foraminifera
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.808207; https://doi.org/10.1594/PANGAEA.808207

High-resolution records of d18O and relative abundances of planktonic foraminifers were generated for ODP Leg 138 Site 846 for the past 800 k.y., with an average sampling interval of 3.6 k.y. The time scale was constructed by correlating the benthic d18O record to the SPECMAP and ODP Site 677 d18O time scales using the mapping function technique of Martinson et al. (1981). Our observations show that variations in the foraminiferal assemblages, although influenced by dissolution, are interpretable in terms of changing characteristics of upper ocean waters. Carbonate dissolution as indicated by fragmentation of planktonic foraminifers shows concentrated variance that is coherent with d18O at the 100 and 41 k.y. orbital periods. At these periods, maximum dissolution occurs during interglacial extremes. This finding differs from previous studies that have indicated that in this region percent carbonate minimum lags global ice volume minimum. N. dutertrei and dextral N. pachyderma dominate the assemblages, but do not show consistent relationships relative to glacial-interglacial cycles. However, less abundant species G. ruber, G. menardii, G. glutinata and G. sacculifer show positive and G. bulloides negative correlation with the d18O record. Q-mode factor analysis of the Site 846 assemblages and comparison with modern assemblages suggest the following. Prior to and during interglacials, the area was considerably warmer and more subtropical than at present; during glacials, the area was colder than at present with greater upwelling and advection off the eastern boundary, and possibly a stronger Peru Current; the equatorial ôcool tongueö was also possibly stronger.