Planktonic foraminiferal assemblages of DSDP Hole 75-532

Qualitative and quantitative analyses of planktonic foraminiferal assemblages from Deep Sea Drilling Project site 532 shed light on hydrographic changes over the Walvis Ridge during the past 500,000 years. From changes in distribution of foraminiferal assemblages, two major hydrographic regimes (coastal and geostrophic branches of the Benguela Current and the Angola Current) can be distinguished at site 532. It is suggested that the hydrographic situation on the northeastern Walvis Ridge was characterized by intensified upwelling and a westward expansion of the coastal upwelling cells during several global cooling pulses. During glacial stages 2-4, the middle part of stage 6, sporadically from the lower stage 8 through upper stage 10, and during stage 12, site 532 was located beneath the coastal branch of the Benguela Current because faunal distribution patterns indicate intensified upwelling. The Angola Current probably intruded the area of study during the lower stages 5, sporadically 6-8, and 11, as documented by the increased abundance of Neogloboquadrina dutertrei.

(Table 2) Geochemistry of ore minerals and magnetization properties at the DSDP Leg 73 Holes

The samples investigated in this study come from DSDP Leg 73 Drill Holes 519A, 522B, and 524, all of which are in the South Atlantic. A general petrographic description of the basalts is given by Carman et al. (1984; doi:10.2973/dsdp.proc.73.120.1984).

Geochemistry and stratigraphy on sediment cores from Leg198 and Leg 208

The first complete cyclic sedimentary successions for the early Paleogene from drilling multiple holes have been retrieved during two ODP expeditions: Leg 198 (Shatsky Rise, NW Pacific Ocean) and Leg 208 (Walvis Ridge, SE Atlantic Ocean). These new records allow us to construct a comprehensive astronomically calibrated stratigraphic framework with an unprecedented accuracy for both the Atlantic and the Pacific Oceans covering the entire Paleocene epoch based on the identification of the stable long-eccentricity cycle (405-kyr). High resolution X-ray fluorescence (XRF) core scanner and non-destructive core logging data from Sites 1209 through1211 (Leg 198) and Sites 1262, 1267 (Leg 208) are the basis for such a robust chronostratigraphy. Former investigated marine (ODP Sites 1001 and 1051) and land-based (e.g., Zumaia) sections have been integrated as well. The high-fidelity chronology is the prerequisite for deciphering mechanisms in relation to prominent transient climatic events as well as completely new insights into Greenhouse climate variability in the early Paleogene. We demonstrate that the Paleocene epoch covers 24 long eccentricity cycles. We also show that no definite absolute age datums for the K/Pg boundary or the Paleocene - Eocene Thermal Maximum (PETM) can be provided by now, because of still existing uncertainties in orbital solutions and radiometric dating. However, we provide two options for tuning of the Paleocene which are only offset by 405-kyr. Our orbitally calibrated integrated Leg 208 magnetostratigraphy is used to revise the Geomagnetic Polarity Time Scale (GPTS) for Chron C29 to C25. We established a high-resolution calcareous nannofossil biostratigraphy for the South Atlantic which allows a much more detailed relative scaling of stages with biozones. The re-evaluation of the South Atlantic spreading rate model features higher frequent oscillations in spreading rates for magnetochron C28r, C27n, and C26n.