Site 522

Abstract

Principal results: Holes 522, 522A, 522B-1. Recovered a complete magnetostratigraphic record for the sedimentary sequence from Quaternary to upper Eocene, or Chron C-16-R, Nannofossil Zone 20, and Foraminifer Zone CP 15b with the exception of the middle and late middle Miocene. The correlation between the magnetostratigraphy and seafloor anomalies is good for the Oligocene and upper Eocene section. The dissolution of the Paleogene fossils is moderate or slight. One of us (K.H.) believes the site should be recommended as a reference locality for the Oligocene magnetostratigraphy.2. Established the highest and lowest occurrences of numerous key foraminifer and nannofossil species useful in the zonation of the Oligocene and upper Eocene sediments.3. Obtained a magnetostratigraphic age of 37.1 m.y. for the nannofossil-dated Eocene/Oligocene boundary (on the basis of assuming a linear rate of seafloor spreading during the 66.5 m.y. of the Cenozoic).4. Established a precisely dated record of increasing dissolution during the Oligocene and of intense dissolution during the Miocene. SITE 5225. Confirmed the occurrence of Braarudosphaera chalk along the 30 °S parallel during the middle Oligocene (Chrons C-10-R and C-12-R), when Oceanographic conditions may have been unusual. 6. Confirmed the near synchroneity of the sediment and basement magnetization to support the previous practice of dating basalt basement on the basis of the paleontology of the oldest sediment.7. Sampled a 19-m sequence of fresh basalt for petrochemical studies.8. Measured the magnetization of sediment and basalt. Basalt magnetization indicates little latitudinal displacement of the site since the beginning of the Eocene; however, sediment magnetization indicates significant latitudinal displacement.9. Obtained two moderately good downhole temperature measurements and a low heat flow value (1.17 heat flow units) that suggests that ocean water is being drawn down into the topmost porous basalt basement. BACKGROUND AND OBJECTIVES

High‐Resolution Coccolithophore Morphological Changes in Response to Orbital Forcings During the Early Oligocene

“…The paleo‐depth of this site is approximately 3,000 m (Tauxe et al., 1983), which is above the temporal paleo‐CCD in the South Atlantic at approximately 4,200 m (Dutkiewicz & Müller, 2021). The sediments consist mainly of calcareous nannofossil ooze with a small amount of clay and foraminifera shells (Hsü et al., 1984). Many studies in this region have reported little to no effect of dissolution on carbonate content (Hartl et al., 1995; Liebrand et al., 2018).…”

“…DSDP Site 522 (26°6.843ʹS, 05°7.748ʹE) is located in the eastern part of the South Atlantic Gyre, in the middle of the Angola Basin, with a modern water depth of 4,441 m (Figure 1) (Hsü et al., 1984). The paleo‐depth of this site is approximately 3,000 m (Tauxe et al., 1983), which is above the temporal paleo‐CCD in the South Atlantic at approximately 4,200 m (Dutkiewicz & Müller, 2021).…”