Site U1553

Abstract

Contents 1 Background and objectives 5 Operations 10 Lithostratigraphy 27 Biostratigraphy and micropaleontology 50 Paleomagnetism 61 Geochemistry 70 Physical properties 75 Stratigraphic correlation 80 Age-depth model and mass accumulation rates 84 References

Apparent Diachroneity of Calcareous Nannofossil Datums During the Early Eocene in the High‐Latitude South Pacific Ocean

“…In order to construct a high‐resolution age model using the full potential of the sediment records from both Holes C and D, we combined data from outside the splice with the in‐splice data by applying the revised splice adjustment (Drury et al., 2022; Wilkens et al., 2022). To improve the reliability of the existing shipboard U1553 age model (Röhl et al., 2022b), we combined our new bulk sediment stable isotope data (δ 13 C) with the updated calcareous nannofossil datums. We then correlated our chemostratigraphic record to published astronomically tuned sections from ODP Site 1262 on the Walvis Ridge (Zachos et al., 2010) and Site 1258 on the Demerara Rise (Kirtland Turner et al., 2014).…”

“…The late Paleocene to early Eocene sediments at Site U1553 were recovered from rotary‐drilled Holes C and D between 409.21 and 461.7 m below sea‐floor (mbsf), consisting of the lithological Subunit IIIb and lithological Unit IV (Röhl et al., 2022b). Lithological Subunit IIIb represents the top ∼10 m of the study interval and consists of white, homogenous nannofossil chalk with foraminifera.…”

“…Lithological Subunit IIIb represents the top ∼10 m of the study interval and consists of white, homogenous nannofossil chalk with foraminifera. The rest of the study interval is represented by lithological Unit IV, which is predominantly composed of limestones and is distinguished from Subunit IIIb by the increased lithification and variable degree of bioturbation (Röhl et al., 2022b). These sediments were deposited at high paleolatitudes (∼59–61°S; Figure 1) in lower to middle bathyal water depths based on the benthic foraminiferal assemblages (∼1,000 m; Hollis, 1997).…”

“…These sediments were deposited at high paleolatitudes (∼59–61°S; Figure 1) in lower to middle bathyal water depths based on the benthic foraminiferal assemblages (∼1,000 m; Hollis, 1997). The PETM interval at Site U1553 was first identified offshore within lithological Unit IV based on the nannoplankton assemblages (Röhl et al., 2022b). At the onset of the PETM, there is an abrupt switch from white, non‐bioturbated limestones to darker green, bioturbated limestones (Röhl et al., 2022b).…”

“…The PETM interval at Site U1553 was first identified offshore within lithological Unit IV based on the nannoplankton assemblages (Röhl et al., 2022b). At the onset of the PETM, there is an abrupt switch from white, non‐bioturbated limestones to darker green, bioturbated limestones (Röhl et al., 2022b). Unlike at many other PETM sites there is no obvious dissolution horizon (e.g., Bralower et al., 2014; Zachos et al., 2005) indicating that sedimentation occurred above the calcite compensation depth (CCD) during the entire study interval.…”