Climate, cryosphere and carbon cycle controls on Southeast Atlantic orbital-scale carbonate deposition since the Oligocene (30–0 Ma)

• Published in: Climate of the Past
• Main Authors: A. J. Drury, D. Liebrand, T. Westerhold, H. M. Beddow, D. A. Hodell, N. Rohlfs, R. H. Wilkens, M. Lyle, D. B. Bell, D. Kroon, H. Pälike, L. J. Lourens
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Antarctic; Antarc*
• Online Access: https://doi.org/10.5194/cp-17-2091-2021; https://doaj.org/article/e1e55902c16e413198a4f8a45414a7cf

The evolution of the Cenozoic cryosphere from unipolar to bipolar over the past 30 million years (Myr) is broadly known. Highly resolved records of carbonate (CaCO 3 ) content provide insight into the evolution of regional and global climate, cryosphere, and carbon cycle dynamics. Here, we generate the first Southeast Atlantic CaCO 3 content record spanning the last 30 Myr, derived from X-ray fluorescence (XRF) ln(Ca <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e653eaf840568ee76bb20ba3bf368ae0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-17-2091-2021-ie00001.svg" width="8pt" height="14pt" src="cp-17-2091-2021-ie00001.png"/></svg:svg> Fe) data collected at Ocean Drilling Program Site 1264 (Walvis Ridge, SE Atlantic Ocean). We present a comprehensive and continuous depth and age model for the entirety of Site 1264 ( ∼ 316 m; 30 Myr). This constitutes a key reference framework for future palaeoclimatic and palaeoceanographic studies at this location. We identify three phases with distinctly different orbital controls on Southeast Atlantic CaCO 3 deposition, corresponding to major developments in climate, the cryosphere and the carbon cycle: (1) strong ∼ 110 kyr eccentricity pacing prevails during Oligocene–Miocene global warmth ( ∼ 30–13 Ma), (2) increased eccentricity-modulated precession pacing appears after the middle Miocene Climate Transition (mMCT) ( ∼ 14–8 Ma), and (3) pervasive obliquity pacing appears in the late Miocene ( ∼ 7.7–3.3 Ma) following greater importance of high-latitude processes, such as increased glacial activity and high-latitude cooling. The lowest CaCO 3 content (92 %–94 %) occurs between 18.5 and 14.5 Ma, potentially reflecting dissolution caused by widespread early Miocene warmth and preceding Antarctic deglaciation across ...