Plio-Pleistocene Perth Basin water temperatures and Leeuwin Current dynamics (Indian Ocean) derived from oxygen and clumped isotope paleothermometry

• DOI: 10.5194/cp-2021-151
• Publication Date: 2021-11-24T14:16:50Z
• Authors: David De Vleescho...; Marion Peral; Marta Marchegiano; Angelina Füllberg; Niklas Meinicke; Heiko Pälike; Gerald Auer; Benjamin Petrick; Christophe Snoeck; Steven Goderis; Philippe Claeys
• Keywords: δ18O; Plio-Pleistocene; Paleoclimatology

Abstract. The Pliocene sedimentary record provides a window into Earth’s climate dynamics under warmer-than-present boundary conditions. However, the cannot be considered stable warm that constitutes solid baseline for middle-road future projections. Indeed, increasing availability of time-continuous archives (e.g., marine sediment cores) reveals complex temporal and spatial patterns ocean variability on astronomical timescales. Perth Basin is particularly interesting in respect because it remains unclear if how Leeuwin Current sustained comparably wet West-Australia, as well influenced Southern Hemisphere paleoclimate variability. To constrain time space, this project constructed new orbitally-resolved planktonic foraminifera (Trilobatus sacculifer) isotope (δ18O clumped isotopes Δ47) Plio-Pleistocene (4–2 Ma) interval International Ocean Discovery Program (IODP) Site U1459. It complements an existing TEX86 from same site similar records Northern Carnarvon (ODP 763 IODP U1463). comparison Δ47 paleothermometers likely reflects sea surface temperatures (SST, 23.8–28.9 °C), whereas T. sacculifer calcification probably echo state lower mixed layer upper thermocline at studied U1459 (18.2–20.8 °C). isotopic δ18O gradient along 19° S–29° S latitudinal transect, between 3.9–2.2 Ma, displays large variability, ranging 0.5 2.0 ‰, whereby low indicative strong vice versa. These results challenge interpretation suggested tectonic event Indonesian Throughflow cause rapid steepening (0.9 to 1.5 ‰) around 3.7 Ma. appears obsolete now clear Ma intermittent, with flat gradients (~0.5 restored latest (2.9–2.6 Ma). Still, analysis affirms combination forcing wind eustatic level controlled intensity. A period relatively weak 3.1 advocated; also marked by cooler conditions throughout Hemisphere. In conclusion, intensity position subtropical front are rooted forcing: Heat transport through (ITF) valve propagated temperate zone Indian poleward heat transport. common ITF explains observed coherence records.