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

• DOI: 10.5194/cp-18-1231-2022
• Publication Date: 2022-06-01T06:32:34Z
• 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; 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-of-the-road future projections. 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 Western Australia, as well influenced Southern Hemisphere paleoclimate variability. To constrain time space, this project obtained eight clumped-isotope Δ47 paleotemperatures constructed new orbitally resolved planktonic foraminifera (Trilobatus sacculifer) isotope (δ18O) Plio-Pleistocene (4–2 Ma) interval International Ocean Discovery Program (IODP) Site U1459. These data complement an existing TEX86 from same site similar records Northern Carnarvon (Ocean Drilling (ODP) 763 IODP U1463). comparison paleothermometers likely reflects sea surface temperatures (SSTs) with seasonal bias (23.8–28.9 ∘C), whereas T. sacculifer calcification probably echo mixed-layer at studied U1459 (18.9–23.2 ∘C). isotopic δ18O gradient along 19–29∘ S latitudinal transect, between 3.9 2.2 Ma, displays large variability, ranging 0.5 ‰ 2.0 ‰. We use proxy strength, inverse relationship both. 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, flat gradients (∼0.5 restored latest (2.9–2.6 Ma). Still, analysis affirms combination forcing wind eustatic level controlled intensity. On secular timescales, period relatively weak observed 3.1 Notably, marked by cooler conditions throughout Hemisphere. In conclusion, intensity position subtropical front are both long-range effects forcing: heat transport through (ITF) valve its propagation Indian poleward transport. common ITF explains coherence records.