Antarctic paleoenvironment and vegetation reconstruction during the early and middle Miocene using biomarkers from Ross Sea sediment drill cores

• Main Author: Lelieveld, Natasha
• Format: Thesis
• Language: unknown
• Published: 2022
• Subjects: Sedimentology; biomarkers; geology; Antarctica; Miocene; School: School of Geography; Environment and Earth Sciences; Unit: Antarctic Research Centre; 040310 Sedimentology; Degree Discipline: Geology; Degree Level: Masters; Degree Name: Master of Science; Antarctic; Ross Sea; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.26686/wgtn.21554862; https://figshare.com/articles/thesis/Antarctic_paleoenvironment_and_vegetation_reconstruction_during_the_early_and_middle_Miocene_using_biomarkers_from_Ross_Sea_sediment_drill_cores/21554862

The Ross Sea during the Early to Middle Miocene was influenced by Antarctic Ice Sheets that were highly variable and potentially contributed to 60 m of sea level variations. This variability is proposed to be regulated by shifts in orbital configurations that influenced atmospheric, oceanic temperatures and circulation patterns, that in turn regulated shifts in atmospheric CO2 levels and ocean heat delivery to the Antarctic region, causing ice sheet loss or advance. The vegetation response to these Miocene changes is also proposed to highly variable, with advancing ice sheets restricting the real extent and elevation of land where higher order plants can grow. This thesis reinvestigates two Deep Sea Drilling Project cores from DSDP sites 272 and 273, which are located in the middle to outer continental shelf of the central Ross Sea, Antarctica, and capture a record of organic remains from inland vegetation that has been transported offshore by glaciers or meltwater outwash. Recent records from International Ocean Discovery Programme Site (IODP) U1521 and ANDRILL site AND-2A has provided records of Early Miocene to Middle Miocene. New age models from the DSDP Site 272 and 273 cores suggest they provide records that compliment these newer cores and fill in key time gaps for the Miocene time period, in particular leading into, and during the Miocene Climate Optimum, a period of notable global warmth between 17 and 14.6 Ma. This thesis presents biomarker and XRF datasets from DSDP Site 272 and 273 in the Ross Sea region, as well as a redescription of the lithological descriptions and to align with more recent lithological frameworks used for IODP site U1521. To construct this new description, XRF data and grain size data was used to define 4 main units in both cores. Only short “snapshot” intervals of the MCO were recorded in DSDP Site 272, between ~15.8 and 15.3 Ma, but contains an offshore hemipelagic signal thorough this time periods, as well as prior to the MCO (between 17-18 Ma). A longer record of the MCO is ...