Subsurface investigations of Marine Plain
Marine Plain at Vestfold Hills, contains a unique record of sea level, climate and glacial history within its sediments and microfossils. Coring of the deeper sediments will reveal how this part of coastal east Antarctica changed during the Neogene (26 million years-the present). Project objectives:...
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/subsurface-investigations-marine-plain/699904 https://doi.org/10.4225/15/574BC0E8CA5A8 https://data.aad.gov.au/metadata/records/ASAC_2400 http://nla.gov.au/nla.party-617536 |
| Summary: | Marine Plain at Vestfold Hills, contains a unique record of sea level, climate and glacial history within its sediments and microfossils. Coring of the deeper sediments will reveal how this part of coastal east Antarctica changed during the Neogene (26 million years-the present). Project objectives: The proposal aims to better understand the Neogene (26 Ma-present) interactions of the East Antarctic ice sheet at Vestfold Hills with global climate and sea level over time scales which extend well beyond ice core records. Specific objectives are; 1. Sedimentary setting - measure (using geophysics) and sample (using a drilling rig) the complete vertical sediment sequence at Marine Plain, 2. Environmental history - determine the environmental history of the major sedimentary units at Marine Plain, 3. Age relationships - investigate the age relationships of the Marine Plain deposit with other glacial-marine sediments in Vestfold Hills, using amino acid racemisation on in situ and glacially transported shell material, 4. Glacial history - correlate this new glacial history from Vestfold Hills with the existing record from the Lambert Graben, and with outputs from the University of Bristol thermomechanical ice sheet model GLIMMER. 2003-2005 Progress: During the 2003/04 summer, geophysical data (resistivity, hammer seismic) were collected at Marine Plain, consisting of four roughly east-west transects and one north-south tie line. Each transect consisted of roughly 3,000 measurements. These transects were surveyed with total station and located using dGPS (thanks to Henk Brolsma). Carbonate shell fossils were also collected for amino acid racemisation analysis, and for kinetics experiments that will allow those ratios to be converted to absolute age estimates. During the 2004/05 summer, the coring gear was placed in the northern part of Marine Plain and an 18 m composite core was taken from the surface to refusal (the rock basement). Coring at a second site further south on Marine Plain was carried out to ~5 m but was not completed due to thick glacial sediments in the section. A second season of fieldwork is on hold while we work with the material in hand. The dataset also includes a written report on the drilling that took place in the 2004/2005 season. This report also details several environmental incidents that took place in relation to fuel spills. Taken from the 2008-2009 Progress Report: Progress against objectives: The proposal aims to better understand the Neogene (26 Ma-present) interactions of the East Antarctic ice sheet at Vestfold Hills with global climate and sea level over time scales which extend well beyond ice core records. Specific objectives are; 1. Sedimentary setting - measure (using geophysics) and sample (using a drilling rig) the complete vertical sediment sequence at Marine Plain, Progress - Objective completed 2. Environmental history - determine the environmental history of the major sedimentary units at Marine Plain, Progress - The core had magnetic susceptibility and gamma density measured. The core was opened, described, photographed digitally and scanned for NIR. The core was sub-sampled for microfabric analysis and that analysis is in train. The remainder of the sampling and analysis is ongoing. 3. Age relationships - investigate the age relationships of the Marine Plain deposit with other glacial-marine sediments in Vestfold Hills, using amino acid racemisation on in situ and glacially transported shell material, Progress - The core was examined and subsampled for shell material. There were no intact shells, and only a few fragments. So, to improve the resolution of the amino acid racemisation analysis collection, legacy collections were re-examined and subsampled and now we have a sound collection of shells awaiting further funds with which to continue amino acid racemisation analyses. 4. Glacial history - correlate this new glacial history from Vestfold Hills with the existing record from the Lambert Graben, and with outputs from the University of Bristol thermomechanical ice sheet model GLIMMER. Progress - No progress this objective (commencement is pending completion of Objectives 1-3) Taken from the 2009/2010 Progress Report: Progress against objectives: Objective 1 - Is complete. The 2D resistivity geophysics showed that the Marine Plain target is a shallow deposit relative to other accommodation space at Vestfold Hills, and that the core recovered is probably from the deepest section (within the sampling resolution of the geophsyics). Objective 2 - This enormous objective is mostly completed. The gamma density logging, magnetic susceptibility, Vis-IR spectroscopy, XRF spectrometry, and X-ray diffractometry are all complete. What remains is the CNS analyses of the core, the microstructural analysis of the core, grain size of the samples, and the microfossil/macrofossil work (Objective 3). Objective 3 - Is on hold due to the paucity of material able to be dated using AAR. We have subsampled for microfossils and these samples lie with collaborator Pat Quilty in Hobart. In order to help constrain the history of the Marine Plain core beyond what has already been determined and published, we have taken shell fragments from tills surrounding Marine Plain and we intend to use amino acid racemisation on them. That work is scheduled for 2011 after work on the Marine Plain core has been completed. Objective 4 - This objective awaits the synthesis phase following the completion of Objectives 2 and 3. |
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