GEOLOGY
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This data were collected as part of the Ocean Drilling Program. All data were collected on Leg 119. The cruise for Leg 119 began at Port Louis Harbor, Mauritius, and finished at the Port of Fremantle, Australia. The objective was to complete a transect, along with Leg 120, to study the Late Cretaceous to Holocene palaeoclimatic history of East Antarctic, tectonic history of the Kerguelen Plateau, and the late Mesozoic rifting history of the Indian plate from East Antarctica. Samples are sediments. Good calibration standards for sediments not available. More information can be obtained from the Ocean Drilling Program website. The data obtained from the drilling is available on the Ocean Drilling Program website (see Download Paleontology Data). From the abstract of one of the papers: The timing and nature of the initiation of the Antarctic Ice Sheet is the subject of considerable discussion. Before Leg 119, the earliest known unequivocal Cenozoic glacial sediments were discovered in a Lower Oligocene sequence from the Ross Sea. Quartz grains of Eocene age from the Subantarctic Pacific Ocean were inferred from their grain texture to be ice-rafted. Previous results obtained by Leg 113 in the Weddell Sea indicate that glaciation at sea level first occurred during the late early Oligocene on East Antarctica and during the late Miocene on western Antarctica. Our new results show that glaciation is present during the earliest Oligocene and possibly the late Miocene.
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This data were collected as part of the Ocean Drilling Program. All data were collected on Leg 119. The cruise for Leg 119 began at Port Louis Harbor, Mauritius, and finished at the Port of Fremantle, Australia. The objective was to complete a transect, along with Leg 120, to study the Late Cretaceous to Holocene palaeoclimatic history of East Antarctic, tectonic history of the Kerguelen Plateau, and the late Mesozoic rifting history of the Indian plate from East Antarctica. Samples are sediments. Good calibration standards for sediments not available. More information can be obtained from the Ocean Drilling Program website. The data obtained from the drilling is available on the Ocean Drilling Program website (see Download Paleontology Data). From the abstract of one of the papers: During Leg 119 of the Ocean Drilling Program, between December 1987 and February 1988, six holes were drilled in the Kerguelen Plateau, southern Indian Ocean, and five in Prydz Bay at the mouth of the Amery Ice Shelf, on the East Antarctic continental shelf. The Prydz Bay holes, reported here, form a transect from the inner shelf to the continental slope, recording a prograding sequence of possible Late Palaeozoic to Eocene to Quaternary glacially dominated sediments. This extends the known onset of large-scale glaciation of Antarctica back to about 36-40 million years ago, the sedimentary record suggesting that a fully developed East Antarctic Ice Sheet reached the coast at Prydz Bay at this time, and was more extensive than the present sheet. Subsequent glacial history is complex, with the bulk of sedimentation in the outer shelf taking place close to the grounding line of an extended Amery Ice Shelf. However, breaks in the record and intervals of no recovery may hide evidence of periods of glacial retreat.
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This dataset represents the collected work arising from ASAC projects 263, 351, 497 and 716 (ASAC_263, ASAC_351, ASAC_497, ASAC_716). The data are pooled together into a single excel file, and presented by year. Descriptions/explanations of acronyms used are given at the bottom of each spreadsheet. One worksheet also details all publications arising from (and related to) the four ASAC projects. The full titles of the four ASAC projects are: ASAC 263: Metamorphic Evolution and Tectonic Setting of Granulites from Eastern Prydz Bay ASAC 351: The Role of Partial Melting in the Genesis of Mafic Migmatites and Orthogenesis within the Rauer islands ASAC 497: Structural and Chemical Processes in Granulite Metamorphism: the Rauer Group and Brattstrand Bluffs Region, Prydz Bay ASAC 716: Archaean Crustal Accretion Histories and Significance for Geological Correlations Between the Vestfold Block and Rauer Group The fields in this dataset are: Archive Collector Sample Number Location Location Code Latitude Longitude Field description Collected for Reported in Comments Type Grid reference Worker
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1.The lakes and ponds in the Larsemann Hills and Bolingen Islands (East-Antarctica) are characterised by cyanobacteria-dominated, benthic microbial mat communities. A 56-lake dataset representing the limnological diversity among the more than 150 lakes and ponds in the region was developed to identify the nature and quantify the effects of the abiotic conditions structuring the cyanobacterial and diatom communities. 2.Limnological diversity in the lakes of the Larsemann Hills and Bolingen Islands is primarily determined by salinity and salinity related variables (concentrations of major ions, conductivity and alkalinity), and variation in lake morphometry (depth, catchment and lake area). Low pigment, phosphate and nitrogen concentrations, and DOC and TOC levels in the water column of most lakes underscore the ecological success of benthic microbial mats in this region. 3.Benthic communities consisted of prostrate, sometimes finely laminated mats, flake mats, epilithic and interstitial microbial mats. Mat physiognomy and chlorophyll/carotenoid ratios were strongly related to lake depth, but not to salinity. 4.Morphological-taxonomic analyses revealed the presence of 27 diatom morphospecies and 34 cyanobacterial morphotypes. Mats of shallow lakes (interstitial and flake mats) and those of deeper lakes (prostrate mats) were characterized by different dominant cyanobacterial morphotypes. No relationship was found between the distribution of these morphotypes and salinity. In contrast, variation in diatom species composition was strongly related to both lake depth and salinity. Shallow ponds are mainly characterised by aerial diatoms (e.g. Diadesmis cf. perpusilla and Hantzschia spp.). In deep lakes, communities are dominated by Psammothidium abundans and Stauroforma inermis. Lakes with conductivities higher than 1.5 mS/cm become susceptible to freezing out of salts and hence pronounced salinity fluctuations. In these lakes Psammothidium abundans and Stauroforma inermis are replaced by Amphora veneta. Stomatocysts were only important in shallow freshwater lakes. 5.Ice cover influences microbial mat structure and composition both directly by physical disturbance in shallow lakes and by influencing light availability in deeper lakes, as well as indirectly by generating salinity increases and promoting the development of seasonal anoxia. 6.The relationship between diatom species composition and salinity and depth is statistically significant. Transfer functions based on these data can therefore be used in paleolimnological reconstruction to infer changes in the precipitation-evaporation balance in continental Antarctic lakes. These data were also collected under the auspices of the Micromat Project, Biodiversity of Microbial mats in Antarctica (see the URL below). The fields in this dataset are: Lake Lake number Location Latitude Longitude Altitude (m) Area (ha) Catchment (ha) Depth (m) Distance from Plateau Distance from Sea Geology Substrate Presence Absence pH Alkalinity Nitrate Nitrite Ammonium Silicate Phosphate Oxygen Salinity Turbidity Conductivity Sodium Potassium Calcium Magnesium Chlorine Sulphur Bicarbonate Hydrocarbonate Total Organic Carbon Dissolved Organic Carbon