An official website of the United States government
Abstract A dataset to describe exposed bedrock and surficial geology of Antarctica has been constructed by the GeoMAP Action Group of the Scientific Committee on Antarctic Research (SCAR) and GNS Science. Our group captured existing geological map data into a geographic information system (GIS), refined its spatial reliability, harmonised classification, and improved representation of glacial sequences and geomorphology, thereby creating a comprehensive and coherent representation of Antarctic geology. A total of 99,080 polygons were unified for depicting geology at 1:250,000 scale, but locally there are some areas with higher spatial resolution. Geological unit definition is based on a mixed chronostratigraphic- and lithostratigraphic-based classification. Description of rock and moraine polygons employs the international Geoscience Markup Language (GeoSciML) data protocols to provide attribute-rich and queryable information, including bibliographic links to 589 source maps and scientific literature. GeoMAP is the first detailed geological map dataset covering all of Antarctica. It depicts ‘known geology’ of rock exposures rather than ‘interpreted’ sub-ice features and is suitable for continent-wide perspectives and cross-discipline interrogation.
more »
« less
Geology of West Antarctica
The work is Chapter Three in a volume that provides a comprehensive overview of the geology of the Antarctic continent. The book represents the first comprehensive update of Antarctic geology in 25 years or more. Knowledge of the geology of Antarctica -- even if based on the meager <2% of rock exposure for this continent-- has immeasurably increased over that quarter-century. Individual chapters cover the regional geology of the seven main physiographic regions of Antarctica: -the Antarctic Peninsula, -West Antarctica (Marie Byrd Land and Enderby Land), -Transantarctic Mountains, -the Shackleton Range and its surroundings (including the Bertrab, Littlewood and Moltke Nunataks), -Dronning Maud Land, -Lambert Glacier and the area surrounding it, -East Antarctica from Kaiser-Wilhelm-II.-Land to George V Land/Terre Adélie. Each chapter contains a topographic, historical and geological overview, a description of the respective geological units, their stratigraphy and related data and the tectonic structure of the respective region. The seven chapters were written by acknowledged specialists in their field who place the regional geology into a continent-wide/plate tectonic/geological context.
more »
« less
- Award ID(s):
- 1443497
- PAR ID:
- 10302737
- Editor(s):
- Kleinschmidt, Georg
- Date Published:
- Journal Name:
- Beiträge zur regionalen Geologie der Erde
- Volume:
- 33
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract We apply a machine learning (ML) earthquake detection technique on over 21 yr of seismic data from on-continent temporary and long-term networks to obtain the most complete catalog of seismicity in Antarctica to date. The new catalog contains 60,006 seismic events within the Antarctic continent for 1 January 2000–1 January 2021, with estimated moment magnitudes (Mw) between −1.0 and 4.5. Most detected seismicity occurs near Ross Island, large ice shelves, ice streams, ice-covered volcanoes, or in distinct and isolated areas within the continental interior. The event locations and waveform characteristics indicate volcanic, tectonic, and cryospheric sources. The catalog shows that Antarctica is more seismically active than prior catalogs would indicate, examples include new tectonic events in East Antarctica, seismic events near and around the vicinity of David Glacier, and many thousands of events in the Mount Erebus region. This catalog provides a resource for more specific studies using other detection and analysis methods such as template matching or transfer learning to further discriminate source types and investigate diverse seismogenic processes across the continent.more » « less
-
Abstract BackgroundAntarctica and its unique biodiversity are increasingly at risk from the effects of global climate change and other human influences. A significant recent element underpinning strategies for Antarctic conservation has been the development of a system of Antarctic Conservation Biogeographic Regions (ACBRs). The datasets supporting this classification are, however, dominated by eukaryotic taxa, with contributions from the bacterial domain restricted to Actinomycetota and Cyanobacteriota. Nevertheless, the ice-free areas of the Antarctic continent and the sub-Antarctic islands are dominated in terms of diversity by bacteria. Our study aims to generate a comprehensive phylogenetic dataset of Antarctic bacteria with wide geographical coverage on the continent and sub-Antarctic islands, to investigate whether bacterial diversity and distribution is reflected in the current ACBRs. ResultsSoil bacterial diversity and community composition did not fully conform with the ACBR classification. Although 19% of the variability was explained by this classification, the largest differences in bacterial community composition were between the broader continental and maritime Antarctic regions, where a degree of structural overlapping within continental and maritime bacterial communities was apparent, not fully reflecting the division into separate ACBRs. Strong divergence in soil bacterial community composition was also apparent between the Antarctic/sub-Antarctic islands and the Antarctic mainland. Bacterial communities were partially shaped by bioclimatic conditions, with 28% of dominant genera showing habitat preferences connected to at least one of the bioclimatic variables included in our analyses. These genera were also reported as indicator taxa for the ACBRs. ConclusionsOverall, our data indicate that the current ACBR subdivision of the Antarctic continent does not fully reflect bacterial distribution and diversity in Antarctica. We observed considerable overlap in the structure of soil bacterial communities within the maritime Antarctic region and within the continental Antarctic region. Our results also suggest that bacterial communities might be impacted by regional climatic and other environmental changes. The dataset developed in this study provides a comprehensive baseline that will provide a valuable tool for biodiversity conservation efforts on the continent. Further studies are clearly required, and we emphasize the need for more extensive campaigns to systematically sample and characterize Antarctic and sub-Antarctic soil microbial communities.more » « less
-
The growth and evolution of the Eurasian continent involved the progressive closure of major ocean basins during the Phanerozoic, including the Tethyan and Paleo-Asian oceanic realms. Unraveling this complicated history requires interpreting multiple overprinted episodes of subduction-related magmatism and collisional orogeny, the products of which were later affected by the Cenozoic construction of the Himalayan-Tibetan orogen due to the India-Asia collision. In particular, the tectonic evolution of northern Tibet surrounding the Cenozoic Qaidam Basin is poorly resolved due to several phases of Phanerozoic orogeny that have been reactivated during the Cenozoic deformation. In this study, we investigated the geology of the northern Qaidam continent, which experienced Paleozoic–Mesozoic tectonic activity associated with the development of the Eastern Kunlun orogen to the south and the Qilian orogen to the north. We combined new and published field observations, geochronologic and thermochronologic ages, and geochemical data to construct regional tectonostratigraphic sections and bracket phases of Paleozoic–Mesozoic magmatism associated with oceanic subduction and continental collision. Results suggest that the Qaidam continent experienced two major phases of subduction magmatism and collision. First, a Cambrian–Ordovician magmatic arc developed in the northern Qaidam continent due to south-dipping subduction. This phase was followed by the closure of the Qilian Ocean and the collision of the North China craton and Qaidam continent, resulting in Silurian–Devonian orogeny and the development of a regional unconformity across northern Tibet. A subsequent Permian–Triassic magmatic arc developed across the northern Qaidam continent due to north-dipping subduction. This phase was followed by the closure of the Neo-Kunlun Ocean and the collision of the Songpan Ganzi terrane in the south and Qaidam continent. These interpretations are incorporated into a new and comprehensive model for the Phanerozoic formation of northern Tibet and the Eurasia continent.more » « less
-
Abstract East Antarctic provinces lay at the heart of both Rodinian and Gondwanan supercontinents, yet poor exposure and limited geophysical data provide few constraints on the region’s tectonic evolution. The shape of the Mawson Continent, the stable nucleus of East Antarctica, is one of Antarctica’s most important, but contested features, with implications for global plate reconstructions and local tectonic models. Here we show a major marginal embayment 500–700 km wide, cuts into the East Antarctic basement in the South Pole region. This embayment, defined by new aeromagnetic and other geophysical data, truncates the Mawson Continent, which is distinct from basement provinces flanking the Weddell Sea. We favour a late Neoproterozoic rifting model for embayment formation and discuss analogies with other continental margins. The embayment and associated basement provinces help define the East Antarctic nucleus for supercontinental reconstructions, while the inherited marginal geometry likely influenced evolution of the paleo-Pacific margin of Gondwana.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
