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1:250 000 Geological Map of Southern Victoria Land, Antarctica

QMAP Antartica

The success of the QMAP 1:250 000 Geological Map of New Zealand project encouraged GNS Science to apply the similar methods to compile a geological map and database for the part of Antarctica where New Zealand earth scientists have made a major contribution. The area is in southern Victoria Land, part of the Ross Dependency, extending between Ross Island and the Polar Plateau and including the largest ice-free area of Antarctica.

Methodology

The work integrates and summarises all previous geological studies in the Dry Valleys and Ross Island area. A comprehensive search and review of existing geological maps, databases, research papers and geological theses has been completed and information compiled at 1:50,000 on 46 sheets. Limited new fieldwork was carried out in some areas in late 2008. A high quality 1:250,000 scale geological map was published in 2012 with a full colour illustrated explanatory book – the final map in the QMAP series. Fully-featured GIS data are available on DVD and through internet services.

Geological Highlights

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Highlights of the new geological map include the differentiation of the Proterozoic high-grade Skelton Group metamorphic basement from four suites of Late Proterozoic to early Paleozoic Granite Harbour Intrusives granitic plutons. Extensive intrusion by the Ordovician Vanda Dike Swarms is also depicted. The Beacon Supergroup stratigraphic succession is depicted in terms of the Devonian Taylor Group and the Permian to Triassic Victoria Group, differentiated into 14 constituent formations. The Jurassic igneous Ferrar Supergroup sills and dikes that intrude across and close to the Kukri Erosion Surface are shown. The map shows for the first time the context of the Cenozoic volcanism (McMurdo Volcanics) of Mt Erebus/Ross Island and southern Ross Sea region with that of the Transantarctic Mountains. Structural features of the intervening Ross Sea Basin are shown together with the recent stratigraphic drilling sites. The map also provides the first systematic overview of glacial deposits in the region, which range from older Miocene-Pliocene sequences inland, to younger Quaternary tills pertaining to the last glacial maximum near the coast. Tills have been grouped on geomorphological criteria using dating, elevation and composition information wherever possible, distinguished from colluvium, scree, lake and delta deposits, dunes, beach deposits, fan gravel and alluvium.

Digital data

Geology of Southern Victoria Land cover

The underpinning GIS dataset provides rich information on the geological features of the area and can be used to emphasise, for example, the Cenozoic glacial deposits or the igneous basement. A web map service (WMS) of some of these digital data has been made available since July 2011. The WMS allows visualisation of the geological features and some querying of the underlying attribute information. These data can be viewed through a webmap application such as the OneGeology portal or directly accessed using GIS software from the host server.

Within the period 1994 - 2011, New Zealand's Institute of Geological and Nuclear Sciences (GNS Science) built QMAP (Quarter-million MAP) - a geographic information systems database of New Zealand geology comprising 21 full colour 1:250 000 geological maps and monographs covering the entire country (ISSN 2230-3776). Rock units are mapped primarily in terms of their rock type (lithology) but also differentiated on age of deposition, eruption and intrusion, either using colour variation or appropriate overprints.

The map also provides the first systematic overview of glacial deposits in the region, which range from older Miocene-Pliocene sequences inland, to younger Quaternary tills pertaining to the last glacial maximum near the coast. Tills have been grouped on geomorphological criteria using dating, elevation and composition information wherever possible, distinguished from colluvium, scree, lake and delta deposits, dunes, beach deposits, fan gravel and alluvium. Other highlights of the map include differentiation of the Proterozoic high-grade metamorphic basement (the metasedimentary Skelton Group) from many Late Proterozoic to early Paleozoic granitic plutons, subdivided into four geochemical/petrogenetic suites, that collectively form the Granite Harbour Intrusives. The Beacon Supergroup stratigraphic succession is depicted in terms of the Devonian Taylor Group and the Permian to Triassic Victoria Group, differentiated into 11 constituent formations, while the Jurassic igneous Ferrar Supergroup and Cenozoic McMurdo Volcanics are also differentiated on the basis of lithology.

Production involved a comprehensive search and review of existing geological maps, databases, research papers and geological theses. Information was compiled at 1:50,000 on 46 sheets. Limited new fieldwork, satellite and aerial photograph interpretation were completed in areas that were poorly known or contentious. Geological data have been captured and stored in an ArcGIS® database, from which a high quality printed map is currently being published and will be included with a full colour illustrated explanatory book and stratigraphic lexicon.