Submarine Eruptive Processes in the Brook St Terrane at Colac Bay, Southland, New Zealand

A sequence of volcanic and volcaniclastic rocks of the Brook Street Terrane crops out along the Southland coast from Howells Point, Riverton, into Colac Bay. This sequence provides an along-strike exposure, revealing lateral variations in these submarine deposits of a Permian oceanic island arc; such sequences are rarely studied, and allow examination of an arc environment within a thin slice of time, in a manner which is impossible in the more common vertical sequences. Lithofacies analysis and mapping, and geochemical analyses were carried out. The sequence includes pillow lavas, dikes, hydroclastic breccias, tuffs, lapilli tuffs and argillites. All is hydrothermally altered and metamorphosed to prehnite-pumpellyite facies, so major and trace element analyses were conducted on the freshest augite phenocrysts wherein the magmatic signal is likely to be preserved. Geochemical data indicate variable primitive island arc to MORB-like magma sources. Two distinct groups of signatures exist, one with typical island arc characteristics, the other more closely resembling back-arc (MORB-like) magma. The distribution of these suggests two separate small volcanic centres, perhaps tapping different mantle domains in a source region transitional between the arc and back-arc. The size and proximity of the two may indicate they are satellite vents of a larger arc volcano. The sedimentary structures and facies relations of tuffs and lapilli tuffs suggest formation in association with pillow lava as hyaloclastite, and redeposition by subaqueous mass flows. The pillow lavas observed have peperitic contacts with the volcaniclastic rocks, indicating that they intruded into these deposits while they were unconsolidated. These relationships indicate that two generations of pillow lava formed in the sequence, the first associated with production of hyaloclastite which was redeposited in fans and channels on the volcano flanks, and the second intruding into these deposits

Submarine Eruptive Processes in the Brook St Terrane at Colac Bay, Southland, New Zealand

A sequence of volcanic and volcaniclastic rocks of the Brook Street Terrane crops out along the Southland coast from Howells Point, Riverton, into Colac Bay. This sequence provides an along-strike exposure, revealing lateral variations in these submarine deposits of a Permian oceanic island arc; such sequences are rarely studied, and allow examination of an arc environment within a thin slice of time, in a manner which is impossible in the more common vertical sequences. Lithofacies analysis and mapping, and geochemical analyses were carried out. The sequence includes pillow lavas, dikes, hydroclastic breccias, tuffs, lapilli tuffs and argillites. All is hydrothermally altered and metamorphosed to prehnite-pumpellyite facies, so major and trace element analyses were conducted on the freshest augite phenocrysts wherein the magmatic signal is likely to be preserved. Geochemical data indicate variable primitive island arc to MORB-like magma sources. Two distinct groups of signatures exist, one with typical island arc characteristics, the other more closely resembling back-arc (MORB-like) magma. The distribution of these suggests two separate small volcanic centres, perhaps tapping different mantle domains in a source region transitional between the arc and back-arc. The size and proximity of the two may indicate they are satellite vents of a larger arc volcano. The sedimentary structures and facies relations of tuffs and lapilli tuffs suggest formation in association with pillow lava as hyaloclastite, and redeposition by subaqueous mass flows. The pillow lavas observed have peperitic contacts with the volcaniclastic rocks, indicating that they intruded into these deposits while they were unconsolidated. These relationships indicate that two generations of pillow lava formed in the sequence, the first associated with production of hyaloclastite which was redeposited in fans and channels on the volcano flanks, and the second intruding into these deposits

Major element geochemistry of volcanic and volcaniclastic rocks from Riverton, Southland, New Zealand

Major element geochemical data from tholeiitic basaltic volcanic and volcaniclastic rocks from the Riverton Peninsula and Colac Bay, Southland, New Zealand. These rocks form part of the Permian Brook Street Terrane

Total major element geochemistry of volcanic and volcaniclastic rocks from Riverton, Southland, New Zealand

Total major element geochemical data from tholeiitic basaltic volcanic and volcaniclastic rocks from the Riverton Peninsula and Colac Bay, Southland, New Zealand. These rocks form part of the Permian Brook Street Terrane

Trace element geochemistry of volcanic and volcaniclastic rocks from Riverton, Southland, New Zealand

Trace element geochemical data from tholeiitic basaltic volcanic and volcaniclastic rocks from the Riverton Peninsula and Colac Bay, Southland, New Zealand. These rocks form part of the Permian Brook Street Terrane. This dataset contains trace element compositions of clinopyroxenes acquired by LA-ICP-MS. Suffixes c and r in the column sample code/label denote measurements taken from the cores and rims of clinopyroxenes, respectively. The data value #0.000 equals "below detection limit"

Major and trace element geochemistry of volcanic and volcaniclastic rocks from Riverton, Southland, New Zealand

Major element and trace element geochemical data from tholeiitic basaltic volcanic and volcaniclastic rocks from the Riverton Peninsula and Colac Bay, Southland, New Zealand. These rocks form part of the Permian Brook Street Terrane

A continent-wide detailed geological map dataset of Antarctica

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

The GeoMAP (v.2022-08) continent-wide detailed geological dataset of Antarctica

A dataset describing exposed bedrock and surficial geology of Antarctica constructed by the GeoMAP Action Group of SCAR (The Scientific Committee on Antarctic Research) and GNS Science, New Zealand. Legacy geological map data have been captured into a geographic information system (GIS), refining its spatial reliability, harmonising classification, then improving representation of glacial sequences and geomorphology. A total 99,080 polygons have been unified for depicting geology at 1:250,000 scale, but locally there are some areas with higher spatial precision. Geological definition in GeoMAP v.2022-08 is founded on a mixed chronostratigraphic- and lithostratigraphic-based classification. Description of rock and moraine polygons employs international GeoSciML data protocols to provide attribute-rich and queriable data; including bibliographic links to 589 source maps and scientific literature. Data are provided under CC-BY License as zipped ArcGIS geodatabase, QGIS geopackage or GoogleEarth kmz files. GeoMAP is the first detailed geological dataset covering all of Antarctica. GeoMAP depicts 'known geology' of rock exposures rather than 'interpreted' sub-ice features and is suitable for continent-wide perspectives and cross-discipline interrogation