Field mapping data and petrological collections for petrography, geochronology and geochemistry, of rocks from Mt Morning, southern Victoria Land, Antarctica
Abstract:
Mt Morning is the most southerly of a series of central type volcanoes that make up the McMurdo Volcanic Group of south Victoria Land. It is characterised by a trachyte - basanite - phonolite assemblage. The distribution of volcanic rock types exposed on the northern flanks of the volcano and Mason Spur (15 km south of the summit caldera) were mapped and a suite of samples were collected for ... petrography, geochemical and geochronological analysis to determine the origin of the parental magma and the mechanism of its evolution to rock types. Rock samples collected include: basalt, basanite, phonolite, trachyte, syenite, gabbro, wehrlite, Iherzolite, breccia, tuff, granulite and granite. A profound unconformity between the older trachyte series (previously dated at 18Ma) and the younger basalt/basanite cinder cone sequence (presumed to be 1 Ma) was established. Numerous xenoliths (fragments of rocks that have been torn off the walls of magma conduits deep in the mantle or crust and carried by magmatic flow to the earth's surface) were found and a spectrum of the rocks were sampled to effectively map the earth's mantle across southern Victoria Land. The xenoliths provide information on mantel and crustal composition and properties as well as mantle processes related to plate movements such as continental rift zones.The geological history and evolution of the volcano has relevance to igneous petrogenesis, to the tectonic history of southern Victoria Land and to the contributions that Mt Morning makes to the detrital budget of adjacent sedimentary basins in southern McMurdo Sound.
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