Geology of the Theron Mountains, Antarctica
The oldest rocks exposed in the Theron Mountains are an approximately 700 m. thick sequence of terrestrial, water-lain elastic sediments. They consist largely of arkosic, feldspathic and quartzitic fine-grained sandstones and siltstones with thin shales and mudstones and subordinate carbonaceous bed...
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| Format: | Thesis |
| Language: | English |
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1972
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| Online Access: | http://etheses.bham.ac.uk//id/eprint/13243/1.hassmallThumbnailVersion/Brook1972PhD.pdf http://etheses.bham.ac.uk//id/eprint/13243/ http://etheses.bham.ac.uk//id/eprint/13243/1/Brook1972PhD.pdf |
| Summary: | The oldest rocks exposed in the Theron Mountains are an approximately 700 m. thick sequence of terrestrial, water-lain elastic sediments. They consist largely of arkosic, feldspathic and quartzitic fine-grained sandstones and siltstones with thin shales and mudstones and subordinate carbonaceous beds and coals. Minor breaks in the succession are of only local significance and there were variable local environments of deposit ion. There are glossopterid fossils indicative of a Lower Permian age. These sediments were intruded during the Jurassic by great thicknesses of dolerite, mainly in the form of sills but with occasional thin dykes. Field, petrographical and chemical evidence indicates major differences between these dolerites and the Ferrar dolerites of Jurassic age elsewhere in eastern Antarctica. Comparison with other Mesozoic tholeiitic rocks of the Southern Hemisphere confirms the distinction of two separate magmatic provinces but modifies their geographical limits. A model is postulated to explain the origin of these magmatic provinces in relation to their association with the break-up and dispersal of Gondwanaland. Minor local tilting and faulting occurred in association with and subsequent to the intrusive activity and there was pervasive thermal metamorphism of most of the sediments. There is no record of tectonic events since the end of the Jurassic but there may have been some blockfaulting, resulting in a graben now occupied by “Main Glacier”. Glacial and periglacial processes have been the dominant factors in determining the landforms of the Theron Mountains since the last glaciation of Antarctica. |
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