Thermal regime and state of hydration of the Antarctic upper mantle from regional-scale electrical properties
| Autor: | M. A. Kordy, Philip E. Wannamaker, John A. Stodt, Graham Hill, Virginie Maris |
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| Rok vydání: | 2021 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Geology Context (language use) Crust 010502 geochemistry & geophysics 01 natural sciences Silicate Ice shelf chemistry.chemical_compound chemistry Magnetotellurics Seismic tomography Lithosphere Petrology Geothermal gradient 0105 earth and related environmental sciences |
| Zdroj: | Geological Society, London, Memoirs. 56:181-194 |
| ISSN: | 2041-4722 0435-4052 |
| Popis: | Large-scale electrical resistivity investigations of the Antarctic crust and upper mantle utilizing the magnetotelluric method (MT) are limited in number compared to temperate regions, but provide physical insights hard to achieve with other techniques. Key to the method's success are the instrumentation advances that allow microvolt (µV)-level measurements of the MT electric field in the face of mega-ohm (MΩ) contact resistances. Primarily in this chapter, we reanalyse existing data from three campaigns over the Antarctic interior using modern 3D non-linear inversion analysis, and offer additional geophysical conclusions and context beyond the original studies. A profile of MT soundings over the transitional Ellsworth–Whitmore block in central West Antarctica implies near-cratonic lithospheric geothermal conditions with interpreted graphite–sulfide horizons deformed along margins of high-grade silicate lithological blocks. Reanalysis of South Pole soundings confirms large-scale low resistivity spanning Moho depths that is consistent with limited seismic tomography and elevated crustal thermal regime inferences. Upper mantle under a presumed adiabatic thermal gradient below the Ross Ice Shelf near the central Transantarctic Mountains appears to be of a moderately hydrated state but not sufficient to induce melting. The degree of hydration there is comparable to that below the north-central Great Basin province of the western USA. |
| Databáze: | OpenAIRE |
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