New constraints on metamorphism in the Highjump Archipelago, East Antarctica
| Autor: | Naomi M. Tucker, Martin Hand |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Geochemistry Metamorphism Geology Cordierite Orogeny engineering.material 010502 geochemistry & geophysics Oceanography Granulite 01 natural sciences Monazite Facies Archipelago engineering Sillimanite Geomorphology Ecology Evolution Behavior and Systematics 0105 earth and related environmental sciences |
| Zdroj: | Antarctic Science. 28:487-503 |
| ISSN: | 1365-2079 0954-1020 |
| DOI: | 10.1017/s095410201600033x |
| Popis: | The age and conditions of metamorphism in the Highjump Archipelago, East Antarctica, are investigated using samples collected during the 1986 Australian Antarctic expedition to the Bunger Hills–Denman Glacier region. In situ U-Pb dating of monazite from three metasedimentary rocks yields ages between c. 1240–1150 Ma and a weighted mean 207Pb/206Pb age of 1183±8 Ma, consistent with previous constraints on the timing of metamorphism in this region and Stage 2 of the Albany–Fraser Orogeny in south-western Australia. This age is interpreted to date the development of garnet ± sillimanite ± rutile-bearing assemblages that formed at c. 850–950°C and 6–9 kbar. Peak granulite facies metamorphism was followed by decompression, evidenced largely by the partial replacement of garnet by cordierite. These new pressure–temperature determinations suggest that the Highjump Archipelago attained slightly higher temperature and pressure conditions than previously proposed and that the rocks probably experienced a clockwise pressure–temperature evolution. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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