Late Palaeozoic-early Mesozoic fore-arc basin Sedimentary rocks at the Pacific margin in Western Antarctica
We infer that the Trinity Peninsula Group of the Antarctic Peninsula was deposited in a fore-arc basin(s) of composite type located between the Gondwanian arc massif (consisting of plutonic and older gneissose basement rocks) and a subduction complex, now represented by “greenschists”, “blueschists”...
Published in: | Geologische Rundschau |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Springer
1981
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Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/524682/ https://doi.org/10.1007/BF01822133 |
Summary: | We infer that the Trinity Peninsula Group of the Antarctic Peninsula was deposited in a fore-arc basin(s) of composite type located between the Gondwanian arc massif (consisting of plutonic and older gneissose basement rocks) and a subduction complex, now represented by “greenschists”, “blueschists” and albite-epidote-hornblende-bearing rocks of the pre-Jurassic metamorphic complex. The Trinity Peninsula Group has been re-examined in the type area and can be divided into the Hope Bay, View Point and Legoupil Formations. Sedimentary rocks of all formations are of turbidite facies; meta-pillow lavas are described for the first time from these rocks. Multiphase folding has been observed in all formations and regional metamorphism reached prehnite-pumpellyite facies. Microprobe analyses of relict pyroxenes in the pillow lavas indicate the parent magma was probably within-plate alkali basalt. Analyses of detrital garnets show that they are different in composition from metamorphic garnets in the subduction complex, indicating that the latter did not supply a significant amount of material to the fore-arc basin(s). A close similarity with the Torlesse terrane in New Zealand is noted and we conclude that a late Palaeozoic-early Mesozoic fore-arc basin environment can be traced almost continuously around the Pacific margin from South America to New Zealand. |
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