The geology of Cape Dubouzet, northern Antarctic Peninsula: continental basement to the Trinity Peninsula Group?

Francisco Hervé, Jorge Lobato, Ignacio Ugalde, Robert J. Pankhurst

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11 Citations (Scopus)

Abstract

Cape Dubouzet is mainly composed of a volcanic-subvolcanic complex of extrusive rhyolitic breccias, a banded rhyolite and a semi-annular body of dacite porphyry rich in xenoliths of metamorphic rocks. Major and gEE geochemistry indicate that the volcanic rocks are calc-alkaline and that they are genetically related by fractional crystallization of a plagioclase- bearing assemblage from a common magma. Rb-Sr data suggest that the rhyolitic complex is of Middle-to-Late Jurassic age, and that it is intruded by Late Cretaceous stocks of banded diorite and gabbro. All these rocks are partially covered by moraines whose clasts are of local provenance. Xenoliths in the dacite porphyry suggest that the northern tip of the Antarctic Peninsula is underlain by a metamorphic complex composed of amphibolites, meta-tonalites and pelitic gneiss containing garnet, sillimanite, cordierite, hercynite, and andalucite. Such rocks are not known in the Scotia metamorphic complex, nor in the Trinity Peninsula Group and its low grade metamorphic derivatives, which also occur as rare xenoliths in the dacite. Previous dating of xenoliths collected from the moraines suggested a late Carboniferous age for this amphibolite-grade metamorphism. Both the Jurassic-Cenozoic magmatic arc of the Antarctic Peninsula and the accretionary complex rocks of the Trinity Peninsula Group were thus developed, at least in part, over pre-existing continental crust.

Original languageEnglish
Pages (from-to)407-414
Number of pages8
JournalAntarctic Science
Volume8
Issue number4
Publication statusPublished - Dec 1996

Keywords

  • Antarctic Peninsula
  • Mesozoic
  • metamorphic basement
  • silicic volcanism
  • xenoliths

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Environmental Science(all)
  • Oceanography
  • Ecology, Evolution, Behavior and Systematics
  • Geology

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