Mesozoic volcanism in the central Transantarctic Mountains, Antarctica: depositional environment and tectonic setting

Abstract

Pyroclastic and related rocks of silicic and basaltic composition form an important part of the uppermost Beacon Supergroup in the central Transantarctic Mountains. The Upper Triassic to Lower Jurassic Falla Formation consists of a sandstone-carbonaceous shale sequence succeeded by a sequence increasingly dominated by silicic tuffs. This volcaniclastic sequence is overlain by basaltic pyroclastic and laharic deposits of the Prebble Formation. The pyroclastic eruptions were abruptly followed by early Middle Jurassic flood-basalt eruption. The pyroclastic deposits were the result in part of Plinian and phreatomagmatic processes. Monoclinal structures, indicative of basement uplifts, affected the sequence in the Early to Middle Jurassic. The depositional and tectonic setting for these rocks is inferred to be a tectono-magmatic rift. In Victoria Land silicic volcanism and vertical movements occurred before onset of basaltic activity. Magmatic activity in the Jurassic was associated with vertical tectonism that was expressed by basement uplifts and development of significant topography. -from Authors

Publication Title

Gondwana Eight: assembly, evolution and dispersal. Proc. 8th Gondwana symposium, Hobart, 1991

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