Marginal marine depositional setting and correlation of the Devonian Sperm Bluff Formation (Taylor Group), southern Victoria Land, Antarctica

• Published in: Antarctic Science
• Main Authors: Savage, Jeni E., Bradshaw, Margaret A., Bassett, Kari N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2013
• Subjects: Altar Mountain; Bull Pass; Mackay; Mackay Glacier; Mount Suess; New Mountain; Sperm Bluff; Victoria Land; Antarc*; Antarctic Science; Antarctica
• Online Access: http://dx.doi.org/10.1017/s0954102013000205; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102013000205

Abstract Analysis of conglomerates and sandstones of the Sperm Bluff Formation at the base of the Taylor Group (Devonian) between the Mackay Glacier and Bull Pass provides new insights into the nature of initial coarse-grained deposition on basement along the northern side of the McMurdo sedimentary basin. Six lithofacies are recognized in the Sperm Bluff Formation: conglomerate lithofacies, pebbly sandstone lithofacies, cross-bedded sandstone lithofacies, low-angle cross-stratified sandstone lithofacies, bioturbated sandstone lithofacies and interbedded siltstone/sandstone lithofacies. Sedimentary environments ranged from wave-dominated delta, estuary or lagoon to shoreface and inner shelf. The assemblage is thought to reflect changes in sea level. Rhyolite is the most abundant clast type in the coarse lithofacies, but is unknown in outcrop in southern Victoria Land. The rhyolites correlate in age and geochemistry with Cambrian granites in the basement. Coarse beds also contain numerous quartzite clasts, probably derived from the late Precambrian Skelton Group. Palaeocurrents on Mount Suess indicate a strong unimodal flow to the west, but other sites show polymodal palaeoflow. The Sperm Bluff Formation is correlated with Terra Cotta Siltstone, New Mountain Sandstone and Altar Mountain formations based on the lithology of sandstones and their ichnology. A northward onlap during the Early Devonian is indicated.