PERMIAN-TRIASSIC BOUNDARY IN THE CENTRAL TRANSANTARCTIC MOUNTAINS, ANTARCTICA

Abstract

The Permian-Triassic boundary occurs within a relatively complete terrestrial sequence in the Shackleton Glacier area of the central Transantarctic Mountains. The boundary is within a 7- to 10-m-thick interval between the Permian Glossopteris flora and the Lower Triassic Lystrosaurus fauna. This interval, representing on the order of 200 k.y., records some of the events that occurred in the transition from the Permian to Triassic. In the best-documented section at Graphite Peak in the Beardmore Glacier region, Photohaploxypinus microcorpus zone palynomorphs, which we assign to the latest Permian, record the declining Glossopteris flora and occur near the top of the Buckley coal measures, just below a previously reported major negative δ 13C excursion. In the Shackleton Glacier area, the Permian Glossopteris flora, including fossil wood, roots, and leaves, occurs within the lower part of the Fremouw Formation. The Antarctic Lystrosaurus assemblage of Early Triassic age has several species in common with the South African fauna that lived 20° to 35° closer to the equator. The migration of vertebrates from southern Africa into Antarctica in the Early Triassic supports hypotheses of runaway greenhouse warming possibly related to CO2 emissions from Siberian flood basalts and large methane gas releases. Changes in flora bracketing the first of the major negative δ13C anomalies near the boundary in Antarctica and in East Greenland support the hypothesis that a global event, perhaps through mutations caused by enhanced ultraviolet radiation, may have played a role in the destruction of floras. © 2006 Geological Society of America.