Geophysical Investigations of the Tectonic Boundary Between East and West Antarctica

Abstract

The Transantarctic Mountains (TAM), which separate the West Antarctic rift system from the stable shield of East Antarctica, are the largest mountains developed adjacent to a rift. The cause of uplift of mountains bordering rifts is poorly understood. One notion based on observations of troughs next to many uplifted blocks is that isostatic rebound produces a coeval uplift and subsidence. The results of an over-snow seismic experiment in Antarctica do not show evidence for a trough next to the TAM but indicate the extension of rifted mantle lithosphere under the TAM. Furthermore, stretching preceded the initiation of uplift, which suggests thermal buoyancy as the cause for uplift.

Paleomagnetic Tests of Pacific Plate Reconstructions and Implications for Motion Between Hotspots

“…The rocks that form these mountains have risen -5 km since 50 Ma at an average rate of -100 m/My (53). The uplift is thought to be a flexural or thermal response to extension (54,55). Other evidence for extension between East and West Antarctica since -70…”

Surface exposure geochronology using cosmogenic nuclides : applications in Antarctic glacial geology

“…Given the ease and reduced sample size requirements of 3 He analysis relative to 10Be analysis (e.g., Brook and Kurz, 1993 [Chapter 3]; Chapter 2), and uncertainty about the age at which 3 He loss becomes significant to exposure dating, further comparison of 3 He and 1 0 Be exposure ages in quartz was also undertaken. Finally, the recent controversy over the age of the Sirius Group and its implications for the uplift history of the TAM and the glacial history of Antarctica (Clapperton and Sugden, 1990;Webb and Harwood, 1991;McKelvey et al, 1991;ten Brink et al, 1993;Marchant, 1993;Barret et al, 1993;Wilch et al, 1993) Preliminary work in other parts of the Transantarctic Mountains suggests that this behavior is a regional phenomenon ). This conceptual model suggests that ice growth in East Antarctica is "out of phase" with northern hemisphere glaciation and the deep sea oxygen isotope record .…”

Age and uplift rates of Sirius Group sediments in the Dominion Range, Antarctica, from surface exposure dating and geomorphology

“…In contrast, regional evidence for recent motion on the rift flank longitudinal normal faults is lacking. Seismic imaging of the transition from the rift shoulder to the off shore at Robb Glacier, shows no evidence of displacement of sedimentary strata (ten Brink et al, 1993). However, it can be argued that these results from the nearby Holland Range block do not place strong constraints on the Dominion Range which occurs within the Beardmore transverse boundary between the Queen Alexandra and Commonwealth blocks (Fitzgerald, 1994).…”