Landscape development in the Royal Society Range, southern Victoria Land, Antarctica: stability since the mid-Miocene

Abstract

Post-rifting landscape development in the Royal Society Range, a rift-flank block in the southern Victoria Land sector of the Transantarctic Mountains, has been reconstructed through a combination of morphological mapping and geochronological data. Creation of the Royal Society Range rift flank ∼55 Ma BP was associated with extension in the Ross Sea Basin and some surface uplift of the Royal Society Range probably occurred at this time. Extrapolation of fission-track data for other sectors of the Transantarctic Mountains, coupled with a reconstruction of pre-rift stratigraphy, indicates that a seaward-thickening wedge of crustal section up to ∼6 km at the coast has been removed since rifting. Much of this crustal stripping probably occurred in the early Cenozoic, and cosmogenic isotope data together with 40 Ar/ 39 Ar -dated volcanic cones and surficial ashes demonstrate that denudation over much of the Royal Society Range has been insignificant since the mid-Miocene. This denudation probably occurred primarily through fluvial processes, and the generally limited impact of subsequent glacial action has led to the preservation of elements of the pre-glacial fluvial landscape. The present elevation of a sub-aerially erupted lava flow constrains maximum surface uplift in the Royal Society Range over the past 7.8 Ma to less than 67 m, assuming present sea level as a datum. Similarities between the denudational and surface uplift histories of the Royal Society Range and the adjacent Dry Valleys area show that the latter has not experienced an unusual tectonic and glacial history, as has been previously suggested. Our analysis strongly supports the notion of a stable East Antarctic Ice Sheet and minimal landscape modification in the Royal Society Range since at least the mid-Miocene.