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

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 simi lar to 55 Ma BP was associated with extension in the Ross Sea Basin and som e surface uplift of the Royal Society Range probably occurred at this time. Extrapolation of fission-track data for other sectors of the Transantarcti c Mountains, coupled with a reconstruction of pre-rift stratigraphy, indica tes that a seaward-thickening wedge of crustal section up to similar to 6 k m at the coast has been removed since rifting. Much of this crustal strippi ng probably occurred in the early Cenozoic, and cosmogenic isotope data tog ether with Ar-40/Ar-39-dated volcanic cones and surficial ashes demonstrate that denudation over much of the Royal Society Range has been insignifican t since the mid-Miocene. This denudation probably occurred primarily throug h 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 constr ains 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 bet ween the denudational and surface uplift histories of the Royal Society Ran ge and the adjacent Dry Valleys area show that the latter has not experienc ed an unusual tectonic and glacial history, as has been previously suggeste d. 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. (C) 1999 Elsevier Science B.V. All rights reserve d.