Monday, 27 August 2007 - 1:55 PM
1.P1.C-2

The Ellsworth Mountains: Critical and enduringly enigmatic

Ian W. D. Dalziel, Institute for Geophysics, University of Texas at Austin, 10100 Burnet Rd., Bldg. 196 (R2200), Pickle Research Campus, Austin, TX 78758-4445

The Ellsworth Mountains, first mapped under the leadership of Campbell Craddock, pose critical geological enigmas, solved and unsolved. The isolation of the mountains, their abrupt structural terminations and Paleozoic stratigraphic affinities are explained by rotation from the cratonic margin during Gondwanaland breakup. The mechanism remains obscure. Absence of intense folding associated with the Ross orogeny can be ascribed to local extension along a subducting margin. Yet tantalizing questions regarding possible Precambrian connections to Laurentia remain, and the cause of the post-Permian folding is controversial.

The elevation (~5000m) is high for an early Mesozoic fold belt. Thermal uplift could have been initiated during Jurassic-Cretaceous block rotation and Weddell Sea opening continuing into the Cenozoic. The history of glaciation provides input for models of ice loading and unloading. Measurements of present-day uplift test these models and help assess change in the mass of the ice sheet and hence in global sea level.

[Manuscript]