This award will support an investigation of transverse geologic structure within the Transantarctic Mountains (TAM), a major intracontinental mountain belt that developed along the crustal boundary between the subcontinents of East and West Antarctic. The TAM appear to be a rift-margin uplift related to extensional tectonism within the Antarctic Plate during the Mesozoic and Cenozoic. Offsets in the TAM suggest an along-strike structural segmentation analogous to that seen in other continental rift systems. In contrast to other rift systems, however, there is no change in tilt direction between segments, and transverse structures in the TAM are associated with physiographic troughs that may represent tensional "pull apart" zones. Kinematic analysis will establish the displacement direction(s) associated with these structures, and provide a test for models invoking extension and translation between East and West Antarctica during rift development. Documentation of the positions and character of these transverse structures will provide a 3-D picture of the rift system that will constrain process- oriented models of rift development and TAM uplift. Comparison of TAM segmentation with that of other rift systems will serve to evaluate controls on along-axis rift propagation as continental lithosphere is stretched prior to breakup.
