Geophysics and Geodynamics Research at
Research in Progress
Geodynamic Models of the West
Antarctica
The West Antarctica Rift System is an unusually
wide zone of extension between the Transantarctic Mountains and Marie Byrd Land. Extension
Began in Late Cretaceous time and continued into late Paleogene. An unusual aspect of rifting
in West Antarctic is the transition from a prolonged period of diffuse extension that was
followed by a later shorter episode of more focused rifing in teh Victoria Land Basin, adjacent
to the Transantarctic Mountains. We attribute the period of diffuse extension to slow extension
rates. This allowed the lithosphere to cool during extension, promoting a continually shifting locus
of extension in throught West Antarctica. During this period, the portion of West Antarctica adjacent
to the Transantarctic Mountains underwne little extension because it was comparatively cool, and
hence strong. The cooler lithosphere in this area was due to a refrigeration effect from the adjacent,
older East Antarctica craton. Ultimately, the colling lithosphere in west Antarctica became stronger
than the region adjacent to the East Antarctica craton, and the locus of extension shifted and became
more foused in this region.
This research is described in Huerta, A. and Harry, D.L., The transition from diffuse to focused
extesion: Modeled evolution of the West Antarctica Rift System, EPSL, 255, 133-147.