LATE GONDWANIDE TECTONIC ROTATIONS WITHIN GONDWANALAND

Geologic and paleomagnetic evidence from the Ellsworth-Whitmore mountains crustal block of West Antarctica, and from the Falkland Islands of South America, indicates that tectonic displacement of major portions of the "Samfrau geosyncline" occurred after the early Mesozoic Gondwanide folding but prior to seafloor spreading. Comparison with continental deformation in the collisional Alpine-Himalayan belt offers a mechanism for the displacements while supporting the hypothesis that the Gondwanian orogeny resulted from collision of a fore-arc and magmatic arc terrane with the Panthalassic margin of the Gondwana craton during closure of a marginal basin. The displacements had major consequences for the ensuing evolution of the South Atlantic-Weddell Sea-Ross Sea region.