| The West Antarctic margin of Gondwanaland has experienced a long, complex history. A combination of paleomagnetism, structural field mapping, microprobe analysis, microfabric analysis and ;Detailed field mapping was conducted on the subduction complexes of the Scotia Metamorphic Complex (SMC) on Smith Island and Elephant Island (Antarctica). Smith Island consists entirely of blueschist tectonites. Elephant Island rocks consist of greenschist, blueschist and albite-epidote amphibolite facies schists. Polyphase ductile deformation characterizes the Smith Island and Elephant Island tectonites. Microprobe analyses indicate that the blue amphiboles from both areas are primarily crossite. Pressure-temperature estimates for Smith Island blueschist metamorphism are ;The ;West Antarctica is composed of four crustal blocks whose relationship to East Antarctica and to each other throughout the Phanerozoic is not well known. These blocks are: the Ellsworth-Whitmore Mountains (EWM); the Antarctic Peninsula (AP); Thurston Island (TI); Marie Byrd Land (MBL). Paleomagnetic sampling and analysis were conducted on rocks from the EWM and TI blocks in the hope of constraining the motion of these blocks and the opening history of the Weddell Sea. The paleomagnetic results suggest that the AP, EWM and TI blocks have moved relative to East Antarctica prior to the mid-Cretaceous and that the main opening of the Weddell Sea was between the Early and mid-Cretaceous. |
