Research Objectives:
Displacements between East and West Antarctica have long been proposed based on global plate circuits, apparent hot-spot motions, geologic grounds, seafloor magnetic anomalies, or paleomagnetism. Such motions require plate boundaries that cross Antarctica, yet these boundaries have never been explicitly defined.
We will attempt to delineate the late Cenozoic boundary between East and West Antarctica along the Terror Rift in the western Ross Sea by using marine and airborne geophysical data to map the fault patterns and volcanic structure along the eastern margin. We will also map the orientations of volcanic fissures and seamount alignments on the seafloor. The volcanic alignments will show the regional extension or shear directions across the rift and the orientations of associated crustal stresses.
Delineation of neotectonic fault patterns will demonstrate whether the eastern margin of the rift forms a continuous boundary and whether the rift itself can be linked with postulated strike-slip faults in the northwestern Ross Sea. We will combine seafloor findings with fault kinematic and stress field determinations from the surrounding volcanic islands and the Transantarctic Mountains.
Over 3 years, we will complete a collaborative structural analysis of existing multichannel and single-channel seismic profiles and aeromagnetic data over the Terror Rift, locating volcanic vents or fissures and any fault scarps on the seafloor and making a preliminary determination of the age and kinematics of deformation in the Terror Rift. We will then carry out multibeam sonar mapping of selected portions of the seafloor and use these data to map the orientations and forms of volcanic bodies and the extent and geometry of neotectonic faulting associated with the Terror Rift.
In summary, we will
+ Complete a map of neotectonic faults and volcanic structures in the Terror Rift,
+ Interpret the structural pattern to derive the motions and stresses associated with the development of the rift,
+ Compare rift structures with faults and lineaments mapped in the Transantarctic Mountains to improve age constraints on the structures, and
+ Integrate the late Cenozoic structural interpretations from the western Ross Sea with Southern Ocean plate boundary kinematics.
