Tectonics and plate-kinematics of the South Pacific and West Antarctica

• Main Authors: Gohl, Karsten, Eagles, G.
• Format: Conference Object
• Language: unknown
• Published: 2005
• Subjects: Antarctic; Byrd; Marie Byrd Land; New Zealand; Pacific; Thurston; Thurston Island; West Antarctica; Antarc*; Antarctica
• Online Access: https://epic.awi.de/id/eprint/13433/; https://hdl.handle.net/10013/epic.23815

Accurate plate-kinematic reconstructions at relatively highspatial and temporal resolution are the basis for understanding theopening of ocean basins and the evolution of seafloor relief and theeffect it has had on controlling deep ocean current directions. Wedeveloped an animated, grid-based plate-kinematic reconstruction of thesouthern Pacific Ocean from 90 Ma to present, using thesatellite-derived gravity anomaly field, and interpolated isochrons andplate rotation parameters from both published and new studies usingmarine geophysical data.The earliest opening with formation of seafloor between Chatham Rise(New Zealand) and Thurston Island (West Antarctica) occurred at 92-90 Maalong a Pacific-Antarctic plate boundary developing along the BountyTrough and Great South Basin of New Zealand. The break-up betweenCampbell Plateau and Marie Byrd Land began at 83 Ma. The onset of anindependent motion of the Bellingshausen Plate adjacent to the WestAntarctic margin can be estimated at 79 Ma. Its motion generated atranspressional eastern plate boundary. The Pacific-Bellingshausenspreading centre developed a set of long offset transform faults (e.g.Udintsev, Tharp, Heezen) that the Pacific-Antarctic plate boundaryinherited around 61 Ma when the Bellingshausen plate ceased to moveindependently as part of a Pacific-wide plate tectonic reorganizationevent. Southwest of these transforms, the Pacific-Antarctic Ridge saw anincrease in transform-fault segmentation by about 58 Ma. At about 47 Ma,the Pacific-Phoenix Ridge jumped northward to directly link thePacific-Antarctic ridge to the Pacific-Farallon ridge as a result of anunstable Pacific-Antarctic-Phoenix triple-junction configuration.Further reconstruction time steps illustrate the development of thedominant transform and fracture zones systems in the South Pacific.