A New Apparent Polar Wander Path for Antarctica
Luigi Jovane1-2, Gary Acton1, Kenneth L. Verosub1, Fabio Florindo2, Leonardo Sagnotti2, Andrew P. Roberts3 and Gary Wilson4
1 Department of Geology, University of California, Davis, CA, 95616, USA
2 Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143, Roma, Italy
3 National Oceanography Centre, University of Southampton, European Way, Southampton SO14-3ZH, UK
4 Geology Department, University of Otago, P.O. Box 56, Dunedin, New Zealand
The apparent polar wander path (APWP) for Antarctica contains very few paleomagnetic observations and is probably the most poorly constrained APWP for any of the major lithospheric plates. The poor coverage and temporal distribution of paleomagnetic studies can be attributed to the sparse occurrence of outcrops and to the small number of deep drill cores that have been collected on the continent and surrounding oceans, in part because of high costs and logistical difficulties. In addition, although studies of the Antarctic APWP have not received much attention, global plate reconstructions that link Pacific basin plates to the plates in the Indian and Atlantic Oceans must pass through Antarctica. Understanding the past position and motion of the Antarctic plate is therefore important for plate reconstructions and has implications for geodynamic, geomagnetic, and paleoclimatic studies.
We are attempting to refine the Antarctic APWP along Cenozoic by using inclination data from DSDP Sites 270 and 274, ODP Sites 689, 690, 738, 744, 748, 1095, 1096, 1101, 1165, 1166, 1167, and the Sedano, Wega, CIROS-1 and CRP-1, 2 and 3 drill cores. Several of these sites have high sedimentation rates and detailed magnetostratigraphy, which provide high-resolution observation and well-constrained ages. We first divided each of these datasets into several time subunits based on sedimentation rate, data availability and lithological discontinuities and have then combined coeval subunits from different cores. This procedure allows us to estimate paleocolatitudes and “relative” virtual geomagnetic poles (VGPs) along with their confidence limits. The paleocolatitudes from all cores of a given age or time period define multiple small circles of possible paleomagnetic pole positions, and their intersection defines the most probable position of the pole. Angular dispersion of the inclination averages has also been calculated in order to test for secular variation and the goodness of the sampling.
