Mid-Cretaceous paleomagnetic results from Marie Byrd Land, West Antarctica: a test of post-100 Ma relative motion between East and West Antarctica

Oriented samples were collected for palaeomagnetic analysis from mid-Cretaceous (circa 100 Ma) intrusive rocks at sampling localities across 350 km of the Ruppert and Hobbs Coast area of Marie Byrd Land, West Antarctica. Palaeomagnetic results are presented along with several lines of evidence, including a positive tilt test based on the attitude of circa 117 Ma volcanic rocks that the circa 100 Ma rocks intrude, which argue that these results are a representative estimate of the mid-Cretaceous magnetic field in Marie Byrd Land. Though the paleomagnetic estimate for east-west Antarctic relative motion may be reconciled with geologic estimates for extensions in the Ross Sea at the extremes of the error envelope, the best paleomagnetic estimate of relative motion suggest a larger amount of total extension between East and West Antarctica than previously suspected. -from Authors