Iberia to Siberia: The single-plate GAD test for the late Permian/early Triassic of Eurasia

One of the few ways of checking the geocentric axial dipole (GAD) model for geological times older than the sea-floor spreading record is the so-called single-plate method, which compares contemporaneous paleopoles from widely separated sites on a single continental block. An excellent opportunity to carry out this test is provided by Eurasia during the late Permian/early Triassic, when it was a continuous land mass spanning the whole range of paleolatitudes from equator to pole. The most robust results yield a patttern of inclinations that does not favour any simple model consisting of zonal terms up to order three (dipole, quadrupole, octupole). Low paleolatitude sites are in reasonable agreement with a GAD field, mid-paleolatitude sites are biassed towards "far-sidedness", and high-paleolatitude sites are biassed towards "near-sidedness". We conclude that the Eurasian data currently available do not warrant any modification to the GAD model for late Permian/early Triassic times.