A paleomagnetic investigation of Jurassic Kirkpatrick Basalt flows from South Victoria Land, Antarctica

Abstract

Eleven flows of the Jurassic Kirkpatrick Basalt Group were sampled from Brimstone Peak (75.82°S, 158.55°E) for paleomagnetic investigation. Magnetic propreties indicate that the primary magnetization is a TRN with very stable pseudo-single domain behavior. NRM directions do not appear to be strongly affected by the present geomagnetic field. After AF demagnetization, the flow mean poles clustered well with a-95 = 3.6° and k = 163. The VGP determined from these poles is located at 55.5°S, 218.2°W. All magnetizations are upward, which indicates normal polarity. The Kirkpatrick Basalt Group, and the Ferrar Supergroup of which it is a member, outcrop in Victoria Land and along the central Transantarctic Mountains. These rocks are geochemically associated with other Jurassic tholeiites in Dronning Maud Land. The VGP for Brimstone Peak is consistant with VGP's reported for the Ferrar Supergroup and the tholeiites from Dronning Maud Land. A new VGP for these Jurassic tholeiites, as calculated from six reliable poles, is 53.3°S, 142.0°W with a-95 = 3.6° and k = 163.