A new Late Middle Cambrian paleomagnetic pole for the Ellsworth Mountains,Antarctica

A paleomagnetic study of the late Middle to possibly early Late Cambrian Li berty Hills Formation in the Ellsworth Mountains, Antarctica, reveals a sta ble magnetization with positive fold and reversal tests. The paleopole is b ased on 16 sites from volcanic and sedimentary rocks and lies at lat 7.3 de grees N and long 326.3 degrees E (A(95) = 6.0 degrees). The new paleomagnet ic data support the view that the Ellsworth Mountains are part of a micropl ate-the Ellsworth-Whitmore Mountains crustal block-that rotated independent ly of the main Gondwana continental blocks during breakup. The Liberty Hill s pole differs from both previous poles recovered from Cambrian rocks in th e Ellsworth Mountains and from the available Gondwana reference pole data. Our pole indicates a more northerly prebreakup position for the Ellsworth M ountains than previously suggested, contradicting the overwhelming geologic evidence for a prebreakup position close to southern Africa. The reasons f or this are uncertain, but we suggest that problems with the Gondwana appar ent polar wander path may be important. More well constrained, early Paleoz oic paleomagnetic data are required from the Ellsworth Mountains and the Go ndwana continents ii the data are to constrain further the Middle-Late Camb rian location of the Ellsworth-Whitmore Mountains block.