EARLY CRETACEOUS PALEOMAGNETIC RESULTS FROM MARIE-BYRD-LAND, WEST ANTARCTICA - IMPLICATIONS FOR THE WEDDELLIA COLLAGE OF CRUSTAL BLOCKS

A new similar to 117 Ma paleomagnetic pole has been defined from the s tudy of volcanic and plutonic rocks from the eastern portion Marie Byr d Land (MBL). The new pole (185.6 degrees E/56.8 degrees S, A(95) = 8. 7 degrees) implies that the eastern portion of MBL was an integral par t of Weddellia, which included the ancestral Antarctic Peninsula, Thur ston Island, and Ellsworth-Whitmore Mountains blocks of West Antarctic a. This pole is generally similar to a similar to 125 Ma pole from Thu rston Island, Both poles call for major clockwise rotation and polewar d motion of eastern MBL and Thurston Island between the Early Cretaceo us (125-117 Ma) and the mid-Cretaceous (110-100 Ma). We propose that i n the Early Cretaceous, eastern MBL and the Eastern Province of New Ze aland were part of a continuous active Pacific margin of Gondwana, con necting with the Antarctic Peninsula, and distinct from western MBL, t he Western Province of New Zealand, and North Victoria Land. These wes tern terranes are thought to have accreted to Gondwana in the Devonian . Eastern MBL and the Eastern Province of New Zealand amalgamated with western MBL and the Western Province of New Zealand by the mid-Cretac eous. Major Early Cretaceous motions of the Weddellia blocks postdate the estimated initiation of seafloor spreading in the Weddell Sea and therefore may be the result of plate reorganization during the Cretace ous Quiet Zone.