THERMAL REJUVENATION OF THE YERMAK PLATEAU

The Yermak Plateau, bordering the Arctic Ocean and the Norwegian-Green land Sea, and adjacent to the continental Svalbard Archipelago, is cha racterized by high heat flow relative to its surrounding region. South of and parallel to the trend of the plateau lies the formerly active- Spitsbergen Shear Zone (De Geer Zone), which is now occupied by the sl owly spreading Knipovich and Molloy Ridges. An analysis of these heat flow data suggest that asymmetric spreading within the Norwegian-Green land Sea propagated northwards along one of the faults associated with the Spitsbergen Shear Zone. The broad zone of faults, once associated with this paleo-shear zone, extends throughout Svalbard as well as on and to the west of the Knipovich Ridge. This network of faults may co mprise a complex system of detachment surfaces along which magma may r ise from a deep-seated source and across which simple shear extension may develop. Dike injection into the Yermak Plateau, north of the prop agating ridge may have been initiated by the thermal response of the h ighly fractured lithosphere to this propagating asthenospheric front. We suggest that one of these faults, acting as a secondary detachment to the main fault underlying the Knipovich Ridge, may be dissecting th e Yermak Plateau. Based on an analysis of the thermal data, simple she ar extension may have been taking place along a broad zone of intrusio n. This region has undergone and is probably still undergoing thermal rejuvenation. Multiple zones of intrusion may be a common phenomena al ong newly rifted continental margins especially when they have been su bstantially faulted prior to rifting.