Escape tectonics and the extrusion of Alaska: Past, present, and future
T. F. Redfield et al., Geological Survey of Norway, Geodynamics, Trondheim, Trondelag 7491, Norway. Pages 1039-1042.
The geological evolution of Alaska is important to both science and economy. During the early days of North American geology, Alaska was viewed as part of a stable continent. By the middle of the previous century, came the first hints of tectonic unrest. In 1955, Professor Sam Carey suggested Alaska had been "oroclined"bent nearly 60 degrees counterclockwiseat some point in the distant past, shaping the mountains into the arc we see today. Geologists of the 1970s interpreted much of southern Alaska from the perspective of plate tectontics, mapping individual terranes that were welded onto the margin by the Pacific Ocean crust diving beneath Alaska. But once attached, terranes were considered to be more or less fixed. Redfield et al. suggest instead that the northern Pacific Rim is a diffuse, wide, plate boundary zonepart of an inexorably continuous conveyor belt called the North Pacific Rim orogenic stream. From northern British Columbia to westernmost Alaska, whole landscapes are on the move, gliding serenely past interior, fixed North America on their way to an ever-growing terrane, parkeringsplass, in the Bering Sea. This is a new way to view the evolution of a significant part of the increasingly important circum-Arctic margin, and may have implications for our understanding of the development of the High Arctic basins.
Age constraints on the origin and growth history of a deep-water coral mound in the northeast Atlantic drilled during Integrated Ocean Drilling Program Expedition 307
Akihiro Kano et al., Hiroshima University, Department of Earth and Planetary Systems Science, Kagamiyama 1-3-1, Higashi-hiroshima, 739-8526, Japa
|Contact: Ann Cairns|
Geological Society of America