HR: 10:35h
AN: T22C-02    [Abstracts]
TI: Rifting of Continental Interiors: Some New Geophysical Data and Interpretations
AU: * Keller, G R
EM: keller@utep.edu
AF: University of Texas at El Paso, Department of Geological Sciences, El Paso, TX 79968 United States
AB: Rifting is one of the major processes that affect the evolution of the continents. This process sometimes leads to continental breakup and the formation of new oceans, but more often does not. This is presumably due to extension not progressing sufficiently to form a new plate margin resulting in a structure, which remains isolated in an intra-plate environment. The Southern Oklahoma aulacogen is such a feature, and the continental portion of the East African rift system may be a modern example. As more detailed geophysical and geological studies of rifts have become available in recent years, a complex picture of rift structure and evolution has emerged. Global patterns that reveal the connections between lithospheric structure (deep and shallow), magmatism (amount and style), amount of extension, uplift, and older structures remain elusive. However, our geophysical studies of modern and paleo rifts in North America, East Africa, and Europe makes it possible to make some general observations: 1). Magmatism in rifts is modest without the presence of a (pre-existing?) thermal anomaly in the mantle. 2). Magmatic modification of the crust takes many forms which probably depend on the nature of older structures present and the state of the lithosphere when rifting is initiated (i.e. cold vs. hot; fertility), 3) There is no clear relation between amount of extension and the amount of magmatic modification of the crust. 4) Brittle deformation in the upper crustal is complex, often asymmetrical and older features often play important roles in focusing deformation. However on a lithospheric scale, rift structure is usually symmetrical. 5) A better understanding of rift processes is emerging as we achieve higher levels of integration of a wide variety of geoscience data.
DE: 7205 Continental crust (1219)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8110 Continental tectonics: general (0905)
SC: Tectonophysics [T]
MN: Fall Meeting 2005