Involvement of deep crust in extension of Basin and Range province
David A. Okaya, George A. Thompson, 1986. "Involvement of deep crust in extension of Basin and Range province", Extensional Tectonics of the Southwestern United States: A Perspective on Processes and Kinematics, Larry Mayer
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Although geologic and reflection seismic studies are making rapid strides in defining the geometry and indicating the processes involved in upper crustal extension of the Basin and Range province, fundamental processes in the deeper crust and the upper mantle are still poorly constrained. We summarize interrelated gravity, elevation, isostatic, and geologic evidence to suggest that the convective mass circuit of rifting is completed partly within the crust by intrusion of material of crustal density from the mantle. If this interpretation is correct, mechanical thinning of the crust by extension, especially in highly extended terranes of the Basin and Range province, is somewhat reduced by additions of new crust. Conceptual models for links between upper crustal faulting-stretching and deeper crustal igneous dilation are presented. The deeper crust has probably been profoundly changed by metamorphic reaction and partial melting.