TOPOGRAPHY AND TECTONIC INHERITANCE OF OROGENIC PLATEAUS

Detailed analysis of Earth's topography can provide important information about the geodynamic history of a region, particularly the interaction between the formative (deterministic)and destructive/erosional (chaotic) processes that sculpt the landscape. The relationship between landscapes and tectonic inheritance, especially in regions of modern or ancient orogenic plateaus, is complex and depends on a number of factors. Influential parameters that exert the greatest control on surface topography include the type, strength, and geometry of inherited tectonic features, that in turn control observable topographic characteristics such as clustering, organization, flatness and grain orientation.

Quantitative topographic analyses can help constrain the influence of inherited tectonics. Motivation for this approach comes from recent studies which show that: 1)topographic spectral power decreases systematically as the tectonic age of the underlying crust increases; 2)mean local relief, mean elevation, and thermo-chronologically-determined exhumation history vary systematically across major Paleozoic accretionary boundaries; 3)Neogene and ongoing rock-uplift is being driven by the creation of mantle buoyancy; and 4)a correlation exists between topography and such deep crustal features as mantle velocity structure, crustal thickness, and Precambrian crustal provinces.

Here we present the results of a quantitative analysis of the topographic roughness, organization, flatness, clustering, grain and spectral power from a 30-arc-second topographic digital elevation model in an effort to evaluate the characteristic topographic signatures associated with the principal tectonic features in the Western U.S. Our preliminary results indicate that inherited features, defined on the basis of geologic and geophysical characteristics are also uniquely defined by topographic characteristics that reflect their tectonic development. In addition to the ancestral Sevier plateau, our correlation also extends to tectonic features such as the major Precambrian crustal sutures, the Saint George and Jemez Lineaments, and the Cheyenne Belt. Finally, we explore the applicability of this technique to other orogenic plateaus such as in the Andes, Appalachians, and Pyrenees, and evaluate the tectonic-topographic corelations on several scales.