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Dynamic topography of the western Great Plains : geomorphic and 40Ar/39Ar evidence for mantle-driven uplift associated with the Jemez lineament, New Mexico and SE Colorado

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/20997

Dynamic topography of the western Great Plains : geomorphic and 40Ar/39Ar evidence for mantle-driven uplift associated with the Jemez lineament, New Mexico and SE Colorado

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Title: Dynamic topography of the western Great Plains : geomorphic and 40Ar/39Ar evidence for mantle-driven uplift associated with the Jemez lineament, New Mexico and SE Colorado
Author: Nereson, Alexander
Advisor(s): Karlstrom, Karl
Committee Member(s): Scuderi, Louis
Crossey, Laura
Department: University of New Mexico. Dept. of Earth and Planetary Sciences
Subject(s): dynamic topography
landscape evolution
argon geochronology
Jemez lineament
LC Subject(s): Neotectonics--Great Plains.
Erosion--Great Plains.
Climatic geomorphology--Great Plains.
Epeirogeny--Great Plains.
Volcanism--New Mexico.
Degree Level: Masters
Abstract: The causal mechanisms for the onset and patterns of post-Miocene erosion of the western Great Plains remain the subject of an enthusiastic debate between the roles of climatically-modulated geomorphic parameters and tectonic rock uplift as drivers of long-term erosion. This study distinguishes between these drivers on the plains of New Mexico and Colorado where post-Miocene erosion and late Cenozoic volcanism of the Jemez lineament have produced distinctive modern landscapes characterized by deep bedrock canyons and inverted, basalt-capped mesas. 40Ar/39Ar ages are used to define an episodic eruption history in the Raton-Clayton volcanic field and to quantify denudation rates from flow-capped paleosurfaces. Several datasets indicate patterns of surface topography that are consistent with dynamic rock uplift along a NE-trending flexural bulge above the Jemez low-velocity mantle anomaly, but are not well-explained by climate. They include: (1) crude volcanic “belts” of similar age, (2) retreating erosional escarpments, (3) differential landscape denudation measured from a NE-trending hinge-line of “low-to-no” erosion, (4) a NE-trending zone of broad (50-100km) convexities in stream profiles identified by an analysis of channel steepness (5) reorganization of stream networks from ESE-flowing streams, to a SSE flowing Canadian River that takes advantage of a relative base level fall in the SE, and (6) a ~150-km-long, 40Ar/39Ar-dated composite paleosurface which indicates total tilting of 64 millidegrees/Ma (and ~34 millidegrees/Ma of tectonic tilting) since 3.4 Ma. Proposed mantle-driven rock uplift along the NE-trending Jemez zone is overprinted on N-S trending mid-Tertiary uplift of the Rocky Mountain orogenic plateau relative to the Great Plains.
Graduation Date: July 2012
URI: http://hdl.handle.net/1928/20997

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