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

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.

Name thesis:degree_name

Earth and Planetary Sciences

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Department of Earth and Planetary Sciences

Year

2012

Author dc:creator

• Nereson, Alexander

Contributors dc:contributor

• Karlstrom, Karl
• Scuderi, Louis
• Crossey, Laura

• dynamic topography
• landscape evolution
• argon geochronology
• Jemez lineament

Language dc:language

English

Identifier

https://digitalrepository.unm.edu/eps_etds/58

OAI identifier oai:identifier

oai:digitalrepository.unm.edu:eps_etds-1057