(U-Th)/He thermochronologic constraints on the evolution of the northern Rio Grande Rift, Gore Range, Colorado, and implications for rift propagation models
Rachel L. Landman and Rebecca M. Flowers, Dept. of Geological Sciences, University of Colorado, Boulder, Colorado 80309, USA. Posted online 17 Dec. 2012; http://dx.doi.org/10.1130/GES00826.1.
The Rio Grande rift system is a zone of intracontinental extension that tapers northward into the center of the southern Rocky Mountains. Near its northern end, the rift is located in a region that contains some of the highest peaks in the Rockies. However, relationships between the rifting process and development of the Rocky Mountains are not well understood. The notion persists that the Rio Grande rift propagated northward in late Cenozoic time, with this propagation proposed as a possible cause of late Cenozoic uplift of the Rocky Mountains. This study by Rachel Landman and Rebecca Flowers of the University of Colorado Boulder uses low-temperature thermochronology to constrain the uplift and exhumation history of the Gore Range, a rift-flank uplift at the northern end of the rift in central Colorado. Their results show that the mid-Tertiary and younger history of the Gore Range area is similar to histories inferred along the rest of the rift to the south, suggesting that the onset and evolution of the Rio Grande rift were roughly synchronous along its length. This conclusion demonstrates that the idea of a northward propagating rift is a misconception.
Detrital zircon age distributions as a discriminator of tectonic versus fluvial transport: An example from the Death Valley, USA, extended terrane
Nathan A. Niemi, Dept. of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. Posted online 17 Dec. 2012; <
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