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University of New Mexico UNM Digital Repository Earth and Planetary Sciences ETDs Electronic Theses and Dissertations 7-1-2014 STRUCTURAL EVOLUTION OF THE RIO GRANDE RIFT: SYNCHRONOUS EXHUMATION OF RIFT FLANKS FROM 20-10 MA, EMBRYONIC CORE COMPLEXES, AND FLUID-ENHANCED QUATERNARY EXTENSION Jason Ricketts Follow this and additional works at: https://digitalrepository.unm.edu/eps_etds Recommended Citation Ricketts, asJ on. "STRUCTURAL EVOLUTION OF THE RIO GRANDE RIFT: SYNCHRONOUS EXHUMATION OF RIFT FLANKS FROM 20-10 MA, EMBRYONIC CORE COMPLEXES, AND FLUID-ENHANCED QUATERNARY EXTENSION." (2014). https://digitalrepository.unm.edu/eps_etds/70 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Earth and Planetary Sciences ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected]. Jason William Ricketts Candidate Earth and Planetary Sciences Department This dissertation is approved, and it is acceptable in quality and form for publication: Approved by the Dissertation Committee: Dr. Karl Karlstrom, Chairperson Dr. Laura Crossey Dr. Brandon Schmandt Dr. Gary Axen Dr. Shari Kelley i STRUCTURAL EVOLUTION OF THE RIO GRANDE RIFT: SYNCHRONOUS EXHUMATION OF RIFT FLANKS FROM 20-10 MA, EMBRYONIC CORE COMPLEXES, AND FLUID- ENHANCED QUATERNARY EXTENSION by JASON WILLIAM RICKETTS B.S., Geological Sciences, San Diego State University, 2008 M.S., Geological Sciences, San Diego State University, 2010 DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Earth and Planetary Sciences The University of New Mexico Albuquerque, New Mexico July 2014 ii © 2014, Jason W. Ricketts iii Acknowledgements The completion of this dissertation would not have been possible without the assistance and guidance of a number of people. First I would like to thank the Department of Earth and Planetary Sciences for financial support, the use of equipment and vehicles, and for giving me the opportunity to study rocks in a place like New Mexico. I would also like to thank the New Mexico Bureau of Geology and Mineral Resources for funding a large portion of my research and for providing me with the opportunity to create geologic maps. I would like to thank my committee members for their guidance and feedback on various aspects of my dissertation. In particular, this dissertation would have not been possible without my main advisor, Karl Karlstrom, who seemed to be always available to discuss ideas, review manuscript drafts, provide funding, and of course do field work. Last, but certainly not least, I would like to thank Sarah de los Santos Upton for her moral support and encouragement, and for patiently listening while I practice giving talks. iv STRUCTURAL EVOLUTION OF THE RIO GRANDE RIFT: SYNCHRONOUS EXHUMATION OF RIFT FLANKS FROM 20-10 MA, EMBRYONIC CORE COMPLEXES, AND FLUID-ENHANCED QUATERNARY EXTENSION By Jason W. Ricketts B.S., Geological Sciences, San Diego State University, 2008 M.S., Geological Sciences, San Diego State University, 2010 Ph.D., Earth and Planetary Sciences, University of New Mexico, 2014 ABSTRACT The Rio Grande rift in Colorado and New Mexico is one of the well-exposed and well-studied continental rifts in the world. Interest in the rift is driven not only by pure scientific intrigue, but also by a desire and a necessity to quantify earthquake hazards in New Mexico as well as to assess various water related issues throughout the state. These motivating topics have thus far led to the publication of two Geological Society of America Special Publication volumes in 1994 and 2013. This dissertation aims at building on the wealth of previous knowledge about the rift, and is composed of three separate chapters that focus on the structural evolution of the Rio Grande rift at several different time and spatial scales. At the largest scale, apatite (U-Th)/He thermochronologic data suggest synchronous extension along the entire length of the Rio Grande rift in Colorado and New Mexico from 20-10 Ma, which is important for understanding and evaluating possible driving mechanisms which are responsible for the rift. Previous tectonic and v magmatic events in western North America were highly influential in the formation of the Rio Grande rift, and the new thermochronologic data suggest that its formation may have been closely linked to foundering and removal of the underlying Farallon Plate. A fundamental result of rift development at these scales is a concentration of strain is some regions of the rift. In these regions of maximum extension, fault networks display a geometry involving both high- and low-angle fault networks. These geometries are similar to the early stages in the development of metamorphic core complexes, and thus these regions in the rift link incipient extensional environments to highly extended terranes. At shorter time scales, heterogeneous strain accumulation may be governed in part by fluids in fault zones. As an example, along the western edge of the Albuquerque basin, travertine deposits are cut by extensional veins that record anomalously high strain rates during the Quaternary at this location. The fluids that precipitated the travertine and calcite in veins also contain a small component of deeply-derived fluids such that surface extension in this part of the rift is coupled with processes at deeper levels. Together, these studies suggest that removal of the Farallon slab beneath Colorado and New Mexico may have been a primary mechanism establishing extension in the Rio Grande rift, while continued extension is heterogeneous in time and space and provides an important link between surface processes and processes that operate at mid-crustal levels. vi TABLE OF CONTENTS LIST OF FIGURES ......................................................................................................... xi LIST OF TABLES ......................................................................................................... xiii CHAPTER 1: Abrupt opening of the Rio Grande rift due to fragmentation of the Farallon slab: Evidence from apatite (U-Th)/He and fission-track thermochronology ............................................................................................................................................. 1 ABSTRACT .................................................................................................................... 1 INTRODUCTION ........................................................................................................... 2 REGIONAL TECTONIC SETTING .............................................................................. 4 GEOLOGY AND GEOPHYSICS OF THE RIO GRANDE RIFT ................................ 8 THERMOCHRONOLOGY METHODS ...................................................................... 10 APATITE (U-TH)/HE RESULTS AND INTERPRETATIONS ................................. 12 Sawatch Range- Mount Princeton Batholith ............................................................. 12 Sangre de Cristo Mountains ...................................................................................... 18 Nacimiento Mountains .............................................................................................. 24 Albuquerque Basin .................................................................................................... 27 Manzano Mountains............................................................................................... 30 Sierra Ladrones and Joyita Hills ........................................................................... 33 Lucero Uplift .......................................................................................................... 35 Southern Rio Grande Rift .......................................................................................... 36 Black Range ........................................................................................................... 37 San Andres and Organ Mountains ......................................................................... 38 vii Sierra Blanca ......................................................................................................... 41 DISCUSSION ............................................................................................................... 43 Space-Time Patterns in Cooling and Comparison with Igneous Activity ................. 44 Discussion of Geodynamic and Kinematic Models for Rio Grande Rifting ............. 47 Gravitational Potential Energy Driving Rifting .................................................... 48 Rotation of the Colorado Plateau .......................................................................... 49 Change in Far Field Stresses ................................................................................. 50 Whole Mantle Flow ................................................................................................ 51 Small-Scale Mantle Convection ............................................................................. 51 A New Geodynamic Model for Initiation and Evolution of the Rio Grande Rift ..... 52 CONCLUSIONS ........................................................................................................... 61 ACKNOWLEDGEMENTS .......................................................................................... 62 REFERENCES .............................................................................................................
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