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An animated tectonic reconstruction of southwestern North America since 36 Ma

McQuarrie, Nadine and Wernicke, Brian P. (2005) An animated tectonic reconstruction of southwestern North America since 36 Ma. Geosphere, 1 (3). pp. 147-172. ISSN 1553-040X.

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We present tectonic reconstructions and an accompanying animation of deformation across the North America–Pacific plate boundary since 36 Ma. Intraplate deformation of southwestern North America was obtained through synthesis of kinematic data (amount, timing, and direction of displacement) along three main transects through the northern (40°N), central (36°N– 37°N), and southern (34°N) portions of the Basin and Range province. We combined these transects with first-order plate boundary constraints from the San Andreas fault and other areas west of the Basin and Range. Extension and strike-slip deformation in all areas were sequentially restored over 2 m.y. (0–18 Ma) to 6 m.y. (18–36 Ma) time intervals using a script written for the ArcGIS program. Regions where the kinematics are known constrain adjacent areas where the kinematics are not well defined. The process of sequential restoration highlighted misalignments, overlaps, or large gaps in each incremental step, particularly in the areas between data transects, which remain problematic. Hence, the value of the reconstructions lies primarily in highlighting questions that might not otherwise be recognized, and thus they should be viewed more as a tool for investigation than as a final product. The new sequential reconstructions show that compatible slip along the entire northsouth extent of the inland right-lateral shear zone from the Gulf of California to the northern Walker Lane is supported by available data and that the east limit of active shear has migrated westward with respect to North America since ca. 10 Ma. The reconstructions also highlight new problems regarding strain-compatible extension east and west of the Sierra Nevada– Great Valley block and strain-compatible deformation between southern Arizona and the Mexican Basin and Range. Our results show ~235 km of extension oriented ~N78°W in both the northern (50% extension) and central (200% extension) parts of the Basin and Range. Following the initiation of east-west to southwest-northeast extension at 15–25 Ma (depending on longitude), a significant portion of right-lateral shear associated with the growing Pacific– North America transform jumped into the continent at 10–12 Ma, totaling ~100 km oriented N25°W, for an average of ~1 cm/yr since that time.

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Wernicke, Brian P.0000-0002-7659-8358
Additional Information:© 2005 Geological Society of America. Manuscript received by the Society 5 April 2005; revised manuscript received 29 August 2005; manuscript accepted 23 September 2005. This paper has benefited greatly from many conversations with scientists familiar with western North America geology. We specifically want to acknowledge Tanya Atwater, Bill Dickinson, Allen Glazner, Steve Graham, Jon Spencer, Joann Stock, Nathan Niemi, Mike Oskin, Jason Saleeby, and John Suppe. We are grateful to Melissa Brenneman at the University of Redlands for creating the ArcMap document and script used for the reconstruction. The movie would not exist without the help of the University of California, Santa Barbara, Educational Multimedia Visualization Center, specifically Carrie Glavich and Grace Giles. Gary Axen, Doug Walker, Craig Jones, and Randy Keller all provided insightful feedback through the review processes that greatly improved the clarity of presentation. This project was funded by the Caltech Tectonics Observatory.
Group:Caltech Tectonics Observatory
Funding AgencyGrant Number
Caltech Tectonics ObservatoryUNSPECIFIED
Subject Keywords:Basin and Range; kinematic reconstruction; extension; plate tectonics; velocity field
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Caltech Tectonics Observatory21
Issue or Number:3
Record Number:CaltechAUTHORS:20101110-111024631
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20746
Deposited By: Tony Diaz
Deposited On:18 Nov 2010 22:12
Last Modified:03 Oct 2019 02:14

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