Complex Proterozoic Crustal Assembly of Southwestern North America in an Arcuate Subduction System: The Black Canyon of the Gunnison, Southwestern Colorado

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  • Micah J. Jessup
  • Karl E. Kalstrom
  • Connelly, James
  • Michael Williams
  • Richard Livaccari
  • Amanda Tyson
  • Steven A. Rogers

The dominant orogenic fabric in Proterozoic rocks of the southwestern U.S. includes a series of NE-striking shear zones that are commonly interpreted as suture zones across which blocks of juvenile crust were assembled to the southern margin of Laurentia. New structural and geochronological data from southwestern Colorado suggest that fabrics related to assembly of tectonostratigraphic terranes in this area strike northwest. The NW-striking foliations represent deformation at ca. 10-20 krn paleodepths (ca. 1.77-1.71 Ga), and are parallel to magnetic anomalies and to gradients in mantle velocity structure. The agreement between these data sets suggests that the NW-striking structures are important at lithospheric scale, extend to >I00 krn depth, and may record assembly of southwestern Colorado across NW-striking tectonic boundaries. Geochronologic data indicate that northwest (central Colorado)-and northeast (Cheyenne belt)-striking boundaries developed simultaneously during accretion of southwestern Laurentia between ca. 1.78-1.73 Ga. We propose that the Yavapai province at ca. 1.75 Ga may have involved a complex arcuate subduction system, with multiple arcs, analogous to that of the modern Banda Sea, in the Indonesia region.

Original languageEnglish
Title of host publicationThe Rocky Mountain Region : An Evolving Lithosphere: Tectonics, Geochemistry, and Geophysics
Number of pages18
PublisherAmerican Geophysical Union
Publication date19 Mar 2013
ISBN (Print)0875904181, 9780875904191
ISBN (Electronic)9781118666326
Publication statusPublished - 19 Mar 2013

Bibliographical note

Publisher Copyright:
© 2005 by the American Geophysical Union. All rights reserved.

    Research areas

  • Core-mantle boundary, Geology, Structural-Rocky Mountains, Geophysics-Rocky Mountains, Orogeny-Rocky Mountains

ID: 334859989