Complex proterozoic crustal assembly of southwestern North America in an arcuate subduction system: The Black Canyon of the Gunnison, Southwestern Colorado
Research output: Chapter in Book/Report/Conference proceeding › Book chapter › Research › peer-review
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 km 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 >100 km 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 simul-taneously 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 language | English |
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Title of host publication | The Rocky Mountain Region?An Evolving Lithosphere : Tectonics, Geochemistry, and Geophysics, 2005 |
Editors | G. Randy Keller, Karl E. Kalstrom |
Number of pages | 18 |
Publisher | Wiley-Blackwell Publishing, Inc. |
Publication date | 2005 |
Pages | 21-38 |
ISBN (Print) | 9780875904191 |
ISBN (Electronic) | 9781118666326 |
DOIs | |
Publication status | Published - 2005 |
Series | Geophysical Monograph Series |
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Volume | 154 |
ISSN | 0065-8448 |
Bibliographical note
Funding Information:
Acknowledgenzents. We are greatly indebtcd to Colin Shaw, Jamey Jones, Martha Eppes, and the University of New Mexico field caillp (summer 200 1 ) for providing assistance with field-work. Also, thanks to thc Black Canyon National Park for a sample pcrmit and acccss to the park. Revicws by Ernic Duebendorfcr and Christine Siddoway improved the manuscript. Funding for this projcct was provided by National Science Foundation grants EAR 0003500 to K. Karlstrom, M. Williams, C. Siddoway, J. Con-nelly and EAR 0208473 to K. Karlstrorn.
Publisher Copyright:
© 2005 by the American Geophysical Union.
ID: 333882583