TY - CHAP

T1 - Complex proterozoic crustal assembly of southwestern North America in an arcuate subduction system

T2 - The Black Canyon of the Gunnison, Southwestern Colorado

AU - Jessup, Micah J.

AU - Karlstrom, Karl E.

AU - Connelly, James

AU - Williams, Michael

AU - Livaccari, Richard

AU - Tyson, Amanda

AU - Rogers, Steven A.

N1 - 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.

PY - 2005

Y1 - 2005

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85040116956&partnerID=8YFLogxK

U2 - 10.1029/154GM03

DO - 10.1029/154GM03

M3 - Book chapter

AN - SCOPUS:85040116956

SN - 9780875904191

T3 - Geophysical Monograph Series

SP - 21

EP - 38

BT - The Rocky Mountain Region?An Evolving Lithosphere

A2 - Randy Keller, G.

A2 - Kalstrom, Karl E.

PB - Wiley-Blackwell Publishing, Inc.

ER -