Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by Holm, D. K. Articles by Schneider, D. Search for Related Content GeoRef GeoRef Citation

U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis

Daniel K. Holm^,1, W. Randall Van Schmus², Leah C. MacNeill², Terrence J. Boerboom³, Daniel Schweitzer¹ and David Schneider⁴

¹ Department of Geology, Kent State University, Kent, Ohio 44242, USA
² Department of Geology, University of Kansas, Lawrence, Kansas 66045, USA
³ Minnesota Geological Survey, 2642 University Avenue, St. Paul, Minnesota 55114, USA
⁴ Department of Geological Sciences, Ohio University, Athens, Ohio 45701, USA

We propose that the late Paleoproterozoic igneous and deformational history preserved in the northern midcontinent United States can be explained by a change in subduction-polarity from geon 18 south-dipping subduction during Penokean accretion to geon 17 north-dipping subduction as convergence continued after Penokean orogenesis. New U-Pb zircon ages indicate that late to post-Penokean magmatism occurred at ca. 1800, 1775, and 1750 Ma and generally migrated southeastward across the newly accreted Penokean terrane. We suggest that geon 17 Yavapai slab rollback caused continental arc magmatism to step southeastward between 1800 and 1750 Ma. As the slab steepened, reduced compressional stresses and magma-induced thermal weakening allowed for collapse of the overthickened portions of the Penokean crust. Postcollapse crustal stabilization (the 1750–1650 Ma Baraboo interval) was followed by geon 16 Mazatzal arc accretion further south. The 1900–1600 Ma tectonic history of the north-central United States, not surprisingly, records events related to the southward growth and tectonic development of the southern Laurentian margin.

New and published ⁴⁰Ar/³⁹Ar mineral ages delineate the northern and western extent of geon 16 Mazatzal deformation. Interestingly, only little exhumed crust intruded by a small volume of shallow-level ca. 1750 Ma plutons (and associated rhyolites) was deformed significantly during geon 16. In contrast, more deeply exhumed crust and crust pervasively invaded by a large volume of post-Penokean magma (i.e., East-Central Minnesota Batholith) were largely unaffected by Mazatzal deformation and reheating. We suggest that posttectonic intrusions and crustal thinning were an important step in strengthening and stabilizing the crust in the southern Lake Superior region.

Key Words: Penokean orogen • U-Pb zircon ages • geon 17 magmatism • Yavapai slab rollback • crustal stabilization

This article has been cited by other articles:

				M.-L. C. Sirbescu, M. A. Leatherman, J. J. Student, and A. R. Beehr APATITE TEXTURES AND COMPOSITIONS AS RECORDS OF CRYSTALLIZATION PROCESSES IN THE ANIMIKIE RED ACE PEGMATITE DIKE, WISCONSIN, USA Can Mineral, August 1, 2009; 47(4): 725 - 743. [Abstract] [Full Text] [PDF]

				P. A. Cawood, A. Kroner, W. J. Collins, T. M. Kusky, W. D. Mooney, and B. F. Windley Accretionary orogens through Earth history Geological Society, London, Special Publications, January 1, 2009; 318(1): 1 - 36. [Abstract] [Full Text] [PDF]

				M.E. Bickford, P.A. Mueller, G. D. Kamenov, and B. M. Hill Crustal evolution of southern Laurentia during the Paleoproterozoic: Insights from zircon Hf isotopic studies of ca. 1.75 Ga rocks in central Colorado Geology, July 1, 2008; 36(7): 555 - 558. [Abstract] [Full Text] [PDF]

				S. J. Whitmeyer and K. E. Karlstrom Tectonic model for the Proterozoic growth of North America Geosphere, August 1, 2007; 3(4): 220 - 259. [Abstract] [Full Text] [PDF]

				P. A. Cawood, A. A. Nemchin, R. Strachan, T. Prave, and M. Krabbendam Sedimentary basin and detrital zircon record along East Laurentia and Baltica during assembly and breakup of Rodinia Journal of the Geological Society, March 1, 2007; 164(2): 257 - 275. [Abstract] [Full Text] [PDF]

				M.D. Schmitz, S.A. Bowring, D.L. Southwick, T.J. Boerboom, and K.R. Wirth High-precision U-Pb geochronology in the Minnesota River Valley subprovince and its bearing on the Neoarchean to Paleoproterozoic evolution of the southern Superior Province Geological Society of America Bulletin, January 1, 2006; 118(1-2): 82 - 93. [Abstract] [Full Text] [PDF]

				M.E. Bickford, J.L. Wooden, and R.L. Bauer SHRIMP study of zircons from Early Archean rocks in the Minnesota River Valley: Implications for the tectonic history of the Superior Province Geological Society of America Bulletin, January 1, 2006; 118(1-2): 94 - 108. [Abstract] [Full Text] [PDF]

				J. F. Dewey Inaugural Article: Orogeny can be very short PNAS, October 25, 2005; 102(43): 15286 - 15293. [Abstract] [Full Text] [PDF]