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Restored transect across the exhumed Grenville orogen of Laurentia and Amazonia, with implications for crustal architecture

2006; Geological Society of America; Volume: 34; Issue: 8 Linguagem: Inglês

10.1130/g22534.1

1943-2682

E. Tohver, Wilson Teixeira, Ben A. van der Pluijm, Mauro César Geraldes, Jorge Silva Bettencourt, Gilmar José Rizzotto,

High-pressure geophysics and materials

Research Article| August 01, 2006 Restored transect across the exhumed Grenville orogen of Laurentia and Amazonia, with implications for crustal architecture Eric Tohver; Eric Tohver 1Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Wilson Teixeira; Wilson Teixeira 1Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Ben van der Pluijm; Ben van der Pluijm 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48104, USA Search for other works by this author on: GSW Google Scholar Mauro C. Geraldes; Mauro C. Geraldes 3Instituto de Geociências, Universidade Estadual, de Rio de Janeiro, Rio de Janeiro, 20550-900, Brazil Search for other works by this author on: GSW Google Scholar Jorge S. Bettencourt; Jorge S. Bettencourt 4Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Search for other works by this author on: GSW Google Scholar Gilmar Rizzotto Gilmar Rizzotto 5Companhia de Pesquisas de Recursos Minerais (CPRM), Porto Velho, Rondônia, Brazil Search for other works by this author on: GSW Google Scholar Author and Article Information Eric Tohver 1Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Wilson Teixeira 1Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Ben van der Pluijm 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48104, USA Mauro C. Geraldes 3Instituto de Geociências, Universidade Estadual, de Rio de Janeiro, Rio de Janeiro, 20550-900, Brazil Jorge S. Bettencourt 4Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080, São Paulo, Brazil Gilmar Rizzotto 5Companhia de Pesquisas de Recursos Minerais (CPRM), Porto Velho, Rondônia, Brazil Publisher: Geological Society of America Received: 30 Dec 2005 Revision Received: 21 Mar 2006 Accepted: 28 Mar 2006 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (8): 669–672. https://doi.org/10.1130/G22534.1 Article history Received: 30 Dec 2005 Revision Received: 21 Mar 2006 Accepted: 28 Mar 2006 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Eric Tohver, Wilson Teixeira, Ben van der Pluijm, Mauro C. Geraldes, Jorge S. Bettencourt, Gilmar Rizzotto; Restored transect across the exhumed Grenville orogen of Laurentia and Amazonia, with implications for crustal architecture. Geology 2006;; 34 (8): 669–672. doi: https://doi.org/10.1130/G22534.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract New 40Ar/39Ar analyses from a transect across the major tectonic units of the southwest Amazon craton document the heterogeneous effects of the late Mesoproterozoic collision with the Grenville margin of North America. Basement rocks of the Amazon and adjacent Paragua cratons mostly preserve pre-Grenvillian ages (older than 1.3 Ga). Localized isotopic age resetting at 1.18–1.12 Ga is caused by Grenvillian activation of widespread, sinistral strike-slip shear zones in the Amazon basement. In the Nova Brasilândia belt between these two cratons, new 40Ar/39Ar data record cooling through 920 Ma after the granulite facies deformation of this suture zone. Regional cooling rates calculated from compiled U/Pb, 40Ar/39Ar, and Rb/Sr thermochronologic data are used to establish post-Grenvillian exhumation patterns for the southwest Amazon and the North American belt. Paleodepths calculated for 1.0 Ga along a transect of the restored 1300-km-wide belt vary from uniformly deep levels (15–30 km) exposed in North America to shallower levels (5– 15 km) observed in the southwest Amazon. We interpret this difference as reflective of a change in tectonic architecture, i.e., thrust-dominated deformation in Laurentia versus strike-slip dominated deformation in the Amazon, with a commensurate variation in crustal thickness. This interpretation explains the widespread preservation of both pre- Grenvillian ages and collisional ages from the Amazon craton, in contrast with the more homogeneous array of cooling ages from the North American Grenville Province marking the postorogenic extensional collapse of an overthickened crust. The asymmetrical orogenic architecture from the reconstructed Grenville belt mirrors cross sections proposed for modern orogenic belts where deep-crustal rocks are not yet exposed. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.