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Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico

2009; Geological Society of America; Volume: 37; Issue: 1 Linguagem: Inglês

10.1130/g25240a.1

1943-2682

Jeffrey M. Amato, Timothy F. Lawton, David J. Mauel, William J. Leggett, Carlos M. González–León, G. Lang Farmer, Joseph L. Wooden,

earthquake and tectonic studies

Research Article| January 01, 2009 Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico Jeffrey M. Amato; Jeffrey M. Amato * 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA *E-mail: amato@nmsu.edu. Search for other works by this author on: GSW Google Scholar Timothy F. Lawton; Timothy F. Lawton 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar David J. Mauel; David J. Mauel 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar William J. Leggett; William J. Leggett 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar Carlos M. González-León; Carlos M. González-León 2Instituto de Geología, Universidad Nacional Autonoma de México, Hermosillo, Sonora, México Search for other works by this author on: GSW Google Scholar G. Lang Farmer; G. Lang Farmer 3Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309, USA Search for other works by this author on: GSW Google Scholar Joseph L. Wooden Joseph L. Wooden 4U.S. Geological Survey, Menlo Park, California 94025, USA Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (1): 75–78. https://doi.org/10.1130/G25240A.1 Article history received: 09 Jun 2008 rev-recd: 05 Sep 2008 accepted: 09 Sep 2008 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Jeffrey M. Amato, Timothy F. Lawton, David J. Mauel, William J. Leggett, Carlos M. González-León, G. Lang Farmer, Joseph L. Wooden; Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico. Geology 2009;; 37 (1): 75–78. doi: https://doi.org/10.1130/G25240A.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 U-Pb ages and Nd isotope values of Proterozoic rocks in Sonora, Mexico, indicate the presence of Caborca-type basement, predicted to lie only south of the Mojave-Sonora mega-shear, 40 km north of the postulated megashear. Granitoids have U-Pb zircon ages of 1763–1737 Ma and 1076 Ma, with ϵNd(t) values from +1.4 to −4.3, typical of the Caborca block. Lower Jurassic strata near the Proterozoic rocks contain large granitic clasts with U-Pb ages and ϵNd(t) values indistinguishable from those of Caborcan basement. Caborca-type basement was thus present at this location north of the megashear by 190 Ma, the depositional age of the Jurassic strata. The Proterozoic rocks are interpreted as parautochthonous, exhumed and juxtaposed against the Mesozoic section by a reverse fault that formed a footwall shortcut across a Jurassic normal fault. Geochronology, isotope geochemistry, and structural geology are therefore inconsistent with Late Jurassic megashear displacement and require either that no major transcurrent structure is present in Sonora or that strike-slip displacement occurred prior to Early Jurassic time. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.