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Constraints on the duration of tectonic processes: Protracted extension and deep-crustal rotation in the Grenville orogen

1995; Geological Society of America; Volume: 23; Issue: 4 Linguagem: Inglês

10.1130/0091-7613(1995)023 2.3.co;2

1943-2682

Michael A. Cosca, Eric J. Essene, Klaus Mezger, Ben A. van der Pluijm,

High-pressure geophysics and materials

Research Article| April 01, 1995 Constraints on the duration of tectonic processes: Protracted extension and deep-crustal rotation in the Grenville orogen Michael A. Cosca; Michael A. Cosca 1Institut de Minéralogie, Université de Lausanne, CH-1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Eric J. Essene; Eric J. Essene 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Search for other works by this author on: GSW Google Scholar Klaus Mezger; Klaus Mezger 3Max-Planck-Institut für Chemie, Postfach 3060, D-55020 Mainz, Germany Search for other works by this author on: GSW Google Scholar Ben A. van der Pluijm Ben A. van der Pluijm 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Search for other works by this author on: GSW Google Scholar Author and Article Information Michael A. Cosca 1Institut de Minéralogie, Université de Lausanne, CH-1015 Lausanne, Switzerland Eric J. Essene 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Klaus Mezger 3Max-Planck-Institut für Chemie, Postfach 3060, D-55020 Mainz, Germany Ben A. van der Pluijm 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (4): 361–364. https://doi.org/10.1130/0091-7613(1995)023 2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Michael A. Cosca, Eric J. Essene, Klaus Mezger, Ben A. van der Pluijm; Constraints on the duration of tectonic processes: Protracted extension and deep-crustal rotation in the Grenville orogen. Geology 1995;; 23 (4): 361–364. doi: https://doi.org/10.1130/0091-7613(1995)023 2.3.CO;2 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 Geochronological data on metamorphic minerals within and outside the Bancroft shear zone, a large-scale roterozoic shear zone, provide evidence for extensional displacement over a period of 150 m.y. This is the longest time interval yet demonstrated for any fault responding to one orogenic phase. Extensional displacement rates along the Bancroft shear zone, averaged over 150 m.y. from 1040 to 893 Ma, are 0.06 to 0.13 km/m.y. During extension, unroofing of the footwall was accompanied by rotation as 5 to 15 km of overlying crust was unloaded. Similar lower-plate rotation has been inferred for many of the Tertiary metamorphic core complexes exposed in the western United States. The protracted displacement and rotation history of the Proterozoic Bancroft shear zone contrasts with the much faster extensional unroofing of the younger metamorphic core complexes, suggesting inherent differences in the tectonic processes operating in these two geologic settings. Similarities, however, indicate that both settings may share common aspects of tectonic deformation. These findings underscore the geologic importance of large, deep-crustal faults and indicate that present-day zones of active extension, such as in the Himalayas, could remain active many millions on years into the future. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.