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Nonlithostatic pressure during subduction and collision and the formation of (ultra)high-pressure rocks

2016; Geological Society of America; Volume: 44; Issue: 5 Linguagem: Inglês

10.1130/g37595.1

1943-2682

Georg Reuber, Boris Kaus, Stefan M. Schmalholz, R. W. White,

Geological and Geochemical Analysis

Research Article| May 01, 2016 Nonlithostatic pressure during subduction and collision and the formation of (ultra)high-pressure rocks Georg Reuber; Georg Reuber 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany2Center for Computational Sciences, Johannes Gutenberg University, 55099 Mainz, Germany Search for other works by this author on: GSW Google Scholar Boris J.P. Kaus; Boris J.P. Kaus * 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany2Center for Computational Sciences, Johannes Gutenberg University, 55099 Mainz, Germany *E-mail: kaus@uni-mainz.de Search for other works by this author on: GSW Google Scholar Stefan M. Schmalholz; Stefan M. Schmalholz 3Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Richard W. White Richard W. White 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Georg Reuber 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany2Center for Computational Sciences, Johannes Gutenberg University, 55099 Mainz, Germany Boris J.P. Kaus * 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany2Center for Computational Sciences, Johannes Gutenberg University, 55099 Mainz, Germany Stefan M. Schmalholz 3Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland Richard W. White 1Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany *E-mail: kaus@uni-mainz.de Publisher: Geological Society of America Received: 08 Dec 2015 Revision Received: 01 Mar 2016 Accepted: 02 Mar 2016 First Online: 09 Mar 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2016 Geological Society of America Geology (2016) 44 (5): 343–346. https://doi.org/10.1130/G37595.1 Article history Received: 08 Dec 2015 Revision Received: 01 Mar 2016 Accepted: 02 Mar 2016 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 Georg Reuber, Boris J.P. Kaus, Stefan M. Schmalholz, Richard W. White; Nonlithostatic pressure during subduction and collision and the formation of (ultra)high-pressure rocks. Geology 2016;; 44 (5): 343–346. doi: https://doi.org/10.1130/G37595.1 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 The mechanisms that result in the formation of high-pressure (HP) and ultrahigh-pressure (UHP) rocks are controversial. The usual interpretation assumes that pressure is close to lithostatic, petrological pressure estimates can be transferred to depth, and (U)HP rocks have been exhumed from great depth. An alternative explanation is that pressure can be larger than lithostatic, particularly in continental collision zones, and (U)HP rocks could thus have formed at shallower depths. To better understand the mechanical feasibility of these hypotheses, we performed thermomechanical numerical simulations of a typical subduction and collision scenario. If the subducting crust is laterally homogeneous and has small effective friction angles (and is thus weak), we reproduce earlier findings that <20% deviation of lithostatic pressure occurs within a subduction channel. However, many orogenies involve rocks that are dry and strong, and the crust is mechanically heterogeneous. If these factors are taken into account, simulations show that pressures can be significantly larger than lithostatic within nappe-size, mechanically strong crustal units, or within a strong lower crust, as a result of tectonic deformation. Systematic simulations show that these effects are most pronounced at the base of the crust (at ∼40 km), where pressures can reach 2–3 GPa (therefore within the coesite stability field) for millions of years. These pressures are often released rapidly during ongoing deformation. Relating metamorphic pressure estimates to depth might thus be problematic in mechanically heterogeneous crustal rock units that appear to have been exhumed in an ultrafast manner. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.