Water in nominally anhydrous minerals: Implications for partial melting and strain localization in the lower crust

Abstract

Research Article| October 01, 2013 Water in nominally anhydrous minerals: Implications for partial melting and strain localization in the lower crust S.J. Seaman; S.J. Seaman 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar M.L. Williams; M.L. Williams 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar M.J. Jercinovic; M.J. Jercinovic 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar G.C. Koteas; G.C. Koteas 2Department of Geology, Norwich University, 158 Harmon Drive, Northfield, Vermont 05663, USA Search for other works by this author on: GSW Google Scholar L.B. Brown L.B. Brown 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar Author and Article Information S.J. Seaman 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA M.L. Williams 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA M.J. Jercinovic 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA G.C. Koteas 2Department of Geology, Norwich University, 158 Harmon Drive, Northfield, Vermont 05663, USA L.B. Brown 1Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA Publisher: Geological Society of America Received: 30 Jan 2013 Revision Received: 17 May 2013 Accepted: 22 May 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2013) 41 (10): 1051–1054. https://doi.org/10.1130/G34435.1 Article history Received: 30 Jan 2013 Revision Received: 17 May 2013 Accepted: 22 May 2013 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 S.J. Seaman, M.L. Williams, M.J. Jercinovic, G.C. Koteas, L.B. Brown; Water in nominally anhydrous minerals: Implications for partial melting and strain localization in the lower crust. Geology 2013;; 41 (10): 1051–1054. doi: https://doi.org/10.1130/G34435.1 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 Low concentrations (tens to hundreds of parts per million) of water in nominally anhydrous minerals (NAMs) of the mantle have been shown to significantly affect the rheology, depth of depressurization melting, and many other properties of the mantle. In this contribution, we evaluate the effect of trace concentrations of water in NAMs on melting of lower continental crust. Water locked in structural sites and in fluid inclusions in nominally anhydrous minerals in lower crustal granitoids may act as a flux for partial melting of these source rocks. Water concentrations of 3000 ppm in minerals that make up large volumes of crustal rocks (K-feldspar, plagioclase, quartz) would lower the dry solidus of granite by 273 °C at 1 GPa. Measurements and maps of water concentration in variably deformed samples of the Stevenson Granite from northern Saskatchewan (Canada) show that, during deformation and recrystallization of K-feldspar megacrysts, water migrated from the interior of megacrysts to finer-grained matrix material. Dark, fine-grained, water-richer matrix material consisting of quartz, plagioclase, alkali feldspar, and fine iron oxides are interpreted to be former melt films that resulted, at least in part, from fluxing by NAM-derived water. Deformation may play a role in moving water from NAMs to phase boundaries where generation of partial melt may lead to further rock weakening and further release of water from NAMs. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.