Calcite-twinning constraints on stress-strain fields along the Mid-Atlantic Ridge, Iceland

Research Article| January 01, 2004 Calcite-twinning constraints on stress-strain fields along the Mid-Atlantic Ridge, Iceland John P. Craddock; John P. Craddock 1Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA Search for other works by this author on: GSW Google Scholar David W. Farris; David W. Farris 1Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA Search for other works by this author on: GSW Google Scholar Aimee Roberson Aimee Roberson 1Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA Search for other works by this author on: GSW Google Scholar Geology (2004) 32 (1): 49–52. https://doi.org/10.1130/G19905.1 Article history received: 30 Jun 2003 rev-recd: 30 Sep 2003 accepted: 07 Oct 2003 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation John P. Craddock, David W. Farris, Aimee Roberson; Calcite-twinning constraints on stress-strain fields along the Mid-Atlantic Ridge, Iceland. Geology 2004;; 32 (1): 49–52. doi: https://doi.org/10.1130/G19905.1 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 Calcite veins and amygdule fillings within basalts (older than 0.7 Ma) are mechanically twinned and preserve a subhorizontal shortening strain that resulted from compression and shortening normal to the Mid-Atlantic Ridge on both sides of the plate boundary. Our sample suite includes 19 specimens, 7 from the North American plate (4 veins, 3 amygdule fillings) and 12 from the European plate (9 veins, 3 amygdule fillings), 18 of which record ridge-normal subhorizontal shortening. Five of the strain analyses, two from the North American plate and three from the European plate, have a high percentage of negative expected values, and these secondary strain results record a ridge-parallel shortening strain with plunges that vary parallel to the ridge axis. Averaged shortening strain magnitudes for the twinned calcite (−2.5%, European plate; −6.02%, North American plate) and inferred differential stresses (−48 MPa) that caused the twinning are modest and are thought to represent regional tectonic conditions (i.e., ridge push), not local (e.g., hotspot or glacial loading) phenomena. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.