The roof of an axial magma chamber: A hornfelsic heat exchanger

Research Article| April 01, 2008 The roof of an axial magma chamber: A hornfelsic heat exchanger Kathryn M. Gillis Kathryn M. Gillis 1School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (4): 299–302. https://doi.org/10.1130/G24590A.1 Article history received: 25 Jul 2007 rev-recd: 03 Dec 2007 accepted: 05 Dec 2007 first online: 03 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 Kathryn M. Gillis; The roof of an axial magma chamber: A hornfelsic heat exchanger. Geology 2008;; 36 (4): 299–302. doi: https://doi.org/10.1130/G24590A.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 heat flux from an axial magma chamber into the convecting hydrothermal system at mid-ocean ridges is governed by the conductive boundary layer separating them. The nature of this critical interface has been modeled and seismically imaged, but its characteristics have hitherto rarely been documented in ocean crust. Here, hornfelsic rocks from the sheeted dike–gabbro transitions at two tectonic exposures of fast-spreading East Pacific Rise crust at the Pito and Hess Deeps and in the Oman and Troodos ophiolites are described. These rocks record thermal metamorphism to hornblende and pyroxene hornfels at 700–1000 °C. These temperatures, in conjunction with their geological relationships, imply that the hornfels are preserved fragments of conductive boundary layers. Their distribution at the base of sheeted dike complexes in narrow contact aureoles and dikes intruding the uppermost gabbros tracks the vertical migration of axial magma chambers over minimum depth ranges of 200–400 m. The heat flux across the hornfelsic aureoles (11–44 MW/km) is comparable to hydrothermal fluxes released along fast-spreading ridges, confirming that the heat driving hydrothermal convection is transferred across conductive boundary layers. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.