Exsolved magnetite inclusions in silicates: Features determining their remanence behavior

Abstract

Research Article| June 01, 2005 Exsolved magnetite inclusions in silicates: Features determining their remanence behavior Joshua M. Feinberg; Joshua M. Feinberg 1Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Gary R. Scott; Gary R. Scott 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Search for other works by this author on: GSW Google Scholar Paul R. Renne; Paul R. Renne 3 Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA, and Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Search for other works by this author on: GSW Google Scholar Hans-Rudolf Wenk Hans-Rudolf Wenk 4Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Joshua M. Feinberg 1Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA Gary R. Scott 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Paul R. Renne 3 Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA, and Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA Hans-Rudolf Wenk 4Department of Earth and Planetary Science, University of California, Berkeley, 340 McCone Hall, Berkeley, California 94720, USA Publisher: Geological Society of America Received: 13 Oct 2004 Revision Received: 19 Jan 2005 Accepted: 26 Jan 2005 First Online: 03 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 The Geological Society of America, Inc. Geology (2005) 33 (6): 513–516. https://doi.org/10.1130/G21290.1 Article history Received: 13 Oct 2004 Revision Received: 19 Jan 2005 Accepted: 26 Jan 2005 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 Joshua M. Feinberg, Gary R. Scott, Paul R. Renne, Hans-Rudolf Wenk; Exsolved magnetite inclusions in silicates: Features determining their remanence behavior. Geology 2005;; 33 (6): 513–516. doi: https://doi.org/10.1130/G21290.1 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 Submicroscopic, needle-shaped titanomagnetite inclusions exsolved in silicate minerals commonly occur in mafic intrusive rocks and are protected from alteration by their silicate hosts, making them excellent candidates for paleomagnetic studies. A suite of samples containing clinopyroxene- and plagioclase-hosted magnetite inclusions from five geologically diverse sites was examined using magnetic force microscopy to image the inclusions' magnetic domain state. Alternating field demagnetization experiments indicate that some inclusions are more stable recorders than others. The two factors controlling the remanence behavior of the inclusions are internal microstructures and inclusion dimensions. Magnetite-ulvöspinel unmixing within an inclusion subdivides the original titanomagnetite solid solution into a boxwork structure composed of 103–105 magnetite prisms separated by thin ulvöspinel lamellae. The conversion of multidomain-sized needles into assemblages of interacting single domains increases the coercivity (and hence relaxation time) of the inclusions, and results in a thermochemical magnetic remanence. In samples without this exsolution microstructure, the inclusions' diameters determine coercivity and their magnetization is thermoremanent. Both styles of high-coercivity inclusions successfully record paleomagnetic directions in Mesozoic rocks, and their ubiquity within silicate minerals (clinopyroxene and plagioclase) of mafic intrusive rocks indicates their value as chemically and magnetically stable tools for elucidating the ancient magnetic field, marine magnetic anomalies, and crustal kinematics. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.