Igneous microstructures in migmatites

Research Article| December 01, 1988 Igneous microstructures in migmatites R. H. Vernon; R. H. Vernon 1School of Earth Sciences, Macquarie University, Sydney, New South Wales 2109, Australia Search for other works by this author on: GSW Google Scholar W. J. Collins W. J. Collins 2Department of Geology, University of Newcastle, Newcastle, New South Wales 2308, Australia Search for other works by this author on: GSW Google Scholar Geology (1988) 16 (12): 1126–1129. https://doi.org/10.1130/0091-7613(1988)0162.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation R. H. Vernon, W. J. Collins; Igneous microstructures in migmatites. Geology 1988;; 16 (12): 1126–1129. doi: https://doi.org/10.1130/0091-7613(1988)0162.3.CO;2 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 Clear differences between the microstructures of leucosomes and mesosomes occur in some nebulitic migmatites in the Proterozoic Arunta block, central Australia. The leucosomes show crystal faces of K-feldspar (microcline-microperthite), cordierite, andalusite, and plagio clase against quartz, indicating crystallization of a melt. In contrast, the mesosomes show predominantly polygonal grain shapes, modified by (001) crystal faces of biotite and rare crystal faces in some porphyroblasts of garnet, cordierite, and orthopyroxene, indicating re-crystallization in the solid state. The occurrence of abundant crystal faces in minerals such as feldspar, cordierite, and andalusite (which typically grow crystal faces in magmas, but generally not in metamorphic rocks) is evidence of former melt. Therefore, igneous microstructures can be preserved in leucosomes that have not undergone penetrative subsolidus deformation and recrystallization. The cores of many of the crystals of cordierite and K-feldspar have small, locally oriented inclusions similar to those in the same minerals in the mesosomes. These indicate that the cores remained solid during crystallization of the leucosome, which produced inclusion-free, euhedral rims. These crystals provide criteria for recognizing possible restite in granitoid magmas. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.