Orthopyroxene-andalusite symplectites replacing cordierite in granulites from the Strangways Range (Arunta block, central Australia): A new twist to the pressure-temperature history

Abstract

Research Article| March 01, 1997 Orthopyroxene-andalusite symplectites replacing cordierite in granulites from the Strangways Range (Arunta block, central Australia): A new twist to the pressure-temperature history Michel Ballèvre; Michel Ballèvre 1Géosciences Rennes, UPR CNRS 4661, Université Rennes-I, 35042 Rennes Cedex, France Search for other works by this author on: GSW Google Scholar Bastiaan J. Hensen; Bastiaan J. Hensen 2Department of Applied Geology, University of New South Wales, Sydney, New South Wales 2052, Australia Search for other works by this author on: GSW Google Scholar Bruno Reynard Bruno Reynard 1Géosciences Rennes, UPR CNRS 4661, Université Rennes-I, 35042 Rennes Cedex, France Search for other works by this author on: GSW Google Scholar Author and Article Information Michel Ballèvre 1Géosciences Rennes, UPR CNRS 4661, Université Rennes-I, 35042 Rennes Cedex, France Bastiaan J. Hensen 2Department of Applied Geology, University of New South Wales, Sydney, New South Wales 2052, Australia Bruno Reynard 1Géosciences Rennes, UPR CNRS 4661, Université Rennes-I, 35042 Rennes Cedex, France Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (3): 215–218. https://doi.org/10.1130/0091-7613(1997)025<0215:OASRCI>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michel Ballèvre, Bastiaan J. Hensen, Bruno Reynard; Orthopyroxene-andalusite symplectites replacing cordierite in granulites from the Strangways Range (Arunta block, central Australia): A new twist to the pressure-temperature history. Geology 1997;; 25 (3): 215–218. doi: https://doi.org/10.1130/0091-7613(1997)025<0215:OASRCI>2.3.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 Andalusite has been identified as the aluminosilicate polymorph intergrown with orthopyroxene in fine-grained symplectites replacing cordierite in granulites from the Strangways Range, Arunta block, central Australia. The reaction cordierite = orthopyroxene + andalusite + quartz, which has never been described before, is possible under extremely low water activity (aH2O < 0.1–0.2) conditions at ∼500 °C and ∼4 kbar. Incursion of low a(H2O) fluids during exhumation of the granulites during the Alice Springs (c. 350 Ma) orogeny resulted in formation of orthopyroxene in the andalusite stability field. This interpretation is radically different from those of earlier workers, who suggested that the orthopyroxene-bearing symplectites formed at high temperature, in response to isobaric cooling, or even during a second high-grade event. The granulites, preserved in low strain domains between retrograde amphibolite facies shear zones, have previously been considered essentially unaffected by the lower-grade metamorphic conditions because they remained anhydrous. Our data show that localized low a(H2O) fluid access during exhumation produced the anomalous orthopyroxene-andalusite assemblage. 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.