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Vapor-absent melting at 10 kbar of a biotite- and amphibole-bearing tonalitic gneiss: Implications for the generation of A-type granites
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1992
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VolcanologyEngineeringEarth ScienceMetamorphic PetrologyHigh Temperature GeochemistryGeochronologyCrustal MeltingMaterials ScienceVapor-absent MeltingAmphibole-bearing Tonalitic GneissA-type GranitesIgneous PetrogenesisGeologyA. Dana JohnstonTectonicsStructural GeologyArchean Tonalitic GneissEconomic GeologyEarth SciencesGeochemistryExperimental PetrologyIgneous PetrologyPetrology
Research Article| March 01, 1992 Vapor-absent melting at 10 kbar of a biotite- and amphibole-bearing tonalitic gneiss: Implications for the generation of A-type granites Kjell P. Skjerlie; Kjell P. Skjerlie 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272 Search for other works by this author on: GSW Google Scholar A. Dana Johnston A. Dana Johnston 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272 Search for other works by this author on: GSW Google Scholar Author and Article Information Kjell P. Skjerlie 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272 A. Dana Johnston 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (3): 263–266. https://doi.org/10.1130/0091-7613(1992)020<0263:VAMAKO>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 Email Permissions Search Site Citation Kjell P. Skjerlie, A. Dana Johnston; Vapor-absent melting at 10 kbar of a biotite- and amphibole-bearing tonalitic gneiss: Implications for the generation of A-type granites. Geology 1992;; 20 (3): 263–266. doi: https://doi.org/10.1130/0091-7613(1992)020<0263:VAMAKO>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 Vapor-absent melting experiments on a biotite- and amphibole-bearing, Archean tonalitic gneiss (AGC150) at 10 kbar and 875 to 1050 °C show that amphibole breaks down from 900 to 950 °C, producing garnet, orthopyroxene, and granitic melt. Biotite-dehydration melting produces <10 wt% melt up to 950 °C via incongruent melting reactions that produce garnet, orthopyroxene, and titanomagnetite. Widespread biotite-dehydration melting occurs between 950 and 975 °C and produces orthopyroxene, magnetite, titanomagnetite, and ∼20 wt% fluorine-rich melt (up to 0.31 wt% F). Minor F-rich (2.7 wt%) biotite is present even at 1000 °C. Our experiments show that, under vapor-absent conditions, intrusion of hot, mantle-derived magmas into the lower crust is necessary to initiate widespread biotite-dehydration melting in rocks with compositions like AGC150. We propose that the high thermal stability of biotite in AGC150 suggests that this rock is residual after a previous episode of partial dehydroxylation that left behind somewhat F-enriched biotite. We show that dehydration melting of such F-enriched biotite produces F-rich granitic liquids, with compositions within the range of A-type granite, and leaves behind a granulitic residue consisting of orthopyroxene, plagioclase, quartz, titanomagnetite, and magnetite. 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.