Extensional versus compressional settings for metamorphism: Garnet chronometry and pressure-temperature-time histories in the Moine Supergroup, northwest Scotland

Abstract

Research Article| October 01, 1998 Extensional versus compressional settings for metamorphism: Garnet chronometry and pressure-temperature-time histories in the Moine Supergroup, northwest Scotland D. Vance; D. Vance 1Institut für Isotopengeologie, Eidgenössische Technische Hochschule, Sonneggstrasse 5, 8092 Zurich, Switzerland Search for other works by this author on: GSW Google Scholar R. A. Strachan; R. A. Strachan 2Department of Geology, School of Construction and Earth Sciences, Oxford Brookes University, Oxford OX3 OBP, United Kingdom Search for other works by this author on: GSW Google Scholar K. A. Jones K. A. Jones 2Department of Geology, School of Construction and Earth Sciences, Oxford Brookes University, Oxford OX3 OBP, United Kingdom Search for other works by this author on: GSW Google Scholar Author and Article Information D. Vance 1Institut für Isotopengeologie, Eidgenössische Technische Hochschule, Sonneggstrasse 5, 8092 Zurich, Switzerland R. A. Strachan 2Department of Geology, School of Construction and Earth Sciences, Oxford Brookes University, Oxford OX3 OBP, United Kingdom K. A. Jones 2Department of Geology, School of Construction and Earth Sciences, Oxford Brookes University, Oxford OX3 OBP, United Kingdom Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (10): 927–930. https://doi.org/10.1130/0091-7613(1998)026<0927:EVCSFM>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 D. Vance, R. A. Strachan, K. A. Jones; Extensional versus compressional settings for metamorphism: Garnet chronometry and pressure-temperature-time histories in the Moine Supergroup, northwest Scotland. Geology 1998;; 26 (10): 927–930. doi: https://doi.org/10.1130/0091-7613(1998)026<0927:EVCSFM>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 Identification of the tectonic setting for metamorphism is often extremely difficult in complex polymetamorphic terranes where individual tectonothermal events are obscured by later thermal and structural reorganizations. The traditional approach is to use mineral parageneses to outline the nature of the pressure-temperature-time path, but assigning an age to that path remains a challenge. In this case study, pressure-temperature data show that garnet in pelites of the polymetamorphic Moine Supergroup of northwest Scotland grew during compressional tectonics. In addition, the Sm-Nd systematics of these garnets demonstrate that growth occurred in the interval 820–790 Ma and was thus coeval with crustal melting documented as ca. 800 Ma. The heat source for the latter event has previously been postulated to be related to extension, but here we provide the first substantive evidence for a collisional orogeny at this time. These data further demonstrate the utility of garnet chronometry in identifying the timing and nature of particular tectonothermal events in polymetamorphic settings. In addition, the data show that the period between Grenville collision and supercontinent assembly in the North Atlantic region ca. 1000–1100 Ma, and rifting and continental breakup ca. 750 Ma was not as quiescent as previously envisaged. Late Proterozoic orogenesis is likely to have resulted from the closure of aborted continental rifts and/or minor oceanic tracts within the Grenville supercontinent prior to final rifting and supercontinent dispersal. 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.