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Pre-Mesozoic Iawsonite in Anglesey, northern Wales: Preservation of ancient blueschists

1983; Geological Society of America; Volume: 11; Issue: 1 Linguagem: Inglês

10.1130/0091-7613(1983)11 2.0.co;2

1943-2682

Wes Gibbons, Andy Mann,

Geological and Geophysical Studies Worldwide

Research Article| January 01, 1983 Pre-Mesozoic Iawsonite in Anglesey, northern Wales: Preservation of ancient blueschists Wes Gibbons; Wes Gibbons 1Department of Geology, University College, P.O. Box 78, Cardiff CF1 1XL, Wales Search for other works by this author on: GSW Google Scholar Andy Mann Andy Mann 1Department of Geology, University College, P.O. Box 78, Cardiff CF1 1XL, Wales Search for other works by this author on: GSW Google Scholar Author and Article Information Wes Gibbons 1Department of Geology, University College, P.O. Box 78, Cardiff CF1 1XL, Wales Andy Mann 1Department of Geology, University College, P.O. Box 78, Cardiff CF1 1XL, Wales Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1983) 11 (1): 3–6. https://doi.org/10.1130/0091-7613(1983)11 2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Wes Gibbons, Andy Mann; Pre-Mesozoic Iawsonite in Anglesey, northern Wales: Preservation of ancient blueschists. Geology 1983;; 11 (1): 3–6. doi: https://doi.org/10.1130/0091-7613(1983)11 2.0.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 The existence of lawsonite blueschists in the Mona Complex of Anglesey, northern Wales has been confirmed using optical and microprobe data. The blueschists occur locally along the eastern margin of one of three belts of fine-grained mylonitic schists known as the Penmynydd Zone of Metamorphism. The Penmynydd Zone is interpreted as representing remnants of deep-seated ductile shear zones produced by the movement of sialic basement up into low-grade melange. The lawsonite schists display complex textures resulting from the overprint of blueschist conditions on greenschist facies rocks followed by a subgreenschist dynamic metamorphism. The blueschist minerals are interpreted as a late product of shear zone metamorphism under conditions of decreasing temperature and high fluid pressure. The schists are no younger than Cambrian (probably Middle Cambrian). Lawsonite of this age is exceptionally rare; older examples are reported only from Russia. Rather than invoking a change in crustal isotherms through time, the paucity of pre-Mesozoic blueschists may simply be a result of the rapid exhumation needed to expose such rocks. The appearance of a blueschist at Earth's surface will be transient unless the uplift responsible for its exposure either slows or ceases. 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.