Title: Synkinematic granite emplacement in a shear zone: The Pleasant Hills pluton, Canadian Appalachians
Abstract: Research Article| April 01, 1998 Synkinematic granite emplacement in a shear zone: The Pleasant Hills pluton, Canadian Appalachians Georgia Pe-Piper; Georgia Pe-Piper 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada Search for other works by this author on: GSW Google Scholar Ioannis Koukouvelas; Ioannis Koukouvelas 2Department of Geology, University of Patras, 26110 Patras, Greece Search for other works by this author on: GSW Google Scholar David J. W. Piper David J. W. Piper 3Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Georgia Pe-Piper 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada Ioannis Koukouvelas 2Department of Geology, University of Patras, 26110 Patras, Greece David J. W. Piper 3Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (4): 523–536. https://doi.org/10.1130/0016-7606(1998)110<0523:SGEIAS>2.3.CO;2 Article history First Online: 01 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 Georgia Pe-Piper, Ioannis Koukouvelas, David J. W. Piper; Synkinematic granite emplacement in a shear zone: The Pleasant Hills pluton, Canadian Appalachians. GSA Bulletin 1998;; 110 (4): 523–536. doi: https://doi.org/10.1130/0016-7606(1998)110<0523:SGEIAS>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 SocietyGSA Bulletin Search Advanced Search Abstract The 361–356 Ma (Late Devonian) Pleasant Hills pluton comprises a series of sheets of mafic, felsic, and hybrid intermediate plutonic rocks that were emplaced along a positive flower structure associated with the crustal-scale Cobequid fault zone. This dextral strike-slip fault zone forms the boundary of the Meguma and Avalon terranes. The sequence of emplacement is inferred from crosscutting structures. Radiometric dating shows that the pluton was crystallized within a few million years. Gabbroic magma was probably derived from partial melting of the mantle beneath the extensional Magdalen basin, and successive batches of mafic magma were progressively richer in H2O, Ti, Zr, and Nb. Felsic magmas were probably derived by partial melting of the lower crust. Small batches of felsic magma show differing trace-element evolution that reflects changes in magma temperature and type of volatiles, younger magmas being generally richer in high field strength elements and fluorine. Rapakivi-textured granite is common.Heat-transfer and mass-transfer along the fault zone resulted in thermal softening and lubrication of all branches of the flower structure, so that there was repeated magma flow through each branch. The presence of magma controlled the localization of strain, which is expressed as synmagmatic deformational structures, and deformation continued under solid-state conditions to produce mylonitic fabrics. Each branch of the flower structure acted as a pathway for many magma batches, and only small volumes of magma reached the highest structural levels. The pluton was emplaced by progressive widening of, and magma emplacement along, branches of the flower structure as a result of country rock translation. This translation involved both lateral and upward movement of blocks within the Cobequid fault zone. Dextral slip is recognized on the southern margin of the escaping block and reverse oblique sinistral slip on its northern margin. The Pleasant Hills pluton shows progressive creation of space for magma along branches of the flower structure and gradual expansion of the pluton from a series of dike-like bodies to a larger composite pluton through the emplacement of numerous small, geochemically distinct, magma batches. 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.
Publication Year: 1998
Publication Date: 1998-04-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 38
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