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Pre-Acadian magmatic suites of the southeastern Gaspé Peninsula

1986; Geological Society of America; Volume: 97; Issue: 10 Linguagem: Inglês

10.1130/0016-7606(1986)97 2.0.co;2

1943-2674

Jean H. Bédard,

Geology and Paleoclimatology Research

Research Article| October 01, 1986 Pre-Acadian magmatic suites of the southeastern Gaspé Peninsula JEAN H. BÉDARD JEAN H. BÉDARD 1Département de Géologie, Université de Montréal, C.P. 6128 succ. "A," Montréal, Québec, Canada H3C 3J7 Search for other works by this author on: GSW Google Scholar Author and Article Information JEAN H. BÉDARD 1Département de Géologie, Université de Montréal, C.P. 6128 succ. "A," Montréal, Québec, Canada H3C 3J7 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (10): 1177–1191. https://doi.org/10.1130/0016-7606(1986)97 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 MailTo Tools Icon Tools Get Permissions Search Site Citation JEAN H. BÉDARD; Pre-Acadian magmatic suites of the southeastern Gaspé Peninsula. GSA Bulletin 1986;; 97 (10): 1177–1191. doi: https://doi.org/10.1130/0016-7606(1986)97 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 SocietyGSA Bulletin Search Advanced Search Abstract There are two phases of post-Taconic, pre-Acadian magmatism in the eastern Gaspé Peninsula of Québec, (A) the Middle to Upper Ordovician Pabos Suite and (B) widespread Silurian-Devonian volcanics and hypabyssal intrusions. The Pabos Suite forms two large intrusions composed of LREE-depleted, N-MORB-like gabbros and ferrogabbros. Evolution within this suite was controlled by fractional crystallization, and the presence of the intrusions implies a tensional event between the Taconic and Acadian orogenies. The Silurian-Devonian volcanic and intrusive rocks are chemically variable (tholeiitic to alkaline, basaltic to rhyolitic) and do not belong to a single fractionation series. Quartz xeno-cryst-bearing rocks are enriched in Si, K, Zr, and LREE's, providing evidence of disequilibrium contamination by a felsic melt similar to locally occurring rhyolites. The lavas and dikes that do not carry felsic xenocrysts also show patterns of enrichment/depletion of trace elements, which suggest that felsic contamination/hybridization was an important factor in their development, but show little Si enrichment. This is interpreted to be due to maintenance of chemical equilibrium during contamination. This would have forced the composition of the magma to remain on the plagioclase + clinopyroxene + olivine cotectic and would thus have inhibited Si enrichment. The xenocryst-bearing rocks superficially resemble a calc-alkaline series, but most of the pre-Acadian Silurian-Devonian volcanics of the Gaspé Peninsula do not appear to have been directly associated with subduction. The preferred model is that of local tensional environments in an orogenic foreland. 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.