Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Journal of the Geological Society

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Valverde-Vaquero, P. Articles by Dunning, G. R. Search for Related Content GeoRef GeoRef Citation

Mid–Late Ordovician magmatism and metamorphism along the Gander margin in central Newfoundland

^{1 1}Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8, Canada (e-mail: pvalverd@NRCan.gc.ca)
^{2 2}Present address: Instituto Geológico y Minero de España, La Calera 1, Tres Cantos, Madrid, Spain
^{3 3}Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X5, Canada

Fieldwork coupled with U–Pb dating has clarified the relationships between the Exploits and Gander-derived rocks in central Newfoundland during the Mid-Ordovician opening of the Exploits back-arc basin, reinforcing correlation across the peri-Gondwanan segments of the Appalachian–Caledonian orogen. We have separated a new back-arc-related unit, the Red Cross Group, from the arc-related Victoria Lake Supergroup. This group includes 466 ± 3 Ma felsic volcanic rock interlayered with alkali basalt–enriched mid-ocean ridge basalt, 457 ± 6 Ma gabbro, Llanvirn–Caradoc normal mid-ocean ridge basalt–island arc tholeite, limestone, black shale and mélange. Locally the Red Cross Group is in parautochthonous contact with low-grade Gander psammite. This contact was overrun by the Meelpaeg Metamorphic Nappe during the Devonian. The nappe contains Gander metapsammite (Meelpaeg Subzone) and the coticule-bearing Howley Waters Complex (Exploits), which hosts 467 ± 3 Ma felsic porphyry. The Gander and Exploits metasediments in the nappe are stitched by Arenig–Llanvirn granite (467 ± 6 Ma and 468 +3.5/–3 Ma) and Caradoc intrusions (458 ± 3 Ma and 454 ± 2 Ma). Metamorphic monazite (462 ± 1 Ma) and titanite (460 ± 3 Ma) from the nearby Mount Cormack Subzone (Gander) indicate the coeval formation of a low-pressure–high-temperature metamorphic dome. The widespread presence of Caradoc magmatism suggests that the width of the back-arc basin remained relatively narrow.

This article has been cited by other articles:

				C.R. van Staal, K.L. Currie, G. Rowbotham, N. Rogers, and W. Goodfellow Pressure-temperature paths and exhumation of Late Ordovician-Early Silurian blueschists and associated metamorphic nappes of the Salinic Brunswick subduction complex, northern Appalachians GSA Bulletin, November 1, 2008; 120(11-12): 1455 - 1477. [Abstract] [Full Text] [PDF]

				A. Zagorevski, C. R. Van Staal, V. McNicoll, and N. Rogers Upper Cambrian to Upper Ordovician peri-Gondwanan Island arc activity in the Victoria Lake Supergroup, Central Newfoundland: Tectonic development of the northern Ganderian margin Am J Sci, February 1, 2007; 307(2): 339 - 370. [Abstract] [Full Text] [PDF]

				S. Lin, D. W. Davis, S. M. Barr, C. R. Van Staal, Y. Chen, and M. Constantin U-Pb Geochronological Constraints On The Evolution Of The ASPY Terrane, Cape Breton Island: Implications For Relationships Between ASPY And BRAS D'OR Terranes And Ganderia In The Canadian Appalachians Am J Sci, February 1, 2007; 307(2): 371 - 398. [Abstract] [Full Text] [PDF]

				J. C. Pollock, D. H. C. Wilton, C. R. van Staal, and K. D. Morrissey U-Pb detrital zircon geochronological constraints on the Early Silurian collision of Ganderia and Laurentia along the Dog Bay Line: The terminal Iapetan suture in the Newfoundland Appalachians Am J Sci, February 1, 2007; 307(2): 399 - 433. [Abstract] [Full Text] [PDF]

				J. N. Aleinikoff, R. P. Wintsch, R. P. Tollo, D. M. Unruh, C. M. Fanning, and M. D. Schmitz Ages and origins of rocks of the Killingworth dome, south-central Connecticut: Implications for the tectonic evolution of southern New England Am J Sci, January 1, 2007; 307(1): 63 - 118. [Abstract] [Full Text] [PDF]

				R. P. Wintsch, J. N. Aleinikoff, G. J. Walsh, W. A. Bothner, A. M. Hussey II, and C. M. Fanning Shrimp U-Pb evidence for a Late Silurian age of metasedimentary rocks in the Merrimack and Putnam-Nashoba terranes, eastern New England Am J Sci, January 1, 2007; 307(1): 119 - 167. [Abstract] [Full Text] [PDF]