Provenance variations in northern Appalachian Avalonia based on detrital zircon age patterns in Ediacaran and Cambrian sedimentary rocks, New Brunswick and Nova Scotia, Canada

Author:

Barr S.M.1,Hamilton M.A.2,Samson S.D.3,Satkoski A.M.3,White C.E.4

Affiliation:

1. Acadia University, Dept. of Earth & Environmental Science, Wolfville, NS B4P 2R6, Canada.

2. University of Toronto, Jack Satterly Geochronology Lab, Toronto, ON M5S 3B1, Canada.

3. Syracuse University, Department of Earth Sciences, Syracuse, NY 13244-1170, USA.

4. Department of Natural Resources, P.O. Box 698, Halifax, NS B3J 2T9, Canada.

Abstract

Avalonia in the northern Appalachian orogen is generally assumed to have originated near the margin of Gondwana, although its position along that extensive margin and the timing of its separation remain disputed. U–Pb ages determined by laser ablation – inductively coupled plasma – mass spectrometry are reported here for detrital zircon from Avalonian clastic sedimentary units, three in southern New Brunswick, and one in southeastern Cape Breton Island, with depositional ages ranging from ca. 630 to ca. 505 Ma. Considered in combination with previously published detrital data sets from two other samples from southern New Brunswick deposited in a similar age range, the samples show a wide spectrum of ages from Ediacaran to Neoarchean (as old as 3.2 Ga). The dominant zircon populations in all six samples are Ediacaran–Cryogenian with ages between 770 and 540 Ma and can be matched with known magmatic events in Avalonia. Pre-Avalonian cycle detrital zircon dates in the samples are relatively sparse and do not reveal a consistent signature that might be used to place Avalonia in a unique paleogeographic position, although they are compatible with Amazonian provenance. An increase in ca. 2.2–1.9 Ga zircon dates in Early Cambrian through Early Ordovician samples suggests that sources for zircon of those ages became available in Avalonia by the end of the Ediacaran, possibly by motion of Avalonia to a different part of the Amazonian margin or to the West African craton.

Publisher

Canadian Science Publishing

Subject

General Earth and Planetary Sciences

Reference67 articles.

1. Detrital zircon ages of Neoproterozoic sequences of the Moroccan Anti-Atlas belt

2. Detrital zircons as tracers of sedimentary provenance: limiting conditions from statistics and numerical simulation

3. Barr, S.M., and White, C.E. 1996. Contrasts in Late Precambrian-Early Paleozoic tectonothermal history between Avalon composite terrane sensu stricto and other possible peri-Gondwanan terranes in southern New Brunswick and Cape Breton Island, Canada. In Avalonian and related peri-Gondwanan terranes of circum-North Atlantic. Edited by R.D. Nance and M.D. Thompson. Geological Society of America, Special Paper 304. pp. 95–108.

4. Barr, S.M., and White, C. 1999. Field relations, petrology, and structure of the Neoproterozoic rocks in the Caledonian Highlands, southern New Brunswick. Geological Survey of Canada, Bulletin 530.

5. Barr, S.M., White, C.E., and Macdonald, A.S. 1992. Revision of upper Precambrian–Cambrian stratigraphy, southeastern Cape Breton Island, Nova Scotia. In Current research, part D. Geological Survey of Canada, Paper 92-1D. pp. 21–26.

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