Start |Author Index | View Uploaded Presentations | Meeting Information

Northeastern Section - 43rd Annual Meeting (27-29 March 2008)

Paper No. 3
Presentation Time: 1:45 PM

THE PENOBSCOTTIAN ARC SYSTEM OF COASTAL MAINE AND SOUTHERN NEW BRUNSWICK


FYFFE, Leslie R.1, JOHNSON, Susan C.2 and MCLEOD, Malcolm J.2, (1)New Brunswick Natural Resources, Geological Surveys Branch, PO Box 6000, Fredericton, NB E3B 5H1, Canada, (2)New Brunswick Natural Resources, Geological Surveys Branch, PO Box 5040, 207 Picadilly Road, Sussex, NB E4E 5L2, Canada, les.fyffe@gnb.ca

Remnants of a Cambrian arc system can be traced from the Penobscot Bay area of coastal Maine for 300 km into southern New Brunswick. This Penobscottian arc is bordered to the southeast by the New River terrane and to the northwest by the Miramichi terrane.

The oldest arc volcanics occur in the Mosquito Lake Road Formation (~ 514 Ma) of southwestern New Brunswick. Detrital zircons from underlying sandstone of the Matthews Lake Formation are dominated by a population (537-567 Ma) derived from exposed Late Neoproterozoic New River basement. Smaller populations include Neoproterozoic (644 - 807 Ma) and Mesoproterozoic (1.20 -1.51 Ga) ages.

Cambrian volcanics in Maine include felsic tuffs of the Ellsworth Formation (~509 Ma) and domal volcanics of the Castine Formation (~502 Ma). Detrital zircons from Ellsworth sandstone are dominated by a population (530-569 Ma) likely derived from unexposed New River basement. Smaller populations include Cambrian (493-515 Ma), Neoproterozoic (630 to 679 Ma), Mesoproterozoic (1.21 - 1.50 Ga), and Paleoproterozoic (1.97-2.09 Ga) ages.

Felsic tuffs and domal volcanics of the Lawson Brook Formation in the Annidale area of New Brunswick were erupted between ~ 497 Ma and ~ 493 Ma. Zircons from the tuffs contain an inherited component of ~ 940 Ma. Lateral facies equivalents to the Lawson Brook Formation have been intruded by high-level felsic intrusions ranging in age from ~ 478 to ~ 469 Ma.

Ages of detrital zircons and inherited xenocrysts are consistent with formation of the Penobscottian arc on continental crust proximal to Amazonia. Along-strike variations in stratigraphy, volcanic geochemistry, and ages of eruption indicate that the tectonic setting of the arc changed from compressional in the Middle Cambrian to extensional in Late Cambrian. Arc magmatism ceased following collision with the Miramichi terrane in the Early Ordovician. Post-orogenic felsic magmatism (478-469 Ma) in the Penoscottian arc was generated contemporaneously with development of the Ordovician Meductic arc and Tetagouche back-arc basin.

Session No. 10

T4. Evidence for Provenance of Peri-Gondwanan Terranes
Thursday, 27 March 2008: 1:00 PM-5:25 PM
Geological Society of America Abstracts with Programs. Vol. 40, No. 2, p.14
© Copyright 2008 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T4. Evidence for Provenance of Peri-Gondwanan Terranes
<< Previous Abstract | Next Abstract >>