Contiguous rather than discrete Paleozoic histories for the Avalon and Meguma Terranes based on detrital zircon data

Upper Ordovician-Lower Devonian strata of the Meguma terrane in the Canadian Appalachians contain zircon populations, including an important Mesoproterozoic zircon population (1.0-1.4 Ga), similar to those in coeval strata of Avalonia, and strongly suggest contiguous rather than discrete histories f...

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Bibliographic Details
Published in:Geology (Boulder) 2004-07, Vol.32 (7), p.585-588
Main Authors: Murphy, J. Brendan, Fernández-Suárez, Javier, Keppie, J. Duncan, Jeffries, Teresa E
Format: Article
Language:English
Subjects:
absolute age
Acadian Phase
accretion
Appalachian Phase
Appalachians
Arisaig Group
Avalon Zone
Avalonia
Canada
dates
detritus
Devonian
Eastern Canada
experimental studies
Geochronology
Geology
Gondwana
ICP mass spectra
IGCP
laser ablation
laser methods
Lower Devonian
Maritime Provinces
mass spectra
Meguma Terrane
nesosilicates
North America
Northern Appalachians
Nova Scotia
Ordovician
orogeny
orthosilicates
paleogeography
Paleozoic
Pb/Th
Permian
Rheic Ocean
silicates
spectra
Structural geology
tectonics
terranes
U/Pb
U/Th/Pb
Upper Ordovician
zircon
zircon group
Zirconium
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Summary:Upper Ordovician-Lower Devonian strata of the Meguma terrane in the Canadian Appalachians contain zircon populations, including an important Mesoproterozoic zircon population (1.0-1.4 Ga), similar to those in coeval strata of Avalonia, and strongly suggest contiguous rather than discrete histories for these terranes throughout the Paleozoic. That these terranes were juxtaposed throughout the early Paleozoic is indicated by the absence of a Cambrian-Ordovician accretionary event, the lack of intervening suture-zone ophiolitic units, and the similarity of Avalonian and Meguma basement Nd isotope signatures in early Paleozoic igneous suites. As Avalonia had accreted to Laurentia-Baltica by the Early Silurian, these data suggest that the Meguma terrane, like Avalonia, resided along the same (northern) margin of the Rheic Ocean at that time. These conclusions have implications for reconstructions of the northern Gondwanan margin in the early Paleozoic and imply that the Silurian-Devonian Acadian orogeny in Maritime Canada occurred in an Andean-type setting and was not related to collision of the Meguma terrane with the Laurentian margin.
ISSN:0091-7613
1943-2682
DOI:10.1130/G20351.1