Timing and spatial distribution of deformation in the Newfoundland Appalachians: a “multi-stage collision ” history
The Newfoundland Appalachians have been interpreted as an area where Lower Paleozoic plate convergence culminated in collision between an Ordovician volcanic chain and the North American craton in Middle Ordovician times. Closure of the intervening proto-Atlantic (Iapetus) ocean was considered incom...
| Main Authors: | , |
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| Format: | Text |
| Language: | English |
| Published: |
1985
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.510.4225 http://globalchange.umich.edu/ben/publications/87_tecto_vdp.pdf |
| Summary: | The Newfoundland Appalachians have been interpreted as an area where Lower Paleozoic plate convergence culminated in collision between an Ordovician volcanic chain and the North American craton in Middle Ordovician times. Closure of the intervening proto-Atlantic (Iapetus) ocean was considered incomplete. Subsequent deformation gave rise to regional folding and faulting. Recent studies in the Newfoundland Dunnage zone have revealed that the deformation history is far more complex than previously recognized. Large-scale thrusting, folding and faulting occurred in Silurian-Devonian times. Further-more, it has been suggested that the Dunnage zone is an allochthonous terrane underlain by dominantly continental crust rather than representing remnants of a “rooted ” ocean basin. In view of these results a revision of tectonic scenarios and zonal subdivision is warranted and a “multi-stage collision ” history will be discussed, with emphasis on the spatial distribution and significance of Silurian-Devonian deformation in central Newfoundland. Subduction in Lower Paleozoic times gave rise to the formation of a volcanic terrane; concurrently, to the southeast a marginal sea was formed (Mariana-type subduction). In Middle Ordovician times the volcanic terrane collided with the North American craton (“first-stage collision”) and back-arc spreading terminated. Continued crustal shortening resulted in the formation of a Silurian accretionary terrane (telescoped marginal sea), and its subsequent deformation |
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