Dr. Lei Wu - A trans-Iapetus transform fault control for the evolution of the Rheic Ocean: Implications for an early Paleozoic transition of accretionary tectonics

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Dr. Lei Wu, McGill

Vendredi 26 mars 2021 à 11h00 - Friday, March 26, 2021 at 11am
https://mcgill.zoom.us/j/86337986906?pwd=R2tnYnVyRmpxWlMxT1pYdEd6RWdnZz09
Résumé / abstract:

The Paleozoic Era begins with the final assembly of Gondwana and ends with the amalgamation of the supercontinent Pangea. Although this tectonic progression is generally well documented, one fundamental but under-studied phenomenon during this era is the transition from two-way to one-way (northward) migration of peripheral terranes between Gondwana and Laurentia-Baltica from Cambrian to Ordovician time. The two-way terrane accretion was likely initiated during the opening of the Rheic Ocean at ca. 510 Ma when several Gondwana-derived terranes comprising Carolinia, Ganderia, Avalonia and the Meguma terrane sequentially drifted from the northern margin of Gondwana and eventually collided with Laurentia or Baltica. Over the same time interval, the Laurentia-derived Cuyania terrane and the Dashwoods microcontinent drifted away from the southern (Ouachita embayment) and proto-Appalachian margins, respectively. During the Ordovician, Cuyania accreted to the proto-Andean margin of Gondwana, whereas Dashwoods re-accreted to the Laurentian margin after being trapped during collision of the Taconic arc. Here we propose a new tectonic model to explain the enigmatic, penecontemporaneous accretion of those peripheral terranes by a trans-Iapetus transform fault that was likely active from 510-450 Ma and extended from the proto-Appalachian margin of Laurentia to the proto-Andean margin of Gondwana. The trans-Iapetus transform fault terminated after the respective accretion of Carolinia and Ganderia to the proto-Appalachian margin and of Cuyania to the proto-Andean margin. We interpret the development of the trans-Iapetus transform during Cambro-Ordovician time as a consequence of the global geodynamic transition from the break-up of Rodinia (continents/terranes drifting away from Laurentia) to Pangea assembly (continents/terranes drifting toward assembling Laurussia). Termination of the trans-Iapetus transform coincides with several global changes during the Late Ordovician to early Silurian including the strongly synchronized global continental motions, mantle mass redistribution, and the short-lived Hirnantian glaciation and mass extinction.

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A trans-Iapetus transform fault control for the evolution of the Rheic Ocean: Implications for an early Paleozoic transition of accretionary tectonics

Ajouter au calendrier 2021-03-26 11:00:00 2024-03-28 16:40:56 Dr. Lei Wu - A trans-Iapetus transform fault control for the evolution of the Rheic Ocean: Implications for an early Paleozoic transition of accretionary tectonics The Paleozoic Era begins with the final assembly of Gondwana and ends with the amalgamation of the supercontinent Pangea. Although this tectonic progression is generally well documented, one fundamental but under-studied phenomenon during this era is the transition from two-way to one-way (northward) migration of peripheral terranes between Gondwana and Laurentia-Baltica from Cambrian to Ordovician time. The two-way terrane accretion was likely initiated during the opening of the Rheic Ocean at ca. 510 Ma when several Gondwana-derived terranes comprising Carolinia, Ganderia, Avalonia and the Meguma terrane sequentially drifted from the northern margin of Gondwana and eventually collided with Laurentia or Baltica. Over the same time interval, the Laurentia-derived Cuyania terrane and the Dashwoods microcontinent drifted away from the southern (Ouachita embayment) and proto-Appalachian margins, respectively. During the Ordovician, Cuyania accreted to the proto-Andean margin of Gondwana, whereas Dashwoods re-accreted to the Laurentian margin after being trapped during collision of the Taconic arc. Here we propose a new tectonic model to explain the enigmatic, penecontemporaneous accretion of those peripheral terranes by a trans-Iapetus transform fault that was likely active from 510-450 Ma and extended from the proto-Appalachian margin of Laurentia to the proto-Andean margin of Gondwana. The trans-Iapetus transform fault terminated after the respective accretion of Carolinia and Ganderia to the proto-Appalachian margin and of Cuyania to the proto-Andean margin. We interpret the development of the trans-Iapetus transform during Cambro-Ordovician time as a consequence of the global geodynamic transition from the break-up of Rodinia (continents/terranes drifting away from Laurentia) to Pangea assembly (continents/terranes drifting toward assembling Laurussia). Termination of the trans-Iapetus transform coincides with several global changes during the Late Ordovician to early Silurian including the strongly synchronized global continental motions, mantle mass redistribution, and the short-lived Hirnantian glaciation and mass extinction. Geotop admin@example.com America/New_York public