Geological Society of America

T70 Recent Advances in Supercontinents: Paleogeography, Geodynamics, and Paleoclimate Evolution I

Tuesday, 27 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

A TRANS-IAPETUS TRANSFORM CONTROL FOR THE EVOLUTION OF THE RHEIC OCEAN

Paper number: T70-14
Program: Technical Sessions
Time: 4:35 PM – 4:50 PM

Authors

Lei Wu Presenting Author
McGill University, Montréal, QC
Brendan Murphy
St. Francis Xavier University, Antigonish, NS
William J. Collins
Stanford University, Stanford, WA
Cecilio Quesada
and Facultad de Geológicas; Universidad Complutense de Madrid, Madrid
Zheng-Xiang Li
Curtin University of Techology, Perth
Sergei Pisarevsky
Curtin University, Perth
Galen Halverson
McGill University, Montreal, QC
John Waldron
University of Alberta, Edmonton, AB
Simon E. Williams
The University of Sydney, Sydney

Abstract

The Rheic Ocean opened at ca. 500 Ma when several peri-Gondwanan domains (e.g., Carolinia, Ganderia, Avalonia and Megumia) sequentially drifted from the northern margin of Gondwana and eventually collided with Baltica and/or northern Laurentia to close the Iapteus Ocean. Over the same time interval, the Precordillera (Cuyania) drifted away from southern Laurentia (the Ouachita margin) to join the paleo-Andean margin of Gondwana. Here we propose a new tectonic model to explain the coeval but opposite sense of transfer of those peripheral terranes by a trans-Iapetus transform fault that was likely located between Carolina-Ganderia and the Precordillera, and was active from 500-450 Ma. Together with two pre-existing Iapetus-bounding transforms, this postulated trans-Iapetus transform suggests that Gondwana and Laurentia were connected in the early to middle Paleozoic, which has important implications for reconstructing their relative paleolongitudes during this time interval. Deactivation of this trans-Iapetus transform at 450-440 Ma coincided with the docking of parts of Ganderia against Laurentia, Avalonia on Baltica, and the Precordillera on the proto-Andean margin of Gondwana. This deactivation event demarcates a fundamental change on the plate boundary topology in the Iapetus–Rheic domain, which is coincident with several global changes during the Late Ordovician to early Silurian, including strongly synchronized global continental motions, mantle mass redistribution, and the short-lived Hirnantian glaciation and associated mass extinction.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-354350

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