Thermal History of the Frontenac Arch in Southeastern Ontario, Canada Constrained From Low-temperature Thermochronology
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Authors
Garcia Ramos, Daniela
Date
Type
thesis
Language
eng
Keyword
Tectonics , Low-temperature thermochronology , Basement faults , Frontenac , Seismicity , Structural Geology , Canada , Grenville Province
Alternative Title
Abstract
The Frontenac Arch is an intraplate low-relief ridge of Precambrian rocks that connects the southeastern Ontario part of the Canadian shield with the Adirondack Massif in New York State. The NW-SE trending ridge is oriented perpendicular to the major tectonic fabric of the Grenville, Appalachian, and St Lawrence rift systems. This thesis research aims to understand the building mechanism(s) and timing of this basement topography. New apatite and zircon (U-Th)/He and apatite fission track data from 19 samples collected along three transects in the Frontenac Arch provide cooling ages ranging from 183.7 - 19.5 Ma (AHe), 196.2 - 109.6 Ma (AFT), and 732.5- 144.1 Ma (ZHe). The T-t paths for the Frontenac Arch define a thermal history dominated by one stage of progressive cooling since the post-Shawinigan phase of the Grenville Orogeny (~1140 Ma) to surface temperatures by ~525 Ma after the culmination of the breakup of Rodinia. This is followed by sediment burial (~ 3-4 km) and reheating to ~160 °C with heating peaks at different times during the Paleozoic resulting in partial resetting of the ZHe dates, and a third cooling stage (0.3-0.5 °C/Ma ) starting during the breakup of Pangea and opening of the Atlantic Ocean in the Early Mezosoic.
The last pulse of cooling in the thermal models between 175-225 Ma coincides with Mesozoic normal fault reactivation documented through AFT age discontinuities in the St. Lawrence and Saguenay fault system at ca. 200 -250 Ma caused by NW-SE extension and breakup of Pangea. A younger faulting event resulting in differential exhumation is likely recorded in the Frontenac Arch along the NE-trending Rideau-Lake normal Fault between 150-190 Ma. A period of differential unroofing started at least since the Late Cretaceous and eroded most of the Early Paleozoic sediments left in the last 120 Ma, as recorded by Devonian clasts in Cretaceous diatremes and kimberlites in Montreal and Lake Timiskaming, respectively.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NoDerivs 3.0 United States