Mesozoic fault reactivation along the St. Lawrence rift system, eastern Canada: Thermochronologic evidence from apatite fission-track dating
Alain Tremblay et al., Dpartement des Sciences de la Terre et de l'Atmosphre and GEOTOP, Universit du Qubec. Posted online 22 Feb. 2013; http://dx.doi.org/10.1130/B30703.1.
The St. Lawrence rift system is formed by a series of northeast-southwest-trending faults in southeastern Qubec that links and includes the northwest-trending Ottawa-Bonnechre and Saguenay River regions. It is an active fault zone where reactivation of Late Precambrian (less than one billion years ago) faults, at times as young as post-Late Devonian (350 million years ago), is believed to occur. Apatite fission-track (AFT) ages, which represent the time that the rocks cooled through 100 degrees Celsius (3-4 km depth) on their way to the surface, have been determined for Late Precambrian rocks from both sides of typical rift faults at different locations in the St. Lawrence and Saguenay river fault systems along the St. Lawrence rift system. Differences in AFT ages were found across all the faults studied, suggesting reactivation of extensional movement approx. 250-200 million years. Along the St. Lawrence River fault system, the AFT ages also suggest a renewal of movement in a compressional sense at ca. 150 Ma. This study provides evidence for extension related to rifting in the Atlantic Ocean followed by compressional deformation in the interior of Canada, more than 500 km west of the Atlantic coastal margin.
Chemical and ecological evolution of the Miocene Ries impact crater lake, Germany: A reinterpretation based on the Enkingen (SUBO 18) drill core
Gernot Arp et al., Ge
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