Timing of tertiary extension in the Southern Canadian Cordillera: constraints from fission-track analysis in the Shuswap metamorphic complex
Lorencak, M.; Seward, D.; Burg, J.-P.
14th Victorian Universities Earth Sciences Conference. Abstract Volume Number 621999
14th Victorian Universities Earth Sciences Conference. Abstract Volume Number 621999
AbstractAbstract
[en] Full text: Nine zircon and eighteen apatite fission-track analyses have been made in order to determine the low temperature cooling history of the Shuswap metamorphic core complex, western Canada. The zircons vary in apparent age from 53.9 ± 5.6 to 37.5 ± 5.0 Ma and the apatites from 48.5 ± 3.2 to 27.7 ± 3.4 Ma. In the footwall of the detachment faults defining the core complex, the cooling histories show a similarity until temperatures of ∼250 C were reached at about 45 Ma. From then on, activity on two normal faults, the Columbia River Fault and the Victor Creek Fault, controlled the regional cooling pattern. The ages and the combination of ages fall into four groups and on the basis of the fission-track data, we suggest that the region can now be divided into four thermotectonic units which are the result of differing tectonic controls during regional extension. Additionally, a complete cooling history of the Shuswap core complex can now be reconstructed, using constraints from U-Pb, Rb-Sr and K-Ar age data from several authors as well as the fission track results presented here. Copyright (1999) Geological Society of Australia
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Geological Society of Australia Inc., Sydney, NSW (Australia); 68 p; 1999; p. 24; 14. Victorian Universities Earth Sciences Conference; Melbourne, VIC (Australia); Sep 1999; Available in abstract form only, full text entered in this record
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