Testing the utility of detrital zircon geochronology across complex terrane boundaries: a case study from the northern Cordillera
Abstract
Detrital zircon geochronology is a widely used tool for identifying the provenance and affinity of allochthonous or parautochthonous crustal fragments. Despite the widespread application of this technique, there is considerable variation in the data reduction and statistical treatment implemented from study to study. To examine the utility of detrital zircon geochronology in defining potential variations across complex terrane boundaries, we compiled new and previously published U-Pb detrital zircon data from Neoproterozoic-Cambrian rocks north and south of the Porcupine shear zone, a complex structure that separates the North Slope subterrane (northeast Alaska and Yukon) from the Yukon block (eastern Alaska to Northwest Territories). Prior work has proposed that the North Slope subterrane was situated adjacent to northeastern Laurentia in the Neoproterozoic-Cambrian and was subsequently translated westward to its current position. We present a compilation of new U-Pb data for 2834 grains from 23 samples and previously published data from 60 samples to test the hypothesis that the North Slope subterrane has a provenance history distinct from the Yukon block. Various age-cutoffs (900, 1200 or 1500 Ma) used for determining which U-Pb system is used to calculate the best estimate of zircon age (i.e., 238U-206Pb or 206Pb-207Pb) affect the position and magnitude of peaks within probability density functions, but in most cases do not result in statistically different distributions. Furthermore, common statistical parameters (e.g., Kolmogorov-Smirnov, Kuiper, cross-correlation coefficient) yield consistent results—the sediment provenance between the North Slope and Yukon block is statistically distinct. These results broadly support the application of detrital zircon geochronology across complex terrane boundaries but reinforce the caveat that such studies require large sample sizes and integrate existing sedimentological, stratigraphic, and structural data.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T31I0320G
- Keywords:
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- 1038 Mantle processes;
- GEOCHEMISTRY;
- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS