| Title | Directly dating deformation with calcite U-Pb; the good, the bad and the ugly! |
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| Author | Mottram, C; Coutand, I; Grujic, D; Kellett, D |
| Source | European Geophysical Union General Assembly 2019; Geophysical Research Abstracts vol. 21, EGU2019-12803, 2019 p. 1  Open Access |
| Links | Online - En ligne
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| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20190401 |
| Publisher | European Geophysical Union |
| Meeting | European Geophysical Union General Assembly 2019; Vienna; AT; April 7-12, 2019 |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Subjects | geochronology; tectonics; Science and Technology; Nature and Environment; tectonic setting; deformation; displacement; fluid flow; mineralization; veins; calcite; radiometric dating; uranium lead
dating; calcite; bedrock geology; structural features; faults; faults, thrust; faults, strike-slip; Methodology |
| Program | GEM2: Geo-mapping for Energy and Minerals Western Cordillera, Yukon Tectonic Evolution - late Mesozoic to Tertiary |
| Released | 2019 04 01 |
| Abstract | Deformation in the upper crust is commonly accommodated by brittle fracturing, faulting and dissolution-precipitation creep. These short-lived, low temperature deformation processes are notoriously
difficult to date as minerals commonly used to record geological time (such as zircon and monazite) typically do not crystallise or recrystallize in response to deformation under these conditions. Brittle fractures provide pathways for fluids,
resulting in abundant calcite/quartz veins in the earths upper crust. Analytical techniques have recently been developed for direct dating of brittle structures using U-Pb in calcite slickenfibres and syn-tectonic veins (e.g. Roberts and Walker,
2016; Nuriel et al., 2017). This has opened up a whole new realm of possible tectonic investigations in the upper crust. This talk will explore the effectiveness of the U-Pb calcite dating technique for providing timing constraints for upper crustal
deformation, fluid flow and mineralisation events. Like other unconventional geochronometers that have low U content and incorporate common Pb into their structures (e.g. titanite), calcite is not always suitable for U-Pb analysis and results can
therefore be ambiguous to interpret. We present examples spanning the range of the good, bad and ugly in the world of calcite U-Pb dating. Despite these challenges, we use case studies from continental-scale thrust and strike-slip faults including
the Main Boundary Thrust in the Himalaya, the North Anatolian Fault, and the Big Creek Fault in the Yukon, Canadian Cordillera to demonstrate how U-Pb calcite dating can be successfully used to reconstruct the displacement history of these various
first-order structures. |
| GEOSCAN ID | 321676 |
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