| Title | Chlorine-36 age determination for Mystery Creek rock avalanche, British Columbia, Canada |
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| Author | Blais-Stevens, A ;
Hermanns, R L; Jermyn, C |
| Source | Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 36, 2011 p. 1; 1 CD-ROM  Open Access |
| Links | Online - En ligne
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| Year | 2011 |
| Alt Series | Earth Sciences Sector, Contribution Series 20100388 |
| Meeting | Geological Association of Canada Annual Meeting; Ottawa; CA; May 25-27, 2011 |
| Document | serial |
| Lang. | English |
| Media | paper; CD-ROM; on-line; digital |
| File format | pdf |
| Province | British Columbia |
| NTS | 92G/06; 92G/11; 92G/14; 92J/02; 92J/07 |
| Area | Sea to Sky Corridor; North Vancouver; Lions Bay; Porteau; Squamish; Whistler; Pemberton |
| Lat/Long WENS | -123.5000 -122.5000 50.5000 49.2500 |
| Subjects | engineering geology; geochronology; Health and Safety; health hazards; landslides; landslide deposits; slope stability; slope failures; chlorine; radiometric dating |
| Program | Public Safety Geoscience Targeted Hazard Assessments in Western Canada |
| Released | 2011 01 01 |
| Abstract | The Sea to Sky Corridor has experienced hundreds of historic and prehistoric landslides. The most common types of historical landslides are rock falls and debris flows, which are relatively small in
volume, but can be damaging. These types of failures are more common in the southern part of the corridor, between Horseshoe Bay and Porteau, where infrastructure has been built in close proximity to steep slopes. Farther north, fewer landslides have
been reported historically, but those that have been recorded, are usually large and date to prehistoric time (e.g., Cheekye fan and Mystery Creek rock avalanche).As part of a Geological Survey of Canada surficial geology and landslide inventory
mapping study, Mystery Creek rock avalanche, near Whistler, British Columbia, was sampled for 36Cl dating. Samples were collected from three large flat boulders of quartz diorite in the rock avalanche deposit to confirm a correlation with the
previously reported radiocarbon age of 800±100 years BP on charcoal. One sample revealed an age of 2400 years and the other two, 4300 and 4800 years, respectively. These new ages point to four possible interpretations: 1) Mystery Creek landslide is
about 800 years old; 2) Based on the overlapping 2 sigma uncertainties, the rock avalanche took place between 2200 and 3600 yrs ago; 3) The rock avalanche deposit is 2400 years old and the other two blocks are too old; and 4) The rock avalanche is
between 4300 and 4800 years old. We favour the second where the age range is broader and statistically significant for all three samples. Moreover, at this time, we favour discounting the radiocarbon age based on a greater number of samples analyzed
for 36Cl analysis, which indicates an older age with the 2 sigma uncertainty. Thus, large landslides such as these remain a present-day hazard to infrastructure like the Sea to Sky Highway, the railway, and population. |
| GEOSCAN ID | 287796 |
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