| dc.contributor.author | Munyikwa, Ken | |
| dc.date.accessioned | 2014-01-16T18:37:14Z | |
| dc.date.available | 2014-01-16T18:37:14Z | |
| dc.date.issued | 2014-01-16T18:37:14Z | |
| dc.identifier.uri | http://hdl.handle.net/2149/3406 | |
| dc.description | This outline summarizes a presentation I made on August 28, 2013 at the 8th International Conference on Geomorphology organized by the International Geomorphological Association at the Cite des Sciences et de l’Industrie in Paris, France. The presentation was titled “The utility of portable optically stimulated luminescence (OSL) readers in providing temporal contexts in clastic depositional systems: opportunities in geomorphology”
Luminescence readers are devices that are used to detect low levels of light emitted by geological samples when stimulated by heat or another light source. The light from the samples comes from energy that accumulates in mineral grains such as quartz or feldspar as a result of low level radioactivity that occurs naturally in earth materials. This energy accumulates over time as long at the samples are shielded from light. Therefore luminescence signals can be used to measure burial age of the samples. Over the last 5-6 years, portable versions of the regular lab-bound luminescence readers have been developed and while these are simpler devices, they can be used to obtain luminescence signals much more rapidly than with the lab-bound OSL readers.
Our presentation in Paris outlined three case studies that we have carried out in Alberta that illustrate the utility of portable OSL in geomorphology, which is the study of the shape of the earth’s surface. In the first study, we used the portable OSL reader to determine relative ages of depositional units in a dune landscape in southern Alberta. In the second study we used the portable reader to demarcate basal sections of wind deposited dunes that overlie glacial sands in central and northern Alberta. In the third study we used the portable reader to differentiate between sedimentary units disrupted by human activity (oil and gas related pipeline work) and those that are still naturally intact.
Overall, the three studies illustrate the usefulness of portable OSL readers in providing a better insight with regards to the timing of deposition in young sedimentary systems, especially in those emplaced by wind. Understanding such contexts is central to the study and interpretation of geological processes that take place near the earth’s surface. | en |
| dc.description.abstract | The recent development ofa functional portable optically stimulated luminescence (POSL) readers has ushered in new opportunities in geomorphology. Although POSL readers do not necessarily provide absolute ages as in regular OSL dating, they can be used to readily acquire luminescence signals from clastic sediments. Such signals can be used to construct luminescence profiles which depict the variation of the luminescence signal with depth within a depositional sequence. Luminescence signals depend on dose rate, sensitivity of the mineral grains, mineralogy, degree of bleaching and burial age of the sediments. When all these parameters apart from burial age are held constant, the luminescence profile can serve as a proxy for the chronostratigraphy.
A number of studies we have carried out on the Canadian prairies with a POSL reader developed by the Scottish Universities Environmental Research Centre serves to illustrate the utility of the readers. Their portability means that the device can be carried to the field and analysis can be performed on bulk samples, negating the need for time-intensive mineralogical separations, as is required in regular OSL dating. In one study we used the POSL reader to profile Holocene eolian dune sequences to determine the relative ages of the depositional units as well as ascertain whether any lengthy depositional hiatuses exist within the sequences. In another study we profiled postglacial dunes that overlie glaciofluvial sands in an effort to delineate the interface between the two depositional facies. In a third study we used luminescence profiling to identify eolian dune sands that were still intact from those that had experienced post-depositional mixing. In all three cases, luminescence profiling afforded an enhanced temporal context of the stratigraphy, permitting better sample targeting for regular OSL dating. Overall the studies underscore the breadth of geomorphological settings in which the POSL readers can be used. | en |
| dc.language.iso | en | en |
| dc.relation.ispartofseries | 92.927.G1435; | |
| dc.subject | Luminescence dating | en |
| dc.subject | Portable OSL reader | en |
| dc.subject | Geomorphology | en |
| dc.title | The utility of portable optically stimulated luminescence (OSL) readers in providing temporal contexts in clastic depositional systems: opportunities in geomorphology | en |
| dc.type | Presentation | en |
