Sam Woor: LL 09.05.24 скачать в хорошем качестве

Sam Woor: LL 09.05.24

Illuminating landscape responses to Quaternary climate change with luminescence Abstract: Upon exposure to daylight, minerals such as quartz and feldspar emit photons of light due to the movement of electrons within their crystal lattices. This phenomenon arises due to their exposure to naturally occurring radiation during their burial and forms the basis for a key geochronological technique in geomorphology: luminescence dating. Luminescence dating allows the quantitative calculation of the time since a grain of sand was buried and, as such, is widely employed to constrain the timing and rates of landscape responses to wider-scale climate forcing. Traditional luminescence dating takes place in the laboratory, however recently developed portable luminescence readers have the potential to help rapidly constrain the age of landforms. Moreover, there is growing interest in what the luminescence characteristics of minerals may tell us about other aspects of sedimentary deposits, such as their transport history and provenance. This talk will first give a brief introduction to luminescence. It will then explore these themes with two case studies of landscapes fundamentally shaped by Quaternary climate changes: one by recurrent periods of greater monsoon rainfall and aridity, the other by advancing and receding ice sheets. First, we will visit the Hajar Mountains of Oman in south-east Arabia to discuss the role of luminescence dating in constraining periods of alluvial fan aggradation over the last 400,000 years, the response of Hajar fans to cyclical changes in Indian Ocean Monsoon dynamics and their role as an important regional palaeoclimate archive. In the second part, we will shift the focus to the aeolian dune deposits of the Northern Great Plains of North America to discuss preliminary results from research being undertaken with a portable luminescence reader to rapidly constrain their age and sedimentary characteristics.