In situ 10Be ages from the Parallel Roads of Glen Roy: Loch Lomond stadial landforms

Geomorphology

Small, David

University:University of Glasgow

关键词: Geomorphology;   

Others  :  http://theses.gla.ac.uk/74135/1/10754048.pdf

来源: University of Glasgow

【 摘 要 】

The Parallel Roads of Glen Roy along with their associated terraces and fans provide one of the best examples of the suite of features produced by the interactions of glacial, fluvial and lacustrine processes. These features have been the subject of numerous studies over many years and as a result are some of the best known geological features in the world. Despite this attention they have proven difficult to date using any of the absolute dating techniques available. Here we present the first absolute ages from the Parallel Roads using in situ 10Be. We sampled from 9 different locations and 2 distinct geomorphologic settings, the 325m shoreline and 2 fans associated with the 260m shoreline. The ages obtained show good agreement within la errors for each of the 2 settings. The shoreline ages indicate that each road was formed synchronously throughout the glen during the Loch Lomond Stadial (LLS). The ages from the fan samples indicate that deposition was occurring on these surfaces into the Holocene, which precludes the possibility that the fans are entirely pre-LLS features as has been previously argued. The ages obtained in this study also let us constrain the occurrence of a large (5.9) seismic event that occurred in this area around the time of shoreline formation to occurring before 11.3 +/- 0.6 ka.