Geology Club Seminar

Luminescence measurements from feldspars which have cooled in the Late Pleistocene may offer a means of assessing thermal histories for geomorphically or tectonically active landscapes. The proportion of electron-trapping sites within the crystal lattice which are naturally filled by ionizing radiation is strongly dependent on temperature. Given that optically- or thermally-stimulated luminescence derives from these trapped electrons, luminescence signals from bedrock feldspar can be measured to determine whether a sample is in thermal steady state or disequilibrium. (new paragraph) K-feldspars have proven to be much brighter than quartz, but the complicated reaction kinetics of feldspar preclude the simple assignment of a closure temperature. Preliminary modeling work in this study and previously by other workers suggests that signals from quartz and feldspar should accumulate at temperatures near or slightly below those involved in Apatite Helium or Apatite Fission Track thermochronology. The fact that the signals begin to accumulate only after cooling to such low temperatures is opportune for the study of Late Quaternary landscape evolution.