TY - CHAP
T1 - Dating Glacial Landforms II: Radiometric techniques
AU - Davies, Bethan
PY - 2021/1/30
Y1 - 2021/1/30
N2 - Numerical ages for glacial landforms are required to position palaeo ice extent at a given point in space and time. Radiometric methods, when appropriately calibrated and measured, allow intra- and inter-regional correlation and the production of large empirical datasets across varied and fragmented Quaternary deposits. This chapter focuses on radiocarbon ages for terrestrial and marine environments, cosmogenic nuclide dating (including exposure ages of bedrock and glacially transported boulders, and burial dating for glacial sediments), optically stimulated luminescence dating of glaciofluvial outwash, and Argon/Argon or Potassium/Argon dating of moraines interbedded with volcanic sequences. For each method, the key principles and concepts are outlined, sampling methodologies are discussed, calibration techniques and protocols are provided, and quality assurance protocols are suggested. All dating stratigraphies should take place within a geomorphological and sedimentological framework, and dating techniques must be used with knowledge of their key assumptions, best-practice guidelines and limitations. Combining glacial geomorphology with carefully constructed numerical age chronologies allows the timing of significant stabilisations of outlet glaciers at moraines to be characterised, whilst vertical transects down mountain ranges provide information on past rates and magnitudes of ice-mass thinning. These typically more expensive methods may be used with great effect in conjunction with archival, relative and incremental dating techniques, and with age-equivalent stratigraphic markers. This greatly increases the spatial coverage of the numerical dating methods and allows regional stratigraphies to be constructed. These data are critical if we are to understand ice mass response to the internal and external, climatic drivers of change.
AB - Numerical ages for glacial landforms are required to position palaeo ice extent at a given point in space and time. Radiometric methods, when appropriately calibrated and measured, allow intra- and inter-regional correlation and the production of large empirical datasets across varied and fragmented Quaternary deposits. This chapter focuses on radiocarbon ages for terrestrial and marine environments, cosmogenic nuclide dating (including exposure ages of bedrock and glacially transported boulders, and burial dating for glacial sediments), optically stimulated luminescence dating of glaciofluvial outwash, and Argon/Argon or Potassium/Argon dating of moraines interbedded with volcanic sequences. For each method, the key principles and concepts are outlined, sampling methodologies are discussed, calibration techniques and protocols are provided, and quality assurance protocols are suggested. All dating stratigraphies should take place within a geomorphological and sedimentological framework, and dating techniques must be used with knowledge of their key assumptions, best-practice guidelines and limitations. Combining glacial geomorphology with carefully constructed numerical age chronologies allows the timing of significant stabilisations of outlet glaciers at moraines to be characterised, whilst vertical transects down mountain ranges provide information on past rates and magnitudes of ice-mass thinning. These typically more expensive methods may be used with great effect in conjunction with archival, relative and incremental dating techniques, and with age-equivalent stratigraphic markers. This greatly increases the spatial coverage of the numerical dating methods and allows regional stratigraphies to be constructed. These data are critical if we are to understand ice mass response to the internal and external, climatic drivers of change.
M3 - Chapter
T3 - Treatise on Geomorphology, 2nd Edition
BT - Cryospheric Geomorphology
A2 - Haritashya, Umesh
PB - Elsevier
ER -