Geochronology

Geochronological

CERSA provides geological dating of sediments and minerals, using optically stimulated luminescence (OSL) and laser ablation ICP-MS (LA-ICP-MS).

The St Andrews Luminescence Laboratory comprises 1) three Risø OSL systems with thermal (TL), infrared and blue LED stimulation; 2) a UV-IR photo spectrometer; and 3) a high sensitivity emission spectrometer (thermal, electron beam or x-ray excitation). This suite of equipment allows us to do conventional continuous-wave and linearly-modulated OSL on quartz, feldspars, and other solid materials, as well as time resolved spectroscopy over a wide range of stimulation wavelengths. Two field gamma spectrometers can be used to calculate dose rates, or elemental abundances and dosimetry can be calculated using ICP-MS and XRF.

We perform single mineral U/Pb geochronology of zircon (and eventually rutile and apatite) using a quadropole ICP-MS with a New Wave 213 nm laser to provide a rapid means of dating zircons with an uncertainty of 5-7%. Analyses include mineral separation, picking and mounting, as well as backscatter and CL analysis of mineral zoning using EPMA prior to LA-ICP-MS analysis.    

CERSA has expertise in dating Quaternary-aged sediments from a broad range of environments from many different climate and tectonic settings around the world, including sediments from fluvial and floodplain systems, fault-generated colluvium, tsunami-generated sediments, glacial systems, hillslopes, lakes, deltas, aeolian systems, and estuarine and shallow marine systems. The age range is typically from 200,000 years to recent (but up to 106 years is possible under certain conditions and typically using feldspar). OSL dating is used to date sediments and artifacts associated with archaeological sites, and can constrain sediment accumulation and transport rates on short and medium-term timescales. CERSA has expertise using U/Pb geochronology for bedrock and detrital zircons in order to constrain provenance and provide maximum ages for stratigraphic sequences, as well as in dating zircons extracted from igneous rocks.

Example Projects:

  • Evolution of the Mekong River and its terraces
  • Luni River sediments, India (related to pipeline development)
  • Earthquake and fault-generated deposits, Chile
  • Tsunami deposits, Thailand
  • Lake shoreline evolution and tectonics, Tibet
  • Age of detrital minerals in Carboniferous sediments, Spain

 

Contact: Dr Ruth Robinson: Ruth.Robinson@st-andrews.ac.uk