Principles & Concepts
The Cosmogenic Nuclide Preparation Laboratory at the School of Earth & Environment, ҕl (ҕl) opened in its new premises in the Ernest Rutherford building in 2018. Be-10 and Al-26 targets are prepared from bedrock and sedimentary deposits for measurement by Accelerator Mass Spectrometery (AMS). The lab engages in multi-disciplinary research projects from regions around the globe. This site provides an overview of the cosmogenic nuclide preparation laboratory.
High-energy cosmic rays shower the Earth's surface and produce long-lived cosmogenic radionuclides (e.g., Be-10 and Al-26)in situin the uppermost few meters of near-surface materials. Production rates are only a few atoms per gram of rock per year, yet by carefully isolating Be and Al from quartz and measuring the concentrations of 10Be and 26Al using accelerator mass spectrometry, we are able to provide quantitative measures of theexposure agesof landforms (e.g., glacial moraines and striated bedrock valleys, fault scarps, landslide detachment surfaces), theerosion ratesof landforms (river incision, bedrock erosion, bedrock erosion beneath soil cover, catchment-averaged erosion) and/or thedepositional agesof sedimentary deposits. The use of cosmogenic nuclides has thus revolutionized the study of earth surface processes by allowing us to obtain dates and rates from landforms. The ҕl Cosmogenic Nuclide Preparation Laboratory completes an important part of this process, by obtaining purified quartz separates and preparing 10Be and 26Al targets from bedrock and sedimentary materials. The team also has experience separating olivine for 3He exposure age dating.
About the Laboratory
The ҕl Cosmogenic Radionuclide Laboratory opened in the former Department of Geological Sciences in 2004. This was replaced with new facilities on campus which have been in use since 2018. Technical assistance with lab planning and development has been provided by the Australian Nuclear Science and Technology Organisation (ANSTO). The lab has a designated technician and produces 10-Be and 26-Al targets for AMS analysis. The scientific directions of the lab are centred on obtaining quantitative measures of (1) the depositional and/or exposure ages of Quaternary landforms and deposits (e.g., glacial moraines, alluvial deposits, fault scarps, landslides) and (2) the rates of climate and/or tectonically-driven geomorphic processes (e.g.,in situbedrock erosion, river incision). We are practised in obtaining clean quartz separates from ‘challenging’ lithologies, as many of our samples come from the fine-grained greywacke that comprises much of the bedrock of New Zealand’s South Island. Samples prepared in our lab are more frequently analysed by our collaborative research partners at the, theat the New Zealand National Isotope Center[http://www.gns.cri.nz/nic/.At present, the laboratory prepares 10-Be and 26-Al targets from rocks, sediments, and clean quartz for cosmogenic nuclide analysis for both in-house research and clients around the globe. We are happy to discuss other techniques as technology changes and science and research experiment with different ideas.
Facilities
Rock Crushing
For crushing and grinding raw samples we have the following pieces of equipment:
- Boyd Jaw Crusher (Rocklabs)
- Disc Pulveriser (Labtech Essa)
- Sieve Shaker (RoTap)
- Magnetic Separator (High intensity Roll mag)
- Magnetic Separator (Franz)
- Hydraulic Press (Rock labs)
- Diamond Saw (MK)
Quartz Separation Room
We have a dedicated lab for separating the quartz from the crushed rock. Some of the methods we use to separate and clean the quartz in the sample involve chemical etching, froth floatation and phosphoric acid digestion. Only when the fraction has been cleaned to the required level does it progress to our isotope separation laboratory.
Isotope Separation Laboratory
All Be-10 and Al-26 separations happen in this lab. The lab is a clean room; it is accessed via the facility office to give separation from the normal day to day corridor traffic flows. The lab has positive pressure with filtered makeup air. It has a Barnstead deionised water supply and fume cupboards with a scrubber. Access is strictly restricted to only those few who work in the lab for reasons of safety, cleanliness and security.
