Nuclide intercalibration Print E-mail

Nuclide intercalibration: Independently dated rock surfaces will be used to calibrate production rates in a manner similar to the natural target network. The aim is to determine all TCN concentrations in minerals, that are not present in basalt from a selection of well-characterised sites. This is important for future applications of TCNs to Earth surface and environmental Science applications since many of the commonest minerals are not present in basal and is providing a robust TCN-intercalibration.

Surfaces created by volcanic eruptions: Volcanic Tableland of the Bishop Tuff, eastern California . Exceptionally well dated eruption 760±2 kyr (Van den Bogard and Schirnick 1995). The upper cooling surface of the welded tuff is very resistant to erosion (Dawers et al. 1993). Both sites are attractive due to their significant age, enabling calibration of very long-term production rates.

Surfaces created by landslides:

  1. Alps : Köfels , Austria and Flims , Switzerland . For both giant landslides accurate independent age constrains are available from radiocarbon dating. The Flims landslide will be used for 36Cl-production rate calibration in carbonate (see also following point).
  2. In Fjordland , Norway a series of radiocarbon dated (Blikra et al. 2002) Holocene landslides occur in varied lithologies (i.e. a large range of suitable target mineral compositions is available).
  3. Multiple Holocene landslides occur in varied lithologies in Northern Patagonia . Age constraints will be obtained form radiocarbon dating of organic material in sediments of landslide-created lakes (Trauth et al. 2000).

Antropogenic surfaces: Roman limestone quarries near Nimes , southern France . The age of the quarry walls is well constrained (1985±35 yr b.p. as the extracted rocks were used for the construction of the amphitheatre in Nimes , and specific work marks exclude later use of quarries (Bessac 1996). This site will be used for 36Cl-production rate calibration in carbonate. This TCN/target mineral pair is highly relevant for paleoseismicity studies in the Mediterranean region. Together with the landslide of Flims an accurate regional calibration will be achieved.

Deliverables of the cross-calibration sites will be:

  1. the cross-calibration of all currently relevant TCNs
  2. determination of long term production rates
  3. 36Cl production rates in carbonates.