Basement characterisation studies normally rely on the analysis of core to either understand the rock type through petrological analysis, or date the material using isotope geochronology. However, basement core is rare and unless these different techniques are properly integrated key information may be missed.
Chemostrat are uniquely placed to be able to characterise igneous and metamorphic basement through our knowledge and ability to integrate isotope geochronology, mineralogy and elemental geochemical data. Importantly this is not restricted to drill core as the method has been designed to be carried out on drill cuttings. This method tells us if:
- The cuttings are representative of the subsurface through comparison of our chemical gamma technique with wireline gamma logs.
- When did the rock form using U-Pb zircon geochronology
- Has the rock been affected by lower temperature metamorphosis through U-Pb apatite geochronology
- What is the rock type through XRD minerology
By integrating geochronology with mineralogy we are able to understand changes in both rock type and age in the subsurface and so thoroughly differentiate rock types and map basement variations through drill cutting analysis.
Figure 1 Zonation of west of Shetland basement by U-Pb geochronology, U-Pb Apatite geochronology and XRD mineralogy (Finlay et al., 2023 and Strachan et al., 2024)
Furthermore, we have the specialist knowledge to use this data to further understand the characteristics of the rock, for example the thermal characteristics for geothermal studies and rock properties for geomechanical work.