Single-grain geochemistry
Single-grain Geochemistry
Single-grain geochemistry techniques can involve the measurement of major elements, trace elements or stable isotopes within a species of mineral in clastic sediments.
Variations in the composition of a specific mineral species can provide insight into the provenance of clastic sediments and can help characterise the source lithologies feeding the sediment. These variations are often consistent within a formation and therefore can also be utilised as a correlation tool within a basin and help enhance interpretations made from chemostratigraphy.
Our primary single-grain geochemistry service is the Pb isotope analysis of feldspars, practically due to their relative abundance in clastic sediments. We also offer single-grain geochemistry on a variety of other mineral species (e.g. garnet, zircon or rutile), with bespoke solutions for specific problems.
Pb-in-feldspar Geochemistry
Pb-in-feldspar analysis is a single-grain geochemical technique which can be employed to determine the provenance of clastic sediments which in turn, can aid the modelling of the distribution of reservoir quality sandstone fairways. Pb-in-feldspar analysis can also be used in combination with bulk geochemical data to enhance well correlations.
Feldspar is a common detrital framework grain in reservoir quality sandstones, reaching up to 50% in arkoses, therefore determining their provenance can account for a high proportion of the sandstone framework mineralogy.
Feldspar crystals experience negligible radiogenic growth and Pb compositions remain unchanged despite weathering, transport and diagenesis, allowing direct correlation of detrital and source data. Having established feldspar source(s), results can be combined with contextual information to determine sediment routing and dispersal patterns, and the distribution of reservoir sandstone fairways.
The Pb-in-feldspar method can be employed on core and cuttings samples. Due to the relative abundance of feldspar, this is a particularly favourable technique in the case of small sample sizes.
