Chemostrat
Chemostratigraphy
Chemostratigraphy sensu stricto is the characterisation and stratigraphic zonation of sequences based on changes in their bulk inorganic geochemical signature. By geographically extending such zonations, chemostratigraphic correlation frameworks can be constructed.
Bulk geochemistry changes in response to subtle variations in mineralogy caused by changes in source composition, facies, weathering or diagenesis. Chemostratigraphy is in effect modeling changes in the mineralogy through changes in the bulk geochemistry.
One way to think of Chemostratigraphy is as an extension of gamma-ray data (K, Th, U), but now with a data array of 50 elements. Our experience in interpretation of these datasets allows us to provide more detailed geological information and model:
- Facies.
- Mineralogy / Diagenesis.
- Provenance.
- Reservoir Quality.
- Key Stratal Surfaces.
- Formation Waters.
- Reservoir / Seal development.
One of the main advantages of chemostratigraphy is its ability to cope with rocks of almost any age from any geological setting. Look at our areas applied section to see the main areas where chemostratigraphy has been applied in geological settings as diverse as Carbonate platforms of the Middle East to deep marine turbidites West of Shetland.
Chemostratigraphy is not restricted by lithology or sample type. It can be applied to samples of any lithology (including but not restricted to claystones, sandstones, volcaniclastics, coals, carbonates and evaporites) and equally as well in core, side wall, outcrop and cutting samples, including turbine drilled cuttings. Analysis can also be performed on a small amount of sample (minimum of 0.25gms) where sample volumes are limited.
The sample quality is what is most important, especially in ditch cuttings, so initial preparation involves washing to remove drilling fluid contamination prior to grinding and milling. Ditch cuttings are also ''picked' to select the desired lithology and any drilling contaminants removed.