Three distinct analytical approaches are embraced in mineral-chemical stratigraphy: mineralogy, whole-rock geochemistry and single-grain geochemical analysis. Mineralogical studies identify and quantify the clastic components of sandstone, even though any clast category may be geochemically diverse. Whole-rock geochemical studies (sometimes referred to as chemostratigraphy), by contrast, quantify the abundance of major and trace elements in sandstone, but provide no information on the distribution and location of the elements in minerals. These approaches are linked by single-grain geochemical analysis, which enables further characterization and subdivision of individual mineralogical components, and identifies sites where specific major and trace elements reside.In this paper, we consider the relationships between minerals, mineral chemistry and whole-rock composition, before exploring the value of mineral-chemical stratigraphy for lithostratigraphic correlation and evaluation of sediment provenance, using published examples from the North Sea region, where the great majority of such studies have been undertaken. We conclude by discussing the important role that alluvial basins play in controlling mineral-chemical signatures.
Mineral -chemical relationships in sandstonesThe mineralogical components of sandstones are typically classified into four main groups, comprising framework grains (quartz, feldspar, rock fragments), heavy minerals, clay minerals, and authigenic phases. Of these, the framework components, the clay minerals, and the heavy minerals may all have some role to play in mineral-chemical stratigraphy. Although a wide variety of authigenic phases are identified in sandstones, their secondary nature precludes their use in reservoir correlation, except in unusual circumstances.