Detrital dolomite: characterization and characteristics

Abstract

Investigating dolomite fragments derived from pre-existing dolomite-containing sediments or rocks, that is detrital dolomites, constitutes a challenge in carbonate sedimentology. Detrital dolomites are generally difficult to recognize and their presence can have profound consequences, even in small quantities, on the interpretation of the tectonosedimentary evolution and palaeoenvironmental conditions of the enclosing basin. In addition, identification and quantification of detrital dolomites may provide insight into provenance and sediment transportation, quality of hydrocarbon reservoirs, and some aspects of the dolomite problem. Typically, detrital dolomites are recognized by their clastic behaviour, such as 1) their wide range of grain sizes and shapes, 2) evidence for transportation and weathering, and 3) their association with other detrital grains. Detrital dolomite can be derived from dolomite-containing sediments (by reworking) or dolomite-containing rocks (by disintegration) and can be transported by various means including wind, water, glaciers and sediment gravity flows. Detrital dolomite can be found in a variety of lithofacies confirming that they are controlled by availability of dolomite detritus and not by depositional environment. The role of detrital dolomite in promoting diagenetic dolomitisation is examined whereby they have provided nucleation sites, for syntaxial overgrowth, or a source of Mg, through dissolution.