Models of dolomitisation : a literature review

From an economic perspective (e.g. in the hydrocarbon and groundwater industries) one of the main questions relating to dolomitisation is the influence the dolomitisation process has on the nature of the dolomitised limestone’s pore system. To this end, one of the key objectives of the “Development of Integrated Methods for Characterising Faults and Fractures in Reservoirs and Aquifers” project is to understand the nature and distribution of pore-systems within dolomitised limestones and in particular to understand the influence of fractures on dolomitisation and/or porosity distribution, and subsequent fluid-flow pathways. This document provides a literature review on the current state of knowledge regarding the dolomitisation process. The “dolomite problem” is introduced, and the kinetic inhibitions on dolomitisation from seawater, which ultimately form the crux of the dolomite problem are summarised. Over the years, various models have been suggested in order to explain the dolomitisation process. Systematic summaries of these models are presented. In essence, each model attempts to provide a mechanism by which the kinetic inhibitions to dolomite formation are overcome (typically through evaporation or dilution of seawater), and a means of pumping large porevolumes of fluid through the body undergoing dolomitisation. Following the summaries of the dolomitisation models, the next section contains an introduction into the classification of dolomite fabrics and pore systems. The final sections outline the regional geology of the Lower Carboniferous in the Midlands of the United Kingdom, and describes potential analogue material in Derbyshire and the Bowland Basin.