Dolomitization – Question One of the enigmas of carbonate diagenesis is that seawater is supersaturated with dolomite, whereas dolomite is rarely directly precipitated today. Discuss the strengths and weaknesses of the different mechanisms that have been postulated to explain dolomitization, and why it is important to understand from a hydrocarbon perspective.IntroductionDolomite (CaMg〖(CO_3)〗_2) is found in carbonate rocks of all ages that formed under a variety of conditions, but today it only forms in hypersaline lagoons, lakes and flats. This suggests that most dolomites are of secondary origin due to dolomitization: the replacement of calcite or aragonite (CaCO_3) with dolomite soon after deposition or during diagenesis, generally increasing porosity. Dolomitization is therefore very important in sedimentology and in hydrocarbon exploration but it is not yet fully understood. A number of models have been proposed to explain its occurrence and why it does not form everywhere, even if the seawater is supersaturated relative to the dolomite (Nichols, 1999; Tucker, 2001).Dolomitization modelsDue to the highly ordered structure of dolomite, there are a number of models. of factors that inhibit its precipitation: high ionic strength of seawater, hydration of Mg2+ and low activity of CO3-, even in supersaturated conditions and therefore certain conditions are required. These are: a sufficient supply of Mg2+ and of long duration, an initial porosity, a pressure differential for the migration of the pore fluid and an intersaturated fluid undersaturated in Ca2+. Therefore, it is common that before dolomitization, the Mg:Ca ratio must increase, forcing the dolomite out of solution. If these conditions are not met, there will be no dolomitization and inste...... middle of article......, G. (1999). Sedimentology & Stratigraphy (p. 355). Blackwell Science Ltd. Potma, K., Weissenberger, JAW, Wong, PK, & Gilhooly, MG (2001). Towards a sequence stratigraphic framework for the Frasnian of the Western Canadian Basin. Bulletin of Canadian Petroleum Geology, 49(1), 37-85. doi:10.2113/49.1.37Tucker, M.E. (2001). Sedimentary Petrology (Third, p. 262). Blackwell Science Ltd. Whitaker, FF, Smart, PL and Jones, GD (2004). Dolomitization: from conceptual models to numerical models. Geological Society, London, Special Publications, 235(1), 99-139. doi:10.1144/GSL.SP.2004.235.01.05 Whitaker, F. F., & Xiao, Y. (2010). Modeling the reactive transport of dolomitization by early burial of carbonate platforms by geothermal convection. AAPG Bulletin, 94(6), 889-917. doi:10.1306/12090909075Wright, VP (2009). Revue de sedimentologie 1 (p. 152). John Wiley and sons.