Hypersaline Fluid Evolution During Burial and Uplift

Abstract

In Chap. 2 we discussed the hydrology of evaporite depositional and early diagenetic (eogenetic) settings, in this chapter we consider diagenetic evolution in subsequent hydrological stages in a sedimentary system containing thick salt, that is, rock-fluid interactions in an evaporite-entraining sequence experiencing ongoing burial, followed by possible uplift (mesogenesis followed by telogenesis. Thick, buried and dissolving evaporites influence subsurface hydrology and formation water chemistries throughout the burial cycle, as they interact with regional and local thermal and pressure regimes. Remobilization of salt and introduction of brine-carried carried components, notably dolomite and anhydrite, can have a significant impacts on reservoir quality, e.g. the Simonette oil field, Swan-Hills Formation (Devonian) Alberta, where late anhydrite and burial dolomite represent up to 50 % of the rock volume (Duggan et al. 2001). Evaporites that enter the metamorphic realm can have an extensive influence consequent rock type and distribution, well after the primary sedimentary and diagenetic salts are long gone ( Chap. 14).