Diagenesis: Sulfate & Halide Cements and Authigenic Precipitates
2015. "Diagenesis: Sulfate & Halide Cements and Authigenic Precipitates", A Color Guide to the Petrography of Sandstones, Siltstones, Shales and Associated Rocks, Dana S. Ulmer-Scholle, Peter A. Scholle, Juergen Schieber, Robert J. Raine
Download citation file:
Sulfates and halides can form significant cements in sandstones but typically only in very specific settings. Early formed gypsum, anhydrite and halite are common in arid, highly evaporitic settings and form not only cements but also bedded deposits and displacive or replacive precipitates. Additional sulfates and halides, such as glauberite (a sodium calcium sulfate), barite (BaSO4), celestine (SrSO4), sylvite (KCl) and many others, can form in surficial settings, but most such minerals are rare and may not survive subsequent diagenetic alterations because of their generally high solubility. Eogenetic sulfates and halides are especially common precipitates in arid-region playa lakes, dunes and interdune flats, as well as continental and coastal sabkhas (e.g., Kinsman, 1969; Benison and Goldstein, 2000; Warren, 2006). Gypsum is the most common of these minerals, and extensive gypsum cementation, mostly within 10 m (33 ft) of the ground surface, can produce gypsiferous soils, gypsum crusts and fully cemented gypcretes (Watson, 1985; Nettleton, 1991; Hartley and May, 1998). Gypsum cements in terrigenous strata can consist of coarsely poikilotopic crystals (encompassing numerous detrital sand grains), isolated lenticular crystals or crystal clusters (desert roses), gypsarenites with graded cement sizes and alabastrine gypsum with individual crystallites that average less than 50 μm in diameter (Watson, 1985). Although gypsum is the major precipitate in such surficial deposits, in settings with especially hot, arid, evaporitic and low humidity conditions, anhydrite (anhydrous calcium sulfate)andevenhalitecanbefoundcementingsurficial and near-surficial sands and muds, especially in sabkhas and saline pans (Kinsman, 1969; Casas and Lowenstein, 1989; Warren, 2006).