Terrestrial Evaporites

Pans, Playas and Salt Lakes

“…The sediments that are received are almost exclusively fine grained, which can be explained in three ways. First, where playas represent drainage terminals, only fine Figure 15.4 Idealised diagram of the depositional subenvironments that can occur in closed arid zone playa basins (after Hardie, Smoot and Eugster, 1978;Chivas, 2007).…”

“…Recent advances in the multidisciplinary study of playas as three-dimensional features, with distinct hydrological, sedimentary, chemical and organic budgets, has allowed the identification of distinct facies associated with the saline pan cycle, and thus allowed the interpretation of their sedimentary record, even where it is discontinuous (Chivas, 2007;Yechieli and Wood, 2002). Geochemical studies have contributed greatly to this, in particular the recognition that common minerals such as gypsum may take on different crystal forms in lacustrine, groundwater, aeolian and pedogenic environments (Magee, 1991;Magee et al, 1995).…”

Analyses of Recent Sediment Surface Dynamic of a Namibian Kalahari Salt Pan Based on Multitemporal Landsat and Hyperspectral Hyperion Data

“…During this >20 years time frame the surface alteration, e.g., by redistribution of surface particles due to surface flooding [15] and or wind erosion [9] are possible scenarios. The formation of fresh halite crust after significant rainfall and flooding events may superimpose underlying less soluble (e.g., clastic) minerals [110] and hide these (minor) components from surface observations, especially in the central halite dominated, dynamic part of the salt pan. The detection of minor crust components may be also limited by the low signal-to-noise ratio of the Hyperion data [16,23].…”

Desert Crusts and Rock Coatings

“…Saline crusts may also impact upon aeolian processes by consolidating the sand on dune slipfaces (Nickling and Ecclestone, 1981;Nickling, 1984). Halite 'salt scalds' in soils are often associated with rising saline groundwater tables which, in some cases, are a function of land management practices such as removal of vegetation or overirrigation (Chivas, 2007). Understanding the factors that control the formation of halite crusts can also be of economic significance, as many petroleum reserves are associated with evaporite sequences.…”

“…Many playas have only a thin surface halite crust, which redissolves upon flooding and reprecipitates by evaporation after flood-borne clastic deposition. By this mechanism the halite crust is preserved as the uppermost horizon, with clastic sediment progressively accumulating 'beneath' the halite layer (Chivas, 2007). The saline mudflat areas surrounding perennial saline lakes and playas are associated with the development of halite efflorescences and intrasediment (displacive) evaporite minerals.…”