Halite dissolution

Kloppman W., Negel P., Casanova J., Klinge H., Schelkes K., and Guerrot C. (2001) Halite dissolution derived brines in the vicinity of a Permian salt dome (N German basin). Evidence from boron, strontium, oxygen, and hydrogen isotopes. Geochim. Cosmochim. Acta 65, 4087-4101. 

In order to investigate the behavior of Br during halite dissolution, we reacted Jurassic halite from a Texas salt dome with distilled water on a shaker table at 25°C. The Cl/Br ratio for the solution after only 18 hr. of reaction (13,500) was lower than that of either the halite or the solution immediately after reaction (both 17,000). After nearly eight months the Cl/Br of the solution had fallen to an apparent steady state (8000), but did not approach... 

Predicting the Ca/Na ratio of the resultant brine accurately is difficult, and depends on the availability and reactivity of plagioclase and whether or not the brine remains in contact with halite -1- quartz -I- plagioclase. If a halite-saturated (or near-halite-saturated) brine flowed into a clastic section lacking halite as a phase, Na removed from the brine by albitization would cause undersaturation with respect to halite but Na could not be replaced by continued halite dissolution. 

Overall, halite dissolution rate does not depend on pH and, according to Palandri and Kharaka, 2004, at 25 °C depends only on the constant in equaton (2.227), which is equal to 0.62 mole-m -s at the activation energy in equation (1.141) equal 7.4 kj-mole Halite solubihty in distilled water under standard condition C,.,, is equal to 6.2 mole/1. 

D and 5 0 data on fluid inclusions and minerals, 8 C of carbonates, salinity of inclusion fluids together with the kind of host rocks indicate that the interaction of meteoric water and evolved seawater with volcanic and sedimentary rocks are important causes for the formation of ore fluids responsible for the base-metal vein-type deposits. High salinity-hydrothermal solution tends to leach hard cations (base metals, Fe, Mn) from the country rocks. Boiling may be also the cause of high salinity of base-metal ore fluids. However, this alone cannot cause very high salinity. Probably the other processes such as ion filtration by clay minerals and dissolution of halite have to be considered, but no detailed studies on these processes have been carried out. 

At the medium reach, the river flows into the Iberian Depression, with marl and gypsum Miocene deposits in some areas. The dissolution of evaporitic sediments (gypsum, halite, and sodium-sulfates) gives rise to numerous sinkholes. However, subsidence is also being masked by morpho-sedimentary dynamic processes such as aggradation and erosion [12]. 

The sulfete and chloride minerals in evaporites (gypsum, anhydrite, halite) undergo congruent dissolution to produce Ca (aq), S04 (aq), Na (aq), and Cl (aq). The dissolution of evaporite and biogenic carbonates (limestone, dolomite, and calcite) generates... 

Answer 12.5 Bromine—to check for possible dissolution of halite (why ) tritium and other anthropogenic contaminants—to exclude samples that contain bomb 36C1 (for what reason ) 14C—to select a number of samples that are very young in terms of the 36C1 half-life (what for ) Cl—to establish the initial 36C1 concentration in studied water samples (how ). 

For example, lakes in drainage basins of easily weathered soils such as calcareous rocks (calcite, dolomite, gypsum, halite) generally have high values of pH, alkalinity, total dissolved solids, conductivity, and hardness. Such is the case for lakes located in cavities formed through the gradual dissolution of water-soluble rocks (solution or Karst lakes). On the other hand if the drainage basin is in an acidic rock basin (i.e., where silicates predominate and are difficult to weather), the water has an acidic pH, low alkalinity, and low total dissolved solids. 

There is also field evidence that halite-derived brines can be transported over long distances in sedimentary basins. For example, the chemical compositions of waters from the Houston-Galveston area, Texas, and several other areas in the northern Gulf of Mexico basin indicate dissolution of halite (Kharaka et al., 1985 Macpherson, 1992). However, in a number of these areas, there are no known salt domes within 50 km of the sampled sites. Large-scale fluid advection is probably the main mechanism for the... 

It is generally agreed that most of the chloride in basinal brines has been derived from some combination of the subsurface dissolution of evaporites (e.g., Kharaka et al., 1985 Land, 1997) and the entrapment and/or infiltration of evaporated seawater (e.g.. Carpenter, 1978 Kharaka et al., 1987 Moldovanyi and Walter, 1992). Dissolution of halite produces waters dominated by sodium chloride. Evaporation of seawater produces waters having the general trends shown for ion-Br (Figure 5), Na-Cl (Figure 3) and Ca-Cl (Figure 4), but most formation waters have neither the cation (nor anion) composition of an... 

Dissolution of halite, as noted earlier, is probably the most important mechanism responsible for the increased sodium (and chloride)... 

Congruent and incongruent dissolution and precipitation reactions, other than for halite, which probably control the major cation compositions of formation waters include dolomitization of limestone, resulting in a major increase of calcium and a major decrease of magnesium, as in reaction (2) ... 

The principal sources of dissolved chloride in the more saline fluids of sedimentary basins include dissolved chloride buried at the time of sediment deposition, chloride derived by refluxing of subaerially evaporated surface brines, chloride derived from subsurface mineral dissolution, principally halite, and marine aerosols. The Cl-Br systematics of sedimentary brines provide useful constraints on interpreting the origin of chloride in these waters (Carpenter, 1978 Kharaka et al., 1987 Kesler et al., 1996). 

Brines formed by subaerial evaporation of seawater should, in theory, have elevated Br/Cl ratios. Brines formed by the dissolution of halite should have low Br/TDS (Rittenhouse, 1967) and Br/Cl ratios (Carpenter, 1978 Kharaka et al., 1987). Brines representing these end-members and mixtures of these and/or meteoric and/or connate marine waters have been identihed in... 

Figure 8 Distribution of Cl and Br in formation waters from the central Mississippi Salt Dome Basin relative to the evaporation line for seawater (SW, A-B) and mixing lines between Norphlet water (Norph. W) and meteoric (MW) and sea (SW) waters. Line E-F gives the trend when the mixture of meteoric and Norphlet waters dissolves halite with 70 ppm Br. Line C-D gives the trend where 50% of the Cl concentration in the mixture of meteoric and Norphlet waters is from dissolution of halite. Note that the samples from Coastal Texas and Louisiana (dashed field) plot in a different field (source Kharaka and Thordsen, 1992).

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