Mesozoic dolomites

As a specific example of the problem, let us calculate the equilibria for an actual case study a deep water from the Sarcidano region (Sardinia, Italy) in equilibrium with Mesozoic dolomites (Bertorino et al., 1981). The compositions in mEq/1 of water sampled in a drilled well are listed in table 8.8. The in situ temperature is 21 °C we assume here that the in situ T is 25 °C at 1 bar, to simplify calculations. We also assume for the sake of simplicity that the main ion species in solution are HCO3, Mg, Ca, CO3, OH, and H, and that all Ca and Mg are in the ionic forms Ca and Mg. ... 

Table 8.8 Compositions of superficial and deep waters of the Sarcidano region (Sardinia, Italy) equilibriated with Mesozoic dolomite limestones (Bertorino et ah, 1981). Values in mEq/1. C-j- total inorganic carbon in mmol/1.

The mineralized district is restricted by two main strike-slip faults of Kubanan to the east and Posht e Bdam to the west (Fig. la). The host rocks are a thick sequence of Upper Precambrian-Cambrian rhyolite, tuff, alkali granite, syenite, mafic dykes, magnetitite, dolomite, gypsum, limestone, black shale, and sandstone. The Upper Percambrian-Cambrian sequence is overlain unconformably by Mesozoic and... 

Colorado, is hosted in folded and brecciated Mississippian dolomite, shale, sandstone and coal, which is in fault contact with Precambrian gneiss. The Precambrian gneiss is anomalously enriched in uranium, and a Mesozoic or Caenozoic age of mineralization in the Mississippian host rocks, formed by downward percolation of uraniferous groundwater from the adjacent Precambrian terrain, is inferred. Mineralization in the Pryor Mountains region, Montana, is hosted in karsts developed with the Mississippian Madison limestone and consists of uraninite-tyuyamunite grading up to 7% UsOg associated with clay minerals and silicified collapse breccias. A Caenozoic age of mineralization, under conditions similar to those of Pitch mine, is favoured. 

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