Character of Brines from the Belle Isle and Weeks Island Salt Mines, Louisiana, U.S.A.

Abstract

Kumar, M.B. and Martinez, J.D., 1981. Character of brines from the Belle Isle and Weeks Island salt mines, Louisiana, U.S.A. In: W. Back and R. Létolle (Guest-Editors), Symposium on Geochemistry of Groundwater — 26th International Geological Congress. J. Hydrol., 54: 107ndash;140. This paper is based on the chemical analyses of 110 samples of brines collected from the Belle Isle and Weeks Island salt mines of Louisiana, U.S.A. These brines are manifested by the active leaks, puddles of water and stalagmites—stalactites in the mines. Most of the waters are a sodium—calcium—chloride brine with minor concentrations of additional ionic species. The ionic compositions of these brines are compared with average seawater, seawater concentrated by evaporation and formation waters (oil-field brines). The ionic distributions of the mine brines resemble those of formation waters except that the mine brines are relatively high in potassium, strontium, boron and bromide. The higher concentrations of potassium and bromide in these brines relative to formation waters indicate a similarity to a residual brine and suggest some genetic relationship. However, the high concentration of Ca, exceeding the concentration of K and, in some instances, even that of Na in the mine brine is highly indicative of formation water. It is concluded that the mine brines may represent an admixture of (Ca-rich) formation water and (K—Br-rich) residual brine or a formation water of unusual character with high concentrations of Ca, K and bromide. Isotopic data strongly support the formation water hypothesis.