Characteristics of the Near-surface Brine Resources in the Newfoundland Basin, Tooele and Box Elder Counties, Utah

摘要

Subtle differences in brine chemistry are not always readily apparent in brine from the Great Salt Lake and the Great Salt Lake Desert when these brines are compared using analyses of the major ions in the brine. This may be due to dilution of the brine by meteoric water or simply to the fact that the brines are dominated by sodium and chloride, which tend to mask differences in the other ions. By evaporating the brines and identifying the minerals that precipitate out of the solution, these subtle differences become more evident. The TEQUIL model at 25°C seems to produce a reasonable prediction of the simple Na-K-Ca-Mg-Cl-SO_4-H,O system to which these brines belong. Application of the model shows that the mineral suite precipitating from Great Salt Lake brine is very different than the minerals precipitating from groundwater brines in the Great Salt Lake Desert. The model also shows that the brine presently in the shallow brine aquifer in the portion of the Great Salt Lake Desert inundated by pumped Great Salt Lake brine contains components of both brines and may represent a mixture of Great Salt Lake and original West Desert brines. These conclusions are based on a limited field investigation, and more sampling should be undertaken to confirm and refine the interpretations. Based on USGS estimates, as much as 386 million tons of salt from the Great Salt Lake was added to the brine resource in the area flooded by the pumping project. This is demonstrated by the elevated levels of potassium and magnesium in the Newfoundland basin. However, TEQUIL modeling indicates that brine from the Great Salt Lake mixed with the existing groundwater brine, resulting in a change in the chemical character of the brine. Instead of a simple halite-sylvite-carnallite system, the mixing of Great Salt Lake brine has resulted in a system with a more complex mineralogy.