THE NATURE OF ABYSSAL CHLORIDE BRINES

Highly mineralized, largely sodium-chloride type, brines in deep artesian basins are similar in composition to the mineralized abyssal hydrothermal waters of present day volcanic regions as well as the material impounded in liquid inclusions of minerals. It is also well established that present brines are very similar to hydrothermal ore-forming solutions. Some highly concentrated brines can be explained by derivation from salt basins but there is no adequate explanation for the worldwide distribution of concentrated brines. Exchange reactions merely change composition, not concentration. Some hydrocarbons found in minerals as well as in brines have originated from CO₂, H₂O, and H₂ liberated from volcanoes and magma chambers. The abyssal brines may be the product of magmatogenic hydrothermal activity or the brines themselves may be the source of ore-forming hydrothermal solutions. If the latter is true, there is still no explanation of the high mineralization of brines. Many brines are deafly similar to sea water but the salts in sea water are largely produced by volcanic activity. It is suggested that many of the brines are formed in deep unexposed parts of artesian basins from highly concentrated hydrothermal solutions migrating from magmatic chambers. --J. A. Redden.