Lithium Contents in Non-marine Salty Springs

Salt springs in the Pyrenees (NE Iberian Peninsula) are common due to diapirism and dissolution of Triassic evaporite-bearing deposits. Various salty sources from Eastern Pyrenees have been analysed in order to elucidate their accurate chemical and isotopic composition. The study includes trace analyses by means of ICP-OES and ICP-MS, and, sulphate (S–O) and water molecule (H–O) isotope analyses by mass spectrometry. Outcropping Na–Cl rich brines contain B, Li (from 0.17 to 2.43 ppm), Rb, Zn and Mn as main trace elements. The origin of the salty composition is due to fluids circulating through evaporite Keuper facies (Triassic; halite-sulphates, calcium carbonates and clays), as clearly revealed by brine S–O isotope signature. Sulphate molecule has not suffered sulphate reduction, thus evidencing simple rock dissolution. Noticeable lithium content in seawater brines is well known due to the conservative behaviour of such element, which increases during evaporation. Studied salty springs are non-marine in origin, and not clearly related to hydrothermalism or volcanic fluids, which will enrich brines in lithium. The negative H–O and C isotope signatures of water also support this evidence. Thus, Li origin is mainly due to dissolution of Keuper evaporites, both considering Li contained in salt rocks and/or in fluid inclusions. Study of such brines will contribute to a better understanding of Li circulation and storage in non-marine salty springs.