Controls on the elemental variations of lake sediments ： a case as Guozha Co, Tibetan Plateau

Abstract Elements in lake sediments and lake water were commonly used in the reconstruction for the paleoenvironment and paleoclimate, and also enriched into mineral deposit, such as lithium deposit. However, previous studies seldom distinguish the elements in pore water and minerals, and also seldom considered the early diagenesis and how the elements of different properties migrated and enriched during the drying climate. This study investigated the major and trace elements of the porewater, and the carbonate and silicate minerals in a 407-cm-long core from Guozha Co, a brackish lake on the northwestern Tibetan Plateau. Our results indicated that (a) the Ca and Sr were predominantly present in carbonate minerals, while the Na, K, Mg, Li, were primarily preserved in silicate minerals. (b) the elements of porewater were closed with those of silicate minerals; (c) the Nawater, Naacid, Liwater, and Liacid were more sensitive to the drying climate than the others; (d) As the molar ratios of Mg/Ca, Sr/Ca Li/Ca were different in porewater, carbonate minerals and silicate minerals, it should be careful to use the geochemical compositions of bulk sediments to discuss the paleoenvironment and paleoclimate; (e) Mgwater/Liwater were much lower than those of Mgacid/Liacid and Mgresidue/Liresidue. Low temperature favors the movement of Li in aqueous solution and carbonate minerals. This is useful for the lithium extraction from brines.