Composition of anoxic hypersaline brines in the Tyro and Bannock Basins, eastern Mediterranean

摘要: At present two brine-filled depressions have been identified in the eastern Mediterranean - The Tyro Basin (33°53′N, 26°02′E) and Bannock (34°20′N, 20°02′E). In both areas, main basin is surrounded by satellite basins that used to or still hypersaline anoxic conditions. brines are thought originate from dissolution of outcropping underlying (Messinian) evaporitic salt layers. The transition normal seawater brine water occurs at a slightly different depth basins; 3383 dbar 3330 Basin. this transition, salinity increases sharply, whereas concentration dissolved oxygen drops rapidly zero across interval only few metres. The Basins almost identical (10 times seawater). However, between differences occur major (and trace) element composition. characterized relatively high Na content, more enriched K, Mg SO4. These related composition serves as source for each these brines. evaporite result depositional ‘stage’ deposits. results late-stage deposit, originates an earlier-stage evaporite. In contrast homogeneous Basin, double-layered observed lower (II) has higher than upper (I) also differ Brine I Ca Sr, Mg, S concentrations ions Scirocco deviate even those II, which indicate degree dolomitization