Interstitial water chemistry at DSDP Leg 79 Holes

Interstitial water analyses of samples collected at Sites 544-547 of DSDP Leg 79 are presented. In Site 547 chloride concentrations increase to almost 80% of the halite saturation values. Gypsum occurrences in the sediments immediately overlying the halite deposit can be explained in terms of migration of Ca**2+ and SO2**2- from the underlying evaporites. At shallower depths sulfate concentrations decrease rapidly as a result of sulfate reduction processes. The same processes lead to the removal of calcium in the form of calcium carbonate. At Site 547, the chloride concentration depth profile suggests a maximum of dissolved chloride which may be the result of advective flow from nearby (abput 6 km) evaporite salt diapirs.本文呈现了深海钻探计划（Deep Sea Drilling Project, DSDP）第79航次544至547站位采集的沉积物样品的间隙水分析结果。在547站位，氯离子浓度升高至近乎盐岩（halite）饱和值的80%。赋存于盐岩矿床直接上覆沉积物中的石膏（gypsum），可通过下伏蒸发岩（evaporite）中钙离子（Ca²+）与硫酸根离子（SO₄²⁻）的运移得到合理解释。在更浅的埋藏深度，硫酸盐浓度因硫酸盐还原作用（sulfate reduction processes）而快速降低。该类还原过程同时会促使钙以碳酸钙（calcium carbonate）的形式被移除。在547站位，氯离子浓度的深度剖面显示溶解氯离子存在浓度峰值，该峰值或源自附近（约6公里）处蒸发岩盐底辟（salt diapirs）的平流流动。