Stable chlorine isotopes in halite and brine from the Gulf Coast Basin : Brine genesis and evolution
Stable chlorine isotopes in halite and brine from the Gulf Coast Basin : Brine genesis and evolution
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DOI：
10.1016/s0009-2541(00)00374-0
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发表时间：
2001-07
期刊：
影响因子：
3.9
通讯作者：
C. Eastoe;A. Long;L. Land;J. Kyle
中科院分区：
文献类型：
--
作者：
C. Eastoe;A. Long;L. Land;J. Kyle
稳定氯同位素数据结合其他地球化学参数，有助于确定盐度与海水盐度不同的地层水中溶质的来源。墨西哥湾沿岸盆地侏罗系盐岩的δ-37Cl范围为−0.5‰~0.3‰(层状)和0.0‰~0.5‰(底辟)。层状盐的值与侏罗纪海水氯化物的δ37Cl值为0.0‰一致，与现代海洋中的值一致。底辟盐值略高可能是由于岩盐溶液不一致造成的。地层水的δ37Cl范围为−1.9‰至0.7‰。在始新世至中新世的硅屑岩层中发现了含有δ37Cl<；−0.6‰的水，而在上新世-更新世地层和中生代碳酸盐岩中没有发现。在始新世至中新世地层中，由于盐岩的不一致溶解，卤水的δ37Cl接近0.0‰，与低矿化度水混合在一起。未演化的海水存在于上更新世地层中。中生代地层含卤水，卤水δ37Cl&Gt；−0.2‰。来自地压含水层的低盐度水似乎是页岩脱水的结果。这种水中的低δ37Cl值与低Mcl/mnA(指示脱水的参数)有关，但与Cl/Br值没有一般关系。它们与异地卤水中氯化物的扩散一致。扩散可以在104-106年内产生几百米尺度的负δ37Cl的水域，也可以在残留的源卤水中产生正的δ37Cl氯化物。
Stable chlorine isotope data, used in conjunction with other geochemical parameters, are useful in determining the origin of solute in formation waters with salinity different from that of seawater. Jurassic salt in the Gulf Coast Basin has δ37Cl ranges of −0.5‰ to 0.3‰ (bedded) and 0.0‰ to 0.5‰ (diapiric). The values for bedded salt are consistent with a δ37Cl value of 0.0‰ for Jurassic seawater chloride, as in modern oceans. The slightly higher values for diapiric salt are possibly caused by incongruent solution of halite. Formation waters have a δ37Cl range of −1.9‰ to 0.7‰. Waters with δ37Cl<−0.6‰ have been found in siliciclastic strata of Eocene to Miocene age, but not in Plio-Pleistocene strata or in Mesozoic carbonate rocks. Brine with δ37Cl near 0.0‰, as expected for incongruent dissolution of halite, has mixed with low-salinity water in Eocene to Miocene strata. Unevolved seawater is present in Plio-Pleistocene strata. Mesozoic strata contain brine with δ37Cl>−0.2‰. Low-salinity water from geopressured aquifers appears to have resulted from shale dewatering. Low δ37Cl values in such water are related to low mCl/mNa(a parameter indicating dewatering) but show no general relationship to Cl/Br. They are consistent with diffusion of chloride from allochthonous brine. Diffusion can generate domains of water with negative δ37Cl on a scale of hundreds of meters in 104–106years, and may also generate positive-δ37Cl chloride in residual source brine.