Interstitial water chemistry of the Santa Barbara Basin sediments
Interstitial water chemistry of the Santa Barbara Basin sediments
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圣巴巴拉盆地沉积物的间隙水化学
DOI：
10.1016/0016-7037(73)90008-2
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发表时间：
1973
影响因子：
5
通讯作者：
E. Sholkovitz
中科院分区：
文献类型：
--
作者：
E. Sholkovitz
间隙水组成（SO 42 −、碱度、硫化物、Ca 2+、Mg 2+、K+、Si（OH）4、磷酸盐、NO2−、NO3−、NH 4+和Cl%）。比较了圣巴巴拉盆地中心的“盆地”沉积物和比盆地底坎浅的“斜坡”沉积物的沉积特征。“盆地”沉积物沉积在几乎缺氧的海水中（0.05-0.1 ml/l）。的O2），而“斜坡”沉积物覆盖着更多的含氧海水（0.3-0.4毫升/升。O2）。这两个地区的沉积物具有相似的粘土矿物学，沉积速度很快（约0.4厘米/年）。研究了沉积物的氧化还原状态、早期成岩作用和孔隙水化学之间的关系。相对于海水，“盆地”沉积物的间隙水显示出SO 42 −和Ca 2+的大量贫化，同时伴随着碱度、NH 4+和磷酸盐的大量富集。相比之下，“斜坡”沉积物孔隙沃茨中的SO 42 −和Ca 2+略有减少，碱度、NH 4+和磷酸盐略有增加。在这两种沉积环境1. (1)Mg 2+耗竭发生在相同的程度;2。(2)溶解的二氧化硅浓度从沉积物-水界面的3- 6cm内开始保持在高的恒定值;3. (3)NO2−和NO3−不存在。利用南加州盆地沉积物有机C：N：P比值的成岩模型能够预测测量的间隙水碱度、氨和磷酸盐浓度，这些浓度来自于涉及通过减少孔隙水SO 42 −和CaCO 3自生沉淀而分解有机物质的反应。粘土矿物对Mg ~（2+）的吸收可以解释海洋间隙沃茨中Mg ~（2+）的贫化。可能是由于粘土矿物与硅质测试溶解产生的二氧化硅的相互作用。从圣巴巴拉盆地的斜坡和盆地区域的比较来看，（例如孔隙水SO 42-还原的程度;碳酸盐饱和度）和钙质微体化石记录的保存对微小的变化（即从0.4到0.1毫升/升的下降）非常敏感。在沉积发生的海水中的氧含量。这种氧控制沉积成岩作用的影响可能是重要的，在最近和过去的海洋环境。
The interstitial water composition (SO42−, alkalinity, sulfide, Ca2+, Mg2+, K+, Si(OH)4, phosphate, NO2−, NO3−, NH4+, and Cl%.) of both the ‘basin’ sediment in the center of the Santa Barbara Basin and the ‘slope’ sediment shallower than the basin sill is compared. The ‘basin’ sediment is deposited in seawater which is almost anoxic (0.05–0.1 ml/l. of O2) whereas the ‘slope’ sediment is overlain with more oxygenated seawater (0.3–0.4 ml/l. O2). The sediments in both regions have similar clay mineralogy and are rapidly deposited (~0.4 cm/yr). The relationship between the redox state of deposition, early diagenesis, and pore water chemistry is investigated.Relative to seawater, the interstitial water of the ‘basin’ sediment shows large depletions in SO42−and Ca2+, accompanied by large enrichments in alkalinity, NH4+, and phosphate. In contrast, the ‘slope’ sediment pore waters show slight depletions in SO42−and Ca2+and small increases in alkalinity, NH4+, and phosphate. In both sedimentary environments1.(1) Mg2+depletions occur to the same extent;2.(2) dissolved silica concentrations are maintained at high, constant values beginning within 3–6 cm of the sediment-water interface;3.(3) NO2−and NO3−are absent.A diagenetic model, which utilizes organic C:N:P ratios of southern California basin sediments, is able to predict the measured interstitial water concentrations of alkalinity, ammonia and phosphate from reactions involving the decomposition of organic material by the reduction of pore water SO42−and the authigenic precipitation of CaCO3. The uptake of Mg2+by clay minerals is proposed to explain Mg2+depletions in marine interstitial waters.Pore water silica values appear to be maintained at equilibrium concentrations, probably resulting from the interaction of clay minerals with silica produced by the dissolution of siliceous tests.From this comparison of the slope and basin regions of the Santa Barbara Basin it appears that the interstitial water chemistry (e.g. extent of pore water SO42−reduction; degree of carbonate saturation) and the preservation of the calcareous microfossil record are extremely sensitive to small changes (i.e. a decrease from 0.4 to 0.1 ml/l.) in the oxygen content of the sea-water under which deposition occurs. Implications of this oxygen control on sedimentary diagenesis may be important in both recent and past marine environments.