Relationship between Sedimentary Facies and Interstitial Water Chemistry of Slope, Trench, and Cocos Plate Sites from the Middle America Trench Transect, Active Margin off Guatemala, Deep Sea Drilling Project Leg 67
Relationship between Sedimentary Facies and Interstitial Water Chemistry of Slope, Trench, and Cocos Plate Sites from the Middle America Trench Transect, Active Margin off Guatemala, Deep Sea Drilling Project Leg 67
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深海钻探项目第 67 段中美洲海沟断面、危地马拉活动边缘的斜坡、海沟和科科斯板块地点沉积相与间隙水化学的关系
DOI：
10.2973/dsdp.proc.67.129.1982
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
J. Gieskes
中科院分区：
文献类型：
--
作者：
W. Harrison;R. Hesse;J. Gieskes
间隙水化学已被证明是早期成岩反应，特别是那些与有机质氧化反应的敏感指标。危地马拉外海中美洲海沟斜坡上深海钻探项目496和497号孔的孔隙沃茨中的井下化学变化是异常的，因为盐度和氯度都显示出强烈下降至海水值的一半，δ 1 8 θ值变为正值（孔底最大值约为+ 2.5%）。这些观察结果解释的稀释孔隙沃茨检索后，由于分解的天然气水合物去除孔隙沃茨由船上挤压技术。在所有孔中，除了495孔（在远洋沉积物中钻探），有机物的分解导致硫酸盐的快速消耗和随后的甲烷生成。与甲烷生成相关的是碱度和溶解氨的大幅增加。后一种成分引起与粘土矿物的离子交换反应，这导致镁和钾的最大值。在更深的地方，还未发现的反应会导致镁的去除。特别是在较深的海沟站点499和500，钙，镁和碱度的快速变化发生在浊积岩序列。
Interstitial water chemistry has proved to be a sensitive indicator for early diagenetic reactions, particularly those related to organic matter oxidation. Downhole chemical variations in the pore waters from Deep Sea Drilling Project Holes 496 and 497 on the Middle America Trench slope off Guatemala are anomalous because both salinity and chlorinity show strong decreases to half the values of seawater, and δ 1 8 θ values become positive (maximum of about + 2.5% at the bottom of the holes). These observations are explained in terms of dilution of pore waters after retrieval as a result of decomposition of the gas hydrates before removal of pore waters by shipboard squeezing techniques. In all holes, except Hole 495 (drilled in pelagic sediments), decomposition of organic matter leads to rapid sulfate depletion and subsequent methane generation. Associated with methane generation are large increases in alkalinity and dissolved ammonia. The latter component causes ion exchange reactions with clay minerals, which results in maxima in magnesium and perhaps potassium. At greater depths, as yet unidentified reactions cause the removal of magnesium. Especially in the deeper Trench Sites 499 and 500, rapid variations in calcium, magnesium, and alkalinity occur in turbidite sequences.