Instability of bottom‐water redox conditions during accumulation of Quaternary sediment in the Japan Sea
Instability of bottom‐water redox conditions during accumulation of Quaternary sediment in the Japan Sea
复制标题
日本海第四纪沉积物堆积过程中底层水氧化还原条件的不稳定性
DOI：
10.1029/95pa03553
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
C. Isaacs
中科院分区：
文献类型：
--
作者：
D. Z. Piper;C. Isaacs
对日本海冲木海岭早第四纪沉积物（1.32 ~ 1.08Ma）中Cd、Cr、Cu、Mo、Ni、Sb、U、V和Zn的含量进行了测定。的元素被分配之间的碎屑部分，由陆源和火山碎屑铝硅酸盐碎片，和海洋部分，由来自海水的生物和氢的碎片。控制微量元素在海洋组分中积累速率的最重要因素是（1）透光层的初级生产力，它在很大程度上控制了通过水柱沉降到海底的颗粒有机物结合的微量元素的通量，以及（2）底层水的氧化还原，它决定了直接从海水中积累的元素。隐岐海脊微量元素的海洋部分记录了六个时期的高微量元素丰度。假设大量沉积物积累速率恒定，每个时期大约持续5 000至10 000年，周期为41 000年。个别元素，如镉，钼和U的积累率表明硫酸盐还原条件建立在底层水中在10,000年的时间;铬和V的积累率在干预期间是指示减少，净化条件。元素间的比例，例如，铜：钼，钒：铬，锑：钼，进一步反映了底层水的不稳定性，这样底层水的氧化还原实际上从硫酸盐还原到氧化还原在最高的微量元素积累率的时期;它从氧化还原到氧化在干预期间。沉积物岩性支持这些解释的微量元素分布;沉积物是精细层压的几个时期所代表的镉，钼，和U最大值和弱层压生物扰动的干预期间。这种沉积物的地球化学表明明确的信号钼，主要是，但其他几个微量元素，以及在记录硫酸盐还原条件在底层水。强迫功能改变了他们的积累，也就是说，改变了初级生产力和底层水氧化还原条件，是有问题的。目前的观点认为，O2耗竭是最强烈的发展在冰川的进步。低海平面在这段时间被解释为提高初级生产力和限制底层水平流。
The concentrations of Cd, Cr, Cu, Mo, Ni, Sb, U, V, and Zn were measured in early Quaternary sediment (1.32 to 1.08 Ma) from the Oki Ridge in the Japan Sea. The elements were partitioned between a detrital fraction, composed of terrigenous and volcaniclastic aluminosilicate debris, and a marine fraction, composed of biogenic and hydrogenous debris derived from seawater. The most important factors controlling minor-element accumulation rates in the marine fraction were (1) primary productivity in the photic zone, which largely controlled the flux of particulate organic-matter-bound minor elements settling through the water column and onto the seafloor, and (2) bottom-water redox, which determined the suite of elements that accumulated directly from seawater. This marine fraction of minor elements on Oki Ridge recorded six periods of high minor-element abundance. Assuming a constant bulk sediment accumulation rate, each period lasted roughly 5,000 to 10,000 years with a 41,000-year cycle. Accumulation rates of individual elements such as Cd, Mo, and U suggest sulfate-reducing conditions were established in the bottom water during the 10,000-year periods; accumulation rates of Cr and V during the intervening periods are indicative of less reducing, denitrifying conditions. Interelement ratios, for example, Cu:Mo, V:Cr, and Sb:Mo, further reflect bottom-water instability, such that bottom-water redox actually varied from sulfate reducing to denitrifying during the periods of highest minor-element accumulation rates; it varied from denitrifying to oxidizing during the intervening periods. Sediment lithology supports these interpretations of the minor-element distributions; the sediment is finely laminated for several of the periods represented by Cd, Mo, and U maxima and weakly laminated to bioturbated for the intervening periods. The geochemistry of this sediment demonstrates the unambiguous signal of Mo, principally, but of several other minor elements as well in recording sulfate-reducing conditions in bottom water. The forcing function that altered their accumulation, that is, that altered primary productivity and bottom water redox conditions, is problematic. Currently held opinion suggests that O2 depletion was most strongly developed during glacial advances. Low sea level during such times is interpreted to have enhanced primary productivity and restricted bottom-water advection.