SOURCES AND MECHANISMS FOR THE ENRICHMENT OF HIGHLY REACTIVE IRON IN EUXINIC BLACK SEA SEDIMENTS
SOURCES AND MECHANISMS FOR THE ENRICHMENT OF HIGHLY REACTIVE IRON IN EUXINIC BLACK SEA SEDIMENTS
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DOI：
10.2475/ajs.304.3.203
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发表时间：
2004-03
影响因子：
2.9
通讯作者：
T. Anderson;R. Raiswell
中科院分区：
文献类型：
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作者：
T. Anderson;R. Raiswell
与黑海的氧化/亚氧化大陆边缘沉积物和全世界的氧化/非氧化大陆边缘和深海沉积物相比，黑海的深盆富氧沉积物富含铁，非常容易硫化。对来自三个深盆地沉积物岩心的铁形态数据进行的质量平衡处理表明，这种富集是由于以下因素的结合：（1）高活性含铁相（硫化物和氧化物），其最终来源是来自大陆架的成岩活动（Wijsman等人，2001年）;（2）深盆地沉积物的成岩成分中铁的活性增强。岩生铁活性增强的原因尚不清楚。可能的机制包括非活性铁硅酸盐的微生物氧化作用以及在穿越大陆架的运输过程中，通过岩生通量的分馏作用，在深盆中优先沉积细粒、活性富铁的岩生组分。应用基于铁反应性的古氧化还原指标（黄铁矿化程度，无氧化性指标）应考虑到高活性铁的可用性，因此沉积物中活性铁相的浓度受各种化学，物理和生物因素的控制，其中一些与水柱中的氧化还原条件没有直接关系。
The deep basinal euxinic sediments of the Black Sea are enriched in iron that is highly susceptible to sulfidization compared to oxic/suboxic continental margin sediments in the Black Sea and oxic/dysoxic continental margin and deep-sea sediments worldwide. A mass balance treatment of iron speciation data from three deep basin sediment cores shows that this enrichment is due to a combination of (1) highly reactive iron-bearing phases (sulfides and oxides) whose ultimate source was by diagenetic mobilization from the shelf (Wijsman and others, 2001) and (2) enhanced iron reactivity in the lithogenous component of deep basinal sediments. The cause of the enhanced reactivity of lithogenous iron is problematical. Possible mechanisms include microbial oxidation of non-reactive iron silicates and the preferential deposi- tion of a fine-grained, reactive iron-enriched lithogenous component in the deep basin by the fractionation of the lithogenous flux during transport across the shelf. The application of paleoredox indicators based on iron reactivity (Degree of Pyritization, Indicator of Anoxicity) should take into account that the availability of highly reactive iron, and hence the concentration of reactive iron phases in the sediment, is controlled by a variety of chemical, physical and biological factors, some of which are not related directly to redox conditions in the water column.