Diagenetic Processes and Authigenic Mineral Formation in Amazon Shelf Sediments

亚马逊陆架沉积物中的成岩过程和自生矿物形成

• 批准号: 8812907
• 负责人: Robert Aller
• 金额: $ 43.68万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-01 至 1994-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8812907&HistoricalAwards=false
• 关键词: Diagenetic; Processes; Authigenic; Mineral; Formation

This research is part of the AmasSeds Project (A Multi- disciplinary Amazon Shelf Sediment Study), which seeks to understand the physical, chemical and geological processes that affect, or are affected by, particle fluxes on the Amazon shelf. High particulate fluxes occur on the Amazon shelf as a result of the enormous sediment discharge from the Amazon River and the extensive resuspension of fine-grained shelf sediment by tidal processes. This component of the research examines Fe and Mn reduction reactions occurring in Amazon inner shelf muds. The dominance of Fe and Mn reactions over SO4 reactions apparently results from a favorable balance between low organic C, moderately Fe-rich particles, and massive nonsteady-state deposition and physical reworking of the seabed. These properties promote the formation of nonsulfidic authigenic minerals (Fe-carbonates, Fe, Al-silicates) more typical of low SO4 deposits, strongly influence export and storage of minor/trace elements during diagenetic remobilization/ precipitation of Fe carrier phases, inhibit benthic communities and shell-bearing fauna, and have major consequences for the nature of the preserved sedimentary record. These characteristics suggest the Amazon shelf may be an analogue to ancient environments of ironstone or greensand formation. Relationships between the variables affecting these processes will be investigated in the Amazon shelf and delta-shelf region. By understanding the processes by which chemical phases of sediment are deposited in this estuary, other river/ocean systems can be better characterized. In particular, Fe and Mn reduction reactions occurring in Amazon inner shelf muds depend upon a balance between low organic C, inner shelf muds depend upon a balance between low organic C, moderately Fe-rich particles, massive nonsteady-state deposition and physical reworking of the seabed. The processes by which in situ precipitates enter the historical geological record will be investigated in the Amazon shelf and delta-shelf region.

这项研究是 AmasSeds 项目（一项多学科亚马逊陆架沉积物研究）的一部分，该项目旨在了解影响亚马逊陆架颗粒通量或受其影响的物理、化学和地质过程。 由于亚马逊河大量沉积物排放以及潮汐过程导致细粒陆架沉积物的广泛再悬浮，亚马逊陆架上出现了高颗粒通量。 该研究的这一部分研究了亚马逊内陆架泥中发生的铁和锰还原反应。 Fe 和 Mn 反应相对于 SO4 反应的主导地位显然是由于低有机碳、中等富铁颗粒、大量非稳态沉积和海底物理改造之间的良好平衡所致。 这些特性促进了非硫化物自生矿物（铁碳酸盐、铁、铝硅酸盐）的形成，这些矿物在低 SO4 矿床中更为典型，强烈影响铁载体相成岩再活化/沉淀过程中微量/微量元素的输出和储存，抑制底栖群落和贝壳动物群，并对保存的沉积记录的性质产生重大影响。 这些特征表明亚马逊大陆架可能类似于铁矿石或绿砂形成的古代环境。 将在亚马逊货架和三角洲货架区域调查影响这些过程的变量之间的关系。 通过了解沉积物化学相在该河口沉积的过程，可以更好地表征其他河流/海洋系统。 特别是，亚马逊内陆架泥中发生的铁和锰还原反应取决于低有机碳之间的平衡，内陆架泥取决于低有机碳、中等富铁颗粒、大量非稳态沉积和海底物理改造之间的平衡。 将在亚马逊陆架和三角洲陆架地区研究原位沉淀物进入历史地质记录的过程。