Early diagenetic aluminosilicate formation and burial of biogenic silica in tropical deltas

生物成因的二氧化硅快速转化为自生粘土并随后埋藏在三角洲中，对海洋硅循环、海洋碱度平衡以及粘土中多种元素(如K+、Li+、Ge和F-)的循环具有潜在的重要意义。在这个项目中，石溪大学的一个研究小组将利用天然宇宙成因放射性核素32Si的新应用、孔隙水和沉积物中Del7Li和Ge的成岩模拟以及实验室孵化实验来限制自生粘土的数量、组成和形成机制，进行一项综合研究。他们将把重点放在巴布亚海湾的斜床状三角洲复合体上，他们已将可用于孔隙水和沉积物分析的样本存档，并开始对法属圭亚那具有代表性的沿海泥滩进行新的采样，这些沉积物代表了亚马逊三角洲的功能成岩延伸。后者将为优化分析技术、实验室实验和推广提供基础。更广泛的影响：硅循环是控制海洋和地球表面组成的生物地球化学过程的中心组成部分。对硅源和硅汇及其对人为扰动的响应的知识对于未来海洋状况的预测模型至关重要。热带三角洲体系中自生铝硅酸盐的形成和埋藏似乎是海相硅循环的重要组成部分，但相对较差。Li和Ge等元素与硅循环密切耦合，并被提取成自生铝硅酸盐，也被用于重建古老的地球表面过程，并提供了现代海洋生物地球化学平衡的前景。本文提出的综合研究，包括具有潜在重大意义的宇宙成因放射性核素32Si的新应用，将为热带三角洲系统在硅循环中的作用以及控制大陆边界Li和Ge等次要元素通量的过程提供重要的新的定量约束。研究生和本科生教育和技术培训将纳入实验室和实地研究。

The rapid diagenetic conversion of biogenic SiO2 to authigenic clay and subsequent burial in deltas has potentially major implications for the marine Si cycle, ocean alkalinity balances, and the cycle of multiple elements that are incorporated into clays (for example, K+, Li+, Ge, and F-).In this project, a research team at Stony Brook University will conduct an integrated study using a novel application of the natural cosmogenic radionuclide 32Si, diagenetic modeling of del7Li and Ge in pore water and sediment, and laboratory incubation experiments to constrain the quantity, compositions, and mechanisms of formation of authigenic clay. They will focus on the clinoform delta complex in the Gulf of Papua, for which they have archived samples available for pore water and sediment analysis, and initiate new sampling of a representative coastal mudbank of French Guiana, deposits that represent a functional diagenetic extension of the Amazon delta. The latter site will provide a basis for optimization of analytical techniques, laboratory experiments, and generalization. Broader impacts: The Si cycle is a central component of biogeochemical processes controlling ocean and Earth surface composition. Knowledge of Si sources and sinks and their response to anthropogenic perturbations are critical to predictive models of future ocean conditions. Authigenic aluminosilicate formation and burial in tropical deltaic systems appears to be a significant component of the marine Si cycle but is relatively poorly constrained. Elements such as Li and Ge that are closely coupled to the Si cycle and extracted into authigenic aluminosilicates are also used in reconstruction of ancient Earth surface processes and provide perspective on modern ocean biogeochemical balances. The integrated study proposed here, including novel application of the cosmogenic radionuclide 32Si with potentially major implications, will provide important new quantitative constraints on the role of tropical deltaic systems in the Si cycle and on processes controlling the flux of minor elements such as Li and Ge at the continental boundary. Graduate and undergraduate education and technical training will be integrated into laboratory and field research.