Ironstone, phosphorite, and nutrient cycling during Paleozoic biodiversification

古生代生物多样性过程中的铁矿石、磷矿石和养分循环

• 批准号: RGPIN-2017-04290
• 负责人: Pufahl, Peir
• 金额: $ 3.21万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750921
• 关键词: Ironstone; phosphorite; nutrient; cycling; during

Ironstone and phosphorite are marine chemical sediments of scientific and industrial importance. Ironstone is enriched in Fe, which is not only required for steel production, but also essential for nearly all living things. It is necessary for photosynthesis in plants, part of many proteins, and involved in microbial metabolisms that cycle other nutrient elements. Phosphorite is the most important source of P in fertilizer, and therefore vital for feeding the Earth's burgeoning population. Like Fe, P is also a bioessential element. It forms skeletons, is a building block of DNA, is essential for cellular energy transfer, and limits biologic productivity over geologic timescales. Because the precipitation of ironstone and phosphorite is so closely tied to biology, these deposits are not simply recorders of geologic processes, but intimately involved in Earth system evolution. Four synchronous episodes of ironstone and phosphorite deposition are recognized in the rock record, reflecting coupled cycling of Fe and P in the ocean. Each represents changes in seawater chemistry and circulation related to variability in the feedbacks regulating the Earth system. Previous NSERC Discovery Grants investigated the first and second episodes, with proposed research focused on the third. The goal is to use fieldwork, modern stratigraphic techniques, and chemical tracers to understand ironstone and related phosphorite in Atlantic Canada, USA, Brazil, UK, and Spain. These deposits were part of a system of Fe and P cycling prior to, during, and after the Great Ordovician Biodiversification Event (GOBE; 480 to 445 million years ago), which is the most important sustained increase in marine biodiversity in Earth history. While the Cambrian Explosion produced skeletonized organisms with a range of new body plans, the GOBE records the staggering increase in diversity of these animals. Results also promise to yield new information about the link between ocean-atmosphere composition, Fe and P deposition, and later extinction events 433 and 372 million years ago. Future Discovery Grants will focus on understanding the fourth episode of coupled Fe and P cycling. Significant to Canada is that this research will develop new Fe and P exploration models that can be applied to understand the geology and metallurgy of poorly understood Canadian ironstone and phosphorite deposits. The reinterpretation of ironstone using state-of-the-art models may define previously unknown reserves that are much closer to infrastructure and market than existing ore bodies. When applied to phosphorite this knowledge will enhance Canada's ability to feed itself. Current use of phosphorite is unsustainable, with Peak Phosphorus estimated by 2050 and depletion of current reserves expected in 100 years. Most of these deposits reside in countries with significant political unrest, amplifying the threat to Canadian and global food security.

铁矿和磷矿是具有重要科学和工业意义的海洋化学沉积物。铁石富含铁，不仅是钢铁生产所必需的，也是几乎所有生物所必需的。它是植物光合作用所必需的，是许多蛋白质的一部分，并参与微生物代谢，使其他营养元素循环。磷矿是肥料中最重要的磷来源，因此对养活地球上迅速增长的人口至关重要。与铁一样，磷也是一种生物必需元素。它形成骨骼，是DNA的组成部分，是细胞能量转移的关键，并限制了地质时间尺度上的生物生产力。由于铁石和磷矿的沉淀与生物息息相关，这些矿床不仅是地质过程的记录，而且与地球系统的演化密切相关。在岩石记录中发现了四个同步的铁矿和磷矿沉积幕，反映了海洋中铁和磷的耦合循环。每一种都代表着与调节地球系统的反馈中的可变性有关的海水化学和循环的变化。之前的NSERC发现基金调查了第一集和第二集，拟议的研究重点是第三集。目标是利用实地考察、现代地层学技术和化学示踪剂来了解大西洋加拿大、美国、巴西、英国和西班牙的铁矿和相关磷岩。这些沉积物是大奥陶纪生物多样化事件(GoBe；4.8亿至4.45亿年前)之前、期间和之后Fe和P循环系统的一部分，这是地球历史上海洋生物多样性最重要的持续增加。虽然寒武纪的爆发产生了一系列新的身体计划的骨骼有机体，但GoBe记录了这些动物多样性的惊人增长。这些结果还有望提供新的信息，说明4.33亿年前和3.72亿年前的海洋-大气成分、铁和磷沉积以及后来的灭绝事件之间的联系。未来的探索基金将专注于了解铁和磷耦合循环的第四集。对加拿大意义重大的是，这项研究将开发新的铁和磷勘探模型，可用于了解知之甚少的加拿大铁矿和磷矿床的地质和冶金。使用最先进的模型对铁矿石进行重新解释，可能会定义出以前未知的储量，这些储量比现有矿体更接近基础设施和市场。当将这一知识应用于磷矿时，将提高加拿大自给自足的能力。目前磷矿的使用是不可持续的，据估计，磷的峰值将在2050年达到，目前的储量预计在100年后耗尽。这些矿藏大多位于政治动荡严重的国家，放大了对加拿大和全球粮食安全的威胁。