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: $ 1.6万
• 依托单位: Acadia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=662700
• 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，铁不仅是炼钢所必需的，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，并参与其他营养元素循环的微生物代谢。磷矿是肥料中磷的最重要来源，因此对养活地球上迅速增长的人口至关重要。和铁一样，P也是一种生物必需元素。它形成骨架，是DNA的组成部分，对细胞能量转移至关重要，并在地质时间尺度上限制生物生产力。因为铁矿和磷矿的沉淀与生物学密切相关，这些沉积物不仅仅是地质过程的记录者，而且与地球系统的演化密切相关。***在岩石记录中识别出四期同步的铁矿和磷矿沉积，反映了海洋中铁和磷的耦合循环。每一个都代表了与调节地球系统的反馈变异性有关的海水化学和环流的变化。以前的NSERC发现资助研究了第一集和第二集，并建议研究集中在第三集。目的是通过实地考察、现代地层技术和化学示踪剂来了解加拿大、美国、巴西、英国和西班牙大西洋地区的铁矿和相关磷矿。这些沉积物是奥陶纪生物多样性大事件（GOBE; 4.8 - 4.45亿年前）之前、期间和之后的铁和磷循环系统的一部分，这是地球历史上最重要的海洋生物多样性持续增长。虽然寒武纪大爆发产生了具有一系列新身体结构的骨架生物，但GOBE记录了这些动物多样性的惊人增长。研究结果还有望提供有关海洋-大气组成、铁和磷沉积以及4.33亿至3.72亿年前后来的灭绝事件之间联系的新信息。未来的发现资助将集中在理解铁和磷耦合循环的第四阶段。***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，可以应用于了解知之甚少的加拿大铁矿和磷矿床的地质和冶金。利用最先进的模型重新解释铁矿石，可能会确定以前未知的储量，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，将提高加拿大养活自己的能力。目前对磷矿的利用是不可持续的，预计到2050年磷将达到峰值，目前的储量预计在100年内耗尽。这些储备大多位于政治动荡严重的国家，加大了对加拿大和全球粮食安全的威胁。