The Origin and Expansion of Silica Biomineralization and Its Influence on the Global Silica Cycle

二氧化硅生物矿化的起源、扩展及其对全球二氧化硅循环的影响

• 批准号: 2207109
• 负责人: Elizabeth Trower
• 金额: $ 47.16万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2207109&HistoricalAwards=false
• 关键词: Origin; Expansion; Silica; Biomineralization; Its

Some marine organisms construct their skeletons from opaline silica. In modern oceans, this process—silica biomineralization—plays an important role in the regulation of Earth’s climate and major elemental cycles. Observations from the rock record offer conflicting views on how long ago the first silica biomineralizers evolved and whether they played as important a role in regulating the oceans as their modern relatives. This project will investigate these questions by measuring the stable isotope composition of silicon in the oldest fossils of sponges and radiolarians, focusing on samples from the western US ranging in age from 520-440 million years. This project will include research training for graduate, undergraduate, and high school students; science engagement experiences for 200 elementary school girls; and the development of a museum exhibit on the first silica biomineralizers. The evolution and expansion of silica biomineralization at the beginning of the Paleozoic Era initiated the transformation of the silica cycle from a system governed by strictly abiotic reactions to the biologically-dominated cycle that characterizes modern oceans. Our current understanding of this transition is limited by conflicting data on the timing of the evolution and expansion of the first silica biomineralizers and untested hypotheses about their influence on the silica cycle. This project will bridge this knowledge gap by address two primary research objectives: (1) document the preservational modes of fossil sponge spicules and radiolarians to evaluate their influence on preservation of primary Si isotope values; and (2) build an improved Cambrian-Ordovician record of Si isotope values in fossil sponge spicules and radiolarians. This work will include Si and O isotope ratio analyses of siliceous fossils in situ via secondary ion mass spectrometry, combined with additional microanalytical characterization via micro X-ray fluorescence, Raman microspectroscopy, and wavelength-dispersive X-ray spectroscopy, and a suite of models describing the marine silica cycle. These data will provide a novel approach to resolving long-standing questions surrounding the early Paleozoic biological transformation of the global silica cycle, including how the marine system responded to major perturbations in silicate weathering fluxes driven by climate and tectonics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

一些海洋生物的骨架是由乳白色的二氧化硅构成的。在现代海洋中，这一过程——二氧化硅生物矿化——在地球气候和主要元素循环的调节中起着重要作用。岩石记录的观察结果提供了相互矛盾的观点，关于第一个硅生物矿化器是在多久以前进化的，以及它们是否在调节海洋方面发挥了与现代亲戚一样重要的作用。该项目将通过测量最古老的海绵和放射虫化石中硅的稳定同位素组成来研究这些问题，重点关注美国西部年龄在5.2 - 4.4亿年之间的样本。该项目将包括研究生、本科生和高中生的研究训练；200名小学女生科学参与体验并在博物馆展出了第一批二氧化硅生物矿化剂。古生代初期二氧化硅生物矿化作用的演化和扩展开始了二氧化硅循环从严格由非生物反应控制的系统向现代海洋生物主导循环的转变。我们目前对这一转变的理解受到关于第一批二氧化硅生物矿化物进化和扩展时间的相互矛盾的数据和关于它们对二氧化硅循环影响的未经检验的假设的限制。本项目将通过解决两个主要研究目标来弥合这一知识差距：(1)记录海绵针状体和放射虫化石的保存模式，以评估它们对原始Si同位素值保存的影响；(2)在海绵针状体和放射虫化石中建立了改进的寒武-奥陶系硅同位素记录。这项工作将包括通过二次离子质谱法对原位硅质化石的Si和O同位素比值进行分析，结合通过微x射线荧光、拉曼微光谱和波长色散x射线光谱进行额外的微量分析表征，以及一套描述海洋硅循环的模型。这些数据将为解决围绕全球硅循环的早古生代生物转化的长期问题提供一种新的方法，包括海洋系统如何响应由气候和构造驱动的硅酸盐风化通量的重大扰动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。