Quantitative analyses and modelling of the microstructures associated with the (hydro)thermally activated aragonite-calcite transformation in single crystals, bivalve shells, and corals

单晶、双壳贝壳和珊瑚中与（水）热激活文石-方解石转变相关的微观结构的定量分析和建模

• 批准号: 319241716
• 负责人: Dr. Ralf Dohmen
• 金额: --
• 依托单位: Institut für Geologie, Mineralogie und Geophysik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/319241716?language=en
• 关键词: Quantitative; analyses; modelling; microstructures; associated

This proposal addresses the need to identify (i) the controlling micromechanisms involved in carbonate archive recrystallization leading to diagenetically altered skeletal hardparts or carbonate cements and to (ii) quantitatively constrain their kinetics as a basis for assessing the possible effect of recrystallization on the distribution of major and minor elements and associated isotope fractionation. We aim at deriving substantial guidelines for the interpretation of microstructural records preserved in naturally altered carbonate archives and at significantly enhancing the qualitative and quantitative understanding of the role of dissolution-precipitation processes in the recrystallization accompanying the aragonite-aragonite and aragonite-calcite-transformation during diagenesis. The project specifically intends to evaluate transformation scenarios on the basis of extensive characterization of the microstructures associated with the experimentally induced aragonite-aragonite and aragonite-calcite-transformation in aragonitic corals (highly porous), aragonitic bivalve shells (porous), and aragonite single crystals (non-porous) by a range of microscopic methods, including CT-scanning, and exploratory micro-hydraulic investigations. The characterization step will initially exploit the unprecedented observational data set from Phase I of FOR 1644. This extensive data set will be complemented by tailored experimental work in the context of Phase II. The outcome of the characterization of the pore space will provide the basis for significant modelling of grain(phase)-boundary migration in carbonates in the presence of pores, solid inclusions (organic compounds etc.), and compositional gradients. The objective of the modelling is to develop a qualitative understanding as well as to quantitatively constrain kinetics of the processes dominating the evolution of experimentally altered samples. The results of the modelling will be applied to microstructural records preserved in naturally altered carbonate archives to deduce their diagenetic pathways.

该建议解决了需要确定（i）控制微观机制，涉及碳酸盐档案重结晶导致成岩改变骨骼硬部或碳酸盐胶结物和（ii）定量限制其动力学的基础上，评估重结晶的可能影响的主要和次要元素的分布和相关的同位素分馏。我们的目标是获得大量的指导方针，用于解释保存在自然蚀变碳酸盐档案中的显微结构记录，并在显着提高溶解-沉淀过程中的作用，伴随着文石-文石和文石-方解石-转化成岩作用的重结晶的定性和定量的理解。该项目特别打算通过一系列显微镜方法，包括CT扫描和探索性微观水力调查，对文石珊瑚（高度多孔）、文石双壳类（多孔）和文石单晶（无孔）中实验诱导的文石-文石和文石-方解石转化的微观结构进行广泛表征，在此基础上评价转化情景。表征步骤将首先利用FOR 1644第一阶段前所未有的观测数据集。这一广泛的数据集将得到第二阶段范围内有针对性的实验工作的补充。孔隙空间表征的结果将为碳酸盐岩中存在孔隙、固体包裹体（有机化合物等）、和成分梯度。建模的目的是发展一个定性的理解，以及定量约束动力学的过程中占主导地位的实验改变样品的演变。模拟结果将应用于保存在自然蚀变碳酸盐档案中的微结构记录，以推断其成岩途径。