Collaborative Research: Quantifying the Dependence of Fabric and Rheology on Finite Strain for Naturally Deformed Rocks

流变学是一个用来描述材料行为的术语，它量化了观察到的变形（应变）和施加的力（应力）之间的关系。 岩石变形和构造板块演化的所有方面都是地质时间尺度上岩石流变学的函数。 描述岩石流变学的困难是由于地质过程的变形速率非常缓慢，以及岩石的多相（两种以上的矿物）性质。 该项目的研究人员使用现场数据来约束和量化渐进有限应变和发展组构之间的关系，从而约束自然变形岩石的流变学。安大略西北部的塞纳河砾岩由于其岩石类型多样且具有明显的有限应变梯度，因此正在进行研究。 详细的有限应变分析的所有碎屑（岩石类型）人口在这些砾岩允许计算不同的碎屑人口在个别露头的相对应变率，并显示如何在有限应变梯度的相对强度关系的变化。 正在对应变梯度上的不同碎屑群进行详细的组构和结构分析。 具体而言，这种分析包括晶格优选取向，形状优选取向，和连接性（小波分析）的每个矿物相内的每个碎屑人口。 这些组构和纹理数据集与有限应变数据相结合，将显示每种不同的碎屑群如何适应有限应变。这种方法明确地解决了以下问题的相对重要性：（1）在渐进有限应变过程中碎屑群体变形行为演变中的组构发展，以及（2）初始组成、初始粒度和初始组构对变形行为的变化。

Rheology, a term used to describe material behavior, quantifies the relation between the observed deformation (strain) and the applied forces (stress). All aspects of rock deformation and evolution of the tectonic plates are a function of rock rheology over geological time scales. The difficulty in characterizing rock rheology occurs because of the extremely slow rates of deformation for geological processes and the polyphase (more than two minerals) nature of rocks. The researchers in this project use field data to constrain and quantify the relationships between progressive finite strain and developing fabrics, and thereby constrain rheology of naturally deformed rocks. The metamorphosed and deformed Seine conglomerates from northwestern Ontario are being studied because they contain a wide variety of rock types and a significant finite strain gradient. Detailed finite strain analysis of all clast (rock type) populations in these conglomerates allow calculations of the relative strain rates of the different clast populations at individual outcrops and show how the relative strength relationships change across the finite strain gradient. Detailed fabric and textural analyses of the different clast populations across the strain gradient are being conducted. Specifically, this analysis includes lattice preferred orientation, shape preferred orientation, and connectivity (wavelet analysis) of each mineral phase within each clast population. These fabric and texture data sets, when coupled with the finite strain data, will show how each different clast population accommodates finite strain. This approach explicitly addresses the relative importance of: (1) fabric development in the evolution of a clast population's deformation behavior during progressive finite strain, and (2) variations in initial composition, initial grain size, and initial fabric on deformation behavior.