Characterization of Quartz Coarse Silt Using Laser Micro- probe and Objective Cathodoluminesence

各种烃源岩提供的石英沉积物可根据其物理和化学性质进行表征。这两种方法都被用来评价石英砂的来源，尽管物理性质已经得到了强调。化学性质已被用于描述整个沉积物样品（沉积物大小和矿物组成的混合物）或单一矿物成分的多个颗粒，但通常不适用于单个颗粒，特别是细粒石英。用主观阴极发光（CL）岩石学观察的间接化学性质适用于单个砂粒，但通常不适用于较细的石英颗粒。石英粗粉砂是泥岩的重要组成部分。这项初步研究的目的是表征石英的属性以前没有确定在这些细颗粒。利用LAMMA激光微探针和物镜CL岩石学技术，记录了在单一排水系统中从不同烃源岩中分离出来的石英粗粉砂的特征。石英粗粉砂将从詹姆斯河流域的几条一级溪流中收集，每条溪流都排出一种已知的烃源岩。每个烃源岩的石英沉积物以及烃源岩中的石英将使用这两种技术进行表征。这种石英，因此指纹，然后可以归因于特定的烃源岩。这项初步研究有两个直接和主要的应用。首先，证明这些技术能够识别石英沉积物的源岩，将使进一步的研究能够确定对现代泥泞环境产生淤泥的主要岩性，这是一个目前有争议的话题，但目前常用的工具可能无法解决。其次，由于这些技术分析的特征预计不会受到成岩作用的影响，如果能够证明烃源岩类型具有独特和可预测的特征，它们就有可能评估泥岩中粉砂的来源。

The quartz sediment provided by various source rocks can be characterized on the basis of physical and chemical properties. Both have been used to evaluate the sources of quartz sand although the physical properties have been emphasized. Chemical properties have been used to characterize whole sediment samples (a mixture of sediment size and mineral composition) or multiple grains of a single mineral component but generally not for individual grains and specifically not for fine-grained quartz. Indirect chemical properties observed using subjective cathodoluminescence (CL) petrography is applied to individual sand grains, but generally not for the finer quartz grains. Quartz coarse silt is an important component of mudrocks. The purpose of this pilot study is to characterize attributes of quartz not previously determined on these fine particles. LAMMA laser microprobe and objective CL petrography will be used to document characteristics of quartz coarse silt liberated from various source rocks in a single drainage system. Quartz coarse silt will be collected from several first order streams each draining a single known source rock in the James River drainage basin. This quartz sediment from each source as well as the quartz in the source rock will be characterized using the two techniques. This quartz, thus fingerprinted, can then be attributed to specific source rocks. There are two immediate and major applications of this pilot study. First, demonstration of the ability of these techniques to identify source rock of quartz sediment will allow further studies to determine the dominant lithologies contributing silt to modern muddy environments, a topic presently debated but possibly not solvable with the commonly used tools at present. Second, because the characteristics analyzed by these techniques are not expected to be affected by diagenetic processes, they have the potential to evaluate the sources of silt in mudrocks if it can be shown that source rock types have unique and predictable characteristics.