Survivability of glacially induced quartz grain microtextures during glacio-fluvial transport

石英颗粒显微结构的扫描电镜（SEM）分析一直被用于评价沉积环境。这一研究领域的最新进展表明，湿冰川在石英颗粒表面产生了一套独特的微纹理，这是冰川运输过程中对颗粒施加的特殊应力的结果。冰川诱导的微织构主要表现为晶粒表面的沟槽、沟槽和微纹，反映了高应力作用下晶粒间的接触。相比之下，石英颗粒的河流搬运已经发现，当颗粒沿着河床反弹时，会产生表明颗粒与颗粒接触的微观结构。这些由河流引起的微纹理表现为v形裂缝和边缘的圆润。本初步研究的目的是通过从冰川前缘逐步采样到下游一段距离的现代河沙，来测试河流系统中冰川诱导微结构的生存能力。本研究利用加拿大不列颠哥伦比亚省的熊河作为初步试验，因为这条河很容易到达，发源于冰川前缘，支流很长，遗传微观结构的可能性很小。这项初步研究的结果将提供数据，证明冰川诱导的微纹理被河流诱导的微纹理逐渐叠加。然而，河流的自然变化是巨大的，需要对许多河流进行测试，以形成有意义的套印趋势。因此，这项试点研究代表了一个更大的研究项目的初步尝试，该项目将试图评估来自各种前冰川河流的冰川诱导微纹理的渐进下游河流叠加。大型项目的成功完成将提供古系统的代用指标：1)提供河流从冰川前缘迁移距离的约束条件，从而确定古冰川系统的范围；2)估算古水力参数。因此，该项目的总体目标将对各种社区有价值，包括冰川和河流沉积学家，微形态学家和地貌学家。这项试点研究为至少2名本科生提供了研究机会，他们可能是第一次接触科学项目。这些学生将在项目的早期参与实地研究、实验室分析和最终在适当的科学场所展示研究成果。让学生在学术道路上尽早掌握科学研究技能，会让他们成为更好的地球科学家。

SURVIVABILITY OF GLACIALLY INDUCED QUARTZ GRAIN MICROTEXTURES DURING GLACIO-FLUVIAL TRANSPORTDUSTIN SWEET, TEXAS TECH UNIVERSITYEAR-1324818ABSTRACTScanning electron microscopy (SEM) analysis of microtextures on quartz grains has long been used to assess depositional environment. Recent advances in this field of study indicates that wet-based glaciers produce a unique suite of microtextures on the surface of quartz grains, as a result of extraordinary stress imparted to grains during glacial transport. Glacially induced microtextures are indicated by grooves, gouges and microstriae exhibited on grain surfaces and reflect grain-to-grain contact under high-stress. In contrast, fluvial transport of quartz grains has been found to produce microtextures indicative of grain-to-grain contact as grains bounce along the river bed. These fluvially induced microtextures are indicated by v-shaped cracks and rounding of edges. The goal of this pilot study is to test the survivability of glacially induced microtextures in a fluvial system by progressively sampling modern river sands from glacial front to a distance downstream. This study utilizes the Bear River in British Columbia, Canada as an initial test because the river is easily accessible, emanates from a glacial front, long reach with minimal tributaries and minimal chance of inheritance of inherited microtextures. The results from this pilot study should provide data that demonstrates a progressive overprinting of glacially induced microtextures by fluvially induced microtextures. Yet, the natural variability of rivers is vast and numerous rivers need to be tested to develop meaningful overprinting trends. Thus, this pilot study represents the initial foray of a much larger research project that will attempt to assess progressive, downstream fluvial overprinting of glacially induced microtextures from a variety of proglacial rivers. Successful completion of the larger project will provide proxies for ancient systems that: 1) provide constraints on distance of fluvial transport from glacial front and thus, extent of ancient glacial systems; and 2) estimate paleohydraulic parameters. Thus, the overarching goals of the project will be valuable to a variety of communities, including glacial and fluvial sedimentologists, micromorphologists and geomorphologists.This pilot study provides research opportunities for at least 2 undergraduate students, likely first exposure to a scientific project. These students will be brought on early in the project and involved with field research, laboratory analysis and ultimate showcasing of findings at appropriate scientific venues. Enabling students with scientific research skills early on in the academic path makes better career geoscientists.