THE INFLUENCE OF RADIATION DAMAGE ON THE SOLUBILITY OF EPIDOTE-GROUP MINERALS DURING CHEMICAL WEATHERING

这项拟议研究的目的是确定从大型河流三角洲沉积物中收集的碎屑绿帘石类矿物的最大辐射剂量。由于这些矿物对化学风化有足够的抵抗力，并在三角洲沉积物中存活下来，因此测量的最大辐射剂量将反映出溶解度的门槛。基于前人对锆石和绿帘石矿物的研究，本研究的假设是，遭受辐射剂量小于~3.5×1015和衰变mg-1的碎屑绿帘石矿物颗粒将抵抗化学风化。由于尼罗河和长江三角洲沉积物中都含有大量绿帘石和尿囊石，因此将从尼罗河和长江三角洲沉积物中提取绿帘石矿物颗粒。尼罗河和长江拥有世界上两条最大的流域--S。由于三角洲沉积物起源于不同时代和岩性的结晶硅酸盐基岩下的大流域，来自这些沉积物的绿帘石矿物套应跨越自然界中常见的抗溶解颗粒的成分和辐射损伤范围。从三角洲沉积物中提取的颗粒将通过扫描电子显微镜(SEM)和能谱(EDS)验证为绿帘石。对于这项拟议研究中使用的每一种绿帘石类矿物颗粒，将完成常量和微量元素分析。主要元素分析将通过电子探针(EMPA)进行，痕量元素(例如U、Th、REE)将通过激光烧蚀微探针-电感耦合质谱仪(LAM-ICPMS)进行测定。将根据年龄和放射性核素浓度计算单个绿帘石族矿物颗粒的衰变损害。这项拟议的研究将通过三种不同的方式解决更广泛的影响。首先，米勒斯维尔大学是一所本科院校，因此本科生将积极参与该项目。其次，该项目将允许在本科生米尔斯维尔大学和加拿大纽芬兰授予博士学位的纪念大学之间建立关系。第三，将在兰开斯特科学工厂开展展览，该工厂距离宾夕法尼亚州兰开斯特市中心附近的米尔斯维尔大学约6公里。兰开斯特科学工厂提供大量与物理科学、工程、技术和数学有关的动手、互动技术和科学展览。这次动手展览的题目是？环境中的辐射？并将提供一种带有棒的数字盖革计数器，该棒与计算机接口，允许检测不同材料之间的放射性。这些材料将包括岩石和矿物，包括绿帘石类矿物的样品，以及更常见的家居用品，如花岗岩台面和陶瓷碗。

The purpose of this proposed study is to determine the maximum radiation dose of detrital epidote-group minerals collected from large river delta sediments. Because these minerals are sufficiently resistant to chemical weathering and survive into delta sediments, the maximum radiation dose measured will reflect a threshold of solubility. Based on previous studies completed on zircon and epidote-group minerals, the hypothesis of this study is that detrital epidote-group mineral grains that have experienced radiation doses less than ~3.5 * 1015 α-decay mg-1 will be resistant to chemical weathering.Epidote-group mineral grains will be extracted from Nile and Yangtze River delta sediments as both sites contain significant quantities of epidote and allanite. The Nile and Yangtze Rivers possess two of the world?s largest watersheds. Because the delta sediments originated from large watersheds underlain by crystalline silicate bedrock of varying age and lithology, the suite of epidote-group minerals derived from these sediments should span the range of compositions and radiation damage commonly observed in nature for grains resistant to dissolution.The grains extracted from the delta sediments will be verified as being epidote-group by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). For each epidote-group mineral grain utilized in this proposed study, major and trace element analyses will be completed. Major element analyses will be determined by electron microprobe (EMPA), and trace elements (e.g., U, Th, REE) determined by laser-ablation microprobe-inductively coupled-mass spectrometry (LAM-ICP-MS). The α-decay damage in the individual epidote-group mineral grains will be calculated using their age and radionuclide concentration.The broader impacts of this proposed study will be addressed in three different ways. First, Millersville University is an undergraduate institution and as a result undergraduates will be actively involved in the project. Second, this project will permit establishment of a relationship between undergraduate Millersville University and the Ph.D.-granting Memorial University of Newfoundland, Canada. Third, there will be development of an exhibit at the Lancaster Science Factory, located approximately 6 km from Millersville University near downtown Lancaster, Pennsylvania. The Lancaster Science Factory provides numerous hands-on, interactive technology and science exhibits relating to the physical sciences, engineering, technology, and mathematics. The hands-on exhibit will be entitled ?Radiation in the Environment,? and will provide a digital Geiger counter with a wand that interfaces to a computer allowing for the detection of radioactivity among different materials. The materials will include rocks and minerals, including samples of epidote-group minerals, as well as more common household items such as pieces of granite countertop and ceramic bowls.