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

本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群矿物的最大辐射剂量。由于这些矿物质对化学风化有足够的抵抗力，并能在三角洲沉积物中存活，因此测量的最大辐射剂量将反映溶解度的阈值。基于前人对锆石和绿石组矿物的研究，本研究假设：受辐射剂量小于~3.5 * 1015 &#945；-衰变mg-1将耐化学风化。绿帘石组矿物颗粒将从尼罗河和长江三角洲沉积物中提取，因为这两个地点都含有大量的绿帘石和allanite。尼罗河和长江拥有世界之二？美国最大的流域。由于三角洲沉积物起源于由不同年龄和岩性的结晶硅酸盐基岩下的大型流域，从这些沉积物中提取的绿帘石群矿物应该跨越了自然界中常见的抗溶解颗粒的组成和辐射损伤范围。通过扫描电镜（SEM）和x射线能谱（EDS）分析，证实了三角洲沉积物中提取的颗粒为绿帘石群。对于本研究中使用的每个绿帘石组矿物颗粒，将完成主要元素和微量元素的分析。主要元素分析将通过电子探针（EMPA）确定，微量元素（例如，U, Th， REE）将通过激光烧蚀微探针-电感耦合质谱（lamp - ms）确定。, # 945;-利用年龄和放射性核素浓度计算绿帘石群矿物颗粒的衰变损伤。这项拟议研究的更广泛影响将以三种不同的方式解决。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。第二，该项目将允许本科生米勒斯维尔大学和授予博士学位的加拿大纽芬兰纪念大学建立关系。第三，将在兰开斯特科学工厂开发一个展览，该工厂位于宾夕法尼亚州兰开斯特市中心附近的米勒斯维尔大学约6公里处。兰开斯特科学工厂提供许多与物理科学、工程、技术和数学有关的动手、互动技术和科学展览。亲身实践的展览将被命名为？环境中的辐射？并将提供一个带有一根棒的数字盖革计数器，该计数器与计算机相连，可以检测不同材料之间的放射性。这些材料将包括岩石和矿物，包括绿帘石矿物的样本，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.