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

化学风化过程中辐射损伤对绿帘石族矿物溶解度的影响

• 批准号: 1037709
• 负责人: Jason Price
• 金额: $ 11.53万
• 依托单位: Millersville University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1037709&HistoricalAwards=false
• 关键词: INFLUENCE; RADIATION; DAMAGE; SOLUBILITY; EPIDOTE

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.

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族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，并能在三角洲沉积物中存活下来，因此测得的最大辐射剂量将反映溶解度的阈值。根据以前对锆石和绿帘石族矿物完成的研究，本研究的假设是，经历了辐射剂量小于~3.5 *& 1015#945;- 衰变mg-1将抵抗化学风化。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，褐帘石尼罗河和长江拥有两条世界？最大的分水岭。由于三角洲沉积物起源于不同年龄和岩性的结晶硅酸盐基岩下方的大型流域，从这些沉积物中提取的绿帘石族矿物应涵盖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）验证为绿帘石族。和能量色散X射线光谱（EDS）。对于本拟议研究中使用的每种绿帘石组矿物颗粒，将完成主要和微量元素分析。主要元素分析将通过电子探针（EMPA）和微量元素（例如，采用激光烧蚀微探针电感耦合质谱法（LAM-ICP-MS）测定铀、钍、稀土元素。#945&;- 将利用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。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，该项目将允许本科米勒斯维尔大学和博士之间的关系建立-加拿大纽芬兰纪念大学。第三，将在距离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公里的兰开斯特科学工厂举办展览。兰开斯特科学工厂提供了许多与物理科学、工程、技术和数学有关的动手、互动技术和科学展览。这次动手展览的题目是？环境中的辐射，？并将提供一个数字式盖革计数器，该计数器带有一个与计算机接口的棒，允许检测不同材料中的放射性。这些材料将包括岩石和矿物，包括绿帘石族矿物的样品，以及更常见的家居用品，如花岗岩台面和陶瓷碗。