Sulfate 17O Anomalies in Cenozoic Volcaniclastic Deposits in the Northern High Plains, North America

北美北部高平原新生代火山碎屑矿床中硫酸盐 17O 异常

• 批准号: 0408986
• 负责人: Huiming Bao
• 金额: $ 20万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408986&HistoricalAwards=false
• 关键词: Sulfate; 17O; Anomalies; Cenozoic; Volcaniclastic

The PI proposes to examine the hypothesis that a series of extreme dry fogs probably delivered a large quantity of sulfate to the northern High Plains, North America, during the peak of the Great Basin volcanism ~ 28 million years ago. The hypothesis is based on a unique type of stable isotope signature, an array of positive sulfate 17O anomalies found in Oligocene volcanic ash beds in the region. This discovery and the proposed interpretation have generated interest, as well as debates on the possibility of past abnormal atmospheric events being recorded by rocks versus alternative explanations of the sulfate 17O anomalies. The PI and his students will (1) map out the spatial heterogeneity of sulfate deposition and isotope compositions at the type locality of the Gering Formation, (2) examine the sedimentological, mineralogical, and diagenetic factors that resulted in the preservation of the anomalous sulfate in the Gering Formation, (3) study a depositional sequence of normal playa sulfate at Wolf Butte, Nebraska, to compare to the abnormal sequence in Scotts Bluff, Nebraska, and (4) establish a temporal pattern of volcanic sulfate deposition in a neighboring locality: Badlands National Park, South Dakota. The aim of these tasks will be to provide sedimentological and geochemical evidence to constrain particular chemical pathways, deposition mode, climatic condition, and diagenetic processes that may be responsible for the 17O-anomalous sulfate in many of the ash beds in the northern High Plains. This project will provide students opportunities to learn a broad spectrum of Earth science, as well as provide the general public educational materials at popular national monuments and parks. If indeed a series of extreme dry fogs occurred in the past, studying these unusual geological events will help civilization prepare for the next big one.

PI提出了这样的假设，即在大盆地火山峰的高峰期间，一系列极端干燥的雾可能向北美北部高原北部平原提供了大量硫酸盐。该假设基于独特类型的稳定同位素特征，这是该地区的渐新世火山灰床中发现的一系列硫酸盐17o异常。这一发现和拟议的解释引起了人们的兴趣，以及关于岩石与硫酸盐17o异常的替代解释所记录的过去异常大气事件的可能性的辩论。 PI和他的学生将（1）绘制硫酸盐沉积和同位素组成的空间异质性，在Gering地层的类型位置，（2）检查导致保存异常硫酸盐的沉积学，矿物学和成岩因素在Gering地层中，（3）研究内布拉斯加州沃尔夫·比特（Wolf Butte）正常硫酸盐的沉积序列，与斯科特斯布拉夫（Scotts Bluff），内布拉斯加州（Scotts Bluff）中的异常序列进行比较，（4）（4）在邻近邻近的位置中建立了一种时间模式。 ：南达科他州荒地国家公园。这些任务的目的是提供沉积学和地球化学证据，以限制特定的化学途径，沉积模式，气候状况和成岩化过程，这些过程可能导致北部高原北部许多灰床中17o-反对硫酸盐的硫酸盐。该项目将为学生提供学习广泛的地球科学的机会，并在流行的国家纪念碑和公园提供通用公共教育材料。如果过去确实发生了一系列极端的雾气，那么研究这些不寻常的地质事件将有助于文明为下一个大型大事做准备。