Determining the Cause of a Magnetic Mineral-Paleorainfall Correlation in Recent Lake Sediments

确定近期湖泊沉积物中磁性矿物与古降雨相关性的原因

• 批准号: 0000948
• 负责人: Kenneth Kodama
• 金额: $ 13.38万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0000948&HistoricalAwards=false
• 关键词: Determining; Cause; Magnetic; Mineral; Paleorainfall

This is a proposal to investigate the mechanism causing a correlation observed between magnetic mineral concentration and paleorainfall variations in recent lake sediments from northeastern Pennsylvania. We propose to study the recent sediments from two different small glacial lakes, one dominated by sediment from allochthonous sources (Lake Waynewood) and one dominated by authigenic sources (Lake Ely), so a general model of the relationship between rainfall and mineral magnetism can be developed. Freeze cores will be collected at several locations in each lake. Mineral magnetic parameters (c, SIRM, ARM, ARM/SIRM, SIRM/c, HIRM) will be measured to magnetically characterize the lake sediments. Elemental analyses will be conducted to determine the importance of erosion (Na, Mg, K) or the possibility of reduction diagenesis (S, Mn, Fe). Electron microscopic (SEM, TEM) examination of magnetic extracts will look for magnetosotnes and evidence of dissolution due to reduction diagenesis. EDS will be used to determine if authigenic, ferromagnetic iron sulfides have been created. High resolution (1 mm) magnetic scanning of the cores with an FIT scanning magnetometer will allow a more detailed look at the SIRM variations and extension of the record into the low sedimentation rate, pre-settlement horizons.

这是一项研究导致磁性矿物浓度与宾夕法尼亚州东北部近期湖泊沉积物古降雨变化之间相关性的机制的建议。我们建议研究两个不同的小冰湖的近期沉积物，一个以外来沉积物为主（waynewwood湖），一个以自生沉积物为主（Ely湖），从而建立降雨与矿物磁性关系的一般模型。冰冻岩芯将在每个湖泊的几个地点收集。通过测量矿物磁性参数（c， SIRM， ARM, ARM/SIRM, SIRM/c， HIRM）来表征湖泊沉积物的磁性特征。将进行元素分析，以确定侵蚀（Na, Mg， K）的重要性或还原成岩作用（S, Mn, Fe）的可能性。磁性萃取物的电子显微镜（SEM， TEM）检查将寻找磁软质和由于还原成岩作用而溶解的证据。能谱分析将用于确定是否产生了自生的铁磁性硫化铁。用FIT扫描磁强计对岩心进行高分辨率（1毫米）磁扫描，可以更详细地观察SIRM的变化，并将记录扩展到低沉积速率、沉降前的层位。