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.

该提案旨在研究宾夕法尼亚州东北部近期湖泊沉积物中磁性矿物浓度与古降雨变化之间观察到的相关性机制。我们建议研究两个不同的小型冰川湖的近期沉积物，一个以外源沉积物（韦恩伍德湖）为主，另一个以自生源（伊利湖）为主，因此可以建立降雨与矿物磁性之间关系的一般模型发达。将在每个湖的多个地点收集冻结核心。将测量矿物磁性参数（c、SIRM、ARM、ARM/SIRM、SIRM/c、HIRM），以对湖泊沉积物进行磁性表征。将进行元素分析以确定侵蚀的重要性（Na、Mg、K）或还原成岩作用的可能性（S、Mn、Fe）。磁性提取物的电子显微镜（SEM、TEM）检查将寻找磁石和由于还原成岩作用而溶解的证据。 EDS 将用于确定是否已产生自生铁磁性硫化铁。使用 FIT 扫描磁力计对岩心进行高分辨率 (1 mm) 磁扫描，可以更详细地观察 SIRM 变化，并将记录扩展到低沉降率、预沉降层位。