Collaborative Research: Paleomagnetic Analysis of Speleothems and High Precision Dating of Geomagnetic Records

合作研究：洞穴古地磁分析和地磁记录高精度测年

• 批准号: 1316385
• 负责人: Joshua Feinberg
• 金额: $ 26.85万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1316385&HistoricalAwards=false
• 关键词: Collaborative; Research; Paleomagnetic; Analysis; Speleothems

Records of past geomagnetic field behavior offer a window into the behavior of the Earth's convecting outer core, and lead to a better understanding of geodynamo processes that generate Earth's magnetic field. This project aims to develop a relatively untapped reservoir of paleomagnetic and rock magnetic information, speleothems (e.g., stalagmites, and flowstone). Speleothems have immense potential for archiving high quality, high resolution geomagnetic records, and can be dated with supreme precision using radiometric techniques. This research investigates the fundamental processes involved in natural remanence acquisition in speleothems using rock magnetic and microscopic imaging techniques, and establishes chronological constraints for geomagnetic field behavior during specific periods in the last 130 ka.The overarching goal of this research project is to construct high-resolution records of geomagnetic field behavior and paleoclimate conditions using the iron oxide mineral assemblages preserved within speleothems. We will address both the mechanical transport and chemical precipitation of iron oxide minerals in speleothems in order to better understand how and when speleothems acquire a recording of the Earth's magnetic field. Recent instrumental progress provides the sensitivity and sample handling capabilities needed to collect a rich variety of magnetic measurements from speleothems, at an unprecedented spatial resolution. The investigation of speleothem magnetization on a sub-millimeter scale will advance the understanding of magnetic processes in speleothems, ranging from changing dripwater conditions to episodic flooding that can be used to produce regional paleohydrology records. Precisely dated, high fidelity paleomagnetic records from speleothems will help better constrain time-dependent, global geomagnetic field models. An additional benefit of having detailed, high-precision chronologies of paleomagnetic variations is that the chronological information can be transferred to existing deposits with correlatable paleomagnetic records, but with less constrained age models (e.g., archaeological sites, and/or sediment cores). High resolution geomagnetic fluctuations recovered from speleothems will contribute valuable information to geodynamo models that focus on small-scale core flow dynamics. The environmental magnetic records of speleothems will bridge the gap that exists between climatic and environmental interpretations from traditional speleothem measurements such as oxygen isotopes, and the environmental magnetic records of other depositional environments.

过去地磁场行为的记录提供了一个了解地球对流外核行为的窗口，并有助于更好地了解产生地球磁场的地球发电机过程。该项目旨在开发一个相对未开发的古地磁和岩石磁性信息库，洞穴沉积物（例如，石笋和流石）。洞穴沉积物有巨大的潜力，存档高质量，高分辨率的地磁记录，并可以与最高精度使用辐射技术的日期。本研究利用岩石磁性和显微成像技术研究了洞穴沉积物中天然剩磁获取的基本过程，并建立了过去130 ka特定时期地磁场行为的时间约束。本研究项目的总体目标是构建高-利用洞穴沉积物中保存的氧化铁矿物组合对地磁场行为和古气候条件的分辨率记录。我们将解决这两个机械运输和化学沉淀的铁氧化物矿物的洞穴沉积物，以更好地了解如何以及何时洞穴沉积物获得地球磁场的记录。最近的仪器进步提供了收集丰富多样的磁测量所需的灵敏度和样品处理能力，从洞穴沉积物，在前所未有的空间分辨率。在亚毫米尺度上对洞穴沉积物磁化的调查将促进对洞穴沉积物中磁过程的理解，从不断变化的滴水条件到可用于产生区域古水文记录的情景洪水。精确定年，高保真古地磁记录洞穴将有助于更好地约束时间依赖性，全球地磁场模型。具有详细的、高精度的古地磁变化年表的另一个好处是，年表信息可以被转移到具有可验证的古地磁记录的现有矿床，但是具有较少约束的年龄模型（例如，考古遗址和/或沉积物岩心）。高分辨率的地磁波动恢复从洞穴沉积物将提供宝贵的信息，地球发电机模型，专注于小规模的核心流动动力学。洞穴沉积物的环境磁性记录将弥补传统洞穴沉积物测量（如氧同位素）与其他沉积环境的环境磁性记录之间存在的气候和环境解释之间的差距。