(ESH) Holocene Climatic Variations in the Midcontinent of North America: Analyses of Annually Laminated Sediments from Minnesota Lakes

来自湖泊的年度层状沉积物(VARVE)为获取具有可靠年代学的大陆古气候数据提供了独特的工具。这项建议旨在分析明尼苏达州四个湖泊的各种沉积物，以获得一套地球化学、沉积学和生物替代指标，以评估北美中部大陆全新世的气候变异性。这些指标包括凹陷厚度、有机和无机碳、碎屑矿物、矿物组成、粒度、碳酸盐和介形虫壳的氧、碳同位素、介形虫壳的微量元素组成和花粉。研究目标是：(1)用过去100年的仪器天气数据校准各种不同沉积物中的气候指标，以评估每个指标与气候因素的关系；(2)根据校准结果，通过解释我们研究地点的代理记录，评估全新世气候变化，特别是周期性和突变；(3)将新的不同沉积物数据与邻近地区其他高分辨率古气候研究的结果相结合，提供全新世气候变化的区域综合；(4)比较北美中部大陆与格陵兰、北大西洋、和全球其他地区，以评估全新世气候变化的机制。

Annually laminated sediments (varves) from lakes provide a unique vehicle to acquire continental paleoclimatic data with secure chronologies. This proposal seeks to analyze varved sediments from four Minnesota lakes for a suite of geochemical, sedimentological, and biological proxies to assess Holocene climatic variability in the midcontinent of North America. These proxies include varve thickness, organic and inorganic carbon, detrital minerals, mineralogical composition, grain size, oxygen and carbon isotopes of carbonates and ostracode shells, trace-element composition of ostracode shells, and pollen. The research objectives are: (1) Calibrate various climatic proxies in varved sediments with instrumental weather data for the last 100 years to evaluate how each proxy is related to climatic factors, (2) Assess Holocene climatic variations, particularly cyclic and abrupt changes, by interpreting proxy records from our study sites on the basis of calibration results, (3) Integrate new varved-sediment data with findings from other high-resolution paleoclimatic studies in adjacent areas to provide a regional synthesis of Holocene climatic variations, (4) Compare patterns of climatic fluctuations in the midcontinent of North America with those in Greenland, the North Atlantic, and other parts of the globe to evaluate mechanisms of Holocene climatic variability.