COLLABORATIVE RESEARCH: (GRGC) Holocene Lacustrine Records of Decade- to Century-Scale Variation in Monsoon Precipitation, Northwestern India

合作研究：（GRGC）印度西北部季风降水十年至百年尺度变化的全新世湖泊记录

• 批准号: 9418189
• 负责人: Lisa Ely
• 金额: $ 13.53万
• 依托单位: Central Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418189&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; GRGC; Holocene; Lacustrine

Ely 9418189 The principal objective of this project is to document and understand decade- to century-scale paleoclimatic variations in the monsoon region of northwestern India, using detailed sedimentary records from three lake in northwestern India. The finely- laminated sediments in these lakes preserve an exceptional record of high-resolution lake-level variations over the last 10,000 to 13,000 years, possibly the most complete and detailed Holocene paleoclimatic record within the Indian Monsoon region. The lakes lie in the arid/semiarid Thar Desert at the boundary of the region dominated by summer monsoon rainfall (Singh et al., 1990), and are thus particularly sensitive to fluctuations in the strength of the monsoon. Analysis of these lacustrine records will address how the decadal-scale variations in the monsoon respond to longer-term shifts in the monsoon paleoclimate, providing a high-resolution record that covers a sufficiently long time scale to fully capture the natural range of variability in the monsoon system, information that is essential for understanding near-term future climatic variations in the monsoon region. This is a collaborative project between researchers at Central Washington University and the of University of Arizona (see accompanying proposal). The methodology involves reconstructine decade- to century-scale changes in lake levels, salinity, and sediment influx in three shallow, closed-basin lakes through a combination of (1) detailed stratigraphy and sedimentology of finely laminated sediments, (2) evaporite and clay mineralogy, and (3) radiocarbon dating. Potential application of microfauna, trace elements, stable isotopes and pollen toward this problem will be explored and tested, but will not be a main focus of the study. These data, along with modern data on precipitation, water-table elevations , evaporation, and temperature, will be used to construct hydrological lake-budget models and quantify the changes in hydro logic and climatic parameters necessary to produce the lake fluctuations. The analyses will concentrate on the high-resolution variations preserved in the primary stratigraphy during extended periods of high, low , and transitional lake-level conditions. We will emphasize specific periods of interest, including (a) internals of high variability and changing conditions, such as wet-dry transitions, (b) short-lived, shallow lakes in the late Holocene that reflect minor climatic fluctuations and/or extreme events in the last 4000 years and (c) periods of particularly high (e.g. 4000-6000 BP) or low lake levels. Analysis of the high- resolution paleohydrological variations will add a new dimension to broader-scale reconstructions of Holocene paleoclimates in monsoonal regions of India, Asia and Africa.

Ely 9418189该项目的主要目的是使用印度西北部三湖的详细沉积记录来记录并了解印度季风地区的十年至世纪的古气候变化。 这些湖泊中的层压沉积物在过去的10,000至13，000年中保留了高分辨率湖泊水平变化的出色记录，这可能是印度季风地区最完整，最详细的全新世古气候记录。 湖泊位于夏季季风降雨（Singh等，1990）主导该地区边界的干旱/半干旱塔尔沙漠中，因此对季风强度的波动特别敏感。 对这些湖间记录的分析将解决季风的衰老尺度变化如何应对季风古气候的长期变化，从而提供了高分辨率的记录，该记录涵盖了足够长的时间范围，以完全捕获季风系统的自然变异性，这对于理解近期季度的季型季度变化至关重要。 这是华盛顿大学中央研究人员与亚利桑那大学研究人员之间的合作项目（请参阅随附的提案）。 该方法涉及通过（1）（1）详细的地层和沉积学的结合，（2）蒸发液和粘土矿物学的详细地层和（3）放射性碳纤维的详细地层学和（3）放射性碳纤维的详细地层学和（3）放射性碳纤维的详细地层学和（3）放射性碳的详细地层学和（3）放射性的结合。 将探索和测试缩影，痕量元素，稳定的同位素和花粉对此问题的潜在应用，但并不是研究的主要重点。 这些数据，以及有关降水，水表高程，蒸发和温度的现代数据，将用于构建水文湖预算模型，并量化产生湖泊波动所需的水力逻辑和气候参数的变化。 分析将集中于在高，低和过渡的湖泊水平条件的延长时期保留的高分辨率变化。 我们将强调特定的感兴趣时期，包括（a）较高的可变性和变化条件的内部，例如湿干的过渡，（b）在全新后期晚期的短寿命，浅层湖中，反映了过去4000年的气候波动和/或极端事件，在过去的4000年中，以及（c）特别高的时期（例如4000-6000 bp）或低湖泊或低湖泊或低湖泊级别。 分析高分辨率古流水学变化将为印度，亚洲和非洲季风地区的全新世古燃料的广泛重建增添新的维度。