Temperature and Summer Monsoon Variability During the Past 500 Ka in China

近500 Ka中国气温和夏季风变化

• 批准号: 0081224
• 负责人: Hong-Chun Li
• 金额: $ 42.18万
• 依托单位: University of Southern California
• 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: 2000-08-15 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0081224&HistoricalAwards=false
• 关键词: Temperature; Summer; Monsoon; Variability; During

This award is for a study of the isotopic composition of stalagmite specimens grown over the past 500,000 years in three caves in China: Buddha Cave south of Xian, Huanglong Cave in northwestern Hunan, and Fengyu Cave south of Guilin. The stalagmites will be dated by TIMS U-series methods to establish precise time frameworks upon which the variations of d18O and d13C are to be examined. In these stalagmites the long-term d18O variations provide the history of temperature changes, with lighter d18O values reflecting colder climate. The d13C record represents vegetation changes, such that warm and dry conditions reduce the C3 /C4 plant ratio, the density of vegetation, and the 13C fractionation for carboxylation in C3 plants, giving rise to heavier d13C values. From the isotopic measurements, the proponents will reconstruct records of the paleotemperature and paleomonsoon variability over the past 500 ka, at 102 -103 year resolutions. The proponents will then compare them with the loess records from Central China and the marine oxygen isotope records, to investigate the response of the winter monsoon to global ice volume change.

该奖项是为了研究中国三个洞穴中50万年来生长的石笋标本的同位素组成：西安南部的佛陀洞，湖南西北部的黄龙洞和桂林南部的丰裕洞。石笋将通过TIMS U系列方法测定年代，以建立精确的时间框架，并在此基础上检查d18 O和d13 C的变化。在这些石笋中，d18 O的长期变化提供了温度变化的历史，较轻的d18 O值反映了较冷的气候。d13 C记录代表植被变化，例如温暖和干燥的条件降低C3 /C4植物比率、植被密度和C3植物中用于羧化的13 C分馏，从而产生较重的d13 C值。通过同位素测量，支持者将重建过去500 ka的古温度和古季风变化记录，分辨率为102 - 103年。研究人员将把它们与中国中部的黄土记录和海洋氧同位素记录进行比较，以研究冬季风对全球冰量变化的响应。