粘土矿物特征是古气候研究的重要指标之一。通过研究乌伦古湖中粘土矿物类型、组合特征,探讨古环境变迁。研究可知:乌伦古湖沉积物中粘土矿物含伊利石、高岭石、蒙脱石和绿泥石,且以伊利石为主,指示了总体干燥的气候环境。其中,16.2cal.kaBP-5.5cal.kaBP阶段,伊利石含量相对较高,高岭石含量、Kübler指数值相对较低,反映此时冷干气候环境。5.5cal.kaBP-1.6 cal.kaBP阶段,高岭石含量增大;伊利石含量、Hw指数值均相对减小,Kübler指数值相对增加指示相对暖湿的气候环境;1.6cal.kaBP至今,伊利石、Hw指数值相对较高,高岭石含量、Kübler指数值相对较低,蒙皂石含量较高指示凉干气候环境。该研究对探讨西风控制区全新世气候环境变迁以及气候驱动机制具有一定参考价值。
Clay mineral has an remarkable advantage for paleoclimatic indication,and it is the effective method being used in paleoclimatic research. In this study,the classicification and combination characteristics of clay minerals from Ulungur Lake sediments were used to study the environmental changing in Ulungur area. AMS 14C ages were used to reconstruct the changing of Westerlies and paleoclimate. Ulungur Lake sediments contain four types of clay minerals,including illite,kaolinite,smectite,and chlorite. Among them,illite is the major mineral in sediments,which indicates arid climate in the Ulungur area. According to the clay mineral assemblages, the paleoclimate change in the Ulungur area can be divided into 3 stages. The first stage ranged from 16. 2 cal. kaBP to 5. 5 cal. kaBP. The illite content and Hw exponent values are relative high,while the kaolinite content and Kübler exponent value are relative low,which indicates cold and dry climate condition. The second stage ranged from 5. 5 cal. kaBP to 1. 6 cal. kaBP. kaolinite content increases,which indicate the warmmoist climate at that time; decreasing illite content and Hw exponent value and increasing Kübler reflect moist environment with strong weathering and eluviation. The third stage ranged from 1. 6 cal. kaBP to present. The illite content and Hw exponent value increase,while the kaolinite content and Kübler exponent value decrease. These features suggest a dry climate with weak weathering and eluviation. In addition,the higher smectite content shows the low temperature.