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湖光岩玛珥湖HUG B孔岩心记录了62kaBP以来的古气候、古环境变化信息。全岩有机碳同位素组成(δ13CTOC)分析表明,62kaBP以来δ13CTOC值变化比较明显,其变化范围为-28.5‰～-15.5‰。结合孢粉和有机地球化学指标进行综合分析,湖光岩玛珥湖δ13CTOC变化曲线可划分为6个演化阶段:62～58和48～40.5kaBP两个时段的δ13CTOC值偏负,沉积物中有机质主要来源于热带—亚热带地区的陆生C3森林植被,反映了温暖潮湿的气候环境;58～48和40.5～17.2kaBP期间δ13CTOC值明显偏正,沉积物中有机质主要源自C4草本植物,反映了湖光岩地区有效降水量减少、干旱程度增加导致湖光岩玛珥湖湖面下降,大量C4草本植物生长在暴露的湖滨岸;17.2～4kaBP时段内δ13CTOC值尽管存在更加频繁的波动,但总体呈现逐渐偏负的趋势,反映了暖湿和冷干气候多次交替但总体上逐渐变暖、变湿的气候环境;4kaBP以来δ13CTOC值存在逐渐偏正的趋势,虽然不排除人类活动的影响,但很可能反映了干旱程度的再次增加。综合分析表明,有效降水量(降水量-蒸发量)是控制湖光岩玛珥湖地区C3/C4植物相对生物量变化的主导因素。湖光岩玛珥湖有机碳同位素的研究结果支持区域气候环境而不是大气CO2浓度变化是末期冰期以来热带低纬度地区C3/C4植被相对生物量变化的主要原因。
Huguangyan Maar Lake HUG B hole core records the paleoclimatic and paleoenvironmental changes since 62kaBP. Total organic carbon isotope composition (δ13CTOC) analysis shows that the δ13CTOC value changes obviously since 62kaBP, and its variation ranges from -28.5 ‰ to -15.5 ‰. Based on the comprehensive analysis of sporopollen and organic geochemical indexes, δ13CTOC curve of Lake Maar Lake can be divided into six evolution stages: the δ13CTOC values of 62 ~ 58 and 48 ~ 40.5kaBP are negative, the organic matter The terrestrial C3 forest vegetation, mainly from the tropical and subtropical regions, reflected the warm and humid climatic environment. The δ13CTOC values were significantly positive during 58-48 and 40.5-17.2 ka BP. The organic matter in the sediments mainly came from the C4 herbaceous plants, The effective precipitation decreased in the Huguangyan area, and the increase of drought led to the decrease of the Lake Ma’er Lake in Huguangyan. A large number of C4 herbs grew on the exposed shore of the lake. In the period of 17.2 ~ 4kaBP, the δ13CTOC value showed more frequent fluctuations, The trend of gradually negative trend reflects that the climate of warm, humid and cold-dry climate alternates several times but generally becomes warmer and more humid. Since the δ-8ctOC value of 4kaBP tends to be more or less positive, although it does not exclude the influence of human activities, It is likely to reflect the renewed increase in the degree of drought. The comprehensive analysis shows that the effective precipitation (precipitation - evaporation) is the dominant factor controlling the relative biomass of C3 / C4 plants in Lake Maar Lake. The results of the research on organic carbon isotopes of Lake Guangar Maar were that the change of regional climate environment rather than atmospheric CO2 concentration was the main reason for the relative biomass change of C3 / C4 vegetation in tropical low latitudes since the last glacial period.