晚冰期月亮湖炭屑记录反映的古气候演化

位于大兴安岭中段的月亮湖地处季风/非季风影响过渡地带,其沉积岩心下部886～546 cm的炭屑记录揭示了末次冰期晚期到全新世早期(20.9～10.8 cal.ka B.P.)的古气候演化历史,反映了东亚季风对研究区气候的影响。研究区炭屑浓度的变化主要由可供燃烧的生物量决定,生长在气候温暖时期的森林草原能够提供更多可供燃烧的生物量。在同一植被类型的条件下,气候寒冷湿润时炭屑浓度低,气候温暖干旱时炭屑浓度高。20.9～18.0 cal.ka B.P.炭屑浓度较低, 气候寒冷偏干,18.0～15.3 cal.ka B.P.炭屑浓度最低,气候寒冷湿润,15.3～14.4 cal.ka B.P.炭屑浓度增高,气候开始向温暖的方向发展,14.4～11.8 cal.ka B.P.炭屑浓度快速变化,气候也经历了一系列的快速变化,11.8～10.8 cal.ka B.P.炭屑浓度总体较高,气候温暖湿润。<50 μm的炭屑浓度指示了区域火演化的历史, >50 μm的炭屑则反映了当地野火发生的状况。

Charcoal-recorded climate changes from Moon Lake in Late Glacial

Moon Lake,in the middle part of the Daxing'an Mountain Range,located at the current northern margin of the East Asian monsoon.Charcoal records of 886～546 cm sediment core of Moon Lake reveal the climate change from the Late Glacial to the early Holocene,which is effected by East Asian monsoon.The changes of charcoal concentration in the study area are mainly decided by the available burning biomass,forest steppe grown during warm period provide more available burning biomass.Low charcoal concentration presents under cold and humid climate conditions,while high charcoal concentration presents under warm and arid climate conditions in the same vegetation type.The result indicates relative low charcoal concentration stand for cold and dry climate conditions between 20.9 and 18.0 cal.ka B.P.; the lowest charcoal concentration are typical of cold and damp climate conditions present between 18.0 and 15.3 cal.ka B.P.; the beginning of charcoal concentration increase marks the Late Glacial climatic amelioration towards warm from 15.3 to 14.4 cal.ka B.P.; the dramatic changes of charcoal concentration from 14.4 to 11.8 cal.ka B.P.correlate with series of climate changes; overall the high charcoal concentration from 11.8 to 10.8 cal.ka B.P.occurred under warm and humid climate.The concentration of charcoal <50 μm indicates the evolution of regional fire history,the concentration of charcoal>50 μm reflects the situation of local fire.