辽宁暖和洞石笋δ^(13)C对全新世气候变化的生态响应  

ECOLOGICAL RESPONSE OF δ^(13)C TO HOLOCENE CLIMATE CHANGES FROM STALAGMITE RECORD IN NUANHE CAVE,LIAONING

作　　者：张伟宏[1] 吴江滢[1] 

机构地区：[1]南京师范大学地理科学学院,南京210046

出　　处：《海洋地质与第四纪地质》2012年第3期147-154,共8页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目(40972111)

摘　　要：基于辽宁暖和洞年层石笋NH5的7个230 Th年龄和962个碳同位素数据,建立了10.6～3.5kaBP时段全新世气候及生态演化的δ13 C序列,其长期演化趋势与北大西洋海表温度变化基本一致。该记录表明,10.6～8.8kaBP,δ13 C值逐渐负偏,由-9.4‰降至-10.3‰,气候逐渐转暖湿;8.8～6.7kaBP,δ13 C值负偏显著,平均值为-11.3‰,此时,气候温暖湿润,对应于全新世适宜期,纹层计数显示其持续时间约为1 945a;6.7～3.5kaBP,δ13 C值显著正偏,由-11.3‰升至-8.3‰,干旱化趋势明显。石笋δ18 O时间序列显示出相似的变化趋势。在6.7kaBP前后,δ13 C、δ18 O均快速正偏,纹层计数显示约在40a内完成气候由暖湿到冷干的突变转型,可能是由于北大西洋海表温度降低和植被-大气系统的反馈作用对太阳辐射减少具有放大效应。A speleothem δ^13C time series was reconstructed based on 962 stable isotope measurements and 7 ^230Th dates. The sequence covers a time range from 10. 6 to 3.5 ka BP, suggesting the evolution of ecological conditions and associated climate changes. The long-term trend of the δ^13C profile bears a high similarity to SST changes in North Atlantic. Three phases are evident in the stalagmite δ^3C record： （1） a transition to humid climate in 10.6-8.8 kaBP, during which δ^13C value displays negative excursions from -9.4‰ to -10.3‰; （2） a humid stage between 8.8 and 6.7 kaBP, in which the 813C value shows negative excursions to the minimum with an average δ^13C value of --11.3‰. Temporally, this period is in line with the Holocene Optimuml （3） a gradually drying period from 6.7 to 3.5 kaBP, during which δ^3C value displays positive excursions from -11.3‰ to -8.3‰. Constrained by annual layer counting, the duration of the Holocene Optimum in our record is about 1945 years. Both δ^13C and δ^18O records show a rapid positive excursion around 6.7 kaBP, indicating an abrupt climate transformation. Annual layer counting suggests that the duration of transformation is about 40 years. It reveals that the interaction of vegetation atmosphere system and lower SST in North Atlantic may amplify the influence of reduced solar insolation via feedback processes.

关 键 词：碳同位素 气候突变 石笋 暖和洞 全新世适宜期 

分 类 号：P532[天文地球—古生物学与地层学]