PALEOCLIMATIC CHANGES AROUND MEDIEVAL WARM PERIOD IN LEIZHOU PENINSULA,CHINA
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摘要: 本文对位于雷洲半岛湖光岩玛珥湖湖沉积物进行了年代学(137Cs、AMS 14C)及总碳(TC)、氮(TN)、无机碳(IC)的分析。对于湖光岩玛珥湖这一热带地区封闭湖泊而言,无机碳含量的变化可能受降水量-蒸发量控制。有机碳、氮的变化可能反映了湖泊生产率及营养状况的变化。在热带地区,湖水温度变化不大,温度可能不是藻类生长的主要控制因素,降水量的增加及湖泊营养物质的变化可能是有机碳、氮含量增加的主要原因。碳酸盐含量的高值期对应于有机碳、氮的低值阶段。1400a来碳酸盐含量有两个高值阶段,分别为AD 880~1260和AD 670~760.这两个高值阶段可能也是干旱期。湖光岩玛珥湖地球化学指标所揭示的干旱期与安徽龙感湖硅藻和孢粉的研究结果有较好的对应性,可能表明我国南部地区中世纪暖期可能存在一个干旱期。Abstract: Huguangyan Maar Lake is located in Leizhou Peninsula,Guangdong Province.The Chronology of its lake sediments is determined by the methods of 137Cs,AMS and 14C,and Organic carbon(TOC),nitrogen(TN) and inorganic carbon(TIC) are analyzed.In this hydrologically closed lake,TIC variations may reflect changes in the precipitation/evaporation ratio.TOC and TN in the sediments are proxy indicators of lake productivity and nutrient input.In this tropical area,where surface water temperatures are high year-round,temperature is probably a less important factor controlling algai productivity.Therefore,increased rainfall may be responsible for the observed increase in TOC,TN and TOC/TN. High TIC content correlates with low concentrations of TOC and TN,and indicates two drought episodes dated to AD 670~760 and AD 880~1260 in the sediments of lake Huguangyan.The drought Medieval Warm Period indicted by geochemical proxy in Huguangyan Maar Lake is temporally correlated with the drought period from diatom and pollen data in Longgan Lake,Anhui Province.They may imply that thereis a drought in Medieval Warm Period in south China.
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Key words:
- Leizhou Peninsula /
- Huguangyan maar lake /
- The Medieval Warm Period
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