内蒙古岱海沉积物近 2200a来Rb/Sr比值、CaCO₃和有机碳含量的变化展现了包括中世纪暖期 (MWP)及小冰期 (LIA)等典型气候事件在内的环境演化过程,总体表现为暖期的沉积物Rb/Sr比值低、冷期的则高;CaCO₃和有机碳含量则相反.这里,以单一流域化学风化记录表明我国北方存在明显的中世纪暖期,发生时间约 900-1200aB P,主要环境特征表现为流域化学风化的显著增强 (低Rb/Sr比值)、生物生产力逐步提高 (高有机碳)、湖泊水位大幅度抬升的湖泊沉积记录,其间经历的化学风化是近两千年内最强的,并且其发生时间与全球其他地区基本一致.;Based on the rubidium to strontium (Rb/Sr)ratio, carbonate (CaCO₃)content and organic carbon concentration (C_org)record in lake sediments from the Daihai Lake, Inner Mongolia, dated by AMS-¹⁴C and ²¹⁰Pb, the climatic and environmental change process was reconstructed since the last 2, 200 years, including two important climate events, i.e.the Medieval Warm Period and Little Ice Age.An increase Rb/Sr ratio but a decrease both CaCO₃ and C_org correspond to a cold period, and vice versa.In this paper, we first sug gest that there existed the Medieval Warm Period in the northern China during 900-1200a B.P.by a high-resolution lake record characterized according to lower Rb/Sr ratios and hig her CaCO₃and C_org concentrations in the sediments from a single watershed, which a warm and humid environment was demonstrated by signif icantincrease of chemical weathering and by a progressive increase of biologic productivity, and by a high lake level.The Medieval Warm Period has no tonly an inner climatic fluctuant, but also the strongest chemical weathering during the last 2, 200 years, which are indicated by a high-resolution natural record in northern China.Furthermore, the Medieval Warm Period in northern China is contemporaneous with the worldwide eventidentified in the lakes, oceans, land mollusk sequences, polarice cores, pollens and historical documents.

JIN Zhang dong

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