摘要
本文根据青藏高原东部希门错短柱岩芯XM9201沉积物的物理、化学和生物指标的综合分析，讨论了该区2000多年来的气候变化过程。结果表明，2000多年来希门错地区总体表现出变暖的趋势，可以区分出4个阶段，即780～430B．C，480～1460A．D．的暖期和430B．C．～480A.D，1460～1900A．D．的冷期。另外，还对比我国东西部历史气候记载及冰芯研究，探讨了不同气候事件的特点。
The climate in the last 2000 years has been highlighted in the field of global change' It is a very important time stream in PAGES to link the geological record with instrumental--gauge data' The past study in China for the climatic change of this time stream is concentrated in the historical record and ice core, because they all have very good resolution' The study on lake sediments is also a good tool for this purpose' With the support by lake drilling session of CCP project 'Study on the Tibetan Plateau uplifting, environmental change and ecological system', the authors choose the Ximen Cuo, which is of little human impact, for the study of the palaeoclimate in the past 2 000 years.Ximen Cuo (33° 23' N, 101°08'E) is a modern glacial lake. It is semi-closed lake and infilled by melt water. The lake has a mean water depth of 40m, and covers an area of 3.8 km2. The catchment area is only 50 km2 and the lake has an altitude of 4020 a. s. l. The core site is at the lake bay, and the core (XM9201) has a depth of 1.47m.The AMS radiocarbon located at the organic mud of 1.4m deep is dated at 2 600±120 a B. P. Meanwhile the radionuclide measurement suggest that the sedimentary rate is about 0.68 mm /a, coinciding with the depositional rate inferred from 14C data. Therefore, the sample at the interval of 2 cm has a resolution of 30 ~ 40 yr.The experimental measurement are concentrated on magnetic susceptibility (x1f,.xhf, xfd), sedimentary pigment (CD, TC, Osc, Myx) and stable carbon isotope (δ13Corg).The high x1f value is consistent with more debris inflow, i. e. much melt water during the warm climate and vise versa. The content of pigment is depended on warm extent of the climate. The variation of the content of 13Corg is attributed to the type of sedimentary organic matter. When the input organic matter is of C3 way in photosynthesis, the high value coincides with kryoclimathem.According to the synthetic analysis in physics, chemistry and biology, the proxies have suggested that the Ximen Cuo (lake), which lies
出处
《第四纪研究》
CAS
CSCD
北大核心
1997年第1期62-69,共8页
Quaternary Sciences
基金
国家攀登计划资助
