华北平原南部全新世古径流状况的研究

Abstract AMS14C dating, analyses of pollen, grain-size, carbonate content, TOC and C/N and carbonate stable isotopic oxygen and carbon, and mineral-magnetism measurements were.conducted for alluvial sediments recovered from Sitan, Quzhou County, southern Hebei Province. Variations of magnetic-parameter values with grain-size are rather similar to those.in the Chinese loess-palaeosol sequences. It is thus postulated that these variations have, to some extent, reflected differences in pedogenic influences on these alluvial deposits..Variations in carbonate content of these alluvial deposits are in line with this postulation. In fluvial environments, either lateral migration of channels or changes in frequency of flood and avulsion can alter the accumulating rates of alluvial grains and thus pedogenic maturities.of them at certain deposition sites. Channel’s lateral migrations have been generally regarded 国家自然科学基金资助项目结题报告4autocyclic behaviours of fluvial systems themselves and thus non-climatically related while.changes in frequency of flood and avulsion are usually ascribed to changes in climatic conditions. Variations in compositions of carbonate stable isotopic oxygen and carbon with.grain-size are also quite similar to those in the Chinese loess-palaeosol sequences and therefore imply that the pedogenic differences as indicated by the variations in mineral-magnetism and carbonate content may have actually resulted from changes in climatic conditions or changes in frequency of flood and avulsion. In terms of these results and 14C dating, the early- and mid-Holocene (10,210-6,500 yr BP) palaeoclimatic conditions were inferenced for this area. This inference is in agreement with what is concluded by other investigators in the neighbouring Loess Plateau and other parts of the North China Plain..With the relationships between magnetic susceptibility and climatic parameters and between stable isotopic oxygen composition and climatic parameters developed by other investigators and values of magnetic susceptibility and stable isotopic oxygen composition of.Quzhou’s alluviums,annual recipitation and annual temperature of the early- and mid-Holocene were estimated for this area. With the modern eteorological and hydrological.data for 30 drainage basins <259 km2 situated in northern China region, a relationship between climatic parameters and annual runoff were developed. With the developed.relationship and estimated early- and mid-Holocene annual precipitation and temperature of Quzhou area, the corresponding early- and mid-Holocene annual runoff was estimated for this.area.To further understand the Holocene palaeoclimatic conditions in northern China region,AMS14C dating, analyses of grain-size, carbonate content, organic content, TOC and C/N and carbonate stable isotopic oxygen and carbon, and mineral-magnetism measurements were.conducted for alluvial and swamp sediments from Huashaoying, Yangyuan County, northern Hebei Province. In terms of these results, palaeoclimatic conditions of the later mid-Holocene.(5,320-3,370 yr BP) were inferenced..Alluvial sediments were cored (Core A) in the palaeochannel belt at Changyi area,Shandong Province and lacustrine sediments (Cores B and C) in the palaeolake at Shougong area, Shandong Province. Analysis of grain-size has been completed for Cores A, B and C and.analyses of TOC and C/N and carbonate stable isotopic oxygen and carbon have been 国家自然科学基金资助项目结题报告5.completed for Cores B and C. 14C dating for Cores A and B and analysis of calcium carbonate for Core A are still under way. It is planned, by undertaking these and other analyses, to see if these alluvial sediments have been also influenced by different degrees of pedogensis as Quzhou’s alluviums and, by comparing and combining the results for the alluvial and lacustrine sediments, to reconstruct the Quaternary palaeoenvironments for this part of the.North China Plain.With the meteorological and hydrological data of 30 years (1951-1980) for

收集和以技术手段获取华北平原南部四个地点的全新世古气候资料数据；据此以现代资料数据建立适用于这些地点的气候－径流关系式或选定已有的此类关系式；以古气候资料数据和现代气候－径流关析式估算这些地点相应的古径流深值；将初步结果与以其它方法获得的结果对比以评估并确认或修改之；以各地占的径流确认或修改的结果推断该区的古径流深状况。.