【作者】 杨前进；

【导师】 黄春长；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2004， 博士

【摘要】 黄土高原的全新世黄土-土壤地层系列很好地记录了过去一万多年土壤发育、季风气候、风尘堆积和农业耕作影响的演变。位于黄土高原东南部的临汾盆地是中华民族的发祥地之一，人类耕作活动开始于新石器时代，长期的农业发展对当地全新世成壤过程具有重要的影响，并在黄土-土壤地层系列中留存下大量的记录。深入研究临汾盆地全新世黄土-土壤剖面，对于揭示汾河下游全新世自然环境变迁、人类对当地土地资源的开发利用和人类活动的影响具有十分重要的意义。 本研究选择的三个全新世黄土剖面位于临汾盆地中部陶寺地区，其中DPG剖面位于塔儿山古洪积扇前沿，TSC剖面和LGK剖面位于与古洪积扇相连的汾河4级阶地。研究区内有著名的龙山文化遗址—陶寺遗址，TSC剖面位于遗址居住区内，DPG剖面和LGK剖面位于遗址边缘。 野外根据土壤颜色、质地、结构、侵入体等对剖面初步分层，然后自上而下按2cm间距连续取样。样品在室内风干后，用门赛尔土壤比色卡描述颜色，进行粒度成分、磁化率、Fe₂O₃、Al₂O₃、Rb、Sr、Ba、Cu、Ni、CaCO₃、TOC（全有机碳）等分析测定。根据实验结果及其成壤环境意义的分析，探讨了全新世陶寺地区土壤发育状况和成壤环境演变、地表面状侵蚀—沉积作用变化。结合考古学成果，分析人类活动对土壤发育的影响，初步探讨了距今4000年前后陶寺地区的洪水问题。所获得的主要认识有： 1．全新世临汾盆地成壤环境和土壤发育具有显著的阶段性。早全新世（11500～8500 a B．P．），降尘速率大，气候干旱，植被稀少，成壤极弱。在全新世大暖期来临前，曾有较大的季节性降水，在塔儿山山麓古洪积扇和阶地面形成雨水面流，在洪积扇前沿和阶地面发生沉积作用。 全新世大暖期（8500～3100a B．P．）是本区土壤发育期，但不同地点成壤过程和强度有显著差别。陶寺文化晚期之前（4050 a B．P．以前），气候温暖，降水丰富，植被发育，生物成壤作用强烈，阶地面的两个剖面出现残积粘化层。洪积扇前沿由于地形对降水的再分配，土壤水分较少，淋溶作用强度小于阶地面。从陶寺文化晚期到大暖期结束（4050～3100a B．P．），气候依然温暖湿润，洪积扇前沿发生面状水流沉积过程，改变了地形条件，改善了土壤水分，促进了成壤过程；但在陶寺遗址聚落区，受人类活动影响，成壤过程中断；LGK剖面在陶寺文化晚期（4050～3850a B．P．）快速堆积的面状水流沉积物构成了一段弱成壤层，陶寺文化结束后（3850一:3]（）0:1 13，l）.)成壤过程增强。 晚全新肚（:3 IOOa日.1，.以来），冬季风环流加强，粉尘堆积加速，气候干旱，植被退化，三个剖面成壤强度显著降低:同时，人类活动作为一个重要成壤因子参与成壤过程，三个剖面成壤强度趋J‘一致。 2.陶寺地区全新世重要的地表而状径流侵蚀一沉积作用有2期:（l）全新世早期（1 1500一8500 a 3.p.），为自然侵蚀一沉积过程，侵蚀区在古洪积扇，沉积区在古洪积扇前沿和‘!’4阶地，‘I’4阶地的沉积作用较强。（2）陶寺文化晚期 （4050一3850 a B.P.），仍然是一占洪积扇为侵蚀区，古洪积扇前沿和T4阶地为沉积区，古洪积扇前沿的沉积作用增强。 3.4000 aB，P.前后陶寺地区降水丰富，人类活动强烈。在古洪积扇和阶地而形成雨水面流，在阶地而浅注地形成内涝积水。传说的大禹治水，可能主要是对地表积水的疏浚。长期内涝积水妨碍了人们的日常生活，农田被淹没，影响农作物生长，最终导致陶寺文化先民迁移，陶寺地区的社会地位下降。 4.陶寺地区的农业耕作始于前仰韶文化期。在陶寺文化晚期之前，人类活动对土壤发育影响微弱。从陶寺文化晚期之后，人类活动对成壤过程和土壤质量有显著影响。陶寺晚期（4050一3850:，l弓.}”.）人类活动强烈，大量林草被毁，引起强烈的面状水流侵蚀一沉积作用，在DPG剖面和I，GK剖面分别堆积厚22cm和IO6cm的而流沉积层。从陶寺晚期到人暖期结束（4050一3lO0a B.P.），在聚落分布区（‘fSC剖面）成壤过程中断;在古洪积扇前沿（DPG剖面），面流沉积物改变了地形条件，改善了土壤水分，提高了成嚷强度。在T4阶地的LGK剖面，面流沉积物的快速堆积，使成壤强度和土壤质量降低。3100a B.P以来，人类活动逐渐成为一个重要的成壤因子，过度开发利用_}二地资源是造成成壤强度和土壤质量下降的原因之一。 本U「究首次从临汾盆地夏文化遗址区选取全新世黄土一土壤剖面进行高分辨率环境变迁研究。通过对临汾盆地全新山.成壤环境演变的研究，揭示出成壤过程不仅受气候、地形等自然因素影响，也受人类活动的影响。人类活动对土壤发育的影!lI6J具有不确定性。现代临汾盆地生态环境恶化、水土流失严重、土壤质量下降是最近3100年来气候干旱化和人类过度开发土地资源的综合结果。更多还原

【Abstract】 The Holocene loess-soil sequence on the Chinese Loess Plateau constitutes an excellent record of evolution of soil formation, monsoonal climate, eolian dust accumulation and influence of arable farming of over 10000 years. The Linfen Basin, one of the prehistoric culture centers in China, lies in the southeastern Loess Plateau. Three high-resolution soil profiles were selected in the Taosi area, middle of the Lifen Basin. DPG profile lies in the front of the palaeo-alluvial-pluvial fans of Ta’ershan hill, and TSC and LGK profiles on the 4th terrace of Fenhe River.Stratigraphic subdivisions were made by examining their color, texture and structure in the field. Samples were taken every 2 cm continuously down the profiles. A Munsell color chart was used to describe the color of sediment for air-dried samples. The profiles were studied using grain-size analysis, measurement of magnetic susceptibility, Fe, Al, Rb, Sr, Ba, Cu, Ni, CaCO3 and TOC (total organic carbon). The Stratigraphic boundaries were then checked with a variety of physical-chemical analytical results. The results provide new insights into the pedogenic environmental evolution and impact of human activities on soil development in this environmental sensitive zone.The main conclusions are following:(1) Influenced by climate, topography, human activities, and other factors, the pedogenic environment and pedogenic process were changeful in Taosi area in the Holocene.In the early Holocene (11500-8500 a B.P.), the sediment is much similar to the Malan Loess indicating that the climate was dominated by the northwest monsoon and dust accumulation was intensive. Pedogenic process was very weak.Before Late Taosi Culture(8500~4050 a B.P.), the sediment are characterized by their high percentage of clay, Fe2O3, Al2O3 , Cu, Ni, TOC and low percentage of CaCO3 , Sr and high magnetic susceptibility indicating climate was dominated by the southeast monsoon and dust accumulation was slow. Bio-pedogenic process was intensive and palaeosol developed. The soil in the front of the palaeo-alluvial-pluvial fans was short of moisture owing to different topographic condition, and thus,pedogenic intensity was lower compared with the profiles on the terrace.During Late Taosi Culture(4050~3850 a B.P.), rainfall was very abundant. Surface erosion took place on the palaeo-alluvial-pluvial fans , and deposition in the front of the fans and above the terrace. A rainwash bed was identified in DPG and LGK profile respectively, in which the sediment consists mainly of re-deposited loess mixed with a small quantity of sand-size grains. But no record of rainwash was in TSC profile which was inside the habitation region of Taosi site.From the end of Late Taosi Culture to the finish of the Holocene Megathermal (3850-3100 a B.P.), the bio-pedogenic process was increased in DPG and LGK sites, and pedogenic process ceased in TSC due to building.Over the last 3100years, as climate has become dry and dust-fall was intensive in Linfen Basin, the recent loess(Lo) has been deposited and covered the mid-Holocene soil(So). The pedogenic process was reduced in all of the three profiles.(2) Arable farming has been traced back to 8000 a B.P at latest in Linfen Basin, but cultivation had not affected the natural soil development until Late Taosi Culture. During Late Taosi Culture, cultivation changed the landform to some extent and promoted rainwash deposition in the front of the fans, and the soil moisture were increased, and thus, bio-pedogenic process increased till 3100 a B.P. In the habitation region, building terminated the soil formation, therefore human impact on the pedogenesis environment has masked the climatic fact in such spot. More and more potter shards, charcoal and sand were found in the recent loess (L0) and the present topsoil(TS) indicating that human impact on pedogenic process was intensive. Modern entironment deterioration and soil erosion have been caused by climate aridity and over cultivation by population pressure.(3) There are two important surface erosi更多还原