The ages of organic matter of some dark-colored horizons and calcareous concretions in some Vertisols from tropical, subtropical and warm-temperate zones of China were studied using radiocarb on dating method. The rel...The ages of organic matter of some dark-colored horizons and calcareous concretions in some Vertisols from tropical, subtropical and warm-temperate zones of China were studied using radiocarb on dating method. The relationship between soil age and genesis of Vertisols was also expounded based on the study of their genetic charactens-tics and micromorphological features. The results show that although Vertisols have developed for a relatively long time, their weathering and soil forming process are weak and young with little horizonation. This is closely related to their special geochemical soil forming environment. Low-lying terrain, heavy texture, clay minerals dominated by montmorillonites and alternative drying- wetting climate give rise to the vertic features expressed in intense swelling-shrinking and cracking-closing in soils. As a result, the soil development and soil leaching process are resisted, and the climatic effect on the horizonation is impeded. Moreover, pedoturbation eliminates the horizonation in the upper part of soil profile, and postpones their evolution into zonal soils. So Vertisols show certain pedogenic inertia and stay at relatively young developmental stage. Therefore, Vertisols are intrazonal soils dominated by local soil forming factors such as the relief and parent materials.展开更多
【目的】时间序列法是定量研究土壤发生过程、演变速率及其变化阈值的重要手段,构建可靠的土壤时间序列需对土壤母质均一性和相对年龄进行判定。【方法】以海南岛北部不同喷发期玄武岩发育土壤所构成的成土时间序列(0.09、0.146、0.64、...【目的】时间序列法是定量研究土壤发生过程、演变速率及其变化阈值的重要手段,构建可靠的土壤时间序列需对土壤母质均一性和相对年龄进行判定。【方法】以海南岛北部不同喷发期玄武岩发育土壤所构成的成土时间序列(0.09、0.146、0.64、1.12、1.81、2.30 Ma B. P.)为对象,利用各种土壤属性参数(包括剖面形态、颗粒组成、稳定元素含量、风化发育指数和元素变化率等)对该时间序列母质均一性和土壤相对年龄进行判定。【结果】各剖面颜色、质地、结构等形态总体呈均一、渐变的特征,去除黏粒后的粗粉粒含量、稳定元素Ti/Zr比值在剖面内和剖面间变化均较小,表明时间序列土壤的起源母质相同。随着成土年龄的增加,黏粒含量和剖面发育指数呈线性增加的趋势,土壤风化强度指标(B指数、CIW指数、CIA指数和ba值)服从对数函数变化规律,在土壤相对年龄的判定中具有较好的指示意义。【结论】研究区土壤母质来源相同,土壤相对年龄可通过相关土壤属性体现出来,为定量研究土壤发生阈值奠定了基础。展开更多
文摘The ages of organic matter of some dark-colored horizons and calcareous concretions in some Vertisols from tropical, subtropical and warm-temperate zones of China were studied using radiocarb on dating method. The relationship between soil age and genesis of Vertisols was also expounded based on the study of their genetic charactens-tics and micromorphological features. The results show that although Vertisols have developed for a relatively long time, their weathering and soil forming process are weak and young with little horizonation. This is closely related to their special geochemical soil forming environment. Low-lying terrain, heavy texture, clay minerals dominated by montmorillonites and alternative drying- wetting climate give rise to the vertic features expressed in intense swelling-shrinking and cracking-closing in soils. As a result, the soil development and soil leaching process are resisted, and the climatic effect on the horizonation is impeded. Moreover, pedoturbation eliminates the horizonation in the upper part of soil profile, and postpones their evolution into zonal soils. So Vertisols show certain pedogenic inertia and stay at relatively young developmental stage. Therefore, Vertisols are intrazonal soils dominated by local soil forming factors such as the relief and parent materials.
文摘【目的】时间序列法是定量研究土壤发生过程、演变速率及其变化阈值的重要手段,构建可靠的土壤时间序列需对土壤母质均一性和相对年龄进行判定。【方法】以海南岛北部不同喷发期玄武岩发育土壤所构成的成土时间序列(0.09、0.146、0.64、1.12、1.81、2.30 Ma B. P.)为对象,利用各种土壤属性参数(包括剖面形态、颗粒组成、稳定元素含量、风化发育指数和元素变化率等)对该时间序列母质均一性和土壤相对年龄进行判定。【结果】各剖面颜色、质地、结构等形态总体呈均一、渐变的特征,去除黏粒后的粗粉粒含量、稳定元素Ti/Zr比值在剖面内和剖面间变化均较小,表明时间序列土壤的起源母质相同。随着成土年龄的增加,黏粒含量和剖面发育指数呈线性增加的趋势,土壤风化强度指标(B指数、CIW指数、CIA指数和ba值)服从对数函数变化规律,在土壤相对年龄的判定中具有较好的指示意义。【结论】研究区土壤母质来源相同,土壤相对年龄可通过相关土壤属性体现出来,为定量研究土壤发生阈值奠定了基础。
