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通过对黄土高原中部朝那黄土-古土壤剖面的孢粉研究,揭示出1.5Ma以来蒿属、藜科等旱生草本与松、桦、栎等乔木花粉含量在黄土-古土壤序列中呈现有规律的互为消长的变化,指示了冰期-间冰期的冷干-暖湿旋回,其中过去无机指标所指示的上、下粉砂层(L9和L15)的两次极端干冷事件,植被变化表明其干冷程度与其他冰期黄土沉积时期相似.从长期演化趋势上来看,以0.95和0.5 MaBP为界,可以分为3个阶段,古生态环境经历了两次阶段性剧烈变化,植被由早期的森林草原转变为中期的疏林草原继而演变为后期的草原,指示了黄土高原阶段性的干旱化过程.
Based on the sporopollen research of the Loess-Paleozoic soil profile in the middle Loess Plateau, it was revealed that the arborous pollen contents of Artemisia, Chenopodiaceae, etc. and arbor, pine, birch and oak in the loess-paleosol sequence The change of law and change of each other indicates the glacial-interglacial cold-warm-wet cycle, in which the two extreme dry-cold events of the upper and lower silt layers (L9 and L15) indicated by the past inorganic indicators indicate that the vegetation changes Its dry-cold degree is similar to that of other glacial sediments, and from the perspective of long-term evolution, it can be divided into three stages with 0.95 and 0.5 MaBP as the boundary, paleoenvironment undergoes two stages of dramatic changes, The transformation of grassland into mid-stage sparse grassland then evolved into the later steppe, indicating the stage of aridification of the Loess Plateau.