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黄土高原地质历史时期不同时间尺度上的植被演化规律与气候环境影响因素,以及植被替代性指标的解译等问题还值得进一步研究.本工作拟通过对灵台黄土剖面450ka以来黄土-古土壤样品总有机碳同位素(δ~(13)CTOC)和正构烷烃含量组合参数如C31/C27进行综合对比研究,从而为明晰这些问题提供一些新的讨论和证据.结果表明,450ka以来黄土高原中部C_3、C_4植物混生,以C_3植物为主;按生活型则草本、木本混生,以草本植物为主.在黄土高原气候较温暖湿润的MIS9(S3时期),MIS5(S1时期)阶段,可能出现过C_3木本植物的短暂增多,但总体上不存在大面积的森林.在阶段性变化上,黄土高原130ka以来草本植物总体增多,可能与区域性气候干旱化有关.在轨道尺度上,全新世较末次冰期,MIS11(S4时期)较MIS12(L5时期)C_3草本植物减少;在其他几个冰期旋回,间冰期较相应冰期C_3草本植物增多.植被替代性指标与建群种蒿属孢粉量的变化吻合较好,其变化可能与冰期旋回上水热配置有关.MIS1(S0时期)与MIS11(S4时期)气候相似,但全新世时期松属乔木的大量增多,暗示了人类活动和生态因子火活动的影响.
In the geological history of the Loess Plateau, the evolution rules of vegetation on different timescales, climate and environmental factors, as well as the interpretation of alternative vegetation indices are worthy of further study.This study intends to pass the study on the total loess-paleosol samples since 450 ka Organic carbon isotope (δ ~ (13) CTOC) and normal paraffin content parameters such as C31 / C27 were compared to provide some new discussions and evidences to clarify these problems.The results show that the C_3, C_4 The plants are mainly mixed with C_3 plants, while the herbaceous plants and woody plants are mainly mixed according to the living patterns.Under the warm and humid climate of MIS9 (S3 period) and MIS5 (S1 period) in Loess Plateau, C_3 In the period of 130 ka, the total number of herbaceous plants in the Loess Plateau increased, which may be related to the regional climate aridification.On the orbital scale, the Holocene more than the last time During the glacial period, MIS11 (S4 period) decreased compared with that of MIS12 (L5 period) C_3 herbaceous plants; during the other several glacial cycles, the interglacial period increased more than that of corresponding C_3 herbaceous plants in the glacial stage. The correlation between the proxy index and the change of pollen amount of Artemisia sp. Was probably good, and the change may be related to the glacial-ephemeral hydrothermal configuration.MIS1 (S0 period) is similar to MIS11 (S4 period), but during the Holocene, The large increase in arbors, suggesting the impact of human activities and ecological factors on fire activities.