陕西蓝田全新世古气候演化特征

了解最近10 000 a来的植被和环境对制定治理黄土高原及其水土流失的战略方针、预测未来黄土高原的气候变化都具有重要的意义.作者在阐述陕西蓝田县城附近地质环境的基础上,利用孢粉图式分析了该区植被的演替,进而分析了该区全新世的古气候演化特征.据17个样品分析发现孢粉和藻类十分丰富,将孢粉图式分为三个带,分别代表全新世早、中、晚三个时期的孢粉带.Ⅰ带为蒿属优势带;Ⅱ带是乔木花粉激增,早期发育有温带阔叶落叶林或针阔叶混交林,晚期是以温带阔叶树或与松混合的疏林草原或森林草原;Ⅲ带是以栎、蒿为主的森林草原或疏林草原.结果表明早全新世气候较冷较干,发育有以蒿为主的大片草原;中全新世气候温暖湿润,发育了疏林草原和森林草原;晚全新世渐变为干燥而寒冷,是以松、蒿为主的森林草原.

Characteristics of Holocene paleo-climate in Lantian, Shaanxi, China

It is meaningful to institute a scheme of governing loessial plateau as well as its loss of water and earth by knowing the vegetations and environments in recent 10 000 years.It can even predict the future climatic changes in the area of loess plateau.The author has done a series of geological investigations specifically in Lantian of Shaanxi in order to study the climate during the period of Holocene in this region thoroughly.This paper expounds the geological outline of this area and analyzes the evolution of the vegetations in this region by using some spore-pollens diagrams,aiming at analyzing the characteristics of the changeable climates during Holocene in this area.A great deal of sporopollens and algas from seventeen samples of the loess section are recognized and a concentration spore-pollens diagram of the loess strata is plotted.The evolution of vegetation during Holocene and the corresponding climate in time and space in the region have been brought to light by analysing the variation of sporopollen assemblages in this section.The results indicate that the climate in the early Holocene was relatively cold and dry,that in the middle Holocene was relatively warm and wet,and that in the late Holocene was dry and cold.