北京地区新5孔晚新生代沉积物中的地球化学特征及古环境意义

The Geochemistry Characteristics and the Paleo-environmental Significance on the Late Cenozoic Sediments in the Beijing Xin-5 Borehole

通过对新5钻孔晚新生代地层中的主要氧化物、微量元素和主要元素比值的变化特点进行研究分析。表明该地区自新近纪以来该地区气候总体趋势是由温暖湿润向温和干旱气候方向发展。其中经历了3个较大的氧化阶段。本文综合分析磁化率、古地磁和孢粉等资料。分析了主要氧化物、微量元素在不同地层中的分布特征。从地球化学角度把新5钻孔的沉积环境分为6个变化波动区间。揭示该地区晚新生代以来的气候经历了温暖湿润-温和湿润—温和偏干—温暖湿润—温凉湿润—温和偏干的气候波动。

In this paper,the characteristics of the main oxidants,trace elements and rate of main elements in the Late Cenozoic in the Xin-5 borehole are analyzed.It＇ s concluded that the overall climate changed from warm and humid to temperate and dry in the target area since Neocene,and three dominant oxidization phrases were experienced.Also the distribution of the main oxidants,trace elements and rate of elements among different strata are studied,combining with the magnetic susceptibility,paleomagnetism and sporopollenin.Based on the geochemical properties,the sedimentary environments of the Xin-5 borehole can be divided into six successive environmental zones to reflect the paleo-climatic fluctuations since Cenozoic,such as warm and moist,temperate and subhumid,cool and moist,temperate and dry,warm and moist,temperate and dry,temperate and moist, temperate and dry,temperate and dry.