作　　者： ; ; ;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《地球科学进展》 1995年第6期590-596,共7页

摘　　要： ８０年代中期，中国和瑞士科技工作者开始联合进行黄土￣（１０）Ｂｅ研究。建立了黄土￣（１０）ＢｅＡＭＳ测量的理想流程，发现了￣（１０）Ｂｅ在黄土地层良好保存性等重要地球化学行为特征，确认了黄土￣（１０）Ｂｅ研究具有重要意义。对洛川黄土剖面０．４～１３８ｍ段６００多个样品进行了￣（１０）Ｂｅ测定，建立了２．５Ｍａ以来大陆堆积物同位素记录曲线。地磁极性倒转期间，￣（１０）Ｂｅ浓度平均增高２０～２５％、持续２０～３０ｋａ。洛川、西峰黄土剖面￣（１０）Ｂｅ变化与深海沉积物δ￣（１８）Ｏ变化之间均存在极好相关性，据此建立了７５万年以来黄土地层相对￣（１０）Ｂｅ时标；黄土堆积速率与各时期￣（１０）Ｂｅ沉降通量之间亦存在良好的线性相关关系，据此可望建立￣（１０）Ｂｅ绝对时标。探讨了Ｒａｉｓｂｅｃｋ峰事件、￣（１０）Ｂｅ／￣（２６）Ａｌ比值等在黄土地层定年中的应用前景和途径。引入物理意义明确的“磁性物质通量”概念，建立了￣（１０）Ｂｅ—磁化率模型，定量估算出磁化率中降尘和成壤两组分相对贡献，求得洛川区域Ｓ＿０、Ｌ＿１、Ｓ＿１三时期年均降水量。精确测定了黄土石英中“就地”成因￣（１０）Ｂｅ含量，获得不同时期黄土源区侵蚀速率。 In the middle of 1980’s,an effective procedure for￣(10)Be measurement in loess by AMShas been established.Some important geochemistry behaviors such as good preservation of“Be in loess strata have been observed,showing obviously that the investigation on￣(10)Be inloess would be very significant.A total of more than 600 samples from the upper 0.4～138m of the Luochuan section was analysed for￣(10)Be concentrations and an isotopic curve ofcontinental deposition since 2.5 Ma has been established. Relative increase of 20～25% of￣(10)Be concentration within 20～30ka duration are observed in the vicinity of the geomagneticreversals.The linearity of relationship between accumulation rate and￣(10)Be flux of loess isalso astonishingly good.It reveals a new way for the dating of loess strata. Both the eventof Raisbeck peak at 35000 a BP and￣(10)Be/￣(26)Al ratio have been studied,which are expectedto be new dating methods for loess strata。 Based on￣(10)Be susceptibility model with a newconcept of magnetic material flux,pedogenic ferromagnetic material flux in Chinese loesshave been estimated quantitatively and average paleoraiiifall values in Luochuan regionhave been calculated.The concentrations of in situ cosmogenic￣(10)Be in quartz from loesshave been measured accurately and the erosion rates of the source regions have also been calculated.

关 键 词： 黄土 铍 地球化学

领　　域： [天文地球] [天文地球] [天文地球]