大别山北麓黄土-古土壤Rb、Sr与磁化率及其古环境意义  

Characteristics of Rb,Sr and Magnetic Susceptibility and Their Palaeoenvironmental Significance in the Northern Slope Loess-Palaeosols of Dabie Mountain

作　　者：张华[1,2] 宋传中[1] 张妍[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽建筑工业学院环境与能源工程学院,合肥230022

出　　处：《地质科技情报》2011年第2期45-51,共7页Geological Science and Technology Information

基　　金：国家自然科学基金项目(40772131)

摘　　要：对大别山北麓0.78 Ma以来的黄土-古土壤样品的磁化率及Rb和Sr的地球化学特征研究表明,相对高的w(Rb)和w(Rb)/w(Sr)值及低w(Sr)值指示夏季风占优势的湿润时期,对应古土壤层;相对低的w(Rb)和w(Rb)/w(Sr)值及高w(Sr)值指示冬季风占优势的干旱期,磁化率相对较低,对应黄土层。剖面的w(Rb)/w(Sr)值自下至上降低反映大别山北麓地区的风化作用逐渐减弱,也揭示自0.78 Ma以来气候具有由湿向干的趋势;磁化率与w(Rb)/w(Sr)值的对比分析表明,它们的变化曲线存在显著不同,原因可能是由于磁化率在古土壤中的增强机制比较复杂所致,w(Rb)/w(Sr)值作为气候替代指标比磁化率更灵敏。与洛川剖面相比,大别山黄土-古土壤的w(Rb)较高而w(Sr)较低及Rb、Sr较强的分异能力特征反映了大别山气候整体较为温湿,沉积物遭受的风化程度更强。This paper studies the characteristics of magnetic susceptibility and Rb and Sr geochemistry element in the northern slope of Dabie Mountain since 0.78 Ma.The results suggest that higher Rb and Rb/Sr ratio and lower Sr concentration mean stronger southeast monsoon and warmer-wetter climate,normally associated with the palaeosol,and lower Rb and Rb/Sr ratio and higher Sr concentration mean stronger northwest monsoon and drier climate,normally associated with the loess.The decrease of the Rb/Sr ratio in the strata from below reveals that the weathering weakened gradually and the climate changed from wet to dry from Middle Pleistocene.It is quite possible that the enhancement mechanism of the magnetic susceptibility is quite complicated,so the variation curves of magnetic susceptibility and Rb/Sr ratio are different significantly.However,the Rb/ Sr parameter is much sensitive than magnetic susceptibility in reflecting smaller-scale climatic change from their curves.Compared with the information from Luochuan profile,the characteristics of higher Rb,lower Sr and the obvious differentiation capacity of Rb and Sr imply the climate of Dabie Mountain was warmer and more humid in this region and its loess-palaeosols should have undergone intense weathering.

关 键 词：大别山 黄土-古土壤 Rb和Sr 磁化率 古环境 

分 类 号：P588.23[天文地球—岩石学]