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中国黄土磁性矿物特征及其古气候意义
引用本文:刘秀铭,刘东生,John Shaw.中国黄土磁性矿物特征及其古气候意义[J].第四纪研究,1993,13(3):281-287.
作者姓名:刘秀铭  刘东生  John Shaw
作者单位:中国科学院地质研究所,中国科学院地质研究所,英国利物浦大学地磁实验室 英国利物浦大学地磁实验室
摘    要:最直观、最直接的古气候记录莫过于陆相黄土地层,它由许多黄土和古土壤层叠覆而成,详细地记录了第四纪以来的古气候变化。黄土高原中部黄土和古土壤的风化和发育程度可以用磁学参数,如磁化率等来描述。本文作者对甘肃西峰剖面约13万年以来的黄土地层做了详细采样,测量其磁滞回线各参数,频率磁化率、低场和高场磁化率、温度磁化率、磁组构等参数。研究表明,黄土与古土壤中的磁性矿物组分相似而且稳定。磁铁矿、赤铁矿和磁赤铁矿(主要是磁铁矿)的含量及其颗粒大小决定了它们的磁学特征。黄土和古土壤的磁学性质差别主要受成土过程中形成细小磁铁矿的影响。

关 键 词:中国黄土  古气候  岩石磁学

MAGNETlC MINERAL CHARACTERISTICS OF CHINESE LOESS AND ITS PALAEOCLIMATIC SIGNIFICANCE
Institution:1. Instizute of Ceofogy, Chinese Rcademy of Sciences;
2. Geomagnetism Laboratory, Uniaersity Lircrpoof, UK;
3. Instizuze of Geology, Chinese Academy of Sciences ;
4. Geomagnetism Laboratory, Unioersity of Lioerpool, UK
Abstract:Chinese loess stratigraphy consists of alternating loess and palaeosol layers. The loess represents dust deposition under cold, arid climatic conditions, and palaeosols were developed from loess in a relatively warm humid environment by weathering. It provides evolutionary records of the palaeoclimate and palaeoenvironment over last 2.5 Ma. The loess stratigraphy is regarded as the arguably best terrestrial records of palaeoclimate not only due to its direct product of the palaeoclimatic process, but also because of its directly visible character in the field. Such pedogenic (or weathering) degree in the central Loess Plateau can be described by magnetic parameters (different from that along Weihe River, such as Baoji and Xi'an), for example, magnetic susceptibility, which now has been accepted by more and more Quaternary scientists as a proxy indicator of palaeoclimate. The susceptibility curves from Xifeng and Luochuan have been widely used for palaeoclimatic reconstruction and correlation betweenland and sea. The nature of the susceptibility variation in loess stratigraphy or characteristics of the magnetic properties is investigated in this paper in detail.
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