摘要
中国黄土-古土壤系列的磁学性质,如磁化率等被广泛用于古气候和古环境研究,这必须建立在对黄土-古土壤的剩磁的性质和获得剩磁的机制以及古土壤磁性增强的原因有深入了解的基础之上。作者通过对洛川和吉县剖面马兰黄土和离石黄土的磁学性质的深入研究,对黄土与古土壤磁学性质差异的各种表现,对它们剩磁的性质,对古土壤磁性增强的原因以及磁性变化对古气候、古环境研究的意义进行了讨论,并对利用某些磁学性质建立的黄土-古土壤形成的时间模式提出了质疑。
The exact nature and acquisition mechanim of the remanent magnetization and the exactorigin of the enhanced magnetic properties of the palaeosols are two main problems in theretrieval of climatic and environmental data of the past extracted from the loess-palaeosol se-quences in China by means of their magnetic properties.Magnetic investigation of the Malan and Lishi Formations mainly in Luochuan and Jixianloess sections shows that:1) The palaeosols differentiate from the parent loess not only by theirenhanced magnetic susceptibility but also by their pronounced natural remanent magnetizationand laboratory-induced remanences;2) The suceptibility and natural magnetization variationscan be mainly attributed to the concentration changes of the primary magnetic minerals,to theeffective grain-size changes and to the authigenesis of strong magnetic minerals (magnetiteand/or maghemite),all of which are induced by climatically controlled pedogenic processes;3) The main remanence in loess layers are magnetite and haematite and in palaeosols are mag-netite,maghemite,haematite and geothite;4) The variation in magnetic properties in loesscan be considered as proxy signals of the climatic changes and may be a semi-quantitative de-scription of the latter and can not be a measure of time.
出处
《第四纪研究》
CAS
CSCD
1991年第4期310-325,共16页
Quaternary Sciences
