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| 黄土-古土壤磁化率述评 | |
| 引用本文： | 鸟居雅之,福间浩司,苏黎,杜克玲,方小敏.黄土-古土壤磁化率述评[J].海洋地质与第四纪地质,1999,19(3):83-96. |
| 作者姓名： | 鸟居雅之 福间浩司 苏黎 杜克玲 方小敏 |
| 作者单位： | 1. 京都大学,大学院理学研究部地球科学系,京都市左京区,北白川追分町 2. 海洋科学技术中心,深海研究所,横须贺市夏岛町2-15,福间浩司 3. 兰州大学,地理科学系,兰州,730000 |
| 摘 要： | 黄土－古土壤是研究亚洲大陆内部过去２．６０Ｍａ间古环境变化的最好记录，特别是研究其与季风气候形成的密切关系，以及黄土扩展到日本甚至广泛的太平洋区域（北半球）等重大气候环境现象。其研究对第四纪古环境恢复具有极大的意义。最近基于黄土－古土壤而进行的古环境研究取得了很大的进展，一是因为黄土－古土壤磁化率的变化与深海沉积物的氧同位素比的变化非常一致，指示陆相沉积物亦可作为古气候的良好代用指标。另一方面，为什么黄土－古土壤中的磁化率存在差别，特别是古土壤磁化率为什么增大等问题，已成为这１０ａ间岩石磁学研究的中心课题。磁化率不单单只与强磁性矿物的含量成比例，同时也与不同种类的强磁性矿物的粒径分布有很大关系。发现在土壤化过程中形成的０．１μｍ以下的单畴－超顺磁性颗粒是造成古土壤磁化率增强的主要原因，它是否与生物作用有关目前仍不确定，但不论哪种情况，都可以肯定暖湿气候是古土壤磁化率增加的共同原因。磁化率增强的系统理论明确建立以来，使得从磁化率的变化来推算降水量，以及建立古气候复元的定量模型等都已成为可行。 |
| 关 键 词： | 磁化率 强磁性矿物 超顺磁性颗粒 古气候 黄土-古土壤 |
| 文章编号： | 0256-1492(1999)-03-0083-14 |
| 修稿时间： | 1998-12-03 |
INITIAL MAGNETIC SUSCEPTIBILITY OF THE CHINESE LOESS-PALEOSOLS:A REVIEW |
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| M Torii,K Fukuma,SU Li,DU Keling,FANG Xiaomin.INITIAL MAGNETIC SUSCEPTIBILITY OF THE CHINESE LOESS-PALEOSOLS:A REVIEW[J].Marine Geology & Quaternary Geology,1999,19(3):83-96. | |
| Authors: | M Torii K Fukuma SU Li DU Keling FANG Xiaomin |
| Abstract: | The Chinese loess is one of the best targets to study paleoclimatic changes spread on the Asian continent for the last 2 6 Ma.The information from the loess is important to understand Quaternary paleoenvironmental changes.The formation of the Chinese Loess Plateau has a close relationship with the initiation of monsoon climate.The aeolian dust observed around Japan and the northern Pacific has been transported by the monsoon wind and the source area can be found in and around the Chinese Loess Plateau.The most important reason which propelled paleoenvironmental study of the Chinese loess is the surprising similarity between the initial magnetic susceptibility curve obtained from the loess section and the oxygen isotope fluctuation from the deep sea sediments.Although the demonstration of a new proxy for paleoclimate from the land sediments was substantial,several important questions have been raised.Why the initial susceptibility fluctuates in the loess sections and what are causes of enhancement of the initial susceptibility in the paleosols?These have been hot topics for the last ten years among the rock magnetic community in the world.The initial susceptibility is not only simply controlled by the abundance of strong magnetic minerals but also controlled by the grain size distribution of each magnetic mineral.The increase in abundance of superparamagnetic grains(<100 nm)in the paleosol enhances initial susceptibility,which is induced by a pedogenesis of the loess.Either biotic or abiotic,the formation of superparamagnetic minerals has been debated.Wet and warm climate could be a common reason to make enhancement of the initial susceptibility of paleosols.It is now getting possible to propose a quantitative,robust model to restore paleoenvironment on the basis of paleoprecipitation deduced from the initial susceptibility fluctuation. |
| Keywords: | loess paleosol susceptibility strong magnetic mineral superparamagnetism paleoclimate |
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