Quaternary International 108 (2003) 33–50 Records of magnetic properties in Quaternary loess and its paleoclimatic significance: a brief review Yanjie Tang a, *, Jianye Jia b , Xiande Xie a a Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640,China b Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou 510070,China Abstract Due to the successive deposition, Quaternary loess–paleosol sequences potentially provide one of the best terrestrial records of paleoclimatic changes. Magnetostratigraphy and paleoclimate are two major aspects of magnetic investigation in northern China and other regions of the world. The classic loess sections across the Chinese Loess Plateau indicate that wind-blown loess deposition began close to the base of Matuyama (2.6 Ma). However, progress has also been made in extending the record below the loess into the Red Clay, and the aeolian record can now be carried back beyond 7 Ma. The surprising similarity between the initial susceptibility (IS) curve obtained from numerous loess–paleosol sequences and the oxygen isotope fluctuation from the deep-sea sediments provides impressive evidence of the global significance of the magnetic record. As a useful proxy in paleoclimatic studies, magnetic susceptibility (MS) has been extensively used to reconstruct the paleoclimate. However, the actual mechanism of MS enhancement of paleosols remains controversial. The important questions—why does IS fluctuate in loess sections, and what are the causes of the IS enhancement in paleosols?—have been matters of debate in the last 10 years. Currently, the viewpoint that pedogenesis plays an important role in the MS enhancement of paleosols has been generally accepted. Pedogenic magnetite is an important contributor to the MS enhancement. IS is not only simply controlled by the abundance of strong magnetic minerals, but also by their grain-size distributions. The increment of superparamagnetic (SP) grains (o0.1 mm), which is induced by pedogenesis, could enhance the IS of paleosols. The formation of SP minerals has been debated as either biotic or abiotic. It is now possible to propose a quantitative model for the reconstruction of paleoclimate according to the paleoprecipitation deduced from proxy indicators, such as IS fluctuation, grain size, stable isotope composition, CaCO 3 content, Rb/Sr, and ratio of citrate-bicarbonate- dithionite-extractable Fe 2 O 3 to total Fe 2 O 3 (FeD/Fet). r 2002 Elsevier Science Ltd and INQUA. All rights reserved. 1. Introduction The discovery of Loess containing interstratified paleosols provides one of the best terrestrial records of past climates, as investigated by Liu Tungsheng and his colleagues (e.g. Liu, 1985). The associated realization that these implied a multi-event Quaternary are re- garded as the truly crucial moment in 20th Century for the development of the scientific study of loess (Smalley et al., 2001). Alternating loess and paleosol sequences in the extensive loess plateau of central China recorded at least 56 soil-forming intervals and the major interglacial soils in the last 2.6 Ma (Heller and Liu, 1982; Liu, 1985; Kukla et al., 1988; Rutter et al., 1990; Guo et al., 1996a). Environmental magnetism has proved to be a valuable scientific tool for reconstructing former environmental processes and climatic history (Verosub and Roberts, 1995). Magnetic susceptibility (MS) has been used as an important environmental proxy indicator in Quaternary environmental science since Thompson and Oldfield (1986) founded environmental magnetism in the 1970s. The introduction of MS analysis has helped to advance Quaternary stratigraphical research and identification of paleoenvironmental reconstruction in loess–paleosol sequences (Kukla, 1987; Zhou et al., 1990; An et al., 1991; Maher and Thompson, 1991). Lacustrine strati- graphic and environmental research was enhanced by consideration of the MS index (Yu et al., 1990). Using the magnetic characteristics of sediments and soils, the reconstruction of paleoclimatic changes has expanded greatly over the past decade, especially with respect to the studies of loess in northern China, Europe, South America and elsewhere (Kukla et al., 1988; Yu et al., *Corresponding author. E-mail address: tangyj@gig.ac.cn (Y. Tang). 1040-6182/03/$-see front matter r 2002 Elsevier Science Ltd and INQUA. All rights reserved. PII:S1040-6182(02)00192-1