LOESSFEST'09 | Aug. 31st – Sept. 3rd, 2009 |Novi Sad-Serbia
Magnetic Properties of New Zealand Loess and its Paleoenvironment Significances
Liu, X.1,2, Hesse, P.2
1Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University Lanzhou 730000, China
2Department of Physical Geography, Macquarie University, NSW 2109, Australia
The magnetic susceptibility of Chinese loess showing a general positive relationship to pedogenic development, which was strongly controlled by climatic condition, has been widely recognized and used for reconstruction of paleoclimate by Quaternary scientists. The in-situ pedogenic enhancement of ferrimagnetic content is normally believed to be the main reason for the increase of susceptibility in soil units. However, this pattern of high magnetic susceptibility in palaeosols, and lower values in loess, is not replicated in some loess deposits.
Alaskan and Siberian loess deposits display a completely opposite susceptibility behavior: high values in loess and low values in palaeosols. New Zealand loess shows no clear relation to loess and soil layers. Magnetic study of samples from China, New Zealand, Siberia and Alaska suggests that, no clear relation between the magnetic susceptibility and pedogenic development is very likely due to different pedogenic environments in the New Zealand loess, where pedogenic development is under various conditions swing between oxidizing and reducing. Therefore, great care should be taken when using susceptibility values for paleoclimatic reconstruction.