Use of magnetic signatures to correlate tephra layers in Holocene loessial soil profiles from a small region, SE Iceland |
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Authors: | Dunsheng Xia Xi Chun Jan Bloemendal Richard C Chiverrell Fahu Chen |
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Institution: | (1) Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China;(2) Department of Geography, University of Liverpool, Roxby Building, Liverpool, L69 3BX, UK;(3) Key Laboratory of West China’s Environmental System (Ministry of Education), CAEP, Lanzhou University, Lanzhou, 730000, China |
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Abstract: | Rock magnetic measurements have been applied to two adjacent loessial soil sections from a small region, SE Iceland. The soils
are composed of reworked locally derived sediment (including airfall tephra) and also contain several visible discrete airfall
tephra layers. The main magnetic minerals in the airfall tephras are ferrimagnetic (e.g. magnetite) with paramagnetic minerals
also present. The main magnetic grain sizes in the tephras are pseudo single domain. The results show that individual tephras
do not have unique magnetic signatures that can be used for identification and correlation between sedimentary sequences.
However, a correlation of tephra layers was achieved through the application of statistical techniques to a comprehensive
dataset of magnetic parameters. Similarity coefficients and Euclidian distance measures were used to identify the best correlation
between tephra layers in the two soil profiles. The technique works well providing some tephras present within both profiles
have been formally identified (e.g. Oraefajokulla
ad 1362) using electron microprobe analyses. Given this initial framework, the statistical analyses of the magnetic parameters
can help in the identification and correlation of unknown tephras between two soil profiles. |
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Keywords: | Environmental magnetism Tephra Principal coordinates analysis Iceland |
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