Catena, ( ISI ), Volume (101), No (1), Year (2013-2) , Pages (56-60)

Title : ( Magnetic susceptibility and morphological characteristics of a loess-paleosol sequence in northeastern Iran )

Authors: Alireza Karimi Karouyeh , Hossein Khademi , Shamsollah Ayoubi ,

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Magnetic susceptibility of loess-paleosol sequences is frequently used for paleoclimatic and paleoenvironmental studies. A penultimate loess-paleosol (Tappeh Salam section) from northeastern Iran was studied to determine i) morphological, sedimentological and magnetic characteristics of the section, ii) the effect of high amount of carbonates and gypsum on the magnetic susceptibility, and iii) if any recognizable relationship between magnetic susceptibility and paleoenvironmental conditions during periods of soil formation and loess deposition existed. The bulk magnetic susceptibility (lfbulk) of genetic horizons was measured. To eliminate the effect of gypsum and carbonates, the minerogenic magnetic susceptibility (lfminero) was calculated. Based on morphological characteristics, five distinct parts were recognized. Part 1 and 4 are composed of unaltered loess deposits with easily visible gypsum crystals. Part 2 includes a series of Bw, By and Bk horizons that ends to a last interglacial paleosol with a Btk horizon in part 3. At the base of the section, because of its extremely hard consistency, part 5 has an abrupt boundary. The lfbulk values of different layers change from 40.9 × 10-8 m3 kg-1 in the weakly developed part 1 to 75.6 × 10-8 m3 kg-1 in the Btk horizon. The amount of gypsum plus carbonates is 13.6-40.9%, making the interpretation of lfbulk difficult. The lfminero makes the difference clearer through the section. The lfminero of part 1 is 108.9 × 10-8 m3 kg-1. This unexpectedly high value may be expressed by anthropogenic addition of magnetic particles. The lfminero of Btk horizon exceeds 103 × 10-8 m3 kg-1 showing the effect of accumulation of iron oxides during warm and humid climate of the last interglacial period. The 70 × 10-8 m3 kg-1 value for lfminero in part 4 can be attributed to parent materials. Part 5 has the lowest lfminero of 50 × 10-8 m3 kg-1. Hydromorphic conditions in part 5 have induced the decomposition of iron oxide, resulting in a decline in magnetic susceptibility. The results of this study show the effectiveness of magnetic susceptibility properties for the interpretation of paleopedological and paleoenvironmental conditions of loess-paleosol sequence in northeastern Iran. It should be noted that in the arid regions, to avoid misinterpretation, the effect of high amount of gypsum and carbonates must be taken into account, by minerogenic magnetic susceptibility calculation.

Keywords

, Loess, paleosol sequence; Minerogenic magnetic susceptibility; Paleopedology; Arid
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@article{paperid:1031439,
author = {Karimi Karouyeh, Alireza and Hossein Khademi and Shamsollah Ayoubi},
title = {Magnetic susceptibility and morphological characteristics of a loess-paleosol sequence in northeastern Iran},
journal = {Catena},
year = {2013},
volume = {101},
number = {1},
month = {February},
issn = {0341-8162},
pages = {56--60},
numpages = {4},
keywords = {Loess-paleosol sequence; Minerogenic magnetic susceptibility; Paleopedology; Arid region},
}

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%0 Journal Article
%T Magnetic susceptibility and morphological characteristics of a loess-paleosol sequence in northeastern Iran
%A Karimi Karouyeh, Alireza
%A Hossein Khademi
%A Shamsollah Ayoubi
%J Catena
%@ 0341-8162
%D 2013

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