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Incipient ferralization and weathering indices along a soil chronosequence in T aiwan
Author(s) -
Jien S.H.,
Baillie I.,
Huang W.S.,
Chen Y.Y.,
Chiu C.Y.
Publication year - 2016
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12363
Subject(s) - chronosequence , weathering , geology , geochemistry , loam , bedrock , andesite , soil horizon , geomorphology , volcano , volcanic rock , soil water , soil science
The low hilly topography of G reen I sland, a volcanic island off southeastern T aiwan, includes an altitudinal sequence of sub‐horizontal benches. We examined eight profiles along this sequence, ranging from pale brown loamy coral sand on the lowest bench that fringes the coast at an elevation of about 10 m to deep, intensely red and acid clay on the highest bench at about 240 m. Chemical analyses, differential Fe extractions, thin sections, X ‐ray diffraction of the clay minerals and indices of pedochemical weathering and strain indicated that soil development progressed by weathering of primary and secondary phyllosilicates through argilluviation in the intermediate stages to the generation of increasing quantities of free Fe . The Fe accumulates as free sesquioxides, which crystallize with age. Taxonomically the soil types progress from sandy coral A renosol, through E utric C ambisol, H ypereutric L ixisol and A crisol to incipient F erralsol ( U dipsamment → E utrudept → U dalf → U dultisol → U dox in S oil T axonomy). The profiles are interpreted as a chronosequence, although this is complicated by minor and upwardly diminishing contributions of reef coral to the mainly igneous parent materials. There are also variations in the andesitic‐basaltic bedrock, and minor aeolian inputs in the higher and older soil types. Regional eustatic sea‐level correlations, 14 C dating of carbonates on the two lowest benches and estimates of local tectonic uplift indicate that the incipient F erralsols on the upper bench might date from about 150 ka. The transition through argilluvial A crisols to incipient sesquioxide‐dominated F erralsols appears, therefore, to develop within 100–200 ka on G reen I sland, which is faster than usual. Highlights Green I sland ( T aiwan) has been volcanically dormant but tectonically active for 2 million years. The island has a toposequence of bevelled surfaces with relatively uniform andesitic regoliths. The soils of the surfaces form a chronosequence from A renosols through A crisols to incipient F erralsols. The transition from argilluvial to ferralitic pedogenesis, at 100–200 ka, is relatively rapid.