OKAYAMA University Earth Science Reports, Vol. 15, No. 1, 9-32, (2008)
Microscopic observations of the recent soils: a step for understanding the paleosols
**
The microscopic observations of the recent soil horizons were conducted in Okayama, Japan (moderate climate). The several soil horizons, including two surface (epipedon) and three subsurface horizons, were recognized in the forest, poorly vegetated hill, and riverside around the Okayama University. The umbric epipedon can be segregated from the organic-rich subsurface horizons by the scattered organic materials in thin sections. The ochrich epipedon shows the sandy matrix without any cements and the illuviation of clay minerals. The subsurface horizons identified in the study area are as follows: albic, argillic, and cambic horizons. Each subsurface horizon shows the specific structures in thin sections. The albic horizon is characterized by the absence of the illuviation. The argillic horizon definitely shows the clayey matrix and the illuviation of clay minerals. The primary structures may be retained in the cambic horizon.
The microscopic examination of the Miocene paleosols from the Ukan-cho, Okayama, was attempted. By comparing the recent soils, the cambic horizon and spodic horizon, which is characterized by the concentration of sesquioxides, are identified in the paleosols. This attempt suggests that the microscopic observations of the recent soils is a useful guide to understanding the paleosols
Keywords : soil, paleosol, soil horizon, soil structure, microscopic observation
I.
, 1987
1960
100-1000
Bullock et al., 1984
1980-1990 Retallack
II.
II.I.
Soil Survey Staff (2003)
1
2
890-0132 1765-3Hanshin Consultants Co., Ltd. 1764-3 Katahirayama, Gumizaki, Satsumasendai-Shi, Kagoshima, 895-0132. Japan
**Department of Earth Sciences, Faculty of Science, Okayama University, Okayama 700-8530, Japan
10
II.II.
2km
1891 - 2007 14.9 ºC
1134 mm
http://www.data.jma.go.jp/obd/stats/etrn/index.php
1 II.III.
surface horizon
epipedon subsurface
horizon
, 1975
FAO, 1974
Soil Survey Staff,
2003
Master horizon
Suffix symbol Subordinate
Gradations between master
horizons
II.IV.
1998
Bullock et al. (1984)
Retallack (2001)
500
500
2% Galehouse, 1971
III.
2 2
3 3
3.1. epipedon
1.
11
III.I. epipedon
3 umbric epipedon
ochric epipedon 2
2 - 10cm
3
4.1 roolet
4.2
ochric epipedon
4.3
Ab
4.4
Bh Ab
2, Loc. G
1 2
3 4
3
III.II. Gradations between
master horizons AB BA 2
AB A
3, Loc. H, I, N,
O 1 – 6 cm umbric epipedon
BA AB A
5- 8 cm
AB
4.5
4
Soil survey Staff, 2003
12
13
2.
14
2.
15
2.
16
2.
17
III.III. subsurface horizon albic E argillic
Bt Bts Bt(s) B(t)
cambic Bw Bw(s) C
1
4
albic 15cm
4.6
3
5Y7/2
4.6.a
4.4
5cm A umbric epipedon
AB 3cm
argillic
4 blocky ped
cambic
Bw
argillic
1
plasmic
microfabric
skelsepic
mosepic
lattice sepic 4.8
4.8
4.7
4.8
cambic
Bw C 2
3. Soil Survey Staff (2003)
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4.9 IV. IV.I.
3
FAO Luvisol
Alfisol Andosol Podzoluvisol
Luvisol Alfisol
lessivage
a. b. 1: A-1 A , 2: Eng-1 A , 3: D-1 A 1mm.
19
Bt
5 AB
Loc. A, C, D, E, G, H, M, N, P
Ultisol
5.1
Andosol Luvisol
cambic Bw
5, Loc. B, F, I, J, K, L, Q, R
AB BA
Loc. F, I, L
5.2
a. b. 4: G-2 Ab , 5: P-1 BA , 6: O-1 E 1mm.
20
Podzoluvisol
albic E
5
Ab
albic
spodic
Podzol Podzoluvisol
5.3;
Loc. O IV.II.
5.4
5.5
5 ochric epipedon
a. b. 7: G-1 Bt , 8: C-4 Bt , 9: E-1 Bw 1mm.
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5 1: Loc. A Luvisol , 2: Loc. F Andosol ,
3: Loc. G Podzoluvisol , 4: Cambisol , 5: ochric
epipedon , 6:
Fluvisol
22
cambic horizon C
FAO
Cambisol Inceptisol
IV.III.
5.6
ochric epipedon
5
cambic horizon (C )
Entisol
: incipient soil
Fluvisol
V.
IC
6.a
6.b,c
6d
glaebule
3
Ukan-1
7.1
skelsepic microfabric
2
8
C
1 2
6 IC 1:
2: 3: , 4:
23
cambic
cambic
spodic Bs
cambic
3m
Ukan-4
7.2
8
7.2
cambic
7 a.
b. 1: Ukan-1 (Bs ) 2: Ukan-4 (Bw ) 3: Ukan-3 (R ) 1mm.
24
Ukan-3
6.
6
umbric epipedon
ochric epipedon
2
albic
argillic spodic cambic
4 albic
argillic
spodic
spodic 2
cambic
FAO
Luvisol Andosol Podzoluvisol Cambisol
Fluvisol 5
8
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Bullock, P., Ferdoroff, N., Jongerius, A., Stoops, G., Tursina, T., Babel, U. 1984. Handbook for Soil Thin Section Description. Waine Research Publication. 152 pp.
. 1998. .
: 328-328.
. 1976. 1975 . , 280: 1-28. F.A.O. 1974. Soil Map of the World Volume 1. Legend. UNESCO. 59pp. Galehouse, J. S. 1971. Point counting. In: Proceedings in sedimentary petrology. Rutherford, G. K. (ed.). Limestone Press:
385-407. . 1987. X . X , 19: 251-262.
Retallack, G. J. 2001. Soils of the Past An introduction to paleopedology. Blackwell Science. 404 pp. Soil Survey Staff, 2003. Keys to Soil Taxonomy. University Press of the Pacific Honolulu, Hawaii. 332 pp.
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