Genesis and evolution of the fragipan in Albeluvisols in the Precarpathians in Ukraine

Catena 119 (2014) 154–165

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Genesis and evolution of the fragipan in Albeluvisols in the Precarpathians in Ukraine Volodymyr A. Nikorych a, Wojciech Szymański b,⁎, Svitlana M. Polchyna a, Michał Skiba c a b c

Yuri Fedkovich Chernivtsi National University, Department of Soil Science, L. Ukrainki St. 25, 58000 Chernivtsi, Ukraine Jagiellonian University, Institute of Geography and Spatial Management, Department of Pedology and Soil Geography, Gronostajowa St. 7, 30-387 Cracow, Poland Jagiellonian University, Institute of Geological Sciences, Department of Mineralogy, Petrology and Geochemistry, Oleandry St. 2a, 30-063 Cracow, Poland

a r t i c l e

i n f o

Article history: Received 27 March 2013 Received in revised form 18 January 2014 Accepted 21 February 2014 Available online 17 March 2014 Keywords: Fragipan Albeluvisols Quantitative X-ray diffraction Micromorphology Precarpathians

a b s t r a c t The fragipan (Bx) is a subsurface soil horizon restricting the penetration of roots and infiltration of water due to its high bulk density, low total porosity, and discontinuous voids (so-called closed box system). Additionally, the pan is characterized by a hard or very hard consistence when dry, but brittle when moist. The genesis and evolution of the fragipan have been the subject of many research studies, and numerous theories and models concerning these issues can be found in the literature. The principal aims of this study were to: 1) explain the genesis of the fragipan in Albeluvisols in the Precarpathians in Ukraine, basing on micromorphological studies and quantitative mineral composition analyses and 2) propose a model of pan formation and evolution under moderately humid climate conditions. The abundance of clay coatings and clay infillings as well as iron–clay cutans within the studied fragipan indicates that the formation of the pan is related to the translocation of colloids (clay minerals and iron hydroxides) from upper soil horizons. This leads to the filling of voids in the Btx horizon and a decrease in the porosity and hydraulic conductivity of the pan. The enrichment of the fragipan in clay minerals (especially in swelling clay minerals) is responsible for the subsequent degradation of the pan due to wetting and drying, leading to the swelling and shrinking of soil material. The occurrence of many Fe–Mn nodules and a mottled color indicates cyclical wetting and drying within the studied fragipan. In effect, vertical cracks are formed, which serve as pathways for water infiltrating down the soil profile. The water washes out weathering products (iron oxides and clay minerals) from soil material adjacent to the cracks. This leads to the formation and development of bleached tongues along the vertical cracks, which penetrate the fragipan. © 2014 Elsevier B.V. All rights reserved.

1. Introduction The fragipan (Bx) is a subsurface soil horizon restricting the penetration of roots and infiltration of water due to its high bulk density, low total porosity, and discontinuous voids (so-called closed box system) (Bockheim and Hartemink, 2013; Ciolkosz et al., 1995; IUSS Working Group WRB, 2006; Lindbo and Veneman, 1989; Lindbo et al., 1994; Smeck et al., 1989; Van Vliet and Langohr, 1981). Furthermore, the pan is characterized by a hard or very hard consistence when dry, but brittle when moist (Soil Survey Staff, 2010; Szymański et al., 2012; Witty and Knox, 1989). The fragipan does not exhibit cementation because its air-dried clods slake immediately once immersed in water (IUSS Working Group WRB, 2006; Lindbo and Rhoton, 1996; Soil Survey Staff, 2010). The occurrences of vertical, bleached tongues forming polygonal patterns in the horizontal section, numerous Fe–Mn nodules as well as a mottled color of soil material are all characteristic morphological features of the fragipan (Jha and Cline, 1963; Lindbo and

⁎ Corresponding author. Tel.: +48 12 664 5264; fax: +48 12 664 5385. E-mail address: [email protected] (W. Szymański).

http://dx.doi.org/10.1016/j.catena.2014.02.011 0341-8162/© 2014 Elsevier B.V. All rights reserved.

Veneman, 1989; Lindbo et al., 1995; Miller et al., 1971; Szymański et al., 2011). The genesis and evolution of the fragipan are the subject of many research studies, and numerous theories and models concerning these issues can be found in the research literature. Some of these attribute to the formation of the pan to processes leading to the densification of soil material due to a so-called hydroconsolidation of soil material, because of its oversaturation with water and collapse under its own weight (Assalay et al., 1998; Bryant, 1989; Certini et al., 2007; Scalenghe et al., 2004). Knox (1957), Yassoglou and Whiteside (1960), Hutcheson and Bailey (1964), Lindbo and Veneman (1989), Aide and Marshaus (2002) and Szymański et al. (2011) claim that the main process leading to the formation of the pan is the translocation of clay minerals from upper soil layers to the lower part of the soil profile (so-called lessivage). According to Harlan et al. (1977), Norton and Franzmeier (1978), Steinhardt and Franzmeier (1979), Steinhardt et al. (1982), Franzmeier et al. (1989) as well as Duncan and Franzmeier (1999), the genesis of the fragipan is connected with the translocation of amorphous silica from the upper part of the soil profile and its subsequent accumulation in the lower horizons. Others (e.g. Hallmark and Smeck, 1979; Karathanasis, 1987, 1989; Norfleet and Karathanasis, 1996)

V.A. Nikorych et al. / Catena 119 (2014) 154–165

indicate that the translocation of amorphous aluminosilicates is responsible for the formation of the Bx horizon. Ajmone-Marsan and Torrent (1989) maintain that fragipans showing the accumulation of silica and goethite are better developed relative to other pans, suggesting that the translocation of SiO2 with iron hydroxides plays a crucial role in the formation of the pan. Smeck et al. (1989) proposed that the formation of the pan is related to a so-called “weathering front” found along the contact of the two parent materials (showing various stages of weathering) and the precipitation of weathering products (clay minerals, iron and aluminum oxides as well as amorphous silica) within voids of the soil profile. The research literature also provides some theories linking some of the already mentioned processes (e.g. Ciolkosz et al., 1995; Weisenborn and Schaetzl, 2005b). The principal aims of this study were to: 1) explain the genesis of the fragipan in Albeluvisols in the Precarpathians in Ukraine, basing on micromorphological studies and quantitative mineral composition analyses and 2) propose a model of pan formation and evolution under moderately humid climate conditions. 2. Materials and methods 2.1. Study area The research was carried out in the Precarpathians in southwestern Ukraine. The study area, which is the outer part of the Eastern Carpathians, is shown in Fig. 1. Interstratified layers of sandstones, siltstones and shales forming the so-called Carpathian flysch are the main bedrock in the study area. The Carpathian flysch is mantled by loess, which does not contain carbonates and serves as the parent material for the studied Albeluvisols. Such loess is often called loess-like deposits due to the lack of carbonates, however in this work it is called loess because this material meets all the criteria of loess (with the exception of carbonate content) (Maruszczak, 2000). The lack of carbonates in the loess, its slightly acidic pH (5.0–6.0), and the domination of swelling clays in the clay fraction are the most important factors (together with humid climate), which are responsible for the translocation of clay fraction down the soil profile (Gunal and Ransom, 2006; Kühn et al., 2006; Quénard et al., 2011; Seta and Karathanasis, 1996, 1997). In many cases, the clay illuviation is observed down to the underlying residue of flysch (Nikorych et al., 2013). The study area is characterized by moderately humid climate conditions with mean annual temperature ranging from 6 to 8 °C, and mean annual rainfall between 650 and 800 mm (National Atlas of Ukraine, 2007). Detailed data for monthly air

Fig. 1. Location of the investigated soil profiles and occurrence of Luvisols and Albeluvisols in the southwestern part of Ukraine. Based on Polchyna (2012).

155

temperature and precipitation is given in Table 1. The study area is largely agricultural, but large parts of the area remain covered by deciduous, mixed and coniferous forests with oak (Quercus sp.), beech (Fagus sylvatica L.), fir (Abies alba Mill.), hornbeam (Carpinus betulus L.), lime (Tilia cordata Mill.), larch (Larix decidua Mill.), and willow (Salix sp.) (Nesteruk, 2000). 2.2. Field and laboratory methods Five representative soil profiles in the investigated area were selected from 20 profiles for a detailed analysis. The location of the pedons studied is shown in Fig. 1 and selected information concerning the study sites is summarized in Table 2. The study profiles are covered by deciduous (Piilo profile), mixed (Nimchych, Ispas, and Mysliv profiles) and coniferous (Storozhynets profile) forests, and formed entirely in loess. The exception is the Storozhynets profile — the lowermost part of which is formed from the residue of Carpathian flysch. All of the studied profiles were excavated on steep or gentle slopes with variable exposure (Table 2). The soil profiles were excavated and sampled. One large bulk sample was taken from each genetic horizon and subsamples were taken from bleached tongues present within the fragipan. In addition, undisturbed soil samples were taken from each genetic horizon for micromorphological studies. In the laboratory, the samples were air dried, crushed with a wooden rolling pin, and screened through a 2 mm steel sieve. Soil organic carbon content was determined using the Tiurin titrimetric method (Nelson and Sommers, 1996). The pH of the soil was measured using a 1:2.5 soil/distilled water ratio (Thomas, 1996). The total of exchangeable bases was determined using 0.1 M HCl and extractable H and Al in 1 M KCl (Summer, 1992) by titration of extracts (after boiling for 10 s) with 0.1 M NaOH in the presence of phenolphthalein. The concentration of amorphous Fe and Al was determined in ammonium oxalate extracts (prepared according to the procedure given by Van Reeuwijk, 2002) via the colorimetric method using 1.10-phenanthroline (Fe) (Jackson, 1969) and aluminon (Al) (Hsu, 1963). A set of sieves (for sand fractions) and a hydrometer method (for silt and clay fractions) were used for the determination of particle size distribution (Gee and Bauder, 1986). Bulk density and total porosity were determined by means of the core method (Blake and Hartge, 1986). The color of the moist soil material was described using the Munsell color soil charts. Shrinking of soil material was conducted on fine earth soil material (fraction b 1 mm). The soil material was placed on a glass plate and moistened with distilled water. Then the soil material was dried at room temperature (~22 °C). Micromorphological observations and analyses were conducted in thin sections under a polarizing microscope (Nikon Eclipse E600POL). The thin sections were prepared using a standard procedure (e.g. FitzPatrick, 1984) and described according to the terminology given by Stoops (2003). X-ray diffraction (XRD) was used to determine the mineral composition of the studied Albeluvisols. Quantitative mineral composition analyses were conducted on bulk soil samples (b1 mm), which were ground in a McCrone micronizing mill for 10 min with Baker ZnO (catalog no. 131413-2) as an internal standard, under ethanol (2.7 g of soil sample and 0.3 g of ZnO were used). The ground mixtures were side-loaded to obtain random powder mounts and analyzed from 2 to 65°2Θ at a counting speed of 0.02°/5 s. Quantitative XRD analysis was performed using the Seifert Rietveld AutoQuan/BGMN computer program (Taut et al., 1998). XRD data from 15 to 65°2Θ were used for the quantification. In addition to bulk samples, separated clay fractions (b2 μm and b0.2 μm) were also studied. The separation of the clay fractions was done by centrifugation after the removal of carbonates and divalent exchangeable cations using an Na-acetate buffer, organic matter (using 10% hydrogen peroxide) and free iron oxides (using Na-citrate–bicarbonate–dithionite solution) according to a procedure given by Jackson (1969). One part of the separated clay fractions was saturated with K+ and the second part was

156

V.A. Nikorych et al. / Catena 119 (2014) 154–165

Table 1 Air temperature and precipitation data for the studied area. Based on Gerenchuk (1973, 1978). Meteorological station

January

Mean air temperature (°C) Ivano-Frankivsk −5.1 Chernivtsi −4.9 Mean precipitation (mm) Ivano-Frankivsk 31 Chernivtsi 32

February −3.2 −2.9 32 32

March

April

May

1.4 1.7

8.1 8.7

13.5 14.3

35 36

54 58

87 77

June 16.6 17.4 98 105

saturated with Mg2+. Then, the fractions were dialyzed to remove excess salt. XRD analyses of clay fractions were conducted on oriented mounts from 2 to 52°2Θ at a counting speed of 0.02°/2 s. K-saturated clay fractions were analyzed in an air dry state, following heating at 330 °C and 550 °C. Mg-saturated clays were analyzed in air dry condition, following solvation with liquid glycerol. The identification of clay minerals was done using operational definitions given by Środoń (2006). All X-ray diffraction analyses were conducted using a Philips X'Pert diffractometer equipped with a vertical goniometer (PW3020), 1° divergence slit, 0.2 mm receiving slit, incident- and diffracted-beam Soller slits, 1° anti-scatter slit, and a graphite diffracted-beam monochromator. CuKα radiation with an applied voltage of 40 kV and a 30 mA current was used. The ClayLab computer program was used to analyze X-ray patterns of clay fractions (Mystkowski, 1999). 3. Results and discussion 3.1. Soil morphology, chemical and physical properties Field descriptions of the morphology of the studied Albeluvisols are summarized in Table 3 and their location is shown in Fig. 1. All of the soil profiles are characterized by a similar morphology and were classified as Stagnic Fragic Albeluvisols (Siltic) according to the WRB classification (IUSS Working Group WRB, 2006). Surface organic horizons (O) occurring in some of the Albeluvisols were not described in detail. The organic horizons are underlain by an A horizon with a grayish yellow brown color (10YR 4/2), subangular blocky structure, soft or slightly hard consistence, and thickness ranging from 6 to 12 cm. The A horizons lie atop eluvial horizons (Eg), which exhibit a stagno-gleyic color pattern (10YR 5/2 to 5/4), subangular blocky, angular blocky or massive structures, slightly hard consistence, and the presence of Fe–Mn nodules. The bleached color of the soil material and the occurrence of Fe–Mn nodules indicate seasonal stagnation of water in this part of the soil profile as well as the occurrence of redox (e.g. Lindbo et al., 2010; Sauer et al., 2013; Szymański and Skiba, 2013; Zhang and Karathanasis, 1997). AE(g) transition horizons are present in the Ispas, Piilo, and Storozhynets profiles. Eluvial horizons are underlain by the fragipan (Btx), which is characterized by a mottled color (10YR 4/3 to 5/6; 10YR 6/2 to 6/3), coarse prismatic, angular or subangular blocky structures, very hard consistence, and brittleness. Additionally, the pan shows the occurrence of numerous reddish-black Fe–Mn nodules and clay coatings on ped faces. The fragipan contains well-expressed, vertical, bleached tongues (10YR 6/2 to 8/1) with rusty rims (7.5YR 5/6) forming polygonal patterns in the horizontal section. The length of the tongues varies between

July 17.9 18.7 104 103

August

September

17.3 18

13.5 14.3

81 61

53 51

October 8.0 8.6 36 32

November 2.6 2.9 37 36

December −2.1 −1.9 41 37

Year 7.4 7.9 689 660

10 and 60 cm and the width between 1 and 10 cm. The thickness of the pan ranges from 27 to 90 cm and its upper boundary occurs between 30 and 43 cm from the surface. The upper boundary of the fragipan studied is abrupt or clear and the lower boundary is gradual or diffuse. The argillic horizon (Btg) occurring under the fragipan shows a dull yellowish brown (10YR 5/4) or yellowish brown (10YR 5/6) color, prismatic structure, slightly hard or very hard consistence, and the presence of Fe–Mn nodules. This type of morphology of soil profiles and the fragipan is typical for Albeluvisols formed from loess at middle latitudes and was previously described by other researchers from the USA, Belgium, Poland, and Norway (Anderson and White, 1958; Jha and Cline, 1963; Lindbo et al., 1994, 1995, 2000; Sauer et al., 2013; Szymański et al., 2011, 2012; Van Vliet and Langohr, 1981). The Albeluvisols studied exhibit an acidic or slightly acidic reaction (pH ranges from 4.5 to 6.0 in distilled water). The low pH is related to a lack of carbonates in the parent material, leaching of bases due to percolation of water in a moderately humid climate as well as the presence of organic acids. The concentration of soil organic carbon is up to 3.7% and decreases down the soil profile (Table 4). Exchangeable acidity produced mainly by Al3 + ranges from 2.4 cmolc/kg to 5.2 cmolc/kg (Table 4). Cation exchange capacity (CEC) increases down the soil profile as a reflection of the clay fraction concentration. Slightly higher or similar CEC in surface horizons (when compared with illuvial horizons in Ispas, Mysliv, and Piilo pedons) is most likely related to a higher concentration of soil organic matter in A and AE horizons versus lower horizons (Table 4). Base saturation of the studied Albeluvisols is quite high, ranging from 66.9% to 89.5%, and generally increases down the soil profile. The concentration of amorphous Fe (Feo) increases with increasing depth, indicating the translocation of iron hydroxides together with clay minerals. In the A, AEg and Eg horizons, the concentration of Feo ranges from 0.81 to 1.59%, and within illuvial horizons (Btx and Btg), the concentration of Feo ranges between 1.04 and 2.21%. The concentration of amorphous Al (Alo) is almost evenly distributed throughout the studied profiles (from 0.02 to 0.07%), with only slightly higher values in illuvial horizons (Table 4). The bleached tongues from the fragipan show lower concentrations of Feo and Alo in comparison with the Btx horizon, indicating their eluviation. This is in accordance with results presented previously by Payton (1993), and Szymański et al. (2011) from England and Poland, respectively. The studied Albeluvisols are characterized by silt loamy, silty clay loamy, clay loamy or loamy texture. Only the lowermost part of the Storozhynets profile shows a clayey texture. The silt fraction clearly prevails in all the studied pedons, ranging from 37% to 73%, with the exception of the lowermost horizons in the Storozhynets profile. The sand fraction

Table 2 Selected information concerning study sites and classification of the soil profiles studied. Profile

Location

Nimchych Ispas Mysliv Piilo Storozhynets

48°11′30 48°16′18 49°00′12 49°00′42 48°09′44

a

According to WRB (2006).

N; 25°09′15E; 560 N; 25°16′14E; 420 N; 24°28′29E; 360 N; 24°18′48E; 309 N; 25°44′37E; 460

m m m m m

a.s.l. a.s.l. a.s.l. a.s.l. a.s.l.

Geomorphology

Vegetation

Classificationa

Slope (30°); exposure SW Slope (10°); exposure N Slope (3°); exposure SW Slope (2°); exposure S Slope (3°); exposure SW

Carpinus betulus, Larix decidua, Abies alba Abies alba, Salix caprea, Asarum europeum Quercus sp., Abies alba, Fagus sylvatica Quercus sp., mosses Picea abies, Abies alba

Stagnic Fragic Albeluvisol (Siltic) Stagnic Fragic Albeluvisol (Siltic) Stagnic Fragic Albeluvisol (Siltic) Stagnic Fragic Albeluvisol (Siltic) Stagnic Fragic Albeluvisol (Siltic)

V.A. Nikorych et al. / Catena 119 (2014) 154–165

157

Table 3 Field description of morphology of the studied soil profiles. Horizon

Color (moist)

Structure

Consistence

Roots

Fe–Mn nodules

Clay coatings

0–6 6–32 32–50 50–90 90–100

10YR 4/2 10YR 5/4 10YR 5/6; 10YR 6/3 10YR 5/6; 10YR 6/3 10YR 5/6

n.a.a Subangular blocky Prismatic Prismatic Prismatic

n.a. Slightly hard Very hard Very hard Very hard

n.a. Common Few Absence Absence

n.a. Few Few Common Common

n.a. Absence Few Few Common

0–6 6–15 15–32 32–52 52–110 110–140

n.a. 10YR 5/3 10YR 5/4 10YR 5/6; 10YR 6/2 10YR 5/6; 10YR 6/2 10YR 5/4

n.a. Subangular blocky Subangular blocky Prismatic Prismatic Prismatic

n.a. Slightly hard Slightly hard Very hard Very hard Very hard

n.a. Many Few Few Absence Absence

n.a. Few Few Common Many Few

n.a. Absence Few Common Many Common

Mysliv profile O A Eg Btx1 Btx2 Btg

0–2 2–14 14–30 30–49 49–57 57–120

n.a. 10YR 4/2 10YR 5/4 10YR 5/4; 10YR 6/2 10YR 5/3; 10YR 6/2 10YR 5/3; 10YR 6/2

n.a. Subangular blocky Massive Angular blocky Prismatic Prismatic

n.a. Soft Slightly hard Very hard Very hard Very hard

n.a. Many Common Few Few Absence

n.a. Absence Few Few Common Many

n.a. Few Absence Common Many Common

Piilo profile O A AE Eg Btx1 Btx2

0–6 6–16 16–31 31–43 43–72 72–110

n.a. 10YR 4/2 10YR 5/2 10YR 5/2 10YR 5/3; 10YR 6/3 10YR 4/3; 10YR 6/3

n.a. Subangular blocky Angular blocky Angular blocky Prismatic Prismatic

n.a. Slightly hard Slightly hard Slightly hard Very hard Very hard

n.a. Many Common Few Few Absence

n.a. Absence Common Common Common Many

n.a. Absence Absence Few Common Many

Storozhynets profile O 0–5 AEg 5–22 Eg 22–33 Btx 33–60 2Btg 60–100 2BC 100–140

n.a. 10YR 5/3 10YR 5/4 10YR 5/6; 10YR 6/2 10YR 5/6; 10YR 6/2 10YR 5/6; 10YR 8/1

n.a. Subangular blocky Subangular blocky Prismatic Prismatic Massive

n.a. Soft Slightly hard Hard Hard Very hard

n.a. Few Few Absence Absence Absence

n.a. Few Few Common Many Common

n.a. Absence Few Many Many Common

Nimchych profile A Eg Btx1 Btx2 Btg Ispas profile A AEg Eg Btx1 Btx2 Btg

a

Depth (cm)

Not analyzed.

ranges between 9% and 38% and the clay fraction ranges from 15% to 36%, with the exception of the 2Btg and 2BC horizons in the Storozhynets profile. The upper horizons of Albeluvisols feature lower concentrations of the clay fraction (i.e. 15–23%) relative to lower horizons (i.e. 17–54%) (Table 5). This is most likely related to the vertical translocation of the finest particles down the soil profile (i.e. lessivage) because many clay coatings and clay infillings within the lower horizons were observed under a polarizing microscope (Fig. 4). The higher amount of clay fraction (with a prevalence of swelling clay minerals) in illuvial horizons (Btx and Btg) is responsible for the shrinking of soil material during drying and formation of cracks (Fig. 2). The Albeluvisols studied exhibit higher bulk density and lower total porosity in illuvial horizons (Btx and Btg) in comparison with A, AE and Eg horizons (Table 5). This is most likely the result of the translocation of the clay fraction, which plugs voids or decreases their diameter. However, such physical properties may also be inherited from the parent material (Lindbo and Veneman, 1989; Lindbo et al., 1994). 3.2. Micromorphological properties Most A horizons feature subangular blocky and channel microstructures. Complex packing voids and channels within A horizons are quite common. Angular and subangular grains of quartz, plagioclases, K-feldspars and flakes of mica (mainly muscovite) are the most common minerals forming the coarse material of the groundmass. In addition, fine fragments of shales were observed. Most of the minerals and fragments of clastic rocks belong to very fine sand and coarse silt fractions. In the Mysliv profile, subangular pellets of glauconite were also present. Fine material consists of brownish-gray and gray humus and small amounts of colloidal clay showing a speckled b-fabric. In A

horizons, numerous organic residues and tissues as well as roots at various stages of decomposition were observed. In the A horizon of the Ispas and Mysliv profiles, few Fe nodules were observed. Eluvial horizons are characterized by subangular blocky, massive, platy, and channel microstructures. Channels and horizontal planes are the most common types of voids in Eg horizons. Coarse soil material is composed of angular and subangular grains of quartz, plagioclases, K-feldspars, mica (muscovite) and fragments of shales belonging to very fine sand and coarse silt fractions. The micromass consists of small amounts of colloidal clay and humus as well as Fe-hydroxides. Eluvial horizons exhibit the presence of Fe and Fe–Mn nodules with sharp (disorthic nodules) or gradual (orthic nodules) boundaries and undifferentiated internal fabric indicating periodic stagnation of water and anaerobic conditions during the year (Fig. 3A and B) (e.g. Lindbo et al., 2000; Rhoton et al., 1993; Szymański and Skiba, 2013; Zhang and Karathanasis, 1997). Additional features indicating the seasonal occurrence of a perched water table within eluvial horizons are mottles — depletion zones of Fe-hydroxides and impregnative pedofeatures (Lindbo et al., 2010; Sauer et al., 2013; Szymański et al., 2011; Vepraskas, 1994). Few clay coatings, clay infillings, and fragments of deformed clay coatings were observed in Eg horizons. The fragipan exhibits subangular blocky, angular blocky and channel microstructures. The most common types of voids are channels and vertical planes (cracks). The fraction and mineral composition of coarse soil material are the same as it is in the upper horizons (i.e. angular and subangular grains of quartz, plagioclases, K-feldspars, mica, and subangular pellets of glauconite). Fine fragments of shales were also present. The micromass of the fragipan studied consists of yellow colloidal clay and reddish yellow colloidal clay with Fe hydroxides forming a porostriated b-fabric. Granostriated b-fabric and speckled b-fabric of the micromass also occur but are less common.

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V.A. Nikorych et al. / Catena 119 (2014) 154–165

Table 4 Selected chemical properties of the studied soil profiles.

Horizon

Depth (cm)

SOCa (%)

pH H2O

Bases

KCl extractable

Exchangeable

Al

acidity

H

CECb

(cmolc/kg) Nimchych profile A Eg Btx1 Btx2 Btg Tongues

BSc

Feod

Aloe

(%)

0–6 6–32 32–50 50–90 90–100

2.4 1.5 0.7 0.4 0.3 0.4

n.a.f 5.8 5.7 5.4 5.5 6.0

n.a. 13.4 8.8 15.5 18.6 20.5

n.a. 2.9 2.8 2.3 2.8 2.1

n.a. 0.7 0.5 0.5 0.4 0.3

n.a. 3.6 3.2 2.7 3.2 2.4

n.a. 17.0 12.0 18.2 21.8 22.9

n.a. 78.8 73.3 85.2 85.3 89.5

n.a. 1.08 1.04 1.19 1.26 n.a.

n.a. 0.02 0.02 0.03 0.03 n.a.

0–6 6–15 15–32 32–52 52–110 110–140

n.a. 2.6 0.9 0.6 0.6 0.5 1.0

n.a. 4.7 4.7 4.7 4.7 5.1 5.3

n.a. 11.6 9.3 16.5 18.5 11.4 10.9

n.a. 3.1 4.2 4.1 4.6 4.0 2.7

n.a. 0.6 0.4 0.3 0.4 0.2 0.5

n.a. 3.6 4.6 4.3 4.9 4.2 3.2

n.a. 15.2 13.9 20.8 23.4 15.6 14.1

n.a. 76.3 66.9 79.3 79.1 73.1 77.3

n.a. 1.39 1.41 1.66 1.88 1.92 1.21

n.a. 0.05 0.05 0.06 0.07 0.06 0.03

Mysliv profile O A Eg Btx1 Btx2 Btg Tongues

0–2 2–14 14–30 30–49 49–57 57–120

n.a. 2.5 1.3 1.0 0.6 0.4 0.8

n.a. 4.8 5.4 5.3 5.4 5.0 5.6

n.a. 14.5 10.4 13.2 15.6 18.3 15.2

n.a. 4.5 3.6 3.2 3.4 3.4 3.3

n.a. 0.7 0.8 1.0 0.7 0.6 0.6

n.a. 5.2 4.4 4.1 4.1 4.0 3.9

n.a. 19.7 14.8 17.3 19.7 22.3 19.1

n.a. 73.6 70.3 76.3 79.2 82.1 79.6

n.a. 1.22 1.49 1.74 1.73 1.98 n.a.

n.a. 0.04 0.05 0.05 0.06 0.06 n.a.

Piilo profile O A AE Eg Btx1 Btx2 Tongues

0–6 6–16 16–31 31–43 43–72 72–110

n.a. 3.7 n.a. 0.8 0.5 n.a. n.a.

n.a. 4.8 n.a. 4.9 5.1 5.2 5.7

n.a. 14.0 n.a. 13.3 14.3 17.0 13.8

n.a. 4.1 n.a. 3.9 3.7 3.1 2.8

n.a. 1.0 n.a. 0.7 0.8 0.6 0.3

n.a. 5.1 n.a. 4.6 4.5 3.6 3.0

n.a. 19.1 n.a. 17.9 18.8 20.6 16.8

n.a. 73.3 n.a. 74.3 76.1 82.5 82.1

n.a. 0.81 0.85 1.55 1.64 1.57 0.73

n.a. 0.03 0.05 0.05 0.07 0.05 0.03

n.a. 2.4 0.6 0.6 0.5 n.a.

n.a. 4.5 4.9 5.3 5.6 n.a.

n.a. 13.2 10.8 17.6 19.8 n.a.

n.a. 8.0 7.3 6.1 3.7 n.a.

n.a. 1.2 0.8 0.5 0.4 n.a.

n.a. 5.1 5.1 4.6 4.0 n.a.

n.a. 18.3 15.9 22.2 23.8 n.a.

n.a. 72.1 67.9 79.3 83.2 n.a.

n.a. 1.49 1.59 1.96 2.21 n.a.

n.a. 0.04 0.04 0.07 0.07 n.a.

Ispas profile A AEg Eg Btx1 Btx2 Btg Tongues

Storozhynets profile O 0–5 AEg 5–22 Eg 22–33 Btx 33–60 2Btg 60–100 2BC 100–140 a b c d e f

Soil organic carbon. Cation exchange capacity. Base saturation. Oxalate ammonium extractable Fe. Oxalate ammonium extractable Al. Not analyzed.

Numerous clay coatings and microlaminated clay infillings occur within the Btx horizon, indicating the translocation of the clay fraction from the upper part of the soil profile (Fig. 4) (Horn and Rutledge, 1965; Lindbo and Veneman, 1993; Miller et al., 1971; Nettleton et al., 1968; Payton, 1993; Sauer et al., 2013; Szymański and Skiba, 2011; Szymański et al., 2011, 2012; Weisenborn and Schaetzl, 2005a; Zasoński, 1983, 1992). However, some of the observed clay coatings and infillings could be also related to stress of soil material because of wetting and drying leading to swelling and shrinking of soil material (Gunal and Ransom, 2006). In addition, a large quantity of fragments of clay coatings and clay infillings was observed, which is most likely related to the swelling and shrinking of soil material as well as its bioturbation (Nettleton et al., 1968; Szymański et al., 2011). Fe and Fe–Mn nodules showing undifferentiated internal fabric and gradual boundaries are very common pedofeatures of the studied fragipan. Depletion and impregnative pedofeatures as well as compound pedofeatures (clay coatings within Fe–Mn nodules and iron–clay coatings and infillings) commonly occur (Fig. 3C and D). Such pedofeatures indicate that the genesis and evolution of the studied fragipan originate from the illuviation of clay minerals and iron hydroxides as well as seasonal redox processes

(Lindbo and Veneman, 1993; Szymański et al., 2011). The argillic horizon is characterized by micromorphological properties similar to those of the Btx horizon; however, Fe–Mn nodules and depletion as well as impregnative pedofeatures and vertical planes (fissures) are less common in comparison with the overlying fragipan. The micromorphological properties of the studied Albeluvisols in the Precarpathians in Ukraine are very similar to those of Albeluvisols in the Carpathian Foothills in Poland and soils containing the fragipan in the United States and Norway (Horn and Rutledge, 1965; Lindbo and Veneman, 1993; Miller et al., 1971; Nettleton et al., 1968; Sauer et al., 2013; Szymański and Skiba, 2011; Szymański et al., 2011, 2012; Weisenborn and Schaetzl, 2005a; Zasoński, 1983, 1992). 3.3. Mineralogical properties The quantitative mineral composition of the studied soil profiles is shown in Table 6. The soil material of the studied profiles is composed of quartz, K-feldspars, plagioclases (mainly albite), dioctahedral micas (i.e. muscovite, illite, and glauconite), and biotite (trioctahedral mica). In addition, kaolinite, chlorite, smectite, and goethite are present

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Table 5 Particle-size distribution, bulk density and total porosity of the investigated soil profiles. Horizon

Depth (cm)

Sand

Silt

Clay

(%)

Clay-free basis (%) 2.0–0.05

0.05–0.02

0.02–0.006

0.006–0.002

Dba (Mg/m3)

Pb (%)

Nimchych profile A 0–6 Eg 6–32 Btx1 32–50 Btx2 50–90 Btg 90–100

35.0 36.0 38.0 32.0 38.0

47.0 44.0 38.0 43.0 37.0

18.0 20.0 24.0 25.0 25.0

42.7 45.0 50.0 42.7 50.7

22.0 20.0 18.4 21.3 16.0

20.7 21.3 19.7 22.7 21.3

14.6 13.8 11.8 13.3 12.0

1.36 1.40 1.48 1.50 1.53

51.2 49.1 46.3 40.5 40.1

Ispas profile A AEg Eg Btx1 Btx2 Btg Tongues

0–6 6–15 15–32 32–52 52–110 110–140

n.a.c 26.0 21.0 19.0 22.0 22.0 19.0

n.a. 54.0 56.0 49.0 49.0 50.0 51.0

n.a. 20.0 23.0 32.0 29.0 28.0 30.0

n.a. 32.5 27.3 27.9 31.0 30.6 27.1

n.a. 25.0 27.3 27.9 25.4 25.0 25.7

n.a. 27.5 28.6 29.4 28.2 27.8 28.6

n.a. 15.0 16.9 14.7 15.5 16.7 18.6

n.a. 1.01 1.37 1.41 1.46 1.46 n.a.

n.a. 58.4 44.8 42.2 40.3 39.9 n.a.

Mysliv profile O A Eg Btx1 Btx2 Btg Tongues

0–2 2–14 14–30 30–49 49–57 57–120

n.a. 14.0 11.0 10.0 11.0 10.0 9.0

n.a. 71.0 68.0 64.0 64.0 73.0 69.0

n.a. 15.0 21.0 26.0 25.0 17.0 22.0

n.a. 16.5 13.9 13.5 14.7 12.0 11.5

n.a. 34.1 36.7 36.5 36.0 33.7 35.9

n.a. 34.1 35.4 36.5 36.0 39.8 35.9

n.a. 15.3 13.9 13.5 13.3 14.5 16.7

n.a. 1.30 1.30 1.37 1.46 1.67 n.a.

n.a. 49.4 46.1 42.3 40.2 35.6 n.a.

Piilo profile O A AE Eg Btx1 Btx2 Tongues

0–6 6–16 16–31 31–43 43–72 72–110

n.a. 17.0 n.a. 16.0 16.0 17.0 16.0

n.a. 63.0 n.a. 66.0 62.0 58.0 59.0

n.a. 20.0 n.a. 18.0 22.0 25.0 25.0

n.a. 21.3 n.a. 19.5 20.5 22.7 21.3

n.a. 32.5 n.a. 32.9 33.3 32.0 30.7

n.a. 35.0 n.a. 36.6 33.3 32.0 33.3

n.a. 11.3 n.a. 11.0 12.8 13.3 14.7

n.a. n.a. n.a. n.a. n.a. n.a. n.a.

n.a. n.a. n.a. n.a. n.a. n.a. n.a.

n.a. 17.0 14.0 12.0 19.0 13.0

n.a. 66.0 63.0 52.0 34.0 33.0

n.a. 17.0 23.0 36.0 47.0 54.0

n.a. 20.5 18.2 18.8 35.8 28.3

n.a. 28.9 29.9 23.4 18.9 21.7

n.a. 32.5 33.8 35.9 26.4 26.1

n.a. 18.1 18.2 21.9 18.9 23.9

n.a. 1.29 1.39 1.53 1.58 1.55

n.a. 48.4 44.2 39.5 37.3 37.6

Storozhynets profile O 0–5 AEg 5–22 Eg 22–33 Btx 33–60 2Btg 60–100 2BC 100–140 a b c

Bulk density. Total porosity. Not analyzed.

(Figs. 5 and 6). Quartz is the most common primary mineral in all the genetic horizons of the studied soil profiles. Its concentration ranges between 34.6% in the 2BCg horizon of the Storozhynets profile and 70% in the A horizon of the Nimchych profile. All the profiles show a clearly higher concentration of quartz in upper horizons relative to lower horizons, which is likely caused by its high resistance to weathering (Table 6). The concentration of K-feldspars ranges from 3% in the 2BCg horizon of the Storozhynets profile to 11.2% in the Eg horizon of the Piilo profile. Plagioclases show a slightly lower concentration than Kfeldspars. Their maximum (i.e. 7.4%) occurs in the Btg horizon of the Ispas profile and the minimum (i.e. 3.5%) occurs in the 2BCg horizon of the Storozhynets profile (Table 6). In the Nimchych and Ispas profiles, K-feldspars prevail over plagioclases in the upper parts of pedons, but in the lower parts of pedons, the concentration of plagioclases is higher than that of K-feldspars. This is most likely related to a higher resistance of K-feldspars to weathering relative to that of plagioclases (e.g. Wilson, 2004). The illuvial horizons of the studied pedons (i.e. Btx and Btg) exhibit higher concentrations of dioctahedral mica relative to the upper horizons (i.e. A, AEg, and Eg), which is most likely linked with illuviation of clay-sized mica (e.g. illite). The amounts of dioctahedral mica range between 5.1% in the A horizon of the Nimchych profile and 15.7% in the 2BCg horizon of the Storozhynets pedon. The lower concentration of dioctahedral mica in the upper part of the studied pedons may also be related to weathering (vermiculitization). A low concentration of

biotite was determined only for the Nimchych, Ispas, and Storozhynets pedons (Table 6). In addition, biotite occurs only in the lower part of these pedons, ranging from 1.4% to 3.4%. Such a distribution of biotite is related to its low resistance against weathering in the soil environment. This is especially true in more acidic surface and eluvial horizons containing higher quantities of organic acids (Ismail, 1969; Wilson, 2004). The complete lack of biotite in the Mysliv and Piilo profiles indicates more weathered (i.e. chemically mature) parent material, and this may also indicate that the parent material of these pedons had been transported a greater distance in comparison with the parent material of the Nimchych, Ispas, and Storozhynets pedons. Swelling clay minerals (mainly smectite) clearly prevail over kaolinite and chlorite (Table 6). The concentrations of swelling clays range between 7.3% in the A horizon of the Mysliv profile and the Eg horizon of the Storozhynets profile and 33.6% in the 2BCg horizon of the Storozhynets profile. All of the pedons studied show clearly lower concentrations of swelling clay minerals in the upper horizons (7.3%–12.6%) versus the lower horizons (9.2%–33.6%). Such a distribution of clays is related to their translocation from the upper part to the lower part of the studied pedons (lessivage). Numerous clay coatings and clay infillings observed in illuvial horizons (i.e. Btx and Btg) also indicate translocation (Fig. 4). The highest concentration of swelling clay minerals occurring in the 2Btg and 2BCg horizons of the Storozhynets profile (29.5 and 33.6%, respectively) is a result of lessivage and the presence of lithological

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On the one hand, bleached tongues found within the fragipan along vertical cracks feature a higher concentration of quartz relative to the pan, and on the other hand, feature a lower concentration of swelling clays than the Btx horizon (Table 6). In the case of the Nimchych and Ispas profiles, this is also true of kaolinite and chlorite. In addition, the tongues do not contain goethite. Such differences in the mineral composition of the soil material from the fragipan and the bleached tongues indicate that the formation of tongues is related to the infiltration of water along vertical cracks (e.g. Payton, 1993). The infiltration leads to the eluviation of Fe-oxides and clay minerals from the soil material along cracks and to the development of bleached tongues. The quantitative mineral composition of Albeluvisols in the Precarpathians in Ukraine is in accordance with data obtained previously for Albeluvisols found in the Polish part of the Carpathian Foothills (Szymański et al., 2011). 3.4. Model of fragipan formation and evolution

Fig. 2. Shrinking of soil material from the studied fragipans and formation of cracks due to drying (A — Btx2 horizon of the Piilo profile; B — Btx2 horizon of the Ispas profile).

discontinuity. Kaolinite and chlorite exhibit a similar distribution as swelling clays (i.e. higher concentrations in illuvial horizons versus the upper part of the pedons studied). The concentrations of kaolinite and chlorite are much lower in comparison with swelling clay minerals. The concentration of kaolinite ranges from 0% in the AEg horizon of the Storozhynets profile to 3.5% in the 2Btg horizon of the same profile, while the concentration of chlorite ranges between 1.8% in the A horizon of the Nimchych pedon and 4.3% in the Eg horizon of the Ispas profile (Table 6). The higher concentration of kaolinite and chlorite in the lower parts of soil profiles is also related to lessivage (Szymański et al., 2011). In each case – apart from the Mysliv profile – the fragipan and argillic horizon contain goethite (about 1%). Only the 2Btg and 2BCg horizons of the Storozhynets profile show a slightly higher concentration of goethite (i.e. 1.8% and 1.9%, respectively). In addition to the mineral phases described above, amorphous phases were identified. Such phases occur mainly in the A, AE, and Eg horizons, where weathering is strong and cyclic reduction and oxidation also occur. The presence of many Fe–Mn nodules and bleaching of the soil material in these horizons are evidence of the periodic stagnation of water and the occurrence of redox (e.g. Lindbo et al., 2000; Rhoton et al., 1993; Zhang and Karathanasis, 1997). These processes are responsible for the decomposition of primary minerals and the formation of secondary, often amorphous materials (e.g. Brinkman, 1977).

A model of the formation and evolution of the fragipan in Albeluvisols formed from loess in moderately humid climate conditions is proposed herein based on the present as well as previous researches (e.g. Aide and Marshaus, 2002; Bryant, 1989; Ciolkosz et al., 1995; Franzmeier et al., 1989; Lindbo et al., 2000; Szymański et al., 2011; Van Vliet and Langohr, 1981; Weisenborn and Schaetzl, 2005b). The Luvisols and Albeluvisols in the Precarpathians in Ukraine and the Carpathian Foothills in Poland were formed from loess, which does not contain carbonates and usually has a thickness of several meters. The loess was deposited during the last glaciation (i.e. Vistulian) under periglacial climate conditions (Klimaszewski, 1967). In such conditions, loess may undergo hydroconsolidation (Assalay et al., 1998; Bryant, 1989). The presence of fine fragments of clastic rocks (especially shales and sandstones) as well as pellets of glauconite (commonly occurring in Carpathian flysch) in the soil material indicates that most probably the residues of Carpathian flysch were the original source of the loess (Szymański et al., 2011; Uziak, 1962; Zasoński, 1983, 1992). The subsequent encroachment of coniferous and deciduous forests across the study area, driven by postglacial warming of the climate, led to accelerated soil formation (e.g. Kühn et al., 2006). A humid climate with a surplus of precipitation, lack of carbonates in the parent material (loess), and its slightly acidic pH favored the translocation of colloids (especially clay minerals) from upper soil horizons to the lower part of the soil profile (lessivage). This is in accordance with data given by e.g. Kühn et al. (2006), Eckmeier et al. (2007), and Gerlach et al. (2012) from Germany, Quénard et al. (2011) from France, and Gunal and Ransom (2006) from Kansas in the USA. These researchers reported that the lack of carbonates in the parent material has an important impact on intense clay illuviation due to dispersion of clay minerals. In addition, domination of swelling clays in the clay fraction of studied soils promotes lessivage because, as showed by Seta and Karathanasis (1996, 1997), such clay minerals disperse easier in comparison with other clays. The intensity of clay migration within the soil profile is also connected with the frequency of drying and wetting of soil material (Quénard et al., 2011). According to the literature (e.g. Eckmeier et al., 2007; Quénard et al., 2011), clay illuviation is related to humid climate and is the most intense in the western part of Europe due to more humid, maritime climate. On the other hand, in the central and eastern parts of Europe clay illuviation is less intense due to a more continental climate (Eckmeier et al., 2007; Quénard et al., 2011). This is probably true for lowlands and plains but not entirely true for uplands and especially for mountains. Thus, the intense clay illuviation in Albeluvisols in the Precarpathians in Ukraine and the Carpathian Foothills in Poland during Holocene is the effect of quite high annual precipitation (from 650 to 900 mm) and quite frequent drying and wetting of the soils (especially during summer and autumn) confirmed by a high content of Fe–Mn nodules and other redoximorphic features. Most likely clay illuviation affected previously densified parent material due to hydroconsolidation under periglacial conditions.

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Fig. 3. Fe–Mn nodule showing undifferentiated internal fabric and sharp boundary in eluvial horizon (Eg) of the Mysliv profile (A, B); depletion zones and impregnative pedofeatures within the fragipan of the Piilo profile (C, D). Plane polarized light (photos: A and C) and crossed polarized light (photos: B and D).

Fig. 4. Clay coatings (A, B) and microlaminated clay infilling (C, D) within the fragipan of the Ispas profile. Plane polarized light (photos: A and C) and crossed polarized light (photos: B and D).

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Furthermore, it increased the bulk density and decreased the porosity of illuvial horizons (Btx and Btg horizons). The illuviation of clays and their deposition on ped faces were also responsible for the formation of discontinuous voids (i.e. closed-box system of voids). The presence of clay coatings and clay infillings in the studied fragipan as well as the close packing of mineral grains forming the soil material indicate that both hydroconsolidation and lessivage had played a crucial role in the genesis of the pan. This is in accordance with a previously proposed model of the fragipan genesis and an evolution in the soils of Michigan in the USA given by Weisenborn and Schaetzl (2005b). The translocation and accumulation of clay minerals – especially swelling clays such as smectite, vermiculite, mica-smectite, and mica-vermiculite – in the fragipan led to its gradual degradation due to the periodic shrinking of the soil material because of drying (Fig. 2). In effect, vertical cracks and prismatic clods were formed (e.g. Ciolkosz et al., 1995). The prismatic structure and bleached tongues occur only in illuvial horizons, where higher amounts of swelling clay minerals are present. The occurrence of Fe–Mn nodules and mottles, being the effect of cyclic reduction and oxidation, indicates periodic wetting and drying of the soil material (e.g. Bigham et al., 2002; Lindbo et al., 2010; McDaniel and Buol, 1991; Schwertmann and Fanning, 1976; Vepraskas, 1994; Zhang and Karathanasis, 1997). Grossman and Carlisle (1969), Van Vliet and Langohr (1981), Kühn (2003), and Kühn et al. (2006) previously suggested (basing on observed frost structures like platy or lenticular microstructure, banded-fabric and vesicles) that the formation of vertical cracks in soil may be also

connected with strong freezing during periglacial conditions. However, in the fragipan studied such structures were not observed indicating that the vertical cracks are not related to freezing in periglacial climate. In addition, the cracks formed by freezing are wider than the cracks that occurred in the studied fragipan. The cracks acted as infiltration channels for water, which could percolate mainly along cracks within the poorly permeable fragipan. The infiltration of water via vertical cracks caused microerosion and microeluviation of clay minerals and iron hydroxides from adjacent soil material leading to the formation and development of bleached tongues (Ciolkosz et al., 1995; Payton, 1993; Szymański et al., 2011; Tornes et al., 2000; Weisenborn and Schaetzl, 2005b). Translocated colloids were deposited in the lower parts of the cracks and at the point of contact of the tongues with dense prisms forming rusty rims. The second process, which could also affect bleached tongue formation, consisted of filling cracks with material from the overlying eluvial horizon (Eg) (Grossman and Carlisle, 1969; Rampelberg et al., 1997; Ranney et al., 1975; Sauer et al., 2013). 4. Conclusions 1. The fragipan commonly occurs within Albeluvisols in the Precarpathians in Ukraine and is overlapped with the upper part of the argillic horizon.

Table 6 Quantitative mineral composition of fine earth material (b1 mm) of the studied soil profiles. Horizon

Depth (cm)

Quartz

K-feldspars

Plagioclases

Di-mica

Biotite

Kaolinite

Chlorite

Smectite

Goethite

Amorphous

(%) Nimchych profile A 0–6 Eg 6–32 Btx1 32–50 Btx2 50–90 Btg 90–100 Tongues

70.0 67.5 55.9 56.8 58.1 59.5

4.8 4.9 4.4 5.2 4.6 4.5

3.9 4.3 5.2 5.3 4.2 5.1

5.1 8.6 13.5 13.6 12.6 12.5

0.0 0.0 1.4 1.5 2.4 2.3

1.5 1.8 2.2 1.9 1.8 1.7

1.8 2.9 3.1 3.3 3.0 3.0

8.2 9.3 13.3 11.5 12.9 11.4

0.0 0.0 0.7 0.9 0.0 0.0

4.7 0.7 0.3 0.0 0.4 0.0

Ispas profile A AEg Eg Btx1 Btx2 Btg Tongues

0–6 6–15 15–32 32–52 52–110 110–140

n.a.a 61.9 59.9 48.0 48.5 46.1 51.8

n.a. 6.9 7.7 5.3 5.8 6.4 5.4

n.a. 6.2 6.2 7.0 6.6 7.4 7.2

n.a. 9.0 10.3 13.7 13.5 14.4 12.9

n.a. 0.0 0.0 1.4 2.9 2.3 2.9

n.a. 1.9 0.8 2.2 2.4 2.6 2.0

n.a. 3.2 4.3 3.8 2.7 4.0 3.2

n.a. 10.5 9.9 17.6 16.4 15.9 14.6

n.a. 0.0 0.0 1.0 1.2 0.9 0.0

n.a. 0.4 0.9 0.0 0.0 0.0 0.0

Mysliv profile O A Eg Btx1 Btx2 Btg Tongues

0–2 2–14 14–30 30–49 49–57 57–120

n.a. 59.5 55.3 53.9 57.4 63.3 57.4

n.a. 6.8 8.8 10.2 10.4 10.1 10.2

n.a. 6.6 6.7 5.6 5.4 5.6 5.8

n.a. 5.8 10.3 10.6 8.9 6.7 9.1

n.a. 0.0 0.0 0.0 0.0 0.0 0.0

n.a. 1.5 2.3 2.0 1.8 1.7 2.0

n.a. 2.0 3.0 2.8 3.2 2.9 2.8

n.a. 7.3 12.6 14.3 12.0 9.2 12.7

n.a. 0.0 0.0 0.0 0.0 0.0 0.0

n.a. 10.5 1.0 0.6 0.9 0.5 0.0

Piilo profile O A AE Eg Btx1 Btx2 Tongues

0–6 6–16 16–31 31–43 43–72 72–110

n.a. 63.9 63.2 61.6 53.9 55.4 56.0

n.a. 9.8 11.2 9.5 8.4 7.2 9.5

n.a. 4.6 5.1 5.5 6.7 5.5 6.5

n.a. 5.2 7.0 7.1 9.1 9.8 9.9

n.a. 0.0 0.0 0.0 0.0 0.0 0.0

n.a. 1.6 1.8 1.6 1.9 2.2 2.1

n.a. 2.2 2.5 3.0 3.1 3.3 2.4

n.a. 9.5 8.2 11.7 16.3 15.7 13.2

n.a. 0.0 0.0 0.0 0.6 0.9 0.0

n.a. 3.2 1.0 0.0 0.0 0.0 0.4

n.a. 66.7 58.0 41.3 39.3 34.6

n.a. 7.3 9.0 6.4 3.3 3.0

n.a. 6.0 5.8 6.0 4.0 3.5

n.a. 6.7 10.5 15.0 13.8 15.7

n.a. 0.0 2.8 3.4 1.4 2.1

n.a. 0.0 2.5 3.2 3.5 3.0

n.a. 2.7 3.1 2.9 3.4 2.6

n.a. 8.0 7.3 20.5 29.5 33.6

n.a. 0.0 0.0 1.3 1.8 1.9

n.a. 2.6 1.0 0.0 0.0 0.0

Storozhynets profile O 0–5 AEg 5–22 Eg 22–33 Btx 33–60 2Btg 60–100 2BCg 100–140 a

Not analyzed.

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Fig. 5. X-ray pattern of fine earth fraction (b1 mm) with internal standard (ZnO) from the fragipan (Btx1), Mysliv profile; Qtz — quartz, M — mica, Pl — plagioclases, Kf — K-feldspars, S — smectite, V — vermiculite, Chl — chlorite, K — kaolinite, M-S — mica-smectite, M-V — mica-vermiculite, M-V–S — mica-vermiculite–smectite, and Zn — zincite (internal standard).

2. The genesis of the pan is related to the translocation of clay minerals and iron hydroxides from the upper part of the soil profile and their accumulation in deeper horizons (lessivage); the process of lessivage most likely occurred on previously compacted soil material due to hydroconsolidation during the sedimentation of the parent material (loess) in periglacial climate conditions. 3. The accumulation of swelling clay minerals (smectite, mica-smectite, mica-vermiculite, and mica-vermiculite–smectite) in the illuvial horizon is responsible for the evolution of the pan in the form of vertical cracks created due to the drying and shrinking of the soil material. 4. The formation and development of bleached tongues along the cracks are linked to the infiltrating water, which washes out iron hydroxides and clay minerals; however, it is not possible to fully rule out the filling of cracks with soil material from the overlying horizon (Eg).

Fig. 6. X-ray patterns of fine clay fraction (b0.2 μm) from the fragipan (Btx1), Mysliv profile; M — mica, S — smectite, V — vermiculite, K — kaolinite, M-S — mica-smectite, and M-V — mica-vermiculite.

Acknowledgments We wish to thank Katarzyna Maj-Szeliga for the preparation of soil samples for mineralogical analysis and the separation of clay fractions. The authors also thank Karl Stahr (Editor) and the anonymous reviewers for their helpful suggestions. Language editing was done by Grzegorz Zębik.

References Aide, M., Marshaus, A., 2002. Fragipan genesis in two Alfisols in east central Missouri. Soil Sci. 167 (7), 453–464. Ajmone-Marsan, F., Torrent, J., 1989. Fragipan bonding by silica and iron oxides in a soil from northwestern Italy. Soil Sci. Soc. Am. J. 53, 1140–1145 (Madison, WI). Anderson, J.V., White, J.L., 1958. A study of fragipans in some southern Indiana soils. Soil Sci. Soc. Am. J. 22, 450–454 (Madison, WI). Assalay, A.M., Jefferson, I., Rogers, C.D.F., Smalley, I.J., 1998. Fragipan formation in loess soils: development of the Bryant hydroconsolidation hypothesis. Geoderma 83, 1–16. Bigham, J.M., Fitzpatrick, R.W., Schulze, D.G., 2002. Iron oxides. In: Dixon, J.B., Schulze, D.G. (Eds.), Soil Mineralogy With Environmental Applications. SSSA Book Ser. 7. SSSA, Madison, WI, USA, pp. 323–366. Blake, G.R., Hartge, K.H., 1986. Bulk density, In: Klute, A. (Ed.), Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods, 2nd edition. Agronomy Monograph, vol. 9. ASA-SSSA, Madison, Wisconsin, pp. 363–375. Bockheim, J.G., Hartemink, A.E., 2013. Soils with fragipans in the USA. Catena 104, 233–242. Brinkman, R., 1977. Surface-water gley soils in Bangladesz: genesis. Geoderma 17 (2), 111–144. Bryant, R.B., 1989. Physical processes of fragipan formation. In: Smeck, N.E., Ciolkosz, E.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis. SSSA Spec. Publ. 24, SSSA, Madison, Wisconsin, pp. 141–150. Certini, G., Ugolini, F.C., Taina, I., Bolla, G., Corti, G., Tescari, F., 2007. Clues of the genesis of a discontinuously distributed fragipan in the northern Apennines, Italy. Catena 69, 161–169. Ciolkosz, E.J., Waltman, W.J., Thurman, N.C., 1995. Fragipans in Pennsylvania soils. Soil Surv. Horiz. 36, 5–20. Duncan, M.M., Franzmeier, D.P., 1999. Role of free silicon, aluminum, and iron in fragipan formation. Soil Sci. Soc. Am. J. 63, 923–929 (Madison, WI). Eckmeier, E., Gerlach, R., Gehrt, E., Schmidt, M.W.I., 2007. Pedogenesis of Chernozems in Central Europe — a review. Geoderma 139, 288–299. FitzPatrick, E.A., 1984. Micromorphology of Soils. Chapman and Hall, London, New York. Franzmeier, D.P., Norton, L.D., Steinhardt, G.C., 1989. Fragipan formation in loess of the Midwestern United States. In: Smeck, N.E., Ciolkosz, E.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis. SSSA Spec. Publ. 24, SSSA, Madison, WI, pp. 69–97. Gee, G.W., Bauder, J.W., 1986. Particle-size analysis. In: Klute, A. (Ed.), Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods. 2nd Edition, vol. 9. ASA-SSSA, Madison, Wisconsin, pp. 427–445.

164

V.A. Nikorych et al. / Catena 119 (2014) 154–165

Gerenchuk, K.I., 1973. Nature of Ivano-Frankivs'k Region. High School, Lviv (168 pp. in Ukrainian). Gerenchuk, K.I., 1978. Nature of Chernivtsi Region. High School, Lviv (170 pp. in Ukrainian). Gerlach, R., Fischer, P., Eckmeier, E., Hilgers, A., 2012. Buried dark soil horizons and archaeological features in the Neolithic settlement region of the Lower Rhine area, NW Germany: formation, geochemistry and chronostratigraphy. Quat. Int. 265, 191–204. Grossman, R.B., Carlisle, F.J., 1969. Fragipan soils of the eastern United States. Adv. Agron. 29, 237–279. Gunal, H., Ransom, M.D., 2006. Clay illuviation and calcium carbonate accumulation along a precipitation gradient in Kansas. Catena 68, 59–69. Hallmark, C.T., Smeck, N.E., 1979. The effect of extractable aluminum, iron, and silicon on strength and bonding of fragipans of northeastern Ohio. Soil Sci. Soc. Am. J. 43, 145–150 (Madison, WI). Harlan, P.W., Franzmeier, D.P., Roth, C.B., 1977. Soil formation on loess in southwestern Indiana: II. Distribution of clay and free oxides and fragipan formation. Soil Sci. Soc. Am. J. 41, 99–103 (Madison, WI). Horn, M.E., Rutledge, E.M., 1965. The Dickson and Zanesville soils of Washington County, Arkansas: II. Micromorphology of their fragipans. Soil Sci. Soc. Am. J. 29, 443–448 (Madison, WI). Hsu, P.H., 1963. Effect of initial pH, phosphate, and silica on the determination of aluminum with aluminon. Soil Sci. 92, 230–238. Hutcheson Jr., T.B., Bailey, H.H., 1964. Fragipan soils: certain genetic implications. Soil Sci. Soc. Am. J. 28, 684–685 (Madison, WI). Ismail, F.T., 1969. Role of ferrous iron oxidation in the alteration of biotite and its effect on the type of clay minerals formed in soils of arid and humid regions. Am. Mineral. 54, 1460–1466. IUSS Working Group WRB, 2006. World reference base for soil resources 2006. World Soil Resources Reports No. 103. FAO, Rome. Jackson, M.L., 1969. Soil Chemical Analysis: Advanced Course. Published by the author 2nd ed. Dept. of Soil Science, Univ. of Wisconsin, Madison, Wisconsin. Jha, P.P., Cline, M.G., 1963. Morphology and genesis of a Sol Brun Acide with fragipan in uniform silty material. Soil Sci. Soc. Am. J. 27, 339–344 (Madison, WI). Karathanasis, A.D., 1987. Thermodynamic evaluation of amorphous aluminosilicate binding agents in fragipans of western Kentucky. Soil Sci. Soc. Am. J. 51, 819–824 (Madison, WI). Karathanasis, A.D., 1989. Solution chemistry of fragipans — thermodynamic approach to understanding fragipan formation. In: Smeck, N.E., Ciolkosz, E,.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis. SSSA Spec. Publ. 24, SSSA, Madison, WI, pp. 113–139. Klimaszewski, M., 1967. The Polish Western Carpathians in Quaternary period. In: Galon, R., Dylik, J. (Eds.), Quaternary of Poland. PWN, Warszawa, pp. 431–497 (in Polish). Knox, E.G., 1957. Fragipan horizons in New York soils: III. The basis of rigidity. Soil Sci. Soc. Am. J. 21, 326–330 (Madison, WI). Kühn, P., 2003. Micromorphology and Late Glacial/Holocene genesis of Luvisols in Mecklenburg–Vorpommern (NE-Germany). Catena 54, 537–555. Kühn, P., Billwitz, K., Bauriegel, A., Kühn, D., Eckelmann, W., 2006. Distribution and genesis of Fahlerden (Albeluvisols) in Germany. J. Plant Nutr. Soil Sci. 169, 420–433. Lindbo, D.L., Rhoton, F.E., 1996. Slaking in fragipan and argillic horizons. Soil Sci. Soc. Am. J. 60, 552–554 (Madison, WI). Lindbo, D.L., Veneman, P.L.M., 1989. Fragipans in the northeastern United States. In: Smeck, N.E., Ciolkosz, E.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis. SSSA Spec. Publ. 24, SSSA, Madison, WI, pp. 11–31. Lindbo, D.L., Veneman, P.L.M., 1993. Micromorphology of selected Massachusetts fragipan soils. Soil Sci. Soc. Am. J. 57, 437–442 (Madison, Wisconsin). Lindbo, D.L., Rhoton, F.E., Bigham, J.M., Hudnall, W.H., Jones, F.S., Smeck, N.E., Tyler, D.D., 1994. Bulk density and fragipan identification in loess soils of the Lower Mississippi River Valley. Soil Sci. Soc. Am. J. 58, 884–891 (Madison, Wisconsin). Lindbo, D.L., Rhoton, F.E., Bigham, J.M., Hudnall, W.H., Jones, F.S., Smeck, N.E., Tyler, D.D., 1995. Loess toposequences in the Lower Mississippi River Valley: I. Fragipan morphology and identification. Soil Sci. Soc. Am. J. 59, 487–500 (Madison, WI). Lindbo, D.L., Rhoton, F.E., Hudnall, W.H., Smeck, N.E., Bigham, J.M., Tyler, D.D., 2000. Fragipan degradation and nodule formation in Glossic Fragiudalfs of the Lower Mississippi River Valley. Soil Sci. Soc. Am. J. 64, 1713–1722 (Madison, Wisconsin). Lindbo, D.L., Stolt, M.H., Vepraskas, M.J., 2010. Redoximorphic features. In: Stoops, G., Marcelino, V., Mees, F. (Eds.), Interpretation of Micromorphological Features of Soils and Regoliths. Elsevier, Amsterdam, the Netherlands, pp. 129–147. Maruszczak, H., 2000. Definition and classification of loess and loess-like sediments. Prz. Geol. 48, 580–586 (in Polish). McDaniel, P.A., Buol, S.W., 1991. Manganese distributions in acid soils of the North Carolina Piedmont. Soil Sci. Soc. Am. J. 55, 152–158. Miller, F.P., Wilding, L.P., Holowaychuk, N., 1971. Canfield silt loam, a Fragiudalf: II. Micromorphology, physical, and chemical properties. Soil Sci. Soc. Am. J. 35, 324–331 (Madison, WI). Mystkowski, K., 1999. ClayLab, a computer program for processing and interpretation of X-ray diffractograms of clays. Conference of European Clay Groups Association, EUROCLAY 1999, Book of abstracts, Kraków, Poland, pp. 114–115. National Atlas of Ukraine, 2007. By Kartohrafiia. Kyiv, Kartohrafiia 166–172 (in Ukrainian). Nelson, D.W., Sommers, L.E., 1996. Total carbon, organic carbon, and organic matter. In: Sparks, D.L., et al. (Eds.), Methods of Soil Analysis. Part 3. Chemical Methods — SSSA Book Series. , vol. 5. SSSA and ASA, Madison, Wisconsin, pp. 961–1010. Nesteruk, Y., 2000. Plants of the Ukrainian Carpathians: Illustrated Guidebook. Polly CO. LTD., Lviv. Nettleton, W.D., McCracken, R.J., Daniels, R.B., 1968. Two North Carolina Coastal Plain catenas: II. Micromorphology, composition and fragipan genesis. Soil Sci. Soc. Am. J. 32, 582–587 (Madison, WI).

Nikorych, V.A., Polchyna, S.M., Szymański, W., Skiba, S., 2013. Variations of the morphogenetic features of the Precarpathian's brownish-podzolic soils (Albeluvisols) depending on the biogeocenosis type. Ecol. Noosferol. (Ecol. Noospherol.) 24 (3–4), 24–41 (in Ukrainian). Norfleet, M.L., Karathanasis, A.D., 1996. Some physical and chemical factors contributing to fragipan strength in Kentucky soils. Geoderma 71, 289–301. Norton, L.D., Franzmeier, D.P., 1978. Toposequences of loess-derived soils in southwestern Indiana. Soil Sci. Soc. Am. J. 42, 622–627 (Madison, WI). Payton, R.W., 1993. Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north-east England. II. Post Devensian developmental processes and the origin of fragipan consistence. J. Soil Sci. 44, 703–723. Polchyna, S.M., 2012. The heterogeneity of profile-differentiated gleyed soils of the Precarpathians. Biol. Syst. 4 (2), 197–201 (in Ukrainian). Quénard, L., Samouëlian, A., Laroche, B., Cornu, S., 2011. Lessivage as a major process of soil formation: a revisitation of existing data. Geoderma 167–168, 135–147. Rampelberg, S., Van der Aa, B., Deckers, J., 1997. Soil morphology and soil water regime of loess soils under oak in the Meerdaal Forest, Belgium. Agric. For. Meteorol. 84, 51–59. Ranney, R.W., Ciolkosz, E.J., Cunningham, R.L., Petersen, G.W., Matelski, R.P., 1975. Fragipans in Pennsylvania soils: properties of bleached prisms face materials. Soil Sci. Soc. Am. Proc. 39/4, 695–698. Rhoton, F.E., Bigham, J.M., Schulze, D.G., 1993. Properties of iron-manganese nodules from a sequence of eroded fragipan soils. Soil Sci. Soc. Am. J. 57, 1386–1392 (Madison, WI). Sauer, D., Schülli-Maurer, I., Sperstad, R., Sørensen, R., 2013. Micromorphological characteristics reflecting soil-forming processes during Albeluvisol development in S Norway. Span. J. Soil Sci. 3 (2), 38–58. Scalenghe, R., Certini, G., Corti, G., Zanini, E., Ugolini, F.C., 2004. Segregated ice and liquefaction effects on compaction of fragipans. Soil Sci. Soc. Am. J. 68, 204–214 (Madison, Wisconsin). Schwertmann, U., Fanning, D.S., 1976. Iron–manganese concretions in hydrosequences of soils in loess in Bavaria. Soil Sci. Soc. Am. J. 40, 731–738. Seta, A.K., Karathanasis, A.D., 1996. Water dispersible colloids and factors influencing their dispersibility from soil aggregates. Geoderma 74, 255–266. Seta, A.K., Karathanasis, A.D., 1997. Stability and transportability of water-dispersible soil colloids. Soil Sci. Soc. Am. J. 61, 604–611 (Madison, Wisconsin). Smeck, N.E., Thompson, M.L., Norton, L.D., Shipitalo, M.J., 1989. Weathering discontinuities: a key to fragipan formation. In: Smeck, N.E., Ciolkosz, E.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis. SSSA Spec. Publ. 24, SSSA, Madison, WI, pp. 99–112. Soil Survey Staff, 2010. Keys to Soil Taxonomy, 11th ed. USDA-NRCS, Washington, DC. Środoń, J., 2006. Identification and quantitative analysis of clay minerals. In: Bergaya, F., et al. (Eds.), Handbook of Clay Science. Elsevier, Amsterdam, pp. 765–787. Steinhardt, G.C., Franzmeier, D.P., 1979. Chemical and mineralogical properties of the fragipans of the Cincinnati catena. Soil Sci. Soc. Am. J. 43, 1008–1013 (Madison, WI). Steinhardt, G.C., Franzmeier, D.P., Norton, L.D., 1982. Silica associated with fragipan and non-fragipan horizons. Soil Sci. Soc. Am. J. 46, 656–657 (Madison, WI). Stoops, G., 2003. Guidelines for Analysis and Description of Soil and Regolith Thin Section. Soil Sci. Soc. Am., INC., Madison, WI. Summer, M.E., 1992. Determination of exchangeable acidity and exchangeable Al using 1 N KCl. In: Donohue, S.J. (Ed.), Reference Soil and Media Diagnostic Procedures for the Southern Region of the U.S., Southern Cooperative Series Bulletin No. 374, Blacksburg, VA, pp. 41–42. Szymański, W., Skiba, S., 2011. Micromorphological properties of the fragipan horizon in Albeluvisols of the Carpathian Foothills. Pol. J. Soil Sci. XLIV (2), 193–200. Szymański, W., Skiba, M., 2013. Distribution, morphology, and chemical composition of Fe–Mn nodules in Albeluvisols of the Carpathian Foothills, Poland. Pedosphere 23 (4), 445–454. Szymański, W., Skiba, M., Skiba, S., 2011. Fragipan horizon degradation and bleached tongues formation in Albeluvisols of the Carpathian Foothills, Poland. Geoderma 167–168, 340–350. Szymański, W., Skiba, M., Skiba, S., 2012. Origin of reversible cementation and brittleness of the fragipan horizon in Albeluvisols of the Carpathian Foothills, Poland. Catena 99, 66–74. Taut, T., Kleeberg, R., Bergmann, J., 1998. The new Seifert Rietveld Program BGMN and its application to quantitative phase analysis. Mater. Struct. 5 (1), 57–64. Thomas, G.W., 1996. Soil pH and soil acidity. In: Sparks, D.L., et al. (Eds.), Methods of Soil Analysis. Part 3. Chemical Methods — SSSA Book Series. , vol. 5. SSSA and ASA, Madison, Wisconsin, pp. 475–490. Tornes, L.A., Miller, K.E., Gerken, J.C., Smeck, N.E., 2000. Distribution of soils in Ohio that are described with fractured substratums in unconsolidated materials. Ohio J. Sci. 3/4, 56–62. Uziak, S., 1962. Typology of Some Silty Soils of the Carpathian Foothills. Sec. B. Ann. UMCS XXX, 1–60 (in Polish). Van Reeuwijk, L.P., 2002. Procedures for soil analysis. Technical Paper 9. ISRIC, Wageningen. Van Vliet, B., Langohr, R., 1981. Correlation between fragipans and permafrost with special reference to silty Weichselian deposits in Belgium and northern France. Catena 8, 137–154. Vepraskas, M.J., 1994. Redoximorphic features for identifying aquic conditions. Tech. Bull., 301. North Carolina Agric. Res. Serv., North Carolina State Univ, Raleigh. Weisenborn, B.N., Schaetzl, R.J., 2005a. Range of fragipan expression in some Michigan soils: I. Morphological, micromorphological, and pedogenic characterization. Soil Sci. Soc. Am. J. 69, 168–177 (Madison, Wisconsin). Weisenborn, B.N., Schaetzl, R.J., 2005b. Range of fragipan expression in some Michigan soils: II. A model for fragipan evolution. Soil Sci. Soc. Am. J. 69, 178–187 (Madison, Wisconsin).

V.A. Nikorych et al. / Catena 119 (2014) 154–165 Wilson, M.J., 2004. Weathering of the primary rock-forming minerals: processes, products and rates. Clay Miner. 39, 233–266. Witty, J.E., Knox, E.G., 1989. Identification, role in soil taxonomy and worldwide distribution of fragipans. In: Smeck, N.E., Ciolkosz, E.J. (Eds.), Fragipans: Their Occurrence, Classification and Genesis, SSSA Spec. Publ. 24. SSSA, Madison, Wisconsin, pp. 1–9. Yassoglou, N.J., Whiteside, E.P., 1960. Morphology and genesis of some soils containing fragipans in northern Michigan. Soil Sci. Soc. Am. J. 24, 396–407 (Madison, WI).

165

Zasoński, S., 1983. Main soil-forming processes in silty deposits of the Wielickie Foothills. Part II. Micromorphological properties. Roczn. Glebozn. XXXIV (4), 123–159 (Warszawa, in Polish). Zasoński, S., 1992. Micromorphological properties of silty soils of the Krosno Valley. Zesz. Nauk. Ar. 265 (30), 19–33 (Kraków, in Polish). Zhang, M., Karathanasis, A.D., 1997. Characterization of iron–manganese concretions in Kentucky Alfisols with perched water tables. Clay Clay Miner. 45 (3), 428–439.