Formation Of Vertisols Research Articles

Climatically-driven cyclicity and peat formation in fluvial setting of the Moscovian – Early Kasimovian Cracow Sandstone Series, Upper Silesia (Poland)

The approximately 1200 m thick Cracow Sandstone Series (Middle – early Late Pennsylvanian) in the Polish part of the Upper Silesian Coal Basin consists of 25–70 m thick fining up and laterally widespread fluvial cycles. The cycles are marked by alternating sheet-like sandstone bodies overlain by much thinner intervals dominated by mudstone and coal. These two-member cycles record the alternation of a sand-dominated fluvial braidplain and floodplain-dominated fluvial system with channels confined to narrow belts. The lateral persistence, internal architecture, and isochronous alternations suggest an allogenic origin for the cycles, possibly related to climate. This interpretation is supported by a three-stage evolution of pedogenic processes operating on floodplain deposits beginning with the formation of vertisols, followed later by gleying and, finally, termination by a Histosol (peat) formation. Such a succession of paleosols indicates a climatic shift from highly seasonal (Vertisol) to humid climate (coal) with the most seasonal part of the cycle likely represented by the sheet-like sandbody. The mechanistic link between climate and the cyclic pattern of strata is explained as climatically-driven variations in clastic supply, which was highest during periods of prominent seasonality. Short-term climatic oscillations generating cyclic patterns in the Cracow Sandstone Series are superimposed on a long-term climatic shift towards increased seasonality near the Middle – Late Pennsylvanian boundary. This is evidenced by the termination of peat formation in the Upper Silesian Basin as well as in some other coeval basins of the equatorial Pangea and is interpreted to represent a potentially regional climatic event.

The Schilfsandstein and its flora; arguments for a humid mid-Carnian episode?

Recently intensified research on the mid-Carnian episode stimulated discussions about the mid-Carnian climate and a supposed humid climate shift. This basin-scale study on the Schilfsandstein, the type-example of the mid-Carnian episode, applied sedimentological, palynological and palaeobotanical proxies of the palaeoclimate to a large dataset of cored wells and outcrops. The results demonstrate the primary control of circum-Tethyan eustatic cycles on the Central European Basin where transgressions contributed to basin-scale facies shifts. The palaeoclimate proxies point to a uniform arid to semi-arid Carnian climate with low chemical weathering and high evaporation. Consequently, transgressions into the Central European Basin led to increased evaporation forcing the hydrological cycle. The increased runoff from source areas resulted in high-groundwater stages on lowlands characterized by hydromorphic palaeosols and intrazonal vegetation with hygrophytic elements. During lowstands, reduced evaporation and runoff led to increased drainage and desiccation of lowlands characterized by formation of vertisols, calcisols and gypsisols and zonal vegetation with xerophytic elements. The proposed model of sea-level control on the hydrological cycle integrates coeval and subsequent occurrences of wet and dry lowlands, hydromorphic and well-drained palaeosols, and intrazonal and zonal vegetations. Thus, the Schilfsandstein does not provide arguments for a humid mid-Carnian episode. Supplementary material: Datasets of Palynomorph Eco Group (PEG) and Macroplant Eco Group (MEG) analyses are available at https://doi.org/10.6084/m9.figshare.c.4182593

Rock-magnetic and geochemical characteristics of relict Vertisols—signs of past climate and recent pedogenic development

Rock-magnetic and geochemical characteristics of three Vertisol profiles with different degree of textural differentiation have been studied. Thermomagnetic analyses, thermal demagnetization of laboratory remanences and acquisition of isothermal remanence curves are applied for identification of iron oxide mineralogy. The main magnetic minerals in Vertisols are ferrihydrite, single-domain magnetite, maghemite and hematite. Variations in magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization, as well as different ratios (Xarm/X, ARM/SIRM, S-ratio) along depth are studied. Concentration of magnetic minerals in Vertisols is low, influenced by the intense reductomorphic processes. The lowest magnetic susceptibility is found in the most texturally differentiated soil. However, rock-magnetic data suggest the presence of small, but well defined fraction of single domain-like magnetite with relatively wide grain-size distribution found in those parts of the profiles, which are subjected to most intense and frequent seasonal changes in oxidation-reduction conditions. It is suggested that this fraction is formed as a result of transformations of ferrihydrite under repeated cycles of anaerobic/aerobic conditions. Based on geochemical data, CALMAG weathering index was calculated for the three Vertisols. Using the established relation between CALMAG and mean annual precipitation (MAP), palaeo-MAP was evaluated for the studied profiles. The obtained MAP estimations fall in the range 1000–1200 mm and are much higher compared to contemporary precipitation in the area (MAP in the interval 540–770 mm). This finding confirms the relict character of Vertisols on Bulgarian territory and gives more information about the palaeoclimate during the initial stages of Vertisol formation.

Paleoenvironment and Human Occupation in the Maya Lowlands of the Usumacinta River, Southern Mexico

Paleosol sequences along the lowest terraces of the Usumacinta River in southern Mexico were used to reconstruct Holocene environmental changes and examine human–environmental interactions. Study sections were correlated through paleosol morphology, radiocarbon dating, and artifact seriation of Formative, Classic, and Postclassic ceramics. The oldest paleosols have gleyic features. Although they contain hard carbonate concretions dating to 5450–5380 cal. yr B.P., these Gleysols formed in the Late Pleistocene to Early Holocene. Carbonates were deposited later. The uppermost paleosols lack gleyic features, the oldest of which contains vertic features, dating to 2000–2700 cal. yr B.P., and contains abundant Formative period ceramics. The upper two paleosols are morphologically less developed and are strongly affected by human activities; radiocarbon ages and ceramic assemblages indicate that they belong to the Maya Classic and Postclassic periods. Stable carbon isotope values from the decalcified organic matter vary among paleosols of different ages and sites. δ13C values are highest (−16 to −20‰) in the Formative period paleosol. Although it is possible that maize cultivation could contribute to the isotopic signatures, we believe that the δ13C values indicate the dominance of drought‐resistant C4 and CAM vegetation due to their association with vertic soils. The Classic period paleosol has a slightly lower isotopic value (−20 to −22‰), while the Postclassic paleosol shows the lowest values (−22 to −23‰), suggesting reforestation of the floodplain. These results indicate that the Early Holocene paleosols formed in a humid climate similar to that of today, which transitions toward dryer conditions around 5500 cal. yr B.P. In the Late Holocene (approximately 3000 B.P.) an increase in seasonality occurs. This condition favored the formation of Vertisols, suitable for agriculture.

Hydropedological model of vertisol formation along the Gulf Coast Prairie land resource area of Texas

Abstract. Vertisols are clayey soils containing slickensides and wedge-shaped aggregates formed by shrink-swell processes in seasonally wet climates. The dynamic distribution of macro- and microvoids as a by-product of this unique pedoturbation process, accompanied by microtopographic lows and highs (gilgai), mitigate our ability to make accurate and precise interpretations of aquic and hydric conditions in these problem soils. We studied Vertisols across a subhumid to humid climosequence to assess the formation of redoximorphic features on shallow, linear (nondepressional) landscape positions in response to varying levels of rainfall. Approximately 1000 mm of mean annual precipitation (MAP) is required to form soft iron masses that then increase in abundance, and to shallower depths, with increasing rainfall. Soft iron masses with diffuse boundaries become more abundant with higher rainfall in microlows, whereas masses with nondiffuse boundaries become more common in microhighs. Most soft iron masses form in oxygenated ped interiors as water first saturates and then reduces void walls where iron depletions form. In contrast, at least 1276 mm of MAP is needed to form iron pore linings in both microlow and microhigh topographic positions. Iron depletions do not correlate with rainfall in terms of abundance or depth of occurrence. The quantity of crayfish burrows co-varies with rainfall and first appears coincidentally with soft iron masses in microlows near 1000 mm of MAP; they do not appear until nearly 1400 mm of MAP in microhighs. Dithionite-citrate extractable and ammonium-oxalate extractable iron oxides increase systematically with rainfall indicating more frequent episodes of iron reduction and precipitation into pedogenic segregations. The sum of our data suggests that Vertisols forming in the Coast Prairie of Texas with MAP greater than 1276 mm should be classified as aquerts because of the presence of aquic conditions. These same soils may also meet the definition of hydric as one criterion for the identification of Federally-protected wetlands. However, there is a considerable disjunct between protracted periods of saturation and limited periods of reduction in these soils. Based on the distribution of redoximorphic features in the study area, regional water table data, and recent electrical resistivity data from a nearby upland Vertisol, non-Darcian bypass flow is the principle mechanism governing the flux of water through deep cracks where water first accumulates and then persists in microlow bowls at depths of 1 to 2 m.

Significance of the Formation of Calcium Carbonate Minerals in the Pedogenesis and Management of Cracking Clay Soils (Vertisols) of India

AbstractMicromorphological studies were performed in order to understand the factors and processes involved in the formation of calcium carbonate (CaCO3) in twenty three soil series of Vertisols representing sub-humid, semi-arid and arid climatic regions of Peninsular India. The study indicates that Vertisols contain both pedogenic calcium carbonate (PC) and non-pedogenic calcium carbonate (NPC) irrespective of the ecosystems to which they belong. The NPCs are part of the parent material of Vertisols. Dissolution of NPCs and recrystallization of dissolved Ca2+ ions are responsible for the formation of PCs. Vertisols of arid and semi-arid climates contain more PC in their soil control section (SCS) than those of sub-humid climates. Formation of PC is the prime chemical reaction responsible for the increase in pH, the decrease in the Ca/Mg ratio of exchange site with depth and in the development of subsoil sodicity. Petrographic and scanning electron microscopic (SEM) examination of quartz, feldspars and micas indicate little or no alteration, discounting the possibile formation of smectite during Vertisol formation. X-ray diffraction (XRD) analysis of clays indicates that smectites of Vertisols are fairly well crystallized and do not show any sign of transformation except for hydroxy interlayering. The preservation of the crystallinity of smectite and the lack of transformation of primary minerals thus validate the hypothesis of positive entropy change during the formation of Vertisols.The precise cause-effect relationship between CaCO3 of pedogenic and non-pedogenic origin, and exchangeable Mg, Na and Ca percentages (EMP, ESP and ECP) has been established in the study. This indicates that impoverishment of Ca2+ ions on the exchange sites of Vertisols needs to be controlled by rehabilitation methods that can replenish Ca2+ ions, and thus the study provides relevant information for future land resource management programmes not only on Vertisols of India but also on similar soils occurring elsewhere.

Closed basins and Vertisol formation in the rincon lagoon (Andalusia, Spain)

A study was made of the genetic relationship between the geomorphological phenomenon of closed basins and Vertisol formation in an area of Southern Spain. The lithology of the area, the low erosive power of the drainage system and the semi-arid climate are factors which favour the seasonal hydromorphism responsible for the evolution of original material into Vertisols. Depth dissolution of Keuper saline materials gives rise to the creation of basins, where water accumulates, forming laggons. Although El Rincón lagoon is now a closed basin, in the past it formed part of a larger lacustrine area which to a great extent gave rise to the blackening of the soils.

Genesis of a So‐called Ferrolysed Soil of Bangladesh

AbstractIt was postulated by Brinkman (1970) that low clay contents in the surface horizon of paddy soils (Planosols) are caused by clay destruction through ferrolysis. In an effort to test this, a rice profile from the site of Brinkman's Eutric Planosol (Salna, Bangladesh) and a neighbouring forest soil (Dystric Cambisol) of the same parent material and particle‐size distribution (Bhawal National Park) were investigated. The micro‐structure, particle‐size distribution, mineral contents, pedogenic oxides, contents of Zr, Ti and K of the fine earth and individual fractions and also the exchangeable ions were studied.The clay fraction of both soils were chloritised by interlaying of hydroxy‐Al in the smectite interlayers in the surface horizons and got stabilized. As a result CEC showed some decrease. The forest profile has a loose and uniform brown‐yellow surface horizon and is relatively rich in coarse sand at 62–75 cm depth which might be caused by a strong termite activity as observed during sampling. On the contrary, the frequent and alternate reducing and oxidizing conditions have resulted in gleying the top soil and forming iron‐oxide films on the surface of aggregates during dry periods in the paddy soil.An evaluation of all results shows that a little clay destruction and an enrichment of silt in the top soil through vertisol formation and also through primary parent material stratification were the reasons for low clay content in epipedons. In forest soil there was a little clay migration, while the epipedon of the paddy soil had low clay in addition, because of selective erosion during heavy rains following the destruction of structure by puddling.The ferrolysis as a dominant factor for a clay‐low epipedon is improbable, because the clay loss of the neighbouring forest soil can not be explained by ferrolysis.

Surface-water gley soils in Bangladesh: Genesis

Extensive areas of periodically wet, acid soils in Bangladesh have a seasonally fluctuating pH of the surface horizon and evidence for net clay loss. Morphological, chemical, mineralogical and other data mainly on a typical profile of these surface-water gley soils indicate a clay loss of some 1.5 kg/dm' ; alteration of smectite to a soil chlorite, interlayered material with trapped ferrous iron; the consequent drop in C.E.C. of the clay fraction; and the presence of amorphous silica. The data were used to reconstruct a sequence of three soil forming processes: Vertisol formation, then argilluviation, followed by ferrolysis. Ferrolysis involves, in the wet season: reduction producing ferrous iron, which displaces part of the exchangeable basic cations and aluminium; leaching of bases and part of the aluminium; and interlayer formation by the remaining aluminium while some exchangeable ferrous iron is trapped in the interlayers. In the dry season, oxidation of exchangeable ferrous iron produces exchangeable hydrogen, part of which attacks the clay minerals and is neutralized by liberation of Al, Mg and other ions from the clay structure. Part of the silica remaining from the clay structure is leached out in the next wet season, part accumulates in amorphous form. In soils long used for paddy cultivation, man has concentrated the ferrolysis process in the ploughed layer by the formation of a slowly permeable ploughpan causing strong reduction only in the surface horizon. The hydromorphic albic horizon over more clayey material is indicative of the dominant process in surface-water gley soils. This sequum could usefully have a more important place in soil classification than it has at present, e.g. at great group level.