|
Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.paleopedology.msu.ru/nl-13/abstracts.html
Дата изменения: Mon Nov 26 14:32:32 2007 Дата индексирования: Mon Oct 1 19:55:27 2012 Кодировка: Поисковые слова: orange soil |
V.M. Alifanov, L.A. Gugalinskaya, Institute of Soil Science and Photosynthesis RAS, Pushchino, Moscow oblast
Paleocryogenesis existed during the whole Pleistocene, and was studied most thoroughly in soils of Mikulino interglacial (140-110 000 years ago) of the Briansk warm epoch (25 000 years ago) and of the final stage of the Valday Glaciation (Late Glacial, 15-10 000 years ago).
The Late Pleistocene loess-like loams sequence in the centre of the Russian Plain comprises two distinct paleosols: Mikulino interglacial (Mezen, Eems, Sangamon) and Briansk interstadial (Middle Valday, Denekampf, Farmdale). Both soils preserved the majority of morphological, micromorphological, chemical and other properties, f.i. clay and humus content, CEC, pH, etc. Well preserved were also features of soil cryomorphism.
Macromorphological paleocryogenic features of Mikulino and Bryansk paleosols were categorised into destructive (evidences of cracking, solifluction) and constructive (cryogenic aggregation).
Micromorphological evidences of paleocryogenesis are the following:
During the final stage of Valday glaciation the paleocryogenic processes were active, so that in recent soils their imprints are recognised. These are:
Paleocryogenesis features are extremely diverse in age as well. The analysis of paleocryogenesis in soils facilitated the solution of soil-historical, soil-evolutionary, soil-environmental problems concerning the nature evolution.
Becze-Deak J. and R. Langohr, International Training Centre for Post-Graduate Soil Scientists, University of Gent, Krijgslaan 281/S8, B-9000 Gent, Belgium
The Last Interglacial soil-sedimentary complex of the Wallertheim site is famous for it's rich Middle Palaeolithic bone and artefact finds. The section is situated at the contact between the alluvial plain and the neighbouring hills and it is composed of alternating more clayey and more silty sediments reflecting the complexity of processes acting at the edge of an alluvial plain. The soil-sedimentary complex studied here shows evidences of an aggradating alluvial plain with vegetation cover.
Careful field observations showed that close to the end of the alluvial sedimentation the soil-sedimentary complex has undergone a very severe frost action, including most probably a short lasting permafrost. The freezing in these fine textured material resulted in a structuration that deleted many of the former soil characteristics, such as the original structure and bioporosity.
The macro-, meso- and micromorphological study shows that there are 3 types of accumulations which can be related to the frost action in this studied complex: 1. Iron hypocoatings occur on the ped faces created by the frost in the upper part of the complex. EDXRA (energy dispersive X-ray analyses) studies show that these hypocoatings have high phosphorus content. In the iron depleted soil matrix no measurable amount of phosphorus could be detected. In the studied complex, known as an important Neanderthal butchering site and with evidences of animal puddling, the source of phosphorus is most probably related with animal excrements. Deeper in the complex similar iron hypocoatings and coatings have been observed along the horizontal frost fissures and pores preserved from before the frost action. 2. Manganese coatings are common in the deeper, but still frost affected part of the soil-sedimentary complex. They are associated with the above mentioned iron accumulations and show a framboidal morphology. 3. In the Eastern part of the excavation 1-2 cm thick vertical cracks filled with CaCO3 are present. In horizontal section these cracks show a polygonal pattern. According to the pedochronostratigraphy these cracks are subsequent to the above described frost action. At the microscale these accumulations are composed of micritic hypocoatings and infillings of several parallel microfissures. The fact that the CaCO3 accumulation in this noncalcareous part of the soil-sedimentary complex is only associated with these cracks indicates that most probably the precipitation occurred along the repeated ice segregation planes now represented by the microfissures.
The described accumulations being related to the pedality and porosity created by frost it is concluded that possibly they have been precipitated at the moment when the soil solution was freezing.
* Research funded by the SC-004 Project of the Federal Services for Scientific matters, Belgian State Science Policy Programming and the Belgian National Science Foundation.
Becze-Deak J., Langohr R., International Training Centre for Post-Graduate Soil Scientists, Univ. of Gent, Krijgslaan 281/S8, B-9000 Gent, Belgium
The seondary carbonates studied here belong to the Last Interglacial and Early Glacial soil-sedimentary complexes of the Wallertheim site.
The Last Interglacial soil-sedimentary complex of the Wallertheim site is situated at the contact between the alluvial plain and the neighbouring hills. The sediments of the alluvial plain consist of an alternation of more clayey, non-calcareous and more silty, calcareous sediments, reflecting the complexity of the processes at the edge of the alluvial plain. In this sequence several morphological forms of secondary carbonates ranging from weak hypocoatings to rough up to 10 cm large nodules have been recorded and sampled in the field. According to the field observations there is a gradient in the vertical and lateral distribution of the various forms of carbonates. The accumulations are composed of micritic impregnation of the matrix and of micritic coatings and infillings of the pores. They all show a rather similar orange red cathodoluminescence, with more brighter orange colours towards the pores and in the younger chronostratigraphical units. It is concluded that the various accumulations are precipitated from the fluctuating calcareous ground water table, in a climate with alternation of pronounced wet and dry season. Moreover their vertical and lateral distribution can be used as indicators of the geomorphological dynamics of the alluvial plain and of the intensity of the water table fluctuation.
The Early Glacial soil-sedimentary complex of the Wallertheim site consists of 2-2.5 meter humiferous material with several levels of 2-3 cm thick CaCO3 cemented, hard layers. Beside the cemented layers common, irregular, 2-10 cm large, hard, CaCO3 cemented nodules have been observed all through the complex. Some of these accumulations clearly resemble fauna galleries. The macro-, meso- and micromorphology combined with the cathodoluminescence observations suggest that the calcium carbonate cemented plates correspond to levels of higher calcareous fragments concentration. Moreover the micromorphological study indicates that the irregular nodules are very similar to the cemented plates. It is concluded that the CaCO3 cemented layers and irregular nodules are syngenetic with the evolution of the soil-sedimentary complex. They formed at the surface during a climate with pronounced and prolonged dry season, when the very little available moisture was only able for local redistribution of the CaCO3. This is also confirmed by the pores resembling gypsum rosettes infilled by subsequent sparitic crystals. While the cemented layers could be formed due to the exceptional concentration of the CaCO3 rich fragments, the irregular nodules are most probably representing fauna galleries, where animals were concentrating calcareous fragments.
The presented examples are clear evidences that the study of the morphological forms of secondary carbonates and the associated soil characteristics, as well as the study of the presence-absence of these items is a potential tool for environmental reconstruction.
* Research funded by the SC-004 Project of the Federal Services for Scientific matters, Belgian State Science Policy Programming and the Belgian National Science Foundation.
Ye. K. Bobrova, A.A. Bobrov, Faculty of Soil Science, Moscow State University
As a result of investigations of phytoliths in 72 plant species in Russia and Ukraine, more than 40 specific morphologic forms of silica were identified in plant cells. More individual in terms of their phytoliths spectra are sedges, cereals and coniferous species. Diagnostic importance of phytoliths in nemoral vegetation proved to be insignificant. The comparison of phytoliths morphology and data of cluster analysis permitted to specify several groups of sedges and cereals with similar phytoliths spectra. They may be recognised at both intra- and inter-genera levels.
In the sequence of soils on various soil forming rocks with different amounts of phytoliths the brown forest and dark coloured soils (Cambisols and Phaeozems) of Sikhote-Alin' mountains were the first (12% of the fine earth weight). The last were sandy soils - 0.6% of phytoliths.
The content of phytoliths in 0-2cm layer of the rehabilitated soils on mantle loams approaches that in sod-podzolic (Podzoluvisols) under primary southern taiga spruce forests already in the first 20-30 years. Most active is the process of phytoliths accumulation in semi-hydromorphic soils under artificial meadows, formed in the course of phyto-rehabilitation of lands.
Cluster Analysis of Phytoliths Spectra in Soils with Buried Horizons Indicates Shifts in Biogeocenoses Pattern During the Evolution History of Sikhote-Alin' Mountainous Soils. The Development of Recently Buried Horizon Proceeded Under the Canopy of Mixed Forest.
Paleosols in burial mounds in Samara-Orel' interfluve (Ukraine), formed at the boundary of Atlantic and Subboreal periods, correspond to ordinary and southern chernozems (Haplic and Calcic Chernozems, respectively) in terms of their phytoliths characteristics (data of comparative analysis with the cluster analysis applied). The second humus horizons of grey forest soils (Greyzems) of Vladimir opol'ie are conspicuous by their high amount of phytoliths (more than 5% of the fine earth) and by their broad spectrum (above 20 forms of sedges and cereals forms). Hence, we assume that the phytolith characteristics of these soils is one more argument in favour of the semi-hydromorphic stage (cereal-herbaceous vegetation) in their long history.
A.BRONGER1 AND S.N.SEDOV2, 1 Department of Geography, University of Kiel, Germany, 2 Department of Soil Science, Moscow Lomonosov University
Selected Terrae rossae of Rhodoxeralfs from calcarenites in all probability of Mid-Pleistocene age along Atlantic coast of Morocco show a considerable to extensive formation of clay minerals especially of kaolinites. Main sources of pedogenic formed kaolinites, mostly of disordered structure and poor crystallinity, are primary feldspars (> 2 m) and smectites (2-0.2 and <0.2 m) inherited from the calcarenites as the parent material although some eolian input is not excluded.
However, there are not enough weatherable minerals in sand and silt fractions including inherited smectites in the clay fractions to explain quantitatively the rate of clay increase by weathering in situ only. To explain the differences in clay mineral content by clay illuviation meet some difficulties; first, almost no well developed or aged illuviation argillans are visible in the Bt horizons of the majority of profiles. However, illuviation argillans are visible in the Bck horizons covering carbonates as unstable surfaces in the "typic xeric" soil moisture regime with still some water surplus in the first 3-3,5 months of the year (station Rabat). With deepening of the leaching front former illuviation argillans might be destroyed, only the "youngest" generation in present Bck horizon is visible. Additional possibilities of destruction of illuviation argillans are argilli pedoturbation, indicated by stress cutans and bioturbation seen e.g. by areas with crescent striated fabric (1). Second, an eluvial horizon is mostly absent. For this soil erosion seems to be responsible, as well as for patchy distribution of Terrae Rossae, as a result of land degradation mainly due to human activity which is still grossly underestimated in comparison with climatic variations in this area.
In areas more to the southwest with a "dry xeric" if not already "aridic" soil moisture regime only very few illuviation argillans can be seen in upper part of Terrae Rossae if any, but never in Bck horizons. Secondary carbonates can be seen already in rubefied Bt horizons.
(1) Stoops, G. 1983. Micromorphology of the oxic horizon. In: Bullock, P. and Murphy, C.P.
(Ed.) Soil Micromorphology, v.2, Soil Genesis, A B Academic Publishers, p. 419-440.
Richard T. BUSH AB and Leigh A. SULLIVAN B, A School of Geography, University of New South Wales, Sydney NSW 2052, Australia, B Resource Science and Management, Southern Cross University, Lismore NSW 2480, Australia
The mineral pyrite (FeS2) is common in coastal floodplain sediments deposited under estuarine conditions. Waterlogged pyrite remains stable, but when pyritic sediments are drained or excavated, it rapidly oxidises liberating sulfuric acid and iron. Once oxidized these sediments remain extremely acidic (ie. pH<3) for tens of years, affecting crop and pasture production and providing a source of toxic leachate, which has caused catastrophic fish kills along the east coast of Australia and elsewhere. An important consideration in the management and amelioration of pyritic sediments is the likely rate of oxidation, where drainage is required. Models describing the oxidation of pyrite exist, yet information about distribution and morphology of the pyrite mineral required in these models is limited.
In these study of the distribution, mineralogy and morphology of pyrite, we collected samples from three buried sediments with different textures, a sand, a clay and a sandy clay. A freeze drier was used to minimize deformation and oxidation. We used both reflected light microscopy on polished impregnated blocks, and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray microprobe (EDX) on fractured surfaces of specimens to assess pyrite distribution. EDX enabled the elemental analysis of individual crystals with different morphologies, to compare sulfur : iron ratios. The main mineral phases were identified by x-ray diffraction (XRD).
Pyrite although concentrated in organic remnants as reported elsewhere, is abundant also along fissure planes, pores and is finely dispersed throughout the clay fraction of the soil matrices. Pyrite occurs as framboids (ie. spherical clusters of individual crystal) and loosely arranged individual crystals. Most framboids ranged in diameter from 4 to 15, while crystal diameter ranged from 0.1 to 2. Crystals exhibited a range of morphologies including those with clearly defined facets including octahedral and pyritohedral habit, to globular forms with no defined facets. Coatings described as pseudo-skins by other researchers are evident on many framboids. These results and their implication on pyrite formation and the likely process of oxidation are discussed.
Buysschaert X., Langohr R. and J. Becze-Deak, International Training Centre for Post-Graduate Soil Scientists, University of Gent, Krijgslaan 281/S8, B-9000 Gent, Belgium
The craters of the East Eifel volcanic province have been important sediment traps during their geological history and are known as very valuable sites, where records of the past are often well preserved. The Tnchesberg site is known for it's important Middle Palaeolithic find horizons preserved in the loess soil-sedimentary complexes accumulated during the Pleistocene. Among the thick soil-sedimentary units present in the Tnchesberg 2 crater, the Last Interglacial sequence has been selected for more detailed study.
The sequence studied here includes a well preserved soil with a 60 cm thick non-calcareous humiferous surface horizon (A), a weakly developed eluvial horizon (E) and textural B (Bt) horizon developed in a 250 cm deep decalcified loess and the overlying soil-sedimentary units described in the literature as "colluvial" deposits. The 21 pedo-lithostarigraphical horizons (H) studied revealed the following soil characteristics and soil forming processes. - At the micromorphological study the upper part of the "colluvial" horizons (down to H6) shows clear evidences of stratification and minor bioturbation. The sediment is very heterometric. This horizons in the field present very abrupt boundaries. - The rest of the "colluvial" horizons (down to H9) have no traces of stratification, neither in the field nor under the microscope. These horizons on the contrary show clear evidences of bioturbation, indicating a more stable environment with continuously vegetated surface - The whole sequence of "colluvial" horizons present a few isolated limpid and dusty clay coatings which probably are of diagenetic origin. - The thick humiferous A horizon (H10-12) is very homogeneous and strongly bioturbated. Based on morphology there are no arguments pro or contra that the upper part of these horizons would correspond to redeposited sediments from an A horizon situated higher in the landscape. Except a few frost fissures no other freeze-thaw evidences could be detected. If the climate at some moment of the evolution was very cold than the soil most have been very dry. - Clay coatings are already common in the weakly expressed E horizon (H13-14). - The Bt (H15-19) shows in the upper half clear evidences of intensive swelling and shrinking with clay coatings incorporated inside the peds and with a striated b-fabric. This is related with a relatively high clay content, with smectites present in the clay fraction and alternating wet and dry seasons. The lower half of the Bt is indicating a much more stable environment with clay coatings only along the larger planes and channels. The b-fabric of the fine material is undifferentiated, indicating the possible presence of some amorphous colloidal fraction. - The carbonate nodules present in this Bt horizon are of diagenetic origin and most probably are the result of a lateral subsurface water flow.
Beside the clarification of the chronosequence of the pedogenetic processes, the main contribution of the micromorphological study is the detection and characterisation of a "special" facies of loess and the particular dynamics of the processes that have been acting in the upper half of the Bt horizon of the Last Interglacial soil.
* Research funded by the SC-004 Project of the Federal Services for Scientific matters, Belgian State Science Policy Programming and the Belgian National Science Foundation.
D.A. Cherniakhovskiy, Ye.M. Naumov, Dokuchaev Soil Institute, Moscow
Investigations of a soil series in cold cryomesomorphi landscapes permitted to make the following statements:
1. The cryometamorphic horizon, located at the depth 5-20 cm, and more subjected to soil weathering than other horizons, may be the source of silt both in present-day and past deflation-accumulative landscapes.
2. Size and shape of aggregates in this horizon depends primarily on parent rock, which may be rather reliably characterised by the bulk chemical composition. Soil moisture is also very important. The finest concretionary aggregates, with high deflation hazard, are proper to cruoxeromorphic soils on almost pure quartz materials with low Fe and Al concentrations (sandstones, f.i.)
3. In soils with elevated Al and Fe content the aggregation process is advanced and the size of aggregates increases.
4. Silt accumulations in recent soils and paleosols consist of 0.01-0.001mm aggregates, enriched in Al and Fe.
5. The following image of Late Pleistocene deflational landscapes may be proposed: a) dry (moisture/field capacity ratio is below 7); b)rich in silica (its total amount is above 70%, Al203 not surpassing 15%, Fe203 - below 4%).
The regularities revealed may be presented by the following scheme:
oxides concentrations landscapes xeromorphic mesomorphic Fe, high saturated Gelic Cambisol fine nodules Distric Leptosols non saturated Gelic Cambisol (non-compact spongy segregations) Al, Fe, low Distric Leptosols saturated Gelic Cambisol Mollic Leptosol fine nodules Al, Fe, highGelic Cambisol (loose flaky) Gelic Regosols (coarse nudules)
M.-A.COURTY, C.N.R.S., C.R.A. Lab. de Science des Sols et Hydrologie, INA P-G, 78850 Grignon, FRANCE
In the recent years, soil micromorphology research in archaeology has broadened from a systematic inventory of microscopic anthropic features to more comprehensive studies of anthropogenic and natural factor interactions. geared toward both cultural and environmental issues. Ancient living surfaces have been specifically investigated by studying distribution of human-derived microscopic residues and anthropogenic micro-fabrics, such as structuration due to human tramping. Results from a wide diversity of geographical contexts now demonstrate how integrity of the archaeological record, evident from the spatial artefact distribution alone, can be fully confirmed by soil micromorphology. Spatial archaeology has, also, benefited from improvement of the micromorphological anthropic facies classification aimed not only to identify well preserved settlements, but also residual traces of habitation areas, and discriminate them from intentional human-refuse dumpings that might characterize ancient cultivated fields.
The challenge of micromorphological research in off-site archaeology concerns our ability to identify anthropogenically induced soil-landscape transformations which differ only in formation rate from natural processes. For example, the micromorphological record of ancient burnt soils suggests that human-induced firing practices, aimed to prepare and maintain agricultural landscapes, had a different impact on the soil ecosystems than the ones of exceptional wildfires associated with climatically unstable short periods. Beyond cultural implication on ancient landscape management, this is an important environmental concern that legitimizes studies of the past soil record to better monitor catastrophic situations in the future.
In urban sites that display evident achitectural lay-out, soil micromorphology has been used to test attribution of a space to one category or another (streets, courtyards, walled-rooms, domestic and public areas) and to further elucidate variations through time in the use and maintenance of space. Analysis of the soil-sedimentary micromorphological signatures, specific of micro-climate conditions, provide distinctive evidence between roofed space from areas open to weather, Research effort has also focused on physical transformations of clay-rich materials, such as bricks, mud floors, owen and ceramics, that contribute to improve the knowledge of ancient earth-technology. Comparative studies of habitation areas in widely excavated sites has considerably stimulated adoption of sequential analysis to refine the archaeological time scale, and improve the precision of spatial micro-stratigraphic correlation. This issue oversteps archaeologist expectations not trained to appreciate the potential of the sedimentary matrix to document everyday use of the space. Our present position should be reinforced by improving the communication of our research products and maintain fascination of archaeologists for soil micromorphology.
Soil micromorphologists of the International Soil Science Society should be keen to provide full support to the increasing number of young geoarchaeologists, now engaged in soil micromorphological research. Publications in international journals should be stimulated, in order not to ruin patient research efforts by storing the golden mine as "shelf" reports. We should also claim that one collected, the micromorphological thin sections are an invaluable record, endlessly refreshed by our continuous progress, and therefore, are not museum objects.
G.A. Demidenko
The buried Holocene paleosols occur on river terraces and on interfluves in a wide zonal spectrum - from southern taiga to the steppe, they occur both as single paleosols and in soil associations. Chernozem-like paleosols (Mollisols or Phaeozems) are more distinct in terms of their morphology when they are found under steppe vegetation. Micromorphologically, chernozem-like paleosols have much in common, although they are encountered now in different zones and they originated in different periods of the Holocene; they are sufficiently well studied. We assume that horizons of similar genesis have the same micromorphological properties.
The Ah (mollic) horizon is blackish-brown in thin sections, it is clay-silty, rather compact, its plasma is humus-clay by composition, anisotropic, with scaly b-fabric dominant, there are also dendritic and granostriated b-fabric types, clay coatings. Moderate pedality: rounded, humus-impregnated aggregates. Intra- and interpedal voids are common. Biopores contain plant residues (with plant tissues preserved to a different extent) and organic castings. Bh horizon is peculiar by its combination of dark coloured and yellowish-brown microzones. Clay plasma has a striated (fibrous) b-fabric and displays mobility features. The parent material has a less compact fabric; the proportion of coarse silty grains increases, there are aggregates-ooids and few clay-humus inclusions.
The Holocene paleosols of the study area are peculiar by the absence of carbonates in Ah horizons, whereas there are carbonates in plasma and