白垩纪钙质古土壤的发生学特征及古环境意义

古土壤形成于过去环境,是揭示环境变化历史的重要材料。新近纪(23.03 M a)以前形成的古土壤,年代久远、埋藏深、受成岩作用改造强烈,其发生学特征研究是古环境重建的基础。本文通过对白垩纪时期不同地点的钙质古土壤的发生学研究,拟恢复研究区域古环境。研究表明,古土壤剖面中的A层和B层形态分别产生变化,但层次差异依然明显,且表层土壤有机质含量一般高于表下层,钙积层(Bk)普遍发生并富含碳酸盐结核。可以观察到古土壤中方解石沿根孔淀积特征以及具滑擦面。钙质古土壤质地偏粗,为壤质砂土和砂质壤土。古土壤Bk层中的Ca、Mn、Sr相对富集,其余常量元素与Ba、Sc、Nb、Th、U、Cr、V、Co、N i等元素降低;δCe和δEu负异常以及相对富集重稀土元素。分别按照中国土壤分类系统和美国土壤系统分类两种分类体系进行了古土壤分类。由古土壤类型和特征可以推断白垩纪不同时期,在四川盆地梓潼—巴中地区、辽宁金岭寺—羊山盆地和松辽盆地出现过半湿润至半干旱的气候环境。     

Upper Permian paleosols developed from limestone in the middle reaches of the Volga River: Morphology and genesis

The results of the study of paleosols preserved in the Upper Permian deposits in the central part of the Russian plate are presented. The paleosol profiles consist of the medium loamy dark brown BMg,ca horizon and the hard cemented calcareous Mm,ca and Mca horizons. The imprints of plant roots in the Mm,ca horizon and in the upper part of the Mca horizon serve as a vivid diagnostic feature of these paleosols. Two paleosol morphotypes are distinguished according to the development of the structural-metamorphic BMg,ca horizon and the micromorphological features. These paleosols were developed from highly calcareous lacustrine deposits that were initially loose and then subjected to cementation. The processes of leaching and redistribution of carbonates, as well as the development of the soil structure, vertic properties, eluvialgley processes, lessivage, and soil creep, can be identified in the studied paleosols. They bear the record of the geomorphic conditions on a flat plain with recurrently drying inland water reservoirs in a semiarid paleoclimate with well-pronounced seasons.     

从古土壤看北京环境变迁

古土壤是在古自然环境条件下形的土壤,西胡林黄土剖面位于北京低山丘陵区,埋藏有七层古土壤,根据形态和微形态特征,可以划分出碳酸盐型古土壤、普通褐土型古土壤,淋溶褐土型古土壤和棕壤型古土壤。其地球化学特征和土壤学特性的研究表明,各古土壤类型之间和发生层之间存在着显著差异,通过古城磁测年和地层对比,确定古土壤的年龄。在研究古土壤性状的基础上,配合孢粉分析,可以勾画出北京低山丘陵区的环境变迁,北京地区自50万年前至1万前,交替经历了14次温湿、冷干的气候变化。     

Buried vertic paleosols of the North Caucasus in the third millennia BC

Paleosols buried under kurgans dating back to the Yamnaya, Catacomb, and Post-Catacomb cultural epochs of the Bronze Age (4600–3900 BP) on the territory of the Stavropol Upland (the North Caucasus) in the area occupied by vertic chernozems were studied. It was found that solonchakous and deeply solonchakous and solonetzic chestnut soils and solonetzes proper predominated in the study area during the Bronze Age. The solonetzic process was the leading pedogenetic process in the automorphic paleosols of the second half of the third millennium BC. The vertic features were weakly developed in the automorphic paleosols; they were better manifested in the paleosols developed on the floodplains. The paleosol data were used to reconstruct the environmental conditions in the region during the Bronze Age. The climatic conditions of that period were more arid and with less sharp contrasts between wet and dry seasons in comparison with the modern climate.     

The biomass of fungal mycelium in buried paleosols and surface soils of the steppe zone

The contents of fungal mycelium have been studied in paleosols of ancient archeological monuments and in surface soils within the steppe, dry steppe, and desert zones of European Russia, on the Stavropol, Privolzhskaya, and Ergeni uplands. The buried paleosols date back to the Bronze Age (4600–4500 and 4000–3900 BP), the Early Iron Age (1900–1800 BP), and the early 18th century (1719–1721). The fungal mycelium has been found in all these paleosols. The biomass of fungal mycelium varies from 2 to 124 μg/g of soil. The distribution patterns of fungal mycelium in the profiles of buried paleosols and surface soils have been identified. It is shown that the dark-colored mycelium is typical of the ancient paleosols. In some cases, the content of the dark-colored mycelium in them may reach 100% of the total mycelium biomass.     

The Mississippian Paleosols in the Brontsy Quarry,Kaluga region

A chronosequence of five Visean (Aleksinian–Venevian interval, C1v, 326–336 Mya) paleosols on the territory of Moscow calcareous sedimentary basin (Brontsy quarry, Kaluga region) was studied in detail. Two lowermost paleosols are coastal peat-bearing paleosols developed under mangrove vegetation. Three upper paleosols develop pedocomplexes, in which the lower part is the marine limestone altered to different degrees by weathering/pedogenesis with the formation of eroded Rendzina-type soil. It is overlain by paleosols developed from terrigenous sediments of playa origin. They are characterized by elevated concentrations of Fe, Mg, Ti, Ga, and some other elements; the formation of secondary micritic carbonates, iron oxides, and smectites; and increased values of geochemical indexes (such as CIA-K). Smectite (low-charged beidellite) predominates in these paleosols. Iron oxides are represented by goethite and lepidocrocite attesting to the predominance of oxygenic environments. Pedocomplex at the Mikhaylovian/Venevian boundary is overlain by non-marine palustrine deposits known as “black rhizoidal limestone.” The paleoclimate reconstruction based on the chemical composition data attests to its polycyclic character. The Mikhaylovian time was most humid was (~1000 mm/yr). Later, starting from Venevian, gradual aridization of the climate began and annual precipitation decreased to 750 mm/yr and less.     

Paleoclimatic implications of micromorphic features of Quaternary paleosols of NW Himalayas and polygenetic soils of the Gangetic Plains — A comparative study

Micromorphological examination of the paleosols (50–10 ka) developed in alluvial fan deposits of the NW Himalayas and the bordering polygenetic soils (mainly Holocene) of the Gangetic Plains has been used to differentiate the pedosedimentary features indicating climatic changes during late Quaternary time. The paleosols within rapidly aggrading sediments of the alluvial fans of the Dehradun valley resulted in response to the reduced rate of sedimentation and climatic changes and correspond to the MIS3 and MIS2 stages. Distinctive micromorphic features of these paleosols provided the details of the prevalent pedogenesis in response to the paleoclimatic changes during 50 ka. Microfabrics of these paleosols show reorganization of the pedality from massive and/or subangular blocky to platy and prismatic structures, strong to very strong mobilization of the plasma, different types of textural pedofeatures along with faunal activities. These pedofeatures are indicative of cold-humid climate with subsequent change to even colder but drier conditions during the last Glaciation. Comparison of the micromorphological characters of the paleosols of the NW Himalayas and the polygenetic soils of the Gangetic Plains show the same degree of soil development indicating 5–10 ka pedogenic intervals in alluvial fans of the Dehradun Valley. However, the difference in their pedofeatures is attributed to different pedogenic environments. The paleosols of the Dehradun Valley show predominance of the illuvial features with superposed impure silty clay on earlier clay pedofeatures and banded clay fabric features without any pedogenic calcium carbonate. The bordering Gangetic Plains are covered with polygenetic soils developed on stable surfaces and are < 13.5 ka. These surficial soils developed during the period marked by deglaciation and correspond to MIS1 stage. These are defined by the juxtaposition of different illuvial pedofeatures along with pedogenic calcium carbonate. This study suggests that formation of the paleosols in NW Himalayas was mainly controlled by warmer intervals during the last glaciation and the movement along the adjacent thrusts. While fluctuating climate punctuated with humid–semiarid–humid conditions played a major role during the formation of soils on the Gangetic Plains in Holocene that favoured illuviation, calcification and dissolution of pedogenic carbonates in the polygenetic soils.     

Comparative characterization of microbial communities in kurgans,paleosols buried under them,and background surface soils in the steppe zone of the Lower Volga region

A comparative analysis of the state of microbial communities in kurgans, paleosols buried under them, and background surface soils in the dry steppe zone of the Lower Volga region has been performed. It is shown that the population density of microorganisms of various trophic groups in the kurgans is an order of magnitude lower than that in the A1 horizon of the corresponding buried paleosols and background surface soils within the areas of chestnut, light chestnut, and solonetzic soils. The respiration activity of the microbial communities in the upper layer of the kurgans is comparable with that in the A1 horizons of the background surface soils; it decreases in the deeper layers of the kurgans. In the A1 horizon of the buried paleosols, the respiration activity is approximately the same as in the deep layers of the kurgans. In the buried paleosols, the spatial variability in the numbers of soil microorganisms is approximately the same or somewhat higher than that in the background surface soils. The spatial variability in the respiration activity of the buried paleosols is two to four times higher than that in the background surface soils.     

黄淮海平原晚第四纪古土壤

本文运用孢子花粉,古生物化石和放射性碳断代等手段,从土壤剖面层段的特征,土壤年龄和环境变化方面证明,分布于黄淮海平原的变性土不是现代土壤,而是古土壤,该古土壤自晚新世晚期以来经历了三次沉积－成土作用旋回,其土壤发育程度较弱,且是由钙质结核土层,暗色土层,表土层和（或）淤土层组成的一个叠置型古土壤。     

AMINO ACIDS IN BURIED PALEOSOLS

A sequence of paleosols date at 80, 7 000, 20 000 and 41 000 years developed on similar parent material in the North Island of New Zealand have been used to study the fate of amino acids with time. Some amino acids were released by hydrolysis with 6M HC1 for 24 h at 110 °C while others were only released after the mineral matrix had been destroyed by HF. The mineral bound amino acids were hydrolysed from each paleosol and their composition analysed. The simplicity of the composition of the older paleosols confirms that the amino acids are fossil. This technique could be used for determining whether paleosol samples submitted for carbon dating are contaminated by more recent material. The differential disappearance of amino acids from a paleosol could be used as a dating system and if this was done quantitatively it may be possible to date paleosols beyond the range of carbon dating.     

EDAPHOIDS AND PALEOSOLS OF BASALTIC ORIGIN IN THE GALILEE, ISRAEL

Red soil-like layers intercalated amid basaltic flows from the Miocene-Pleistocene in the Galilee, Israel, were examined. Micromorphological features which can be related to (a) translocation of materials, and (b) biological activity, and are therefore of distinct pedological origin, identify two of the layers as paleosols. Absence of these features and preservation of the fabric of the parent basalt serve to identify the third layer as an edaphoid. A fourth layer consists of an edaphoid superimposed on a paleosol. The edaphoids are composed almost entirely of a dioctahedral smectite. In two of the paleosols dioctahedral smectites predominate. In the third kaolinite and haematite are present also in considerable amounts. The presence of quartz in the paleosols is attributed partly to precipitation from Si-rich solutions percolating the upper basalt layer and partly to aeolian contamination. In all the layers the free iron is predominantly in an anhydrous form. Similarity in the clay mineral composition of the Plio-Pleistocene paleosols with that of contemporaneous basaltic soils is taken to indicate similarity in climatic conditions of formation. Differentiation between paleosols and edaphoids cannot be made by the use of a single criterion but must be based on corroborative evidence derived from micromorphological and mineralogical examinations.     

PaleoVertisols of the northwest Caucasus: (Micro)morphological,physical, chemical,and isotopic constraints on early to late Pleistocene climate

Physical and chemical properties, macro‐ and micromorphology, clay mineralogy, and stable‐isotope compositions of paleosols within a pedostratigraphic column (PSC) of early to late Pleistocene age, interstratified paleosols, and loess (NW Caucasus, S Russia) were examined to better understand the evolution of the pedogenic environment over this time period, separating the effects of postpedogenic diagenesis. The column includes eight paleosols and six intercalated loessic horizons. Most of paleosols represent Vertisols or vertic intergrades. Vertic features increase in the middle of the PSC, where the paleosols are more clayey in texture and reddish in color. The morphology of carbonate nodules and soft masses, morphology‐ and depth(age)‐related changes in stable C and O isotope compositions, soil color, redoximorphic features, clay mineralogy, and illuviated clay indicate periods of wetter pedoenvironment in the past and suggest the Pleistocene paleosols are polygenetic and were formed with several wet/dry stages under a climate generally similar to the modern environment in the N Caucasus (mean annual temperature approx. 9°C–12°C). Interpretation of the time sequence of climate/environmental change requires careful separation of pedogenic mineral phases from phases altered by later diagenesis. The early Pleistocene period of paleosol formation appeared to be wetter or more humid, resulting in more significant development of vertic features. The terrestrial ecosystem remained dominated by C3 vegetation throughout the formation of the PSC, with four small periods of change towards a greater proportion of C4 plants or increased moisture stress.     

Microbiological investigations of paleosols of archeological monuments in the steppe zone

Microbiological studies of the paleosols of archeological monuments (burial mounds) of the Neolithic, Bronze, Early Iron, and Middle Ages (the fourth millennium BC to the fourteenth century AD) located in the dry and desert steppe of the Lower Volga River basin were conducted. The microbial communities that existed at the time of creating the burial mounds were shown to be preserved up to the present time. This fact was confirmed by the regularities of the distribution of the microorganisms in the “mound-buried soil” system and by the data on the determination of the age for the microbial fraction of the paleosols using the method of ¹⁴C atomic mass spectrometry. The total biomass of the microbial communities in the paleosols amounted to 20–40% of the microbial biomass in their background analogues. In all the paleosols, a special pool of viable microorganisms was present. In the microbial community of the paleosols, the biomass of the active microorganisms corresponded to 0.30–41.0% of the biomass in the present-day soil; the content of mycelium of microscopic fungi composed 43–50% of that in the recent soil. In the mycelium structure in the paleosols, the share of the dark-colored mycelium increased to 98–100%. The microbiological parameters that give a contrasting characterization of the state of the microbial communities in the soils during the arid and humid climatic periods were revealed. The changes of the arid and humid climatic epochs were reflected in the structure of the microbial communities in the paleosols at the ecological-trophic, metabolic, and genetic levels.     

Stratigraphy and land use of the Post-Diamond Hill Paleosol,western Oregon

The Post-Diamond Hill Paleosol generally underlies Late Pleistocene sediments of the Willamette Formation. However, in numerous localities in the Willamette Valley, reddish gray clay paleosols either outcrop at the surface or occur within soil profile depth. Then they are part of soils of the modern landscape. Where the paleosols outcrop, the soils are mostly Typic Pelloxererts in the fine, montmorillonitic, mesic family. Because of the nature of the paleosols, these soils are poorly suited for nearly all intensive uses; the dominant use is hay and pasture.     

The morphology of cells and the biomass of microorganisms in the buried paleosols and modern steppe soils of the Lower Volga region

The morphology of microbial cells was studied, and the biomass of microorganisms was estimated in the modern steppe soils and paleosols buried under kurgans in the Lower Volga region with the methods of electron microscopy. The shape and ultrastructure of the cells in the modern soils and paleosols were similar, though their average volumes differed (0.37 and 0.28 μm³, respectively). The portion of cells with a volume above 1 μm³ in the surface soils and paleosols reached 10.9 and 9.2%, respectively, and the portion of cells with a volume less than 0.01 μm³ in the surface soils was 10% lower than that in the buried paleosols. It was found that the cells of the microorganisms have an external organomineral layer, which increases the cell volume by 4.9 times, and this fact was taken into account in the calculation of the microbial biomass. In the chestnut and light chestnut paleosols, the latter comprised 1500 and 230 μg of C/g soil, respectively.     

Upper Permian paleosols of the East European Platform: Diagnostics of pedogenesis and paleogeographic reconstruction

A vertical sequence of seven buried paleosols composing the Klimovsk pedocomplex was studied in the basin of the Sukhona River (Vologda oblast). These paleosols were formed according to the accumulative model of pedogenesis (pedosedimentation model). They had monogenetic profiles with eluvial-gley, structural, and carbonate-illuvial types of differentiation. The set of elementary pedogenic processes responsible for the development of these soils included gleyzation in the surface horizon and around the roots, the inter- and intrahorizon translocation and segregation of iron, structuring, humification, weathering, lessivage, the migration and segregation of carbonates, and the synthesis of palygorskite and analcime. The studied paleosol profiles make it possible to reconstruct seven pedogenetic stages; each of them lasted for about n × 10²–10³ years. The paleosols were formed on a flat lacustrine-alluvial plain with drying lakes and temporary streams. The stages of inundation and water stagnation on the surface alternated with the stages of drying of the territory. The climate was warm, with well-pronounced wet and dry seasons. Against this general climatic background, arid climatic epochs marked by the development of calcic paleosols alternated with humid climatic epochs marked by the development of noncalcareous paleosols.     

Nonhydrolyzable Part of Soil Organic Matter in Buried and Modern Soils

Eurasian Soil Science - Results of the study of humus composition in about 200 modern soils of different genesis and more than 100 buried Pleistocene and Holocene paleosols have been collected and...     

Mineralogical composition of the clay fraction and micromorphology of the Middle and Late Pleistocene loesses and paleosols in the center of the East European Plain

The mineralogical composition of the clay fraction and microfabrics of the cryogenic soil-loess sequences of the Middle and Late Pleistocene ages have been studied near the northern boundary of loess sediments on the East European Plain. Poorly ordered mixed-layered mica-smectitic minerals with different portions of smectitic layers predominate in the clay fraction; di-and trioctahedral hydromicas occupy the second place. The clay fraction also contains chlorite, clay-size quartz grains, and feldspars. Individual smectite is present in some of the samples. Interstadial chernozem-like paleosols are specified by the higher content of clay, the maximum concentration of smectitic layers in the mixed-layered minerals, and the presence of individual smectite. The clay fraction in the profiles of interglacial paleosols is sharply differentiated: in the eluvial part, it is depleted of smectite and enriched in kaolinite, hydromica, and clay-size quartz. These features allow us to suppose that interglacial paleosols were subjected to podzolization processes. According to the mineralogical indices, Middle Pleistocene paleosols can be differentiated into those subjected to lessivage (the Kamenskii interglacial paleosol) and podzolization (the Inzhavin interglacial paleosol).     

Assessment of the living and total biomass of microbial communities in the background chestnut soil and in the paleosols under burial mounds

The contents of phospholipids and carbon of the total microbial biomass were determined in the modern chestnut soil and in the paleosols buried under mounds of the Bronze and Early Iron Ages (5000–1800 years ago) in the dry steppe of the Lower Volga River basin. Judging from data on the ratio between the contents of phospholipids and organic carbon in the microbial cells, the carbon content of the living microbial biomass was calculated and compared with the total microbial biomass and total organic carbon in the studied soils. In the background chestnut soil, the content of phospholipids in the A1, B1, and B2 horizons amounted to 452, 205, and 189 nmol/g, respectively; in the paleosols, it was 28–130% of the present-day level. The maximum content was measured in the paleosols buried 5000 and 2000 years ago, in the periods with an increased humidity of the climate. In the background chestnut soil, the total microbial biomass was estimated at 5680 (the A1 horizon), 3380 (B1), and 4250 (B2) μg C/g; in the paleosols, it was by 2.5–7.0 times lower. In the upper horizons of the background soil, the portion of the living microbial biomass in the total biomass was much less than that in the paleosols under the burial mounds; it varied within 8.5–15.3% and 15–81%, respectively. The portion of living microbial biomass in the total organic carbon content of the background chestnut soil was about 4–8%. In the paleosols buried in the Early Iron Age (2000 and 1800 years ago), this value did not exceed 3–8%; in the paleosols of the Bronze Age (5000–4000 years ago), it reached 40% of the total organic carbon.