Cenozoic paleosols San Diego area,California

Ancient weathering profiles provide mute evidence of the major climatic regimes that operated in the southern California area during the Cenozoic Era. A tropical climate during part of the Paleocene and Early Eocene caused severe weathering of Jurassic andesitic rocks, Cretaceous granitic rocks and Late Cretaceous and Early Eocene terrigenous rocks. Erosional remnants of this paleosol exist as buried soils up to 30 meters thick and as exhumed soils on some modern hills. The main weathering horizon is overwhelmingly composed of kaolinite with residual quartz grains and minor amounts of iron oxides. This tropical climate was in effect at 35° to 40° north latitude.Late Eocene sedimentary rocks were deposited under a semi-arid climate with 50 to 60 cm of annual rainfall that was concentrated during one season. This interpretation is based on: 1) the dominance of conglomerate and immature sandstone in the Upper Eocene section compared to the relative scarcity of claystone, 2) the immaturity of the clay mineral suite which is dominated by smectite and vermiculite, 3) the presence of fractured clasts presumably split by growth and differential expansion of salts, 4) the multiple caliche beds that individually are up to one meter thick, and 5) the paleohydrology of the fluvial deposits which transported rhyolite gravels over 300 km distance from an eastern bedrock source about 4,000 m high in a river of 1.3 sinuosity with 100 year flood discharges up to 30,000 m³/sec.The extensive marine terraces in San Diego are mantled by relict soils that record composite weathering characteristics from glacial and interglacial climates from Late Pliocene to present. Maximal development of the paleosol includes an ironstone concretion layer (B_ir horizon) above an illuvial clay layer (B_t horizon) which rests on an iron- and silicacemented hardpan (C_m horizon).     

Genesis,evolution, and catastrophic burying of the Ryshkovo paleosol of the Mikulino Interglacial (MIS 5e)

The results of a hierarchical morphogenetic, physicochemical, and mineralogical study of the Ryshkovo full-profile texture-differentiated paleosol of the Mikulino Interglacial from the section at Aleksandrov quarry in Kursk oblast are discussed. The correlation analysis of the stratigraphy of this section with global geological records made it possible to determine the position of the Ryshkovo paleosol in the chronostratigraphic system of the Late Pleistocene and to attribute it to stage MIS 5e; the duration of pedogenesis for this paleosol was no more than 12–15 ka. The results of the study indicate that the Ryshkovo paleosol is close in its properties to the Holocene soddy-podzolic soils of the East European Plain. No direct evidences in favor of the former interpretation of this paleosol as a lessivated soil genetically close to Luvisols of nemoral broadleaved forest of Central Europe have been found. The difference between the paleosol of the Mikulino Interglacial and the modern soddy-podzolic soils is mainly related to the distribution of clay coatings. In the upper part of the illuvial horizon of Mikulino paleosol, clay coatings are few in number, and typical tongues of podzolized (albic) material are absent in the profile. At the same time, silty coatings (skeletans) are abundant even in the lower part of the illuvial horizon. In general, the Mikulino paleosol is characterized by a smaller diversity of clay pedofeatures. These differences might be related to less contrasting fluctuations of the environmental conditions in the second half of the Mikulino Interglacial, to the periodical renewal of the eluvial part of Mikulino paleosol by erosional and accumulative processes, and to the absence of anthropogenic impacts on the soil during the Mikulino Interglacial. The burying of the Ryshkovo paleosol took place due to the intense development of erosional processes induced by the contrasting climatic events at the end of the interglacial period accompanied by catastrophic forest fires and sharp cooling of the climate upon the transition to the Valdai glaciation.     

Characteristics and classification of three granite-derived soils in peninsular Thailand

The Phuket, Thung Wa and Huai Pong soils of this study form the Phuket catena and are extensive in Narathiwat province in the southern part of peninsular Thailand where they were studied in the field and sampled. The Phuket soils on the higher-lying positions and the Huai Pong soils on the nearly-level, lower positions, have developed argillic horizons and are Ultisols. The Thung Wa soils, which occur on intermediate positions and receive sediments from upslope, have cambic horizons and are classified as Inceptisols.All soils formed from Late Cretaceous or Early Tertiary granite or from sediments derived frome these granites under a tropical rain forest climate. They contain kaolinite as the predominant clay mineral and are highly leached, with base saturation of less than 35% in their B horizons. Cation exchange capacities are less than 6 mequiv. per 100 g soil and exchange acidity and exchangeable aluminium are high. Field and thin-section studies as well as particle-size analysis indicate considerable clay translocation from A to B horizons in the Phuket and Huai Pong soils and little clay movement in the Thung Wa soils.     

Characteristics of the soils developed under broad-leaved evergreen forests in okinawa prefecture and the kinki district with special reference to their pedogenetic processes

Abstract

Properties of sesquioxides, clay mineralogical composition, and charge characteristics of the soils developed under broad-leaved evergreen forests in Okinawa Prefecture (subtropical climate) and the Kinki District (warm temperate climate) were studied with special reference to their pedogenetic processes in order to reexamine the corresponding parameters of Brown Forest soils and related soils in Japan.

The soils in Okinawa Prefecture were characterized by a higher degree of weathering as compared to the soils in the Kinki District. Major differences involved the values of the Fed/Fet ratio for the soil samples throughout the profile, and those of the ratios of (Fed-Feo)/Fet, CEC/clay, and (Feo + Alo)/ clay and the content of CaO plus Na₂O for the B horizon. The soils in the Kinki District did not show andic soil properties, nor Al translocation in the profile and, both of which were characteristic of Brown Forest soils developed under cool temperate climatic conditions at high altitudes in the same District.

The difference in the degree of weathering were reflected on the charge characteristics at the very surface of the soils, i.e., the surface of the particles of the soils in Okinawa Prefecture exhibited a lower reactivity as compared with those of the soils in the Kinki District.     

Weathering patterns in representative soils of Guanxi Province, south-east China, as indicated by detailed clay mineralogy

The mineralogy of five soils situated on a south-west to north-east transect of Guanxi Province, south-east China was determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA) and chemical composition. One soil had formed on granite under tropical conditions, the others on sedimentary rocks under subtropical conditions. In all soils, kaolinite dominates the clay fractions, and is accompanied by vermiculite or chloritized vermiculite. In the saprolites of the granite-derived and sandstone-derived soils, the kaolinite has a morphology close to that of hydrated halloysite. The formamide and hydrazine/water tests suggested the presence of both poorly-crystalline (dehydrated halloysite) and well-ordered kaolinite. Gibbsite was identified in the saprolites of the granite-derived and sandstone-derived soils but not in the soils themselves. Gibbsite was also identified in the lowermost horizon of a soil derived from Pleistocene sediments. The upper horizon clay of a Rendzina soil formed on Permian limestone contains much more gibbsite and is much more weathered than the corresponding lower horizon clay. Only in the more humid, southernmost soil can the mineral composition be explained by present-day climatic conditions. In the soils from drier areas, the clay mineral composition reflects weathering that had taken place under moister, paleoclimatic conditions. Some of these paleoclimatic conditions had been conducive to lateritic weathering, as is indicated by the presence of goethite-containing pisolitic nodules in one of the soils and in its parent material. Two of the soils appear to be polymorphic, with one part of the soil having weathered more strongly than the other part.     

Formation of clay minerals in soils developed from basic volcanic rocks under semiarid climatic conditions in Lanzarote,Spain

Clay formation in soils was studied in four landscapes of different ages in Lanzarote (Canary Islands). Landscape IV_B is about 250 years old, IV_A subrecent, III early young pleistocene, and landscape I, late tertiary. The soils have developed from basic to ultrabasic pyroclastic fall deposits or basalt.Clay formation in soils of landscape IV_B is in an initial stage having a clay content of 1–2 kg/m², whereas in landscape IV_A 30–40 kg/m² and in landscape III 100–200 kg clay/m² are accumulated. In polygenetic soils of landscape I more than 3000 kg clay/m² can be found. In the youngest soils IV_B, smectite is the most prominent clay mineral, whereas IV_A-soils are dominated by “amorphous” clay. The clay fraction in older soils contains illite, smectite as well as kaolinite in smaller quantities.The chemical composition of the clay fraction of soils with different ages changes significantly according to the mineral composition.     

Micromorphology and Late Glacial/Holocene genesis of Luvisols in Mecklenburg–Vorpommern (NE-Germany)

In the German soil science literature, Luvisols formed in Weichselian sediments (except from the Early Weichselian) are normally regarded as purely Holocene soils with the main period of development assumed to have been during the Atlantic phase. Although debated at some length since the 1960s, the genesis of the widespread albic Luvisols, with a simplified Ap/Bw/(Eb)/(EBtb)/Btb(g)/C horizon sequence and developed on the flat and slightly undulating till plains of the north German Mecklenburgian Stage (deglaciation 14 000 BP), has yet to be clarified. Periglacial climate during the Late Weichselian led to the formation of sand-filled wedge-shaped structures penetrating Bt horizons. Systematic micromorphologic investigations of soil profiles with sand wedges revealed the occurrence of numerous fragments of rounded limpid clay coatings within periglacial formed lenticular microplates as well as in and at the margins of the sand wedge infillings. Assuming the Younger Dryas as the latest possible phase of formation, the lenticular microplates and the undisturbed sand wedges postdate clay illuviation. Undisrupted clay coatings next to fragmented clay coatings prove a subsequent Holocene clay illuviation. Clay illuviation must have occurred at least in warmer phases of the Late Glacial, together with the already accepted pedogenic processes of decalcification, organic matter accumulation (Ahb horizons), podzolisation and silicate weathering (Bwb horizons) on sites not influenced by groundwater.     

Paleosols of kurgans of the Early Iron Age in the Transural steppe zone

Paleosol studies of archaeological monuments of different ages have been conducted on the Transural Plateau. The morphological and physicochemical properties of paleosols under burial mounds (kurgans) of the Early Iron Age (the fifth and fourth centuries BC) were compared with the properties of background surface soils. A paleosol of the Savromat epoch (2500 BP) is characterized by high contents of gypsum and soluble salts. The presence of humus tongues in its profile attests to the aridity and continentality of the climatic conditions during that epoch. Paleosols buried under kurgans of the Late Sarmatian epoch and the Hun epoch (about 1600 BP) are characterized by a higher content of humus and greater depth of the carbonate horizon, which attests to the humidization of climatic conditions. The evolution of soils as related to climate dynamics in the first millennium BC and the first millennium AD is characterized.     

Andosol to Luvisol evolution in Central Mexico: timing, mechanisms and environmental setting

Surface and buried Andosols and buried Luvisols of the Nevado de Toluca Late Quaternary tephra-paleosol sequence (Central Mexico) were studied to show whether these soils present an evolutionary sequence and to determine the pedogenic mechanisms and environmental factors involved in the evolutionary process. Micromorphological observations and mineralogical composition of fine sand and clay fractions were used to detect type and succession of soil-forming process. Some of the buried Andosols, defined as “intergrade” Andosols, have a predominantly blocky structure, humus-depleted areas, redoximorphic features and thin clay coatings in Ah horizons. Clay fractions of buried Andosols contain halloysite besides amorphous components, whereas in modern Andosols, allophane is dominant. Luvisols have micro-areas with granular structure and abundant phytoliths in the groundmass of Bt horizons assumed to be the relict Andosol features. Luvisol clay fractions are dominated by halloysite and kaolinite. Primary minerals show micromorphological weathering features in all studied soils being stronger in Luvisols; however, even in Luvisols, sand fractions consist mostly of unstable volcanic silicates. We hypothesise that the studied profiles form an evolutionary sequence: Andosols–“intergrade” Andosols–Luvisols; the soil transformation is supposed to be linked to progressive crystallisation of 1:1 clay minerals. Comparing the Nevado de Toluca paleosol properties with the existing data on volcanic soil climo- and chronesequences and assessing the regional paleopedological and lacustrine records of Quaternary paleoclimates, we concluded that wet/dry climatic oscillations took place during the formation of the studied paleosols. Rapid crystallisation of 1:1 minerals occurred during dry phases, which speeded up the Andosol to Luvisol transformation and made it independent from the primary mineral weathering status. The Andosol to Luvisol transformation accelerated by climatic fluctuations is thought to be a common soil evolutionary pathway in the subtropical and tropical regions of recent volcanism, which suffered contrasting precipitation oscillations in the Quaternary.     

Natural and anthropogenic components of soil acidification

The following 8 theses are theoretically founded and experimentally quantified. 1. Rocks contain only bases and no acid precursors. Therefore, with the exception of sulfide containing rocks, soils cannot acidify as a result of atmospheric rock weathering. 2. A consumption of protons in rocks and soils results in a decrease of their acid neutralizing capacity (ANC) and can result in the buildup of a base neutralizing capacity (BNC). Strong soil acidification leads to the formation of stronger acids from weaker acids in the solid phase; this may be connected with a decrease in the BNC. 3. Weak acids (carbonic acid) lead in geological times to the depletion of bases without a larger accumulation of labile cation acids. Strong acids (HNO₃, organic acids, H₂SO₄) can lead within a few decades to soil acidification, i.e. to leaching of nutrient cations and the accumulation of labile cation acids. 4. The acid input caused by the natural emission of SO₂ and NO_x can be buffered by silicate weathering even in soils low in silicates. 5. The cause of soil impoverishment and soil acidification is a decoupling of the ion cycle in the ecosystem. 6. Acid deposition in forest ecosystems which persists over decades leads to soil acidification. 7. Formation and deposition of strong acids with conservative anions (SO₄, NO₃) shifts soil chemistry into the Al or Al/Fe buffer range up to great soil depth. In such soils eluvial conditions prevail throughout the solum and even in upper part of the C horizon: in connection with the decomposition of clay minerals, Al and eventually Fe are being eluviated. The present soil classification does not include this soil forming process. 8. In the long run, soil acidification by acid deposition results in the retraction of the root system of acid tolerant tree species from the mineral soil, and in water acidification.     

Potassium release characteristics and mineralogical characteristics of some delaware soils

Abstract

Twenty‐eight agriculturally important Delaware soils were cropped intensively in a greenhouse experiment. There was no consistent positive correlation between K uptake and percent sand, silt, clay, clay minerals of the clay fraction, K‐feld‐spars of the sand fraction or K‐feldspar weathering of the soils from the A horizon. Only potassium feldspar from the sand fraction and K‐feldspar weathering correlated with K uptake in the soils of the B horizon. This correlation was only significant at the latter part of the experiment when nonexchangeable K was probably the source of plant available K.     

湘中下寒武统黑色页岩土壤的地球化学特征

以湘中发育于下寒武统黑色页岩之上的土壤为研究对象,选择安化东坪、烟溪,桃江,宁乡等地的典型土壤及相应成土母岩,利用等离子质谱(ICP-MS)、X射线荧光光谱(XRF)等分析技术,对土壤、成土母岩(黑色页岩)的主量元素和微量元素(包括重金属元素、稀土元素等)进行了较系统的分析测定。结果表明,湘中下寒武统黑色页岩土壤风化作用强烈,风化指数CIA均在73以上。强烈的风化使得土壤具有明显贫CaO、Na2O,而富Al2O3、Fe2O3的化学组成特征。土壤因继承成土母岩(黑色页岩)的特征而富集Mo、Cd、Sn、Sb、U、V、Cr、Co、Ni、Cu、Zn、Tl、Pb、Th等多种重金属元素,其综合富集指数(EI值)平均在3以上,最高达17。地质累计指数(Igeo)评价结果显示,土壤重金属的富集已达到污染程度,土壤存在Cd、Mo、Sb、U、Sn、V、Cu、Tl、Ba等重金属的污染,并以Cd、Mo、Sb等重金属污染最强,达中度至极强污染程度。重金属与主量元素的相关性分析显示,土壤中的重金属主要赋存于黏土矿物和铁氧化物(针铁矿)等矿物相中,其中Ba、Sn、Th、Cu、Sc等主要赋存黏土矿物中;Zn、Ni、Mn、Co、Cd、Tl、Pb等则主要赋存于铁氧化物矿物(针铁矿)中;而Cr、V、Mo、Sb、U等则不受黏土矿物和铁氧化物矿物的控制。此外,不同地区土壤的Zr/Hf、Ta/Nb、Nd/Sm等元素比值相对稳定,依次为36.20、0.085、5.30(n=73),并与相应的成土母岩(黑色页岩)相应值基本一致。土壤与成土母岩具有相同的稀土配分型式,且成土过程中稀土元素不发生明显的分异。微量元素比值和稀土元素特征指示土壤中的重金属来自成土母岩(黑色页岩)本身,为自然污染源。     

福建主要土壤的粘粒云母含量和供钾潜力

利用X射线衍射法估算了福建省221个土壤样品中粘粒云母含量并讨论了与粘粒云母含量变化有关的因素。结果表明母质是影响粘粒云母含量的主要因素。海积物、河积物及页岩上发育的土壤粘粒云母含量一般较高;基性岩上发育的土壤粘粒云母含量一般较低。风化度较高的赤红壤、红壤、黄红壤和黄壤等土类的粘粒云母含量一般较低。风化度较低的C层的粘粒云母含量一般较B层和A层高,但异源母质的堆积可以使A层粘粒云母含量高于B层和C层。     

An experience in using the world reference base for soil resources for the soils of western Georgia

New and previously published data on the soils of western Georgia are generalized, and traditional soil names are correlated with the units of the World Reference Base for Soil Resources. It is argued that krasnozems (red ferrallitic soils) can be attributed to the group of Nitisols (the soils characterized by intense weathering (ferralization) and having shiny ped faces in the nitic horizon); yellow and yellow-brown soils (zheltozems), to the group of Luvisols (the soils with relatively high adsorption capacity in the eluvial horizons and with the horizon of the illuvial accumulation of clay); yellow-podzolic (zheltozem-podzolic) soils, to Alisols (slightly acid soils with the low adsorption capacity, poor aggregation of the upper horizons, low-activity (kaolinite) clay, and with the horizon of clay accumulation (argic horizon)); brown forest soils, to Cambisols (the soils with the cambic horizon characterized by some alteration of the lithogenic texture and structure into the pedogenic texture and structure); and mountainous forest-meadow and meadow soils, to Umbrisols (the soils with the dark-colored unsaturated umbric horizon).     

西安少陵塬黄土—古土壤序列S_3剖面元素迁移及古气候意义

以西安少陵塬S3古土壤剖面为研究对象,通过地球化学分析并结合野外剖面观察,探讨该剖面的元素迁移、化学风化特征及其所揭示的气候变化等问题。结果表明:(1)少陵塬剖面S3黏化层具有3层结构,根据铁质胶膜发育、Ca CO3迁移等可以将S3剖面构型划分为黏化层(Bts1-Bts2-Bts3)、风化淋滤黄土层(BC)和Ca CO3结核淀积层(Bck);(2)Bts层Ca O与Ca CO3迁移程度最大,淋失率分别达到了-99.3%、-83.1%,Sr、Na2O和Mg O也发生了显著迁移,而Fe2O3、Al2O3和Rb则在黏化层略有富集,尤其Fe2O3和Al2O3在Bts3层有明显富集;(3)少陵塬S3古土壤介于初等风化向中等强度风化的过渡阶段,风化作用由BC→Bts2→Bts1→Bts3逐渐增强,Bts3已基本完成初期脱Ca、Na风化过程;(4)依据Ca CO3与Fe2O3的迁移富集特点确定,少陵塬剖面S3古土壤Bts3发育时的土壤为弱碱性,而Bts1和Bts2为碱性;初步确定少陵塬S3为黄褐土,S3发育时期西安地区的年均降水量为800 mm左右。     

The weathering of ferruginous chlorite in a podzol from argyllshire,Scotland

The dominant mineral in the clay fractions from the basal horizons of a podzol developed on till derived mainly from chlorite-schists in Argyllshire is oxidized, iron-rich chlorite. Towards the profile surface, the chlorite decreases in amount, becoming absent in the A₂ horizon in which the dominant mineral is a complex dioctahedral interstratified phase formed from dioctahedral mica and composed of mica and vermiculite. The absence of any trioctahedral mineral in the A₂ horizon together with the marked loss of iron and magnesium from the clay fraction from this horizon indicates that the chlorite, a thuringite, has been destroyed, the only detectable product being goethite. In other apparently similar soils chlorite persists throughout the profiles. As the Eredine podzol contains translocated humus in the B₂ horizon, it is suggested that during podzolization, organic solutions percolated downwards from the surface, formed complexes with iron and aluminium from the chlorite structure, removing them to the B₂ horizon, and thus eventually dissolved out the chlorite from the A₂ horizon.     

Clay minerals from diallage in a warm and humid climate

In the course of chemical weathering, rockforming minerals release constituent ions changing into secondary minerals by alteration or recrystallization. Minerals formed in this way are primarily of colloidal nature, and are the most active portion in soils together with humus. The chemical weathering has dual meaning for soil fertility, that is, it provides soils with nutrients released and inorganic colloids formed, namely clay minerals. It has been well established that climate, vegetation, parent material, topography and time influence the formation of soils. Generally speaking, Japanese soils have developed under a warm and humid climate which causes leaching of released bases resulting in acid reactions, and a predominance of kaolin in soils. Accumulated information pertaining to Japanese soils, however, has disclosed that physical, chemical, and mineralogical properties of parent rocks are still obviously reflected in the clay minerals of soils.     

Mineralogic evolution in hydromorphic sandy soils and podzols in “landes du médoc”, France

Soils of the nearly level “Landes du Médoc” in southwestern France have a pattern of alternating bodies of hydromorphic podzols (Haplaquods) and low humic hydromorphic soils (Psammaquents). The soils are formed in a sedimentary mantle of coarse, quartzose sands with a slight microrelief consisting of low, elongated ridges and shallow, intervening troughs. The water table is at shallow depths throughout the plain, even at the surface in places. The podzols on the crests of the low ridges have distinct A₂ and cemented B₂ h horizons. Podzols persist down the sides of ridges but going downslope first lose the A₂ horizon and then the cementation of the Bh horizon. Soils in the shallow troughs have A₁ and Cg horizons without B horizons.The fine silt (2–20 μm) and clay (0–2 μm) fractions of the parent sand contain primary trioctahedral chlorite, mica, feldspars, and quartz, with the last mineral predominant. During soil development, the first three minerals undergo weathering at different rates and to different extents. Chlorite is most strongly weathered, followed in order by plagioclases and K-minerals. In the fine silt fraction, weathering seems to occur mostly by fragmentation of particles. In the clay fraction, the phyllosilicates successively form irregularly interstratified minerals with contractible but not expandable vermiculitic layers, interstratified minerals with contractible and expandable smectitic layers, and finally smectites.The extent to which the silicate minerals are weathered becomes progressively greater from the low humic hydromorphic soils to the podzols with friable Bh horizons to the podzols with cemented Bh horizons. Smectite is present only in the A₂ horizons of these last podzols.The aluminum release by weathering of silicate minerals is translocated in part in the form of organo-metal complexes into the Bh horizons of the podzols. Greatest concentrations of Al are associated with coatings of monomorphic organic matter on mineral grains in the cemented Bh horizons, in which some Al has also crystallized into gibbsite. That mineral was not detected in friable B horizons of podzols nor in the low humic hydromorphic soil. Contrary to expectations, the mobile Al did not enter interlayer spaces of expanding 2:1 clay minerals.     

Holozäne Terrae fuscae aus Carbonatgesteinen in den Nördlichen Kalkalpen

Formation of Terrae fuscae from carbonate parent rocks in the Northern Calcareous Alps during the holocene period The paper describes loamy to clayey soils, which developed mainly as clay residue by the desintegration of stratified slope deposits derived from Hauptdolomit. They are occuring in the Tegernsee mountains, a typical part of the calcareous Alps in Bavaria. These soils exhibit a typical difference in texture and structure (5-30 cm silty subpolyedric loam covering 10-30 cm loamy clay with polyedric structure), which determines many other physical and chemical characteristics of the soils. The clay fraction of both layers is dominated by 2:1 minerals, mainly illite. The stratified solum is further modified by clay migration and may show weak hydromorphic features induced by slope wetness or some podzolisation. Those profiles are classified as Parabraunerde-Terra fusca (Eutroboralf) with A_h-A₁B_v - II B_tv-B_vC_v-C_v-horizons derived from a silty sediment overlying Hauptdolomit detritus; there is clear evidence that these soils developed during the holocene period.     

PALEOsolS DEVELOPED ON CHALKY BOULDER CLAY IN ESSEX

Soils with paleosol features occur at the surface on the Chalky Boulder Clay in the Chelmsford area, Essex. Their particle size distribution, micromorphology and sand, silt and clay mineralogy indicate periods of weathering, clay illuviation and hydromorphism before deposition of loess in the Late Devensian. These periods are provisionally related to the Ipswichian and/or Hoxnian Interglacials.