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1.
Mineralogical, physical and chemical analyses of the soils derived from Xiashu loess were carried out. The primary minerals of these soils were found to be mainly composed of light minerals, such as quartz, feldspar and mica, with traces of heavy minerals. Clay minerals, more complicate in composition, were dominated by hydromica, accompanied by smectite, vermiculite, chlorite, kaolinite, 2:1/1:1 randomly interstratified minerals and small amounts of quartz, goethite, lepidocrocite and hematite, Clay minerals were characterized by low crystallinity and fine particle size. In light of the quartz/feldspars ratio of the 0.01-0.05mm silt fraction, and the clay mineral composition, the freeness of iron oxide, and the silica/sesquioxide and silica/alumina ratios in < 0.002mm clay fraction, it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth, but higher than that of brown earth, and that the soil allitization, depotassication and hydroxylation of cl 相似文献
2.
Per Nørnberg 《Geoderma》1980,24(1):25-43
This paper deals with possible mineralogical changes from one particle size fraction to another and from one horizon to another in a Typic Haplorthod. X-ray diffraction and chemical analysis were the main methods used. The investigation indicates that a large part of the fine material in the soil is developed during weathering in situ. Less resistant minerals seem to be protected by being parts of rock fragments in coarser fractions, but once freed from that protection they quickly undergo fragmentation into finer particles. Most of the sand and silt fractions are quartz. The K-feldspar content ranges between about 10 and 20%, the Na-feldspar content from about 15 to 30% and the Ca-feldspar content is very small. The clay minerals are mostly kaolinite and mica and in the A2 horizon, expandable 2:1 minerals containing both smectite and vermiculite layers. The B horizon contains 14 A minerals that resemble interstratified vermiculite—chlorite. In the C horizon both vermiculite—chlorite and clorite occur. 相似文献
3.
Chemical and mineralogical properties of a soil chronosequence in the high mountain zone between 3857 m and 4120 m a.s.l. in Central Nepal (Langtang valley) are presented. The soils have been developed in moraine deposits which consist of acid gneisses. They were classified as Entisols, and Spodosols. XRD analyses of the clay and fine silt fraction show increasing changes with distance from the recent Lirung glacier, depending on the time of deposition, resp. soil age. Alteration of illite to interstratified minerals and to hydroxy-Al interlayered minerals or pedogenic chlorite with increasing soil development could be observed. The interstratified minerals could be identified as random and regular illite-interlayered vermiculite mixed-layer minerals. Intensification of the X-ray signals of the fine silt fraction is given compared to the clay. With increasing soil development differences between the clay and fine silt fraction seem to increase. Indications are given of interstratification of the mica-pedogenic chlorite and chloriteinterlayered vermiculite type in the more intensively weathered soils. 相似文献
4.
Limited information is available concerning the mineralogy of paddy soils in the southeastern China. Using chemical methods in conjunction with X-ray diffractometry, we studied the mineral composition of three paddy soils: Jinghua (paddy soil on Quaternary red clay), Fuyang (Hapl-percogenic loamy paddy soil), and Shaoxing (gleyic clayey paddy soil). All the soils contained quartz, mica, vermiculite, chlorite and kaolinite, and the distribution of these minerals varied with soil particle size fractions. The clay fraction of the Fuyang and Shaoxing soils also contained smectite. Although X-ray data did not show the presence of smectite in the Jinghua soil, this mineral was identified by the chemical method, suggesting a transitional property of the mineral in the soil. Hydroxy-Al interlayered minerals were also present in the clay fraction. The amount of smectite in the soils was 31.6 (Shaoxing), 16.5 (Fuyang), and 21.4 (Jinghua) g kg-1; for vermiculite it was 33.3 (Shaoxing), 16.5 (Fuyang), and 8.5 (Jinghua) g kg-1. Smectite was only found in the clay fraction. In contrast, amounts of vermiculite in soil particle size fractions were 3.0~11.4 (sand), 2.1~6.0 (coarse silt), 4.6~18.9 (medium silt), 0.9~40.0 (fine silt), and 17.0~108 (clay) g kg-1. The amount of noncrystalline aluminosilicates in the soils in g kg-1 decreased in the order: Shaoxing (2.4) > Jinghua (1.9) > Fuyang (1.7). This study has provided useful mineralogical information that is fundamental in future development of management strategies of the soils. 相似文献
5.
《Geoderma》1987,39(3):193-207
Mineralogies of a soil catena in the Pampa of Ulla Ulla (4,300–4,600 m) and the soils of the steep slopes of the Cordillera de las Muñecas (“steep area”) were investigated. The latter area includes three altitudinal zones: herbaceous zone (3,900–4,800 m), shrub zone (2,700–3,900 m), and mountain forest zone (up to 2,700/2,800 m). The soils were classified according to Soil Taxonomy as Entisols, Mollisols, and Inceptisols. They were mainly derived from quartzitic schists and slope debris. Each horizon of each profile was representatively sampled for analyses.Muscovites and illites were the dominant minerals in the fine silt and clay fraction, respectively. Besides kaolinite, pyrophyllite and vermiculite, regular illite/vermiculite mixed layers, chlorite, feldspar and quartz were detected in both fractions. In a Typic Cryaquent from the Pampa of Ulla Ulla, smectites had been formed. Pyrophyllite, illite/vermiculite mixed layers and chlorite seemed to be unstable under acid conditions in most of these soils. 相似文献
6.
The mineralogical composition of agrogray, dark gray, and agro-dark gray soils (Luvic Greyzemic Retic Phaeozems); agro-dark gray residual-calcareous soils (Calcaric Cambic Phaeozems); clay-illuvial agrochernozems (Luvic Chernic Phaeozems); and agrochernozems with migrational–mycelial carbonates (Haplic Chernozems) developed in the forest-steppe of Central Siberia within the Irkutsk Depression has been studied. The clay (<1 μm) fraction separated from these soils consists of mixed-layer minerals with alternating layers of hydromica, smectite, vermiculite, and chlorite; the proportions between them change within the soil profiles. The clay fraction also contains hydromicas, kaolinite, chlorite, and some admixture of the fine-dispersed quartz. Each type of the soils is characterized by its own distribution pattern of clay material with specific alternation of layers in the mixed-layer formations. Mixed-layer minerals of the chlorite–vermiculite type predominate in the upper horizons of texture-differentiated soils. Down the soil profile, the content of mixed-layer mica–smectitic minerals increases. In the clay fraction of arable dark gray-humus soils with residual carbonates, the distribution of the clay fraction and major mineral phases in the soil profile is relatively even. An increased content of well-crystallized kaolinite is typical of these soils. The parent material of agrochernozems has a layered character: the upper horizons are generally depleted of clay, and the middle-profile and lower horizons are characterized by the considerable kaolinite content. In general, the clay material of soils of the Tulun–Irkutsk forest-steppe differs considerably from the clay material of foreststeppe soils developed from loesslike and mantle loams in the European part of Russia. In particular, this difference is seen in the proportions between major mineral phases and between biotitic and muscovitic components, as well as in the degree of crystallinity and behavior of kaolinite and chlorite. 相似文献
7.
The mineralogies of ‘Tirs’ (Typic Pelloxererts), and ‘Debs’ (Typic Haploxerolls and Typic Xerochrepts) soils of the Gharb plain in north-western Morocco are investigated, with special attention given to the determination of the nature of the smectitic phase using the lithium test (Li test) and the alkylammonium method. The sand and silt mineralogy of Tirs soils is dominated by quartz with small amounts of feldspars and kaolinite. The sand and silt fractions of Dehs soils also contain significant amounts of mica, chlorite, and interstratified phyllosilicates. The clay minerals of Tirs soils are predominantly a high-charge smectite. The estimated interlayer charge for this phase is 0.61 mol(c)/O10(OH)2 and the fraction of tetrahedral charge varies from 38 to 44%. Although the percentage tetrahedral charge is less than 50%, the smectitic phase behaves as beidellite with the Li test. Dehs clays are more heterogeneous, consisting of smectite, vermiculite, illite, kaolinite, chlorite, and interstratified illite/smectite and illite/vermiculite. The Li test and the alkylammonium method demonstrate that a high-charge smectite or vermiculite is interstratified with illite. A low-charge montmorillonite is also present both in Tirs and in Dehs soils. The high-charge beidellitic phase is believed to be a transformation product of mica, whilst the low charge montmorillonite is thought to be inherited from the parent material. 相似文献
8.
Characteristics of Clay Minerals in Podzols and Podzolic Soils 总被引：1，自引：0，他引：1
Yasuo Kitagawa 《Soil Science and Plant Nutrition》2005,51(2):151-158
The clay minerals in Podzols and podzolic soils developed under coniferous forests in the Subarctic and Cool-temperate zones are characterized by the predominance of smectite and/or mica-smectite interstratified minerals in the eluvial horizons and chlorite-vermiculite intergrade in the illuvial horizons. A large amount of vermiculite is present in the eluvial horizons of some podzolic soils in the Cool-temperate zone. The illuvial horizons of these soils also contain free iron oxides such as goethite. Imogolite and allophane are present in the illuvial horizons of several soils derived from volcanic ashes. It is suggested that the critical bioclimate for the release of interlayered aluminum from the 2:1-type minerals lies between the Cool- and Warm-temperate zone. In the eluvial horizons of Podzols and podzolic soils, mica minerals and chlorite, as primary minerals, have been transformed to smectite through the pedogenic process. Based on previous studies on the structure and degradation of the dioctahedral mica minerals, it is considered that smectite is transformed from 1M-type mica minerals directly, and from 2M-type mica minerals via mica-smectite interstratifled minerals. The formation of a smectite lattice in the eluvial horizon should be a clay-mineralogical indicator of podzolization. 相似文献
9.
G. A. Ajiboye C. A. Oyetunji J. Talbot 《Communications in Soil Science and Plant Analysis》2019,50(3):333-349
The pedogenic horizons of nine profile pits dug across three toposequences were studied to determine the soil mineralogical characteristics and its implications on sustainable management of the fertility of some tropical Alfisols in Nigeria. Results showed that the epipedon which were predominantly ochric had textures that ranged from sand to sandy loam, while the subsurface (B/Bt) horizons had sandy clay loam to sandy clay texture and were gravelly (31.79–83.04%). The soil reaction ranged from strongly acid to neutral (pH 5.10 to 7.05). Calcium and magnesium dominated the exchange sites and accounted for about 75% of the exchangeable bases. Illite/mica and kaolinite were the dominant minerals in the clay fractions, while quartz, mica, and feldspars dominated the fine sand and silt fractions of the soils. While the presence of illite and mica could be important for potassium nutrition in these soils, kaolinite and oxides of iron could also cause phosphorus fixation. 相似文献
10.
The presence of so-valled chlorite-like minerals has been reported in many soils of not only acid but also of alkaline reaction (1). The minerals have been designated by, many terms, for example, dioctahedral vermiculite (2), dioctahedral analogue of vermiculite (3), 14A mineral (4), chlorite-like mineral (5), interstratified chlorite-vermiculite (6), intergradient chlorite-expansible 2:1 layer silicate, intergradient chlorite-vermiculite, intergradient chlorite-vermiculite-montmorillonite, intergrade, or interlayered vermiculite (7), and 2: 1-2: 2 intergrade (1). The minerals designated by these terms are evidently of the same category, and some of them are synonymous. Although they are of intermediate properties, between true chlorite and true vermiculite or montomorillonite, they could be regarded as an independent group of minerals in the course of pedochemical weathering. Jackson (1), for instance, has given the minerals the position of “weathering index 9”, placing them between vermiculite and kaolin as equivalent to montmorillonite, or secondary chlorite and kaolin in his weathering sequence. An explanation of the diagenesis of the minerals has been recently attempted by synthesis of the chlorite-like structures from montmorillonite (8), (9) and vermiculite (10) and mineralogical analyses of soil clay fractions (7). 相似文献
11.
N. P. Chizhikova N. B. Khitrov A. A. Samsonova E. B. Varlamov N. A. Churilin L. V. Rogovneva Yu. I. Cheverdin 《Eurasian Soil Science》2017,50(4):456-469
Properties and mineralogy of fine fractions separated from agrochernozems forming a three-component noncontrasting soil combination in the Kamennaya Steppe have been characterized. The soil cover consists of zooturbated (Haplic Chernozems (Clayic, Aric, Pachic, Calcaric)), migrational-mycelial (Haplic Chernozems (Clayic, Aric, Pachic)), and clay-illuvial (Luvic Chernozems (Clayic, Aric, Pachic)) agrochernozems. All the soils are deeply quasi-gleyed because of periodical groundwater rise. The mineralogy of the fraction <1μm includes irregular mica–smectite interstratifications, di- and trioctahedral hydromicas, imperfect kaolinite, and magnesium–iron chlorite. The profile distribution of these minerals slightly varies depending on the subtype of spot-forming soils. A uniform distribution of clay minerals is observed in zooturbated agrochernozem; a poorly manifested eluvial–illuvial distribution of the smectite phase is observed in the clay-illuvial agrochernozem. The fractions of fine (1–5 μm) and medium (5–10 μm) silt consist of quartz, micas, potassium feldspars, plagioclases, kaolinite, and chlorite. There is no dominant mineral, because the share of each mineral is lower than 35–45%. The silt fractions differ in the quartz-to-mica ratio. The medium silt fraction contains more quartz, and the fine silt fraction contains more micas. 相似文献
12.
Li Huang Wenfeng Tan Fan Liu Hongqing Hu Qiaoyun Huang 《Journal of Soils and Sediments》2007,7(4):240-246
Background, Aims, and Scope Hydroxy interlayered vermiculite (HIV) and vermiculite are commonly referred to as 1.4 nm minerals. In the subtropical soils
of central China, the concentration of vermiculites decreased while that of HIVs increased gradually from north to south as
the intensity of soil formation or eluviation increases in the same direction. The cutans in these soils closely interact
with air, roots, microbes, water and dissolved ions in soils. Cutans may therefore be expected to exert an important influence
on the formation of 1.4 nm minerals relative to the matrix soils. However, little is known about the transformation of 1.4
nm minerals in Alfisols in central China. Here, we investigate the compositional differences of 1.4 nm minerals in cutans
and matrix soils, and the probable transformation of vermiculite to HIV or vice versa when sodium citrate and sodium acetate
are added to matrix Alfisols.
Methods Cutans and matrix soils were separated from three soils in the northern subtropical zone in China. The samples were analyzed
for Fe, Mn, exchangeable cations, organic matter(O.M.), pH, and clay minerals. To 10 mL of matrix soil, suspensions containing
about 250 mg (oven-dry weight) of clay was added with 5 mL of 0.4 mol/dm3 or 2 mol/dm3 of sodium citrate or sodium acetate solution and 5 mL of 0.2 mol/dm3 mixed solutions of CaCl2, Mg(NO3)2 and KCl. After its pH was adjusted to 6.0, the mixture was ‘incubated’ for 120 or 210 days (more than one season or half
a year) during which period it was shaken for 1 hour every day. The clay mineral composition of the samples was determined
after incubation.
Results Both vermiculites and HIVs were present in matrix soils, but only vermiculties were detected in cutans. The addition of organic
ligands (citrate and acetate) promoted the transformation of HIV to vermiculite. This transformation was obvious for the matrix
soils that had been incubated with 0.5 mol/dm3 sodium citrate for 210 days while sodium acetate was less effective in this regard. The promoting effect of organic ligands
is dependent on type and concentration as well as incubation time. This would suggest the reverse transformation occurred
in the formation of cutans compared with a vermiculite-to-HIV transformation in the subtropical soils of central China from
north to south.
Discussion The position and environment of cutans in the B horizon together with the pH, organic matter and exchangeable base status
in cutans seem conducive to the co-existence of vermiculite and HIV in the soils, but only vermiculite is found in cutans.
The transformation of HIV to vermiculite in incubation experiments could be divided into two steps: 1) Cheluviation of organic
matter to the interlayer hydroxy-aluminums from HIVs. 2) Rebasification of hydrated cations into the interlayers of vermiculites.
Conclusions The clay minerals in cutans can interact with organic ligands and nutrient elements excreted by roots. Under conditions of
frequent wetting and drying and high pH, and when the concentrations of exchangeable bases, iron-manganese oxides, clays,
and organic matter are high, the exchangeable cations can be incorporated into the interlayers of HIV, thereby promoting the
partial transformation of HIV to vermiculite in rhizosphere soils.
Recommendations and Perspectives Cutan is at the interface of material and energy exchange involved in physical, chemical and biochemical reactions in the
rhizosphere. These factors strongly affect the compositions of cutans. HIVs in (upper or adjacent) matrix soils may transform
to vermiculites during cutan formation in these special soil environments.
ESS-Submission Editor: Jizheng (Jim) He (jzhe@rcees.ac.cn) 相似文献
13.
Yu Zhan Zhang Yangzhu Sheng Hao Zhang Liang Zhou Qing Yan Xiong 《Journal of Soils and Sediments》2020,20(3):1558-1570
Purpose
The aims of this study were to investigate the composition of clay minerals in soils derived from different parent materials and to elucidate how parent materials and pedogenic environment affect the distribution of clay minerals and reveal the implications for pedogenetics and taxonomy in Stagnic Anthrosols.
Materials and methodsClay mineralogy and physicochemical properties of the Hydragric horizon of Stagnic Anthrosols derived from granite (GR), plate shale (PS), quaternary red clays (QRC), limestone (LS), purple sandy shale (PSS) and fluvial-lacustrine deposit (FLD) located in Hunan Province of China were analysed to explore the relationships between the conditions influencing the formation of the soil and the composition of clay minerals.
Results and discussionResults indicated that the composition of clay minerals is closely related to both parent material and type of Stagnic Anthrosols: the soils derived from GR, PS and QRC, which are mostly classified as Fe-accumulic-Stagnic Anthrosols, are dominantly 1:1 type kaolinite and vermiculite and illite/vermiculite mixed layer minerals of widespread distribution. However, soils derived from LS, PSS and FLD were mainly classified as Hapli-Stagnic Anthrosols and are mainly composed of 2:1 type illite/smectite mixed layer minerals, where chlorite is commonly found. Illite is widely distributed and its content varies the least among different parent materials. An extremely significant relationship between pH and kaolinite, chlorite and mixed layer minerals was noted, and the two kinds of mixed layer minerals showed highly significant negative correlation.
ConclusionsThis study revealed that the types and quantities of clay minerals in the soil are closely related to the types of parent material. This reflected better direction and degree of development in Stagnic Anthrosols, which is related to the physicochemical properties of parent material and can be used as one of the bases for the classification of soil groups and subgroups within the soil family for Stagnic Anthrosols in Chinese Soil Taxonomy.
相似文献14.
西藏高原突起于我国西南,绝大部分地面的海拔高度在4000米以上,为世界上最高的大高原。它大致在第三纪开始形成,后来曾受第四纪冰川的深刻作用,高山顶部至今仍是冰川的活动场所[1,2]。高原为昆仑山、唐古拉山、喜马拉雅山和横断山等大山脉所盘踞。 相似文献
15.
D.C. Bain 《Geoderma》1977,17(3):193-208
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. 相似文献
16.
M. J. WILSON 《European Journal of Soil Science》1973,24(1):26-41
The clay mineralogy of thirty-two profiles located mainly in the Vale of Strathmore and developed on glacial till derived from Lower Red Sandstone sediments and lavas has been investigated by X-ray diffraction. The soils were selected so that the parent material was related predominantly to one of the rock types common in the Lower Old Red Sandstone succession—namely, marl, sandstone, lava, or conglomerate. Comparison of the < 1.4μm fractions separated from fresh rock samples with those separated from the C horizons of the soils clearly established the dominant influence of parent rock on the soil-clay mineralogy. The clay minerals inherited by the soil often include unusual trioctahedral expansible minerals such as saponite, interstratified vermiculite-chlorite, and smectite-vermiculite, as well as more common types like mica, montmorillonite, and chlorite. Kaolinite is also found but it is not certain that it is only of inherited origin. Weathering of the clays during soil formation brings about complete degradation of the expansible trioctahedral minerals, a process usually well advanced in the B or even at the top of the C horizon, and vermiculitization of mica. The latter process occurs mainly in the A horizon, with concomitant precipitation of interlayer aquohydroxy-aluminium ions thereby forming a vermiculite-chlorite intergrade. Chlorite and kaolinite appear to be little affected by weathering. The weathering transformations are most pronounced in freely drained acid soils (pH < s) and are at a minimum in poorly drained soils and where the pH remains above 6. The susceptibility to weathering of the trioctahedral expansible minerals results in relatively high values for exchangeable magnesium at the base of the profile. 相似文献
17.
辽宁省西部是低山丘陵区,年平均温度7.1℃,年平均降雨量400—500毫米,降雨集中在夏季,具有明显的大陆性气候特征,干燥度小于1,属半干旱类型.植被为油松柞木和草原灌木丛林.土壤属棕色森林土向栗钙土过渡的褐土地带.母质主要为花岗片麻岩风化物.山麓缓坡和河谷两岸为黄土丘陵.在黄土沉积物覆盖层下,常见红色风化壳露头,即红色粘土层.此外,并有松软易风化岩层,如砂岩、页岩和变质岩等.本区近百年来,由于自然植被受到严重破坏,大量水土流失,土壤侵蚀严重,土壤有机质含量低,成为辽宁省的低产区.因此,鉴定本区不同母质的土壤矿物胶体组成及其特征,不仅可以研究这一特定自然条件下土壤矿物的转化和形成,并且有助于了解土壤特性和肥力特征. 相似文献
18.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):401-412
Abstract Six mica dominant soils representing a landform sequence were used for the present investigation. The effect of extraction of nonexchangeable potassium (K) by boiling 1 M HNO3 treatment and its associated structural changes of micaceous clay minerals was studied by employing x‐ray diffraction technique. Potassium release was rapid in the first three extractions and slowed down to a constant rate thereafter in all the clay samples. The first extraction contributed about 45.57–62.69% towards the total K release. The calculated values of rate constant (first order) decreased sharply from 0.065–0.025 min‐1 after third extraction and reached a constant value thereafter. The calculated integral width of first order reflection of mica peak (10Å) decreased considerably with nitric acid treatment, but no such effect was observed in 5Å peak. The differential x‐ray diffraction (DXRD) traces showed that the HNO3 treatment dissolved finer particles of mica particularly trioctahedral component and mixed layer minerals, smectite, chlorite and vermiculite. 相似文献
19.
Characteristics of the soils include well-defined horizons, very low pH values and base saturation percentages, and a slight but general increase in the silt-plusclay content down the profile. X-ray diffraction shows that the soil clays are rich in mica and chlorite with subsidiary amounts of kaolinite, goethite, and lepidocrocite. The general distribution of the clay minerals in the profiles studied suggests that the weathering of chlorite leads to the formation of kaolinite in the A horizons and to the accumulation of crystalline iron-oxide minerals in the B horizons. The presence of kaolinite, taken in conjunction with recent clay mineral studies of Scandinavian and Canadian podzols, indicates that the Ben Lawers soils may pre-date the last glacial period. 相似文献
20.
A study was made of the weathering of trioctahedral, iron-rich chlorite and dioctahedral mica in a Spodosol (Haplorthod) developed on till derived from chlorite-mica schist.Chlorite in the clay of the B and C horizons has weathered to small amounts of regularly interstratified chlorite-vermiculite, vermiculite and goethite. Chlorite vermiculitization is associated with a loss of iron and aluminum and appears to result in a change toward dioctahedral structure. Chlorite and its trioctahedral vermiculitic products are absent from the clay, silt and sand of the Ae horizon which is probably due to decomposition by organic acids.Mica in this soil weathers and expands to dioctahedral, regularly interstratified mica-ermiculite and discrete vermiculite products that increase in abundance towards the profile surface and are dominant in the clay of the Ae horizon. Amounts of mica-derived vermiculite products decrease with increase in particle size and are practically absent in the sand of the Ae horizon.Comparing mineral weathering in this Spodosol with that in other soils, developed on similar greenschist material but in warmer climates or during longer times, shows that amounts of chlorite-derived vermiculite in the subsoils of the latter soils are much larger, decrease towards the profile surface, and increase with larger particle size. The evidence indicates that weathering of chlorite to vermiculite and accumulation of the vermiculite products are optimal in non-eluvial, moderate weathering conditions. 相似文献