Hasil untuk "Mineralogy"

ستار مهدوری, کورش شهریار, علیرضا بهادربیگی

در روش استخراج جبهه‌کار طولانی پس از استخراج هر برش از لایه زغال‌سنگ و پیشروی جبهه‌کار، تمرکز تنش شدیدی بلافاصله در محدوده سقف کارگاه و پیشانی جبهه‌کار به علت اغتشاش تنش و نیز تخریب سقف به وجود می‌آید که به صورت جابه‌جایی سقف، انتشار ترک‌ها و شکست سقف پدیدار می‌شود. به علت تخریب سقف بلافاصله و نیز جابه‌جایی لایه‌های روباره همزمان با پیشروی جبهه‌کار، امکان گسترش شکستگی‌ها و ناپایداری سقف کارگاه وجود دارد. شکست سقف در یک کارگاه جبهه‌کار طولانی پیامدهای نامطلوبی از جمله توقف عملیات استخراج، خسارت به تجهیزات، جراحات و مرگ‌ومیر پرسنل معدن را به همراه خواهد داشت. در این پژوهش، رویدادهای بحرانی که بر شکست سقف کارگاه E3 معدن زغال‌سنگ پروده طبس موثر هستند، شناسایی شدند و با تکمیل پرسشنامه توسط کارشناسان معدن و اساتید دانشگاه، ریسک شکست سقف کارگاه با استفاده از رویکرد تحلیل درخت رویداد فازی ارزیابی شد. به این ترتیب برای تحلیل ریسک شکست سقف کارگاه، ده سناریو برای بررسی شکست یا عدم ‌شکست سقف بررسی و احتمال وقوع رویدادهای بحرانی محاسبه شد. بر اساس نتایج حاصل، احتمال وقوع شکست سقف در سناریوهای چهارم، دهم و هفتم به ‌ترتیب 68/5، 21/4 و 70/1 درصد و مقدار ریسک در این سه سناریو به ترتیب حدود 42/28، 05/21 و 51/8 است، بنابراین بحرانی‌ترین سناریو در این کارگاه، سناریو چهارم است که باید با کنترل به موقع رویدادهای بحرانی موثر بر این سناریو، اقدامات پیشگیرانه برای کاهش ریسک یا جلوگیری از وقوع شکست سقف اتخاذ شود.

Neshka Manchorova-Veleva, Mina Pencheva, David Baruh et al.

<b>Background</b>: Aging is associated with progressive structural and functional changes in dentin, reducing its mechanical integrity and increasing vulnerability to damage. Among the most important regulators of dentin physiology are extracellular matrix proteins from the SIBLING family, including Dentin Matrix Protein 1 (DMP-1), Dentin Sialophosphoprotein (DSPP), and Osteopontin (OPN). These proteins are essential for dentin mineralization, collagen organization, and tissue remodeling. Despite their critical role, knowledge about their age-related distribution and correlation with dentin structure and morphology remains limited. <b>Aim</b>: To examine age-dependent changes in the expression of SIBLING proteins (DMP-1, DSPP, OPN) in human dentin and to evaluate their relationship with collagen structure and ultramorphology using polarized light microscopy (PLM), immunohistochemistry (IHC), and scanning electron microscopy (SEM). <b>Materials and Methods</b>: Ninety extracted human teeth were categorized into young (≤17 years), mature (18–50 years), and old (>51 years) groups. IHC was applied to detect protein distribution, PLM to assess collagen organization, and SEM to evaluate dentinal morphology. <b>Results and Conclusions</b>: Aging was associated with increased expression of DMP-1 and OPN and a reduction in DSPP, which is particularly evident in peritubular dentin. Older samples showed collagen disorganization, reduced birefringence, and extensive intratubular mineralization. These findings suggest that age-related alterations in SIBLING proteins contribute to structural changes in dentin, providing new insights relevant to dental care in elderly patients.

Valentina Nikolova, Radostina Rizova, Ivan Dimitrov et al.

Torrential flows are hazardous hydro-geomorphological phenomena characterized by sudden water discharge and intense sediment transport. They occur in mountainous areas where hydrometeorological monitoring is often limited or absent. The lack of such data hinders the identification of flow types and sediment transport conditions, reducing the effectiveness of mitigation measures. To address this issue, the current study focuses on geomorphic characteristics of torrential watersheds and identifies indirect indicators of torrential activity. The sedimentological and geomorphic signatures of torrential flows in the lower Damdere River catchment (Eastern Rhodopes Mountains, southern Bulgaria) were characterized. To capture inter-annual variability in torrential activity and differences between the Damdere and its tributary the Duandere, we sampled riverbed deposits. We also sampled areas upstream and downstream of the check dam to assess its influence. Samples were analyzed for grain size distribution, petrography, and mineralogy (X-ray diffraction). Results show contrasting controls on sediment supply and transport: the Duandere delivers relatively coarse material, whereas the Damdere attains higher transport capacity during torrential events. The check dam is largely infilled and exerts only local effects by trapping finer sediments upstream. Downstream, the channel retains its torrential character. Inter-annual comparison upstream of the structure shows sediment fining linked to lower flows. Petrographic and XRD data point to mechanically driven erosion and rapid sediment transfer. The results underline the importance of geological–geomorphological indicators in the lack of long-term monitoring in similar mountain catchments and can support flood risk management.

Anna Saukko, Kaisa Nikkilä, Olav Eklund et al.

In the southernmost part of the Svecofennian province in Finland, leucogranites and migmatites stemming from both igneous and sedimentary protoliths reflect the complex magmatic history of the Svecofennian orogeny between 1.89 and 1.82 Ga. Although the migmatites and leucogranites in southernmost Finland display similar ages as their counterparts elsewhere in the Southern Finland Subprovince, they differ in field appearance and composition. Field and petrographical observations reveal K-feldspar megacrysts of varying sizes in the migmatized early Svecofennian (c. 1.89–1.87 Ga) supracrustal rocks and granitoids. Whole-rock geochemical analyses likewise display anomalously high K-contents in the early Svecofennian granitoids. Zircon U-Pb dating of migmatites and related leucogranites shows that a late Svecofennian partial melting event occurred at 1.84–1.82 Ga, possibly in several pulses. The morphological features of the migmatites as well as neosome mineralogy indicate a formation mechanism different from the dehydration melting prevalent elsewhere in the Subprovince.

L. Kabanova

The article examines petrography and mineralogy of rocks of the Berkut quartz-feldspar vein in the South Urals, which is characterized by intense deformation in comparison with numerous quartz veins of the Kyshtym block. These data allowed the sequence of formation and transformation of the Berkut vein. The vein is a typical vein of replacement, which is composed of blocks of quartz and granite rocks, and contains relics of host rocks (amphibolites and gneisses). Our studies revealed the tectonic transformations of rocks and minerals, as well as the deformation mechanisms with leading plastic deformation and processes of dissolution of minerals under pressure together with brittle fracturing. Dissolution and further deposition led to the crystallization of minerals of new generations (quartz, albite, and oligoclase) and often minerals of different composition (biotite after amphibole). Subsequent metasomatosis is responsible for new generations of minerals (quartz, albite, microcline, muscovite, epidote, zoisite, and clinozoisite) with different morphology and crystal optical properties.

Yongpeng Ying, Yuqing Zhao, Yan Xiong et al.

This is an eassay in the field of process mineralogy. Using optical microscope, chemical multi-element analysis, chemical phase analysis, X-ray diffraction, scanning electron microscopy-energy spectrometer and other comprehensive methods, the process mineralogical characteristics of a pegmatite lithium beryllium ore were studied. The mineral composition, chemical properties, symbiosis relationship of minerals, particle size distribution of main minerals and connection growth characteristics in the ore were ascertained. On this basis, the occurrence state of valuable elements such as lithium and beryllium in the ore and the mineralogical factors affecting the recovery of valuable elements such as lithium and beryllium in the ore are described, which provides a basis for the beneficiation work of the mine.

Martha Lustosa Carvalho, Victor Ferreira Maciel, Ricardo de Oliveira Bordonal et al.

ABSTRACT Soils are the largest terrestrial carbon (C) reservoir, and most of this C is retained as soil organic matter (SOM). Due to its ability to capture, stabilize, and store C for extended periods, soils are considered important allies in decarbonizing the atmosphere. The term ‘C stabilization’ includes a series of mechanisms or processes by which soil C is protected within soils and its losses are reduced through microbial decomposition or leaching. Due to their relevance in the global C cycle, C stabilization mechanisms have received intensive attention from the scientific community. As new analytic technologies push the boundaries of what was previously possible to know, new paradigms emerge. This literature review summarizes the current knowledge of the main mechanisms that may promote SOM stabilization. Factors that govern accumulation of SOM are also addressed. We highlight the role of organo-mineral associations and spatial inaccessibility of SOM due to occlusion within soil aggregates to understand the relative contribution of these mechanisms in different soil conditions (e.g., soil texture, mineralogy, and land- use). In addition, the contribution of cutting-edge approaches and analytical techniques to advance the understanding of SOM protection is presented. Modern techniques to evaluate SOM on a micro, nano, and molecular scale can contribute to the mechanistic understanding of SOM stabilization and the study and adoption of management strategies that maintain and increase C stocks in soils.

Christophe Hissler, Emmanuelle Montarges-Pelletier, Emmanuelle Montarges-Pelletier et al.

New technologies significantly disturb the natural riverine cycle of some Rare Earth Elements and Yttrium (REY). Whereas large evidence exists on the anthropogenic impact on REY dissolved and colloidal loads in rivers, there is still a knowledge gap on how suspended load could be impacted. As the river suspended matter is a key driver for the quantity of trace metal transport and mobility toward the other river compartments, it is of importance to evaluate how anthropogenic activity could affect its REY composition. Here, we report how past steel-making processes impacted the REY composition and potential mobility in riverbank sediments collected from a French River basin heavily disturbed by this industrial activity. In comparison to sediment originated from the local soil erosion, the industrial waste released in the river presented very unusual REY patterns. We observed specific LaN/GdN, LaN/LuN and Y/Ho ratios that indicate a strong heritage in the industrial waste of the iron ore used to produce steel. REY enrichments were also highlighted and can be classified as follow: Eu&gt;Yb&gt;Sm&gt;Ce&gt;Tm. The different enrichments might illustrate various fractionation processes that occurred separately on the different lanthanides inside the blast furnace according to temperature, pressure and oxygen fugacity changes. Sequential extractions performed on natural and industrial waste samples showed that REY enrichments in the industrial waste are included in one main fraction, which is strongly labile, whereas REYs contained in the sediment originating from the soil erosion are related to different mineralogical fractions having lower and more specific lability. Finally, REY composition showed that the sediment deposited on the riverbank is composed of two types of materials, which progressively evolved, after the ending of the industrial activity in this region, from a pure industrial waste in depth to a pure natural suspended sediment originated from local soil erosion at the surface.

A. Engelhardt, J. Koepke, C. Zhang et al.

<p>The Oman ophiolite (Samail massif, Sultanate of Oman) is the largest sub-aerial exposure of oceanic lithosphere on Earth and provides the opportunity to study the accretion and alteration of oceanic lithosphere formed under fast-spreading conditions. Drill hole GT3A (23<span class="inline-formula">^∘</span>06<span class="inline-formula">^′</span>50.7<span class="inline-formula">^′′</span> N, 58<span class="inline-formula">^∘</span>12<span class="inline-formula">^′</span>42.2<span class="inline-formula">^′′</span> E) of the ICDP (International Continental Scientific Drilling Program) Oman Drilling Project with a length of 400 m aimed at penetrating the dike–gabbro transition of the Samail ophiolite paleocrust in order to shed light on the role of the axial melt lens (AML) during accretion of the lower plutonic crust. AMLs beneath fast-spreading mid-ocean ridges are sandwiched between the sheeted dike complex and the uppermost gabbros and are believed to feed the upper crust and, at least partially, the underlying crystal mush.</p> <p>Typical gabbroic rocks from dike–gabbro transitions of fast-spreading systems are the so-called “varitextured gabbros”, often showing considerable variations in mineral mode, texture and grain size, which are regarded as the frozen fillings of axial melt lenses. Here, we present a detailed petrographic, microanalytical and bulk-chemical investigation of 36 mafic rocks from the drill hole GT3A, which represent mostly varitextured gabbros, revealing a complex formation with several evolution stages. Poikilitic domains formed first, corresponding to an early crystallization stage, where only plagioclase and clinopyroxene of more primitive composition crystallized. Later, domains of granular textures containing also interstitial amphibole and Fe–Ti oxide were formed. This stage is characterized by a magma evolution that underwent crystal fractionation established by lower temperatures due to more efficient hydrothermal cooling at the margin of the AML. A last stage is characterized by pervasive hydrothermal alteration, where all primary minerals have been altered under temperature conditions, varying from the magmatic regime down to greenschist facies. A highlight of this stage is amphiboles showing noticeable compositional zoning. The observation of peculiar microgranular domains, representing relics of stoped exogenic material from the sheeted dike complex, documents the upward migration of an AML in a replenishment event, forcing the AML to burn through previously altered sheeted dikes. This process is responsible for significant assimilation of hydrothermally altered components, indicated by a marked Cl enrichment in the outer zones of magmatic amphiboles. Petrological modeling involving gabbros and basalts revealed that the GT3A rock suite followed a fractional crystallization evolution trend, with a primitive MORB as parental melt with an estimated water content of 0.2 wt % to 0.8 wt %. The modeled liquid lines of descent suggest a magmatic evolution via fractional crystallization, where the basalts correspond to frozen liquids, while the gabbros, especially the more primitive ones, show a significant cumulate component.</p>

Bahrican Ar, Mehmet Arslan, Emel Abdioğlu et al.

The highly siderophile element (HSE) or platinum group element (PGE) and Os isotope systematics of basaltic volcanics have recently received a significant attention because of their potential to constrain the petrological processes on magma generation and evolution. The HSE and Os isotope data, which are generally observed at very low concentrations in basalts and obtained by modern enrichment and analytical techniques, are frequently used in petrological studies. The HSE contents and ratios from whole-rock analysis of basalts, and combined evaluation with the theoretical knowledge and modelling of HSE behaviour during the partial melting of mantle and the differentiation of basaltic magma would provide opportunity for geochemical modelling on mantle melting. Besides, HSE contents and Pd-PGE/Ir-PGE ratios are important indicators for the nature of mantle sulfides, the sulfur saturation conditions of the mantle source, sulfide segregation, fractional crystallization, crustal assimilation and partial melting degrees in the origin and evolution of mantle-derived magmas. Therefore, in addition to the traditional whole-rock geochemical data obtained from Cenozoic aged basalts observed widely in Turkey, HSE and Os isotope systematics of these basalts can contribute to define the geochemical features of the mantle source, and to model petrological processes which are effective in the magma evolution.

N.S. Chukhareva, E.V. Belogub, Yu.A. Ryzhkova et al.

The morphology and chemical composition of native gold from the Murtykty deposit (South Urals) are discussed in the paper. Native gold is subdivided into five types: 1) inclusions in sulfides, 2) grains in fractures and interstices of pyrite and other sulfides, 3) grains at the boundaries of sulfides and gangue minerals, 4) inclusions in gangue minerals and their interstices and 5) «free╗ grains from heavy concentrates. The chemical composition of 128 gold grains is studied. In accordance with Ag content (from 6.49 to 30.8 wt. %), native gold from the deposit varies from high- to low-fineness (rare grains). Native gold in sphalerite contains Cu (0.85–2.27 wt. %)., The morphological features of 264 gold grains are quantified using Image Tool software. The morphological characteristics of native gold from types 1–4 are similar. The data on morphology and size of native gold grains can be used for improvement of technology of gold extraction.

Ismail Khan Chuban, Behzad Haj Alilou, Mohsen Moayyed et al.

Introduction It is generally understood that manganese deposits have a diverse origin, based on their mineralogy, chemical composition and tectonic setting. Marine Mn-bearing deposits are classified as hydrogenous, hydrothermal and also biogenetic-bacterial deposits (Bonatti et al., 1972; Hein et al., 1997; Bau et al., 2014; Polgári et al., 2012; Schmidt et al., 2014). Hydrogenous processes can form ferromanganese crusts, which result from slow precipitation of seawater at the seafloor often via microbial mediation (Toth, 1980; Dymond et al., 1984; Bau and Dulski, 1999; Usui and Someya, 1997; Hein et al., 2000; Jach and Dudek, 2005). Diagenetic manganese deposits occur as nodules and precipitate from hydrothermal solutions or pore water (Polgári et al., 1991; Oksuz, 2011; Polgári et al., 2012), whereas hydrothermal ore deposits are stratabound or occur as irregular bodies and epithermal veins, where they are formed in a marine environment near spreading centers, intraplate seamounts or in subduction-related island arc setting (Roy, 1992; Roy, 1997; Hein et al., 2008; Edwards et al., 2011). Materials and Method Eighteen Ore samples (~ 500 g each) were collected systematically from the Gezeldash Daghi manganese deposit. All these ore samples were taken representatively from the surface outcrops ore beds in different places for geochemical analyses. Ore samples were powdered under 200 meshes and analyzed at Iran mineral processing research center laboratories, Tehran. After being prepared by the Lithium Borate Fusion method, their major oxide and trace element contents were determined with ICP-OES. The results of the analyses are given in Tables 1 and 2. Results and Discussion The deposit is hosted in various lithology and horizons consisting of: 1) tuffite interlayered with limestone, 2) conglomerate and sandstone lithology into volcano-sedimentary basin located at 25 km northwest of Marand city (N38°35ʹ40ʺ, E45°42ʹ40ʺ). Major and trace element assessments show that hydrothermal solutions were effective in the formation of the Gezeldash Daghi manganese deposit. Also, field observations reveal that manganese mineralization occurred as laminated-layered and fracture-filling form in limestone and tuffite at horizon I and the space-filling form between conglomerate clasts and veinlet form in sandstone at horizon II with quaternary age. Therefore, it can be concluded that hydrothermal solutions were caused in the formation of the manganese deposit which may be described as related to volcano-hydrothermal occurrence. Acknowledgements The authors are grateful to the Tabriz University Grant Committee for research funding.

Hassan Karimian

<p>Knowledge of the number and location of mines of the ancient periods has been the subject of common research between archaeologists and archaeo-mineralogists. The scientific significance of the subject becomes apparent when the direct relation between the power of the ancient rulers and number of the mines they owned is perceived. The gold and silver mines, like today, were accounted as the main economic credit and backing of the ancient states. Although mixing silver with other metals was used to produce diverse metal artefacts, silver on its own was most popular for minting coins. Since coin was a symbol of the sovereignty of rulers and an indicator of the economic power of ancient civilizations, silver mining was probably one of the main activities of the ancient craftsmen.  </p><p>The main aim of this research is to investigate the conditions surrounding, and the techniques used for, extraction of silver from different mines during the reign of Alexander of Macedon, Seleucid rulers (336-129 BC), and Parthian kings (247 BC-224 AD). The kings, whose coins are studied in this research, ruled in Iran from 4^th -1^st BC. This research is focused on the laboratory results obtained from XRF tests on 24 coins belonging to the mentioned kings.</p><p>The analysis of the results revealed that despite the advanced technology used for recovering silver from zinc and lead mines in the Seleucid era, the Parthian craftsmen were not highly skilled in this field. In other words, the silver recovery technology was more advanced in the Seleucid era than the Parthian period.</p>

Doğan Can Karataş, Uğur Zaman, Emin U. Ulugergerli

Kuyu logu ölçümlerinde, kuyu içindeki akışkanın özdirenç log eğrilerine etkisi ile 16 ve 64 inch loglar için araştırma derinliği/uzaklığı yer altı yapılarının bakışımlı olduğu varsayımı ile iki boyutlu sayısal modelleme ile incelenmiştir. Gerçek özdirenç değerlerinin eldesinde ampirik yaklaşım yerine ters çözüm kullanılması ile yapısal bilgiye ulaşılmıştır. Genel olarak, birimin kalınlığının (k) log boyuna (l) oranına (k/l) bağlı olarak, iletken akışkan (1 ohm.m &lt;) kullanılması durumunda yalıtkan formasyonlar k/l &lt; 1 için “M” biçimli belirti üretmekte veride sanal yapılara neden olarak iletken birim olarak görünmektedir. Araştırma derinliği /uzaklığı ise log boyuna ve uzaklığa bağlı olarak yapı özdirencinde sapmalara neden olmaktadır. Ters Çözüm çalışması ile olası modellerden biri elde edilmektedir. Bu tür çalışmalara katkısı ise, diğer yaklaşımlarda ihmal edilen, elde edilen özdirenç modellinin veriye uyumunun ortaya konmasıdır.

Víctor Cárdenes, Jorge C. Lafuente, Raúl Merinero et al.

E. G. Vologina, I. A. Kalugin, A. V. Dar’in et al.

The article presents the detailed analysis results considering bottom sediments from the Chukchi Sea. Two core samples, b16 and НС–8 were taken from the northern Herald Canyon 150 km northeast from NE Wrangel Island. Core b16 has been studied in more detail. According to the 210Pb measurements, the recent sedimentation rate amounts to 0.9 mm/y–1 at the sampling point. In the bottom layer of the core sample, the minimum concentrations of biogenic components (SiO2bio, Corg, Ntot, and Br) and the increased concentrations of cold-water diatom species Thalassiosira antarctica may result from low biological productivity during the Maunder Minimum. A correlation with recent global warming (11–22 years) is shown by the increased concentrations of SiO2bio, Corg, Ntot, and Br and the decreased values of magnetic susceptibility and X-ray density in the top layer (1–2 cm) of the same core sample. The results of our geochemical and diatom analysis support the available literature data and confirm that the Late Holocene sedimentation in the Chukchi Sea takes place in the zone wherein the water transits from the Pacific to the Arctic Ocean.

Encarnación Ruiz-Agudo, Alejandro Burgos-Cara, Cristina Ruiz-Agudo et al.

The formation mechanism of abundant calcium oxalate biomaterials is unresolved. Here the authors show the early stages of calcium oxalate formation in pure and citrate-bearing solutions by using a titration set-up in conjunction with solution quenching, transmission electron microscopy and analytical ultracentrifugation.

Xiande Xie, Ming Chen

Celmo Aparecido Ferreira, Alexandre Christófaro Silva, Pablo Vidal Torrado et al.

The Brazilian System of Soil Classification (SiBCS) is a taxonomic system, open and in permanent construction, as new knowledge on Brazilian soils is obtained. The objective of this study was to characterize the chemical, physical, morphological, micro-morphological and mineralogical properties of four pedons of Oxisols in a highland toposequence in the upper Jequitinhonha Valley, emphasizing aspects of their genesis, classification and landscape development. The pedons occupy the following slope positions: summit - Red Oxisol (LV), mid slope (upper third) - Yellow-Red Oxisol (LVA), lower slope (middle third)- Yellow Oxisol (LA) and bottom of the valley (lowest third) - "Gray Oxisol" ("LAC"). These pedons were described and sampled for characterization in chemical and physical routine analyses. The total Fe, Al and Mn contents were determined by sulfuric attack and the Fe, Al and Mn oxides in dithionite-citrate-bicarbonate and oxalate extraction. The mineralogy of silicate clays was identified by X ray diffraction and the Fe oxides were detected by differential X ray diffraction. Total Ti, Ga and Zr contents were determined by X ray fluorescence spectrometry. The "LAC" is gray-colored and contains significant fragments of structure units in the form of a dense paste, characteristic of a gleysoil, in the horizons A and BA. All pedons are very clayey, dystrophic and have low contents of available P and a pH of around 5. The soil color was related to the Fe oxide content, which decreased along the slope. The decrease of crystalline and low- crystalline Fe along the slope confirmed the loss of Fe from the "LAC". Total Si increased along the slope and total Al remained constant. The clay fraction in all pedons was dominated by kaolinite and gibbsite. Hematite and goethite were identified in LV, low-intensity hematite and goethite in LVA, goethite in LA. In the "LAC", no hematite peaks and goethite were detected by differential X ray diffraction. The micro-morphology indicated prevalence of granular microstructure and porosity with complex stacking patterns.. The soil properties in the toposequence converged to a single soil class, the Oxisols, derived from the same source material. The landscape evolution and genesis of Oxisols of the highlands in the upper Jequitinhonha Valley are related to the evolution of the drainage system and the activity of excavating fauna.<br>O Sistema Brasileiro de Classificação de Solos (SiBCS) é um sistema taxonômico, aberto e que se encontra em construção permanente, conforme são obtidos novos conhecimentos sobre solos brasileiros. O objetivo deste trabalho foi efetuar as caracterizações química, física, morfológica, micromorfológica e mineralógica de quatro pedons de Latossolos em topossequência de uma chapada do Alto Vale do Jequitinhonha, enfatizando aspectos de sua gênese, classificação e da evolução da paisagem. Tais pedons ocupam as seguintes posições da vertente: topo - Latossolo Vermelho (LV), terço médio - Latossolo Vermelho-Amarelo (LVA), terço inferior - Latossolo Amarelo (LA) e sopé - Latossolo Amarelo, de cor cinzenta, aqui denominado "Latossolo Acinzentado" ("LAC"). Esses pedons foram descritos e amostrados para caracterização com análises químicas e físicas de rotina. Os teores totais de Fe, Ti, Al, Mn e Si foram determinados pelo método do ataque sulfúrico, e os óxidos de Fe, Al e Mn foram avaliados nos extratos de ditionito-citrato-bicarbonato e oxalato. A mineralogia das argilas silicatadas foi identificada pela difratometria de raios X, e a dos óxidos de Fe, pela difratometria diferencial de raios X. Por espectrometria de fluorescência de raios X, foram determinados os teores totais de Ti, Ga e Zr. O "LAC" apresentou cores acinzentadas e significativos fragmentos de unidades estruturais na forma de uma massa adensada, característica de Gleissolos, nos horizontes A e BA. Todos os pedons são muito argilosos, distróficos, com baixos teores de P disponível e pH em torno de 5. Os óxidos de Fe refletiram a cor dos solos e diminuíram ao longo da vertente. A diminuição dos teores de Fe cristalino e de baixa cristalinidade ao longo da vertente confirmou a perda de Fe do "LAC". O Si total aumentou ao longo da vertente e o Al total permaneceu constante. A fração argila, em todos os pedons, é dominada por caulinita e gibbsita. No LV, foram identificados hematita e goethita; no LVA, hematita com baixa intensidade e goethita; no LA, goethita; e no "LAC" não foram identificados picos de hematita e de goethita no difratograma diferencial de raios X. A micromorfologia mostrou a predominância da microestrutura granular e porosidade do tipo empilhamento complexo. Os atributos dos solos da topossequência convergem para uma única classe de solo, a dos Latossolos, que são provenientes do mesmo material de origem. A evolução da paisagem e a gênese dos Latossolos das chapadas do Alto Vale do Jequitinhonha estão relacionadas com a evolução da rede de drenagem e com a ação da fauna escavadora.

B. Scaillet, R. Macdonald