Brown Carbonate Research Articles

Ichnological response to the Middle Eocene Climatic Optimum (MECO) in the Bartonian deposits of Kutch Basin, India

The Middle Eocene Climatic Optimum (MECO) represents a short-lived interval of global warming that disrupted the long-term cooling episode extending from the middle to late Eocene time. Biostratigraphically the MECO corresponds to the upper interval of planktic foraminiferal zones E11–E12 and the shallow benthic zone 17. Both the planktic and benthic foraminiferal zones are well-documented within the Bartonian mixed siliciclastic‑carbonate sequence of the Kutch Basin in western India. This case study aims to investigate the impact of MECO on the endobenthic community using ichnology as a proxy. The studied sequence comprises the underlying Harudi Formation, consisting of the marine green and grey shale and bioclastic limestone beds, and the overlying Fulra Limestone characterized by benthic foraminifera-rich limestones. The Harudi Formation is bereft of trace fossils except in one bioturbated firmground and two bioeroded hardground horizons. The MECO corresponds to the thin carbonate packstone, the middle green shale, and the Nummulites obtusus rudstone occurring at the middle to upper part of the Harudi succession, established earlier by a concurrent negative δ13Corg isotopic excursion. The shelly limestone or bivalve coquina bed deposited immediately prior to the beginning of the MECO consists of a monospecific firmground ichnofabric characterized by Balanoglossites triadicus. Out of two bioeroded beds, the lower one coincides with the earliest MECO interval and is marked by a brown carbonate hardground colonized with two ichnospecies of Gastrochaenolites. The upper bioeroded horizon corresponding to the end of the MECO is characterized by a series of top- and side-bioeroded (with Gastrochaenolites, Entobia, and Oichnus) carbonate nodules containing multigenerational septarian cracks. The upper hardground demarcates the top of the Nummulites obtusus coquina bed and the starkest basin-wide sediment starvation, making it a major condensed horizon that developed following a steady glacio-eustatic rise during the warming event. The MECO prompted the subsequent deposition of shallow-marine platform carbonates of the Fulra Limestone by accelerating a sharp rise in the sea-level and proliferation of diverse Larger Benthic Foraminifera in a warm oligotrophic seawater.

Экологическая оценка накопления и миграции меди в почве возрастных ампелоценозов в результате длительного применения медьсодержащих фунгицидов в регионе Фрушка Гора Республики Сербия

The data on soil copper accumulation and slope migration due to long-term use of copper-containing pesticides in vineyards over 200 years old with different management systems in the conditions of the Fruska Gora region of the Autonomous Province of Vojvodina, Republic of Serbia are discussed. The study focused on brown forest residual carbonate soils found in sloping landscapes with different length, steepness and exposure. The total copper content in the soil on a permanently vegetated slope with a 10º steepness was 2-4 times higher on the farm with an archaic management system compared to the farm with a traditional management system on a 5º steep slope. The copper content variation ranged from 84.5-136.6, 72.3-189.4, and 41.0-247.5 mg/kg in horizons 0-5, 5-15, and 15-30 cm respectively. Copper migration down the slope was observed in both vineyards, although with different intensities. The coefficient of lateral differentiation for farms with lower slope steepness was between 0.90 and 1.45, while for those with higher steepness, it ranged from 0.96 to 5.57. The highest values of the coefficient were observed in the transaccumulative facies at a depth of 15-30 cm. The total copper content in the topsoil of the transit site of the ampelocenosis slope with archaic cultivation system exceeded by 21-47% the maximum permissible value in the Republic of Serbia, while in the lower part of the slope, in the horizons 5-15 and 15-30 cm, it was 2-3 times higher than the normative value. Keywords: COPPER, COPPER-CONTAINING PESTICIDES, VINEYARDS, AMPELOCENOSIS, ACCUMULATION, LATERAL DIFFERENTIATION, SLOPE, SLOPE STEEPNESS, BROWN FOREST SOIL

The relationship of nitrogen nutrition conditions with the productivity of Tamasha potatoes

The article presents the results of three-year (2015-2017) studies research on the influence of nitrogen nutrition conditions on the productivity and quality of potatoes variety Tamasha. The studies were carried out on dark brown heavy loamy carbonate soils of Central Kazakhstan with a humus content of 2.73-2.79 %, total nitrogen - 0.147-0.172 %, total phosphorus - 0.20-0.25 %, with a high level of availability of mobile phosphorus and potassium, low content of nitrate nitrogen, slightly alkaline reaction of soil solution. Studies have shown a high responsiveness of potatoes to nitrogen fertilizers. According to the results of the research, a high correlation between potato productivity and the nitrate nitrogen content in the soil (R=0.85-0.96) was revealed, the optimal level of nitrate nitrogen in the 0-40 cm soil layer was determined for Tamasha potatoes - 17-19 mg/kg. The increased nitrogen content of nitrates in the soil slightly reduced the starchiness of potatoes.

Approaches to the development of environmental standards for the content of petroleum hydrocarbons and Pb, Cr, Cu, Ni in soils of Greatest Caucasus

<p>The development of tourism and leisure infrastructure results in a continuous increase of anthropogenic impact on soils of wet and dry subtropics of the Greatest Caucasus. It is very important for the region to preserve the sustainable functions of soils and ecosystems, maintain a comfortable life and recreation environment create environmentally friendly agricultural products. It is conducted studies to determine the limits of resistance of soils in wet and dry sub-tropics to priority pollutants, especially petroleum hydrocarbons and heavy metals (Pb, Cr, Cu, Ni). It was found that the soils of wet and dry subtropics for resistance by Pb, Cr, Cu, and Ni are located as follows: south-ern chernozem > typical sod-carbonate soil ≥ brown typical soil ≥ brown carbonate soil = brown leached soil ≥ leached sod-carbonate soil = yellow soil >acid brown forest soil ≥ acid brown forest podzolized soil. In terms of the degree of resistance to oil pollution, studied soils create certain series: brown carbonate ≥ brown typical = sod-carbonate leached ≥ sod-carbonate typical > southern chernozem ≥ yellow soil ≥ brown leached soil > acid brown forest soil = acid brown forest podzolized soil. Heavy metals by ecotoxicity to the soils of wet and dry subtropics from the following series: Cr> Cu ≥ Ni = Pb. Based on the degradation of ecological functions of soils, we offer regional standards of the maximum permissible content of Pb, Cr, Cu, and Ni for the main soils of wet and dry subtropics.</p>

Biodiagnostics of Resistance to the Copper (Cu) Pollution of Forest Soils at the Dry and Humid Subtropics in the Greater Caucasus Region

Forest ecosystems perform important forestry and ecological functions. However, mining and processing companies cause significant soil contamination by heavy metals, in particular, copper (Cu). The resistance of nine types and subtypes of forest soils of the dry and humid subtropics in the Greater Caucasus region to Cu contamination at concentrations of 100, 1000, and 10,000 mg/kg was evaluated for the first time following the most sensitive and informative biological (microbiological, biochemical, and phytotoxic) indicators via a laboratory simulation study. Contamination was simulated under laboratory conditions. The series of forest soils was established following their resistance to Cu pollution: brown leached soils (Haplic Cambisols Eutric) = brown typical soils (Haplic Cambisols Eutric) > brown carbonate soils (Haplic Cambisols Eutric) = sod-carbonate typical soils (Rendzic Leptosols Eutric) ≥ yellow soils (Albic Luvisols Abruptic) ≥ leached sod-carbonate soils (Rendzic Leptosols Eutric) > brown forest slightly unsaturated soils (Haplic Cambisols Eutric) > acid brown forest soils (Haplic Cambisols Eutric) > acid brown forest podzolized soils (Haplic Cambisols Eutric). Regional environmentally safe standards for the Cu content in forest soils of the dry and humid subtropics of the Greater Caucasus were proposed: for brown typical soils, brown leached soils, brown carbonate soils, brown forest slightly unsaturated soils, sod-carbonate typical soils, leached sod-carbonate soils, and yellow soils, the rMPC was 100 mg/kg; for acid brown forest soils and acid brown forest podzolized soils, the rMPC was 70 mg/kg.

Угрозы сибиреязвенных захоронений для экологической безопасности Таджикистана и меры их предупреждения

Abstract. The aim of our research is to study the prevalence of anthrax soil foci that pose a threat to biological safety ,the role of soil structure and climatic factors in the epizootic process of anthrax in Tajikistan to substantiate anti epizootic and epidemic measures. Methods. The features of the manifestation of anthrax were studied in dynamic measurement by methods of applied epizootology. Results. The results of monitoring of natural foci of anthrax of animals for the period from 1937 to 2019 among farm, domestic and wild animals are presented. It was found that natural foci of anthrax animals are widespread in South-West and Central Tajikistan. As a result of the analysis of the soil structure and territorial distribution of anthrax, as well as the identification of the influence of soil structure on the vegetation of the causative agent of anthrax, the territory of the Republic of Tajikistan was divided into 5 landscape zones: light and typical gray earth, high – mountain desert and meadow and mountain – brown carbonate. At the same time, light and typically gray-earth soils of the 44 administrative divisions of the country are characterized by favorable physicochemical factors (humus content in the soil – 4–11.0 %, pH – 6–7, temperature at a depth of 15–20 cm from +2 to +33 °C, movable phosphorus 16–60 mg/kg, zinc 0.5–1.5 mg/kg, copper 0.4–0.8 mg/kg, manganese 70–100 mg/kg, soil moisture 30–60 %) for vegetation of the causative agent of anthrax in the soil. Studies have also found that of the majority of areas located in the valleys, the most disadvantaged for anthrax are territories located at an altitude of up to 1000 m above sea level. So, the share of these areas is 83.9 % of the total number of disadvantaged places, respectively, at an altitude of 1000–2000 m – 15.1 %, and at an altitude of over 2000 m – 1.5 %. The relationship between the incidence of anthrax animals and the registration of soil foci in Tajikistan with climatic factors was revealed, so the highest incidence of the disease occurs in the hotter months of the year, from May to September, when the air temperature reaches 30–45 °C with a significant decrease in atmospheric precipitation. Scientific novelty. For the first time, a retrospective analysis and expert assessment of an epizootic situation and ant epizootic measures with a chronological depth of up to 82 years was carried out. The role of the soil structure on the survival and vegetation of the causative agent of anthrax was revealed. It was found that the light – and typically gray soil 44 of the 63 administrative divisions of the country are characterized by favorable physical and chemical factors for the growing of anthrax in the soil. It was revealed that of the most districts located in the valleys, the most disadvantaged by anthrax are territories located at an altitude of up to 1000 m above sea level, as well as the relationship between the incidence of anthrax animals and the registration of soil foci in Tajikistan with climatic factors.

The application of biogas fermentation digestate as soil fertilizer

As organic manure is becoming less available, using different materials as soil fertilizers and the application of the inorganic fertilizers raises many questions. Therefore, it is increasingly important to use compost and biogas digestate to improve soil quality. The activity of the microbial communities ensures the fertility of the soil. One of the most important enzymes is dehydrogenase. This enzyme group catalyses the hydrogen transfer in the process of biological oxidation. Our aim was to examine the effect of biogas digestate on dehydrogenase enzyme activity (DHA) in 3 different types of soil. Hungarian standard method was used to evaluate DHA. The applied biogas digestate was obtained from the Kaposvár Sugar Factory of Hungarian Sugar Ltd. The dose is equal to 16,7 m3ha-1 and 533 kg organic matterha-1. The treatment was performed in three different groups of soil: brown forest soil, calcareous chernozem and carbonate meadow soil. The results showed an increase in DHA in all types of soil. DHA values were the highest in case of the carbonate meadow soil, specifically 0.337 mg formazan/1 g soil/24 h immediately after the treatment and 0.410 after 28 days. A critical aspect to consider during the construction of biogas plants is the soil protection agency’s ban on using soil fertilizers during the winter months. Analysis carried out according to the protocol of sewage sludge examination revealed that biofermentate produced during biogas generation does not contain any environmentally harmful components. After the elaboration of a soil protection plan, the recommended way to apply biogas digestate to arable land is via injectors.

BIOINDICATION IN ECOLOGICAL ASSESSMENT OF ERODED SOILS IN MOUNTAIN AREAS

In the article it is provided a material on determination of quantitative and qualitative composition, as well as invertebrates’ distribution in the profile of various types of the eroded mountain soils; on determination of regional regularities of alterations in the morphogenetic structure, agrochemical and agrophysical indicators of eroded mountain and foothill (typical sierozem soils, dark sierozem soils, mountain brown carbonate, mountain brown typical, mountain brown weakly leached) soils; on determination of the correlative relationship between soil fauna (earthworms, mollusks, nematodes, ticks, collembolans) and soil properties.

INVESTIGATION OF PHOSPHATE-ION RETENTION STRENGHT IN SOME TYPES OF KAKHETI SOILS

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

The Limits of Resistance of Soils and Ecosystems of Crimea to Heavy Metals Pollution

A study is carried out to determine the limits of resistance of soils and ecosystems of Crimea to pollution of Pb, Cr, Cu, Ni by biological indicators. It is established that the Crimean soil in terms of resistance to Pb, Cr, Cu, Ni pollution is located as follows: residual carbonate chernozems> southern chernozems> dark chestnut alkaline ≥ mountain meadow ≥ brown carbonate> brown forest soils, and terrestrial ecosystems have the following series of stability: true steppes> dry steppes ≥ mountain meadows ≥ light forests> broad-leaved forests. In terms of ecotoxicity to heavy soils and ecosystems of Crimea, heavy metals form a series: Cr> Cu ≥ Pb ≥ Ni. The regional standards of the maximum permissible content of Pb, Cr, Cu, Ni in the main soils of the Crimea and the most effective ways of their rehabilitation in case of pollution are proposed.

Investigation of phosphate-ion retention strenght in some types of Kakheti soils

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

EFFECT OF IRRIGATION AND GRASSING TO CHANGE SOME OF THE BIOLOGICAL PROPERTIES OF THE MINING OF BROWN CALCAREOUS SOILS

In this article is showing, that the irrigation mountain brown carbonate soils prone methods of irrigation and grassing comes the rapid growth and development of natural vegetation, which leads to intensive humus accumulation. Humus content in the upper layer is increased by 0.98% and a significantly smaller severely eroded. Increasing the amount of humus promotes accumulation mainly humic acids, that conducts to expansion of relations the content of humic acid: The content of folic acid. When grassing of soil traced sharp increase in the number associated with the related and R2 O3 humic acid.

Laboratory Investigation of Dynamic Strain Development in Sandstone and Carbonate Rocks Under Diametrical Compression Using Digital-Image Correlation

Summary Understanding the mechanical behavior (compression, shear, or tension) of rocks plays an important role in wellbore-stability design and hydraulic-fracturing optimization. Among rock mechanical properties, strain is a critical parameter describing rock deformation under stress with respect to its original condition, yet conventional methods for strain measurement have several deficiencies. In this paper, we analyze the application of the optical method digital-image correlation (DIC) to provide detailed information regarding fracture patterns and dynamic strain development under Brazilian testing conditions. The effects of porosity, rock type, lamination, and saturation (freshwater and brine) on indirect tensile strength are also discussed. To examine the effect of rock type, 60 samples of sandstone (Parker, Nugget, and Berea) and carbonate rocks (Winterset Limestone, Silurian Dolomite, Edwards Brown Carbonate, and Austin Chalk) were tested under dry and saturated conditions with regard to lamination angle in laminated samples. A photogrammetry system was used to monitor the samples in a noncontact manner while conducting the indirect tensile experiment. DIC depends on the photogrammetry system, which helps to visualize and examine rock-fracture patterns from the recorded images of the rock before and after deformation by assessing the strain development in samples. The experimental results show the following. Average tensile strength declines with increasing porosity for homogeneous, laminated, and heterogeneous rock specimens. Lower tensile strengths are observed in carbonate-rock samples compared with sandstones, except for Silurian Dolomite. Saturation reduces rock strength; for homogeneous samples, the highest strength decline (28%) was observed in Berea Sandstone, whereas the largest decrease (65%) for heterogeneous samples was observed in fully heterogeneous Edwards Brown Carbonate samples. Increase of lamination angle (from 0 to 90°) affects the tensile strength. Average tensile strength observed for the Parker and Nugget Sandstones was greater in the direction perpendicular to the lamination direction (θ = 90°) compared with that of the parallel direction (θ = 0°). Fracture patterns examined for homogeneous rocks are nearly centrally propagated and relatively linear. Three different fracture patterns (central fracture, layer activation, and noncentral or mixed mode) were investigated for laminated and heterogeneous samples. Finally, DIC results illustrated the fracture creation and propagation with consistent strain mapping. The homogeneous samples produced a uniform fracture strain until the diametrical split, where the laminated samples were influenced by planes of weakness and fully heterogeneous anisotropic rocks produced winding and erratic fractures.

Microscopic fungi spread in different types of soils in Western Georgia

200 cultures of microscopic fungi have been isolated from the different types of soils (yellow brown forest, raw carbonate, yellow, red, bog, alluvial, yellow podzolic, mountain meadow and brown forest) of Western Georgia. Mainly, representatives of the following classes Zygomycetes, Ascomycetes and Deuteromycetes are spread in the above-mentioned types of soils. Microscopic fungi from the class of Ascomycetes prevailed in the five types of soils: yellow brown forest, raw carbonate, red, alluvial and yellow-podzolic; and as well in mountain meadow soils. Cultures from the class of Deuteromycetes are spread in two types of soils: yellow and brown forest. As concerns microscopic fungi cultures isolated from the bog soils, no expressed dominant genus was found, only the microscopic fungi from the class of Zygomycetes prevailed in general.

Glendonites (pseudomorphs after ikaite) in late carboniferous Marine Dwyka beds in Southern Africa

Research Article| September 01, 2001 Glendonites (pseudomorphs after ikaite) in late carboniferous Marine Dwyka beds in Southern Africa I. R. McLachlan; I. R. McLachlan Honorary Research Associate, Bernard Price Institute for Palaeont. Research, PO Box 1174, Parow, 7499, email: mclachlai@petroleumagencysa Search for other works by this author on: GSW Google Scholar H. Tsikos; H. Tsikos Rand Afrikaans University, PO Box 524, Auckland Park, Johannesburg, 2006. *Present address: Department Earth Sciences, University Oxford, Parks Rd, OX1 3PR, Oxford, UK. Search for other works by this author on: GSW Google Scholar B. Cairncross B. Cairncross Rand Afrikaans University, PO Box 524, Auckland Park, Johannesburg, 2006. Search for other works by this author on: GSW Google Scholar South African Journal of Geology (2001) 104 (3): 265–272. https://doi.org/10.2113/1040265 Article history first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation I. R. McLachlan, H. Tsikos, B. Cairncross; Glendonites (pseudomorphs after ikaite) in late carboniferous Marine Dwyka beds in Southern Africa. South African Journal of Geology 2001;; 104 (3): 265–272. doi: https://doi.org/10.2113/1040265 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract Glendonites are carbonate pseudomorphs after monoclinic crystals of ikaite (calcium carbonate hexahydrate: CaCO3.6H2O). Ikaite forms at present within organic-rich marine or brackish sediments that are at near freezing temperatures and decomposes to a mush of calcium carbonate and water when the temperature rises above 5°C. These unusual pseudomorphs were first recognised in southern Africa in 1972 as a rare component in marine shales just above the top of the Dwyka Group in the Great Karoo basin in South Africa. The crystal casts are rhomb-shaped in cross-section, show well-developed pyramid faces and are up to 19cm long. The glendonites occur in two forms: 1. as hollow or ochre-filled casts of ikaite crystals in concretions in fossiliferous marine Dwyka shales at Blaauwkrantz near Kimberley and also in the Ganigobis Shale at Zwartbas on the Orange River. 2. as carbonate pseudomorphs after ikaite, in concretions within shaly siltstone in the upper part of the marine glacial boulder mudstone at De Kalk (adjacent to Blaauwkrantz). The concretions are unweathered and the crystal casts are filled with a hard dark brown granular carbonate. Each granule encloses one or more stellate aggregates of zoned calcite crystals with an outer layer of brown carbonate. Electron microprobe analysis shows that the stellate crystals are pure calcite CaO: 55% (by wt.), Mg: 0.19% and the enclosing brown carbonate layer is Fe/Mg/Mn-enriched calcite (FeO+MgO+MnO: 6.18%, CaO: 48.5%).The presence of glendonite demonstrates that the fossiliferous host sediments accummulated under near freezing, highly alkaline, orthophosphate-rich bottom water conditions. These stressful conditions help to explain the observed severely limited species diversity of the associated fossil assemblage. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Diagenetic Enrichment of Manganese and Other Heavy Metals in Hemipelagic Brown Clay of the Palau Trench Floor

ABSTRACT A 1089 cm long piston core recovered from the floor of the Palau Trench (8053 m water depth) shows an interbedded sequence of brown clay and carbonate turbidites, with three Mn-enriched layers. The brown clay is recognized as hemipelagic clay by the relation of Fe-Mg in residual clay fractions of the samples and by stratigraphical and mineralogical characteristics. One of the Mn-enriched layers is associated with redox cycles of dark band and brown clay, whereas the others are observed at the boundaries between the uppermost layers of the turbidites and the overlying hemipelagic brown clays. A series of selective leachings with fractionation of Mn and other heavy metals into carbonate and oxyhydroxide fractions indicates that Mn-, Cu-, Ni-, and Co-oxyhydroxides are highly concentrated in the Mn-enriched layers. The enrichment mechanism is interpreted to be a catalytic reaction of Fe-oxyhydroxide in the brown clay with Mn++ in the overlying waters as a result of Mn++ enrichment, the result of either reducing conditions during the formation of redox cycles or to the dissolution of carbonate-bound Mn during the turbiditic sedimentation. Responding to the enrichment mechanism of Mn, other heavy metals such as Cu, Ni, and Co are also enriched in the form of oxyhydroxides. The lack of any Mn-micronodules in the brown clay may be the result of the duration of Mn++ enrichment events in the water column which was not long enough to form them, as well as to the rather high sedimentation rate of the hemipelagic brown clay.

Sedimentología y petrología de los abanicos aluviales y facies adyacentes en el Neogeno de Paracuellos de Jarama (Madrid)

Lateral and vertical variations of middle Miocene lithofacies (Lower and Intermediate Units of the Miocene of the Madrid Basin) have been analyzed in the Paracuellos de Jarama area, near Madrid. A complete transition from medial to distal alluvial fan facies and palustrinelshaltow 1acustrine deposits can be observed. This sedimentary evolution is inferred from the detailed sedimentological. analysis carried out in each of the previously defined lithostratigraphic units: a 1 ) Green shale and dolomite Unit, a 2 ) Brown clays, arkosic and carbonate Unit; these two units are linked together into a Lower Group. b) Coarse Arkosic Unit (Upper Group). Facies relationsbips within the Lower Group show a lateral change pattern between alluvial fan deposits, and palustrine deposits. Also the former ones gradually prograde over the palustrine deposits, as deduced from vertical evolution in the southernmost parts of the area. Upper Group represents a sudden progradation of the alluvial fan systems, that extensively overlie the distal facies observed in the Lower Group. Wide development of calcretes, sepiolite deposits, and nodular chert is an outstanding feature in the most distal parts of the alluvial fan bodies. They are studied in some detail provided the scarcity of well described examples of facies relationships in the kinds of deposits.

The soils of Aldabra

The soils of Aldabra are of patchy distribution, consisting of pockets of either accumulated organic matter or of biogenic mineral detritus. The soils are shallow (10-20 cm) but locally deeper and more extensive soil covers do occur. Organic covers occur under well established Casuarina stands and mineral soil covers occur on the floors of rock basins or where sands are present. The organic soils originate from leaf litter, with local increments of faecal material and bird remains. The mineral soils are primarily carbonate and are derived mechanically from carbonate rocks, from windblown bioclastic carbonate grains or from terrestrial sediments. Solution residues and phosphatic particles also contribute to these soils. Attempts are made to cross-correlate existing soil information, and several organic and carbonate soil types can be recognized. These are: shallow organic (including litter, pellet and guano varieties); deep organic; calcarenaceous bioclastic soils; brown (silt or silt loam) carbonate soils (including a phosphatic variety) and a widespread organic brown carbonate soil. The soils may be slightly acid but are mostly circumneutral or alkaline; high salinity may occur in coastal locations. Phosphate levels are usually low. Insufficient profile data are available at present to define soil type in any rigorous way and the spatial distribution of soil types is only scantily known.

Application of fluorescence microscopy in coal petrology and oil exploration

SUMMARYFluorescence microscopy of polished surfaces allows more satisfactory study and identification of the hydrogen‐rich constituents (liptinites) that are the precursors of petroleum and which, in soft brown coals, fine‐grained clastic and carbonate sediments can hardly be detected using normal reflected light. Diagnostic properties of liptinites and lipoid substances are their colour, intensity and variation of fluorescence (both colour and intensity) during irradiation which may allow distinction of organic and inorganic constituents in coals and bituminous shales. Fluorescence properties also change with increasing degree of diagenesis (‘rank’) of organic matter, although organic constituents cease to fluoresce beyond the medium‐volatile, bituminous‐rank stage. In this paper fluorescence microscopy as a means of studying the rank of coaly and lipoid substances in sedimentary rocks is discussed after a brief description of the method. The influence of facies on fluorescence properties is considered and the relative merits of fluorescence and reflectance measurements in different parts of the rank range are discussed. The importance of fluorescence microscopy in petroleum exploration is also emphasized. Finally, consideration is given to the future of fluorescence microscopy in relation to the ‘bituminization range’ of coalification which has important implications to both petroleum generation and to the coking and hydrogenation of coals.

Dolostone from the South African Continental Slope

ABSTRACT Reports of lithified dolostone from deep-water environments are relatively rare. A large quantity of dolostone has recently been recovered from a single station on the South African continental slope at a depth of 790 m. Microspar-sized protodolomite crystals make up about 90% of the rock; other components are mostly silt-sized terrigenous grains and hematite dendrites. The rocks are covered by a brown carbonate fluorapatite-illite-hematite crust and rock surfaces have a distinctive pattern of ridges, grooves, and depressions. The origin of this dolostone facies is uncertain, but is believed to be the product of refluxing brines which originated at shallower levels on the shell Subsurface migration of these hypersaline, Mg-rich brines dolomitized the carbonate sediments through which they passed. The surficial depressions, grooves, and ridges are attributed to submarine solution and the crust to submarine replacement while the semi-lithified rocks were exposed on the sea floor.