Silicic Research Articles

Lólegelők és kaszálók természetvédelmi értékelése Sukoró melletti lovasközpontban

The test was carried out in Sukoró, on the lawns of the Sukoró Equestrian Center in May 2023. The purpose of the survey was to present the natural state and economic value of grasslands with different uses. The ceenological surveys were carried out using the Braun-Blanquet method, during which we recorded the data using 2x2 meter squares and gave the cover values in %. The squares were placed randomly in the given areas. During the survey, we analyzed five sample areas in three units. Our sample area I. is degraded fresh grassland, which was a horse pasture that was overgrazed in 2023, II. the sample area was a meadow dominated by sedge, which is utilized by mowing. The III. the sample area is Siki lawn dominated by Festuca pseudovina, which was also mowed. The IV. the deepest part of the mowing area, marsh meadow-fen, which is also used as a mowing area. Sample area V is silicate rock grassland, which is also grazed by horses, but was left alone in 2023. With the exception of sample area I, which was intensively grazed in 2023, and therefore overgrazed by trampling, based on the tests, the natural state of the lawns remained valuable even after treatments, mowing and grazing. In the lawns, the largest proportion of elements of the native flora can be found. In the deeper spot on the mowing field, bog elements and the protected species Anacampts pyramidalis also appeared. A protected species, Allium sphaerocephalon, also occurred in the silicate rock lawn. The lawn management methods carried out by the riding center are suitable for maintaining the area's vegetation in a close-to-nature and long-term manner.

Structural control of the deposition and subsequent deformation of the Killary Habour-Joyce Country Silurian succession

Abstract: The Killary Harbour–Joyce Country succession of Silurian rocks forms the remnant of one of three successor basins that developed after the Grampian Orogeny and which are preserved in western Ireland. Its outcrop everywhere obscures the contact between the Dalradian rocks of Connemara and the Ordovician rocks of the South Mayo Trough. The outcrop is bisected by the prominent north-west trending Maam Valley Fault Zone that is shown to have a component of synsedimentary movement down-throwing to the southwest. The original basin margins lay well outside the current outcrop area. North-south shortening and inversion of the basin was accomplished by reactivation and inversion of earlier fault structures and was exclusively in the brittle zone. Folding of the Silurian rocks with weak to moderate cleavage and deformation of the basement rocks of Connemara was accomplished by largely vertical movements along numerous strike parallel and oblique fractures. Break-back inversion structures were developed along the southern margin of the South Mayo Trough, which include thrusting associated with footwall shortcut faults and clockwise rotation. Although the timing of deformation overlaps that of diorite sill emplacement, it remains poorly constrained in absolute terms.

Extracting photometric determination of antimony with 5–pyridylazo–2–monoethylaminoparacresol (PAAC)

The developed extraction-spectrophotometric method for the determination of antimony utilizing 5-(pyridylazo)-2-monoethylaminoparacresol (PAAC) stands out for its selectivity, sensitivity, and rapidity. This method proves to be effective in the determination of antimony in various complex matrices, including model solutions of silicate rocks and ores. The robustness of the method is evident as it successfully analyzes these samples without the need for preliminary separation of accompanying elements. PAAC is chosen as the complexing agent for antimony. Its selectivity and sensitivity contribute to the precision of the method. The method involves an extraction step, likely utilizing a suitable organic solvent, to selectively extract the antimony-PAAC complex from the sample matrix. The concentration of antimony in the extracted complex is determined spectrophotometrically. This involves measuring the absorbance of the complex at a specific wavelength, typically chosen based on the characteristics of the PAAC-antimony complex. The method is validated by analyzing model solutions of silicate rocks and ores. This step assesses the applicability and accuracy of the method in samples that simulate real-world conditions. The method demonstrates a reproducibility of 2-5%, indicating its reliability and precision across multiple analyses. The developed method is recommended for the analysis of chemically complex materials such as industrial wastewater, ores, concentrates, and rocks.

Chemical activity score of siliceous rocks in development of self-cleaning cement material

The development of photocatalytically active cement materials characterized by a complex of positive properties, such as self-cleaning ability, decompose atmospheric air pollutants, eliminate unwanted odors, etc., is actual scientific direction in the field of building materials science. It is known that ‘core-shell’ compositions obtained by precipitation of photocatalyst particles on dispersed carriers (substrates) are one of the effective types of photocatalytic additives for cement systems. It should be noted that mineral raw materials of various genesis can act as a substrate. Foreign and domestic experience in obtaining ‘core-shell’ photocatalytic systems for cement materials shows that the type of photocatalytic agent carrier has a primary influence on the final parameters of the synthesized composite modifier. The purpose of this study was to establish patterns of influence of the composition of 3 types of opal-cristobalite rocks (diatomite, trepel, opoka) on their chemical activity. It was identified that the reactivity of siliceous rocks grows in the order of trepel → opoka → diatomite. Meanwhile, it was recorded that increase in the content of opal silica in the composition contributed to growth in the sedimentary rock reactivity. The obtained research results indicate the prospects of using diatomite and opoka as dispersed carriers of photocatalytic agents in the composition of self-cleaning cement concretes.

High-precision measurement of Ag isotopes for silicate rocks by MC-ICP-MS

A new protocol for the high-precision measurement of Ag isotopes for samples with low Ag contents by MC-ICP-MS.

Evaluation of two methods allowing the full preparation in a single day of silicate rocks in view of radiogenic isotope (Nd, Sr, and Pb) analyses

In this paper, two approaches are described aiming to circumvent the bottle-neck associated with sample decomposition of silicate samples and subsequent isolation of three elements (Nd, Sr, and Pb) of interest for their radiogenic isotope compositions.

Juvenile source nature of the North Tianshan turbidites and its tectonic implication

Abstract Sediments within accretionary complexes, preserving key information on crust growth history of Central Asian Orogenic Belt, did not get enough attention previously. Here, we conduct comprehensive geochemical study on the turbidites from the North Tianshan Accretionary Complex (NTAC) in the Chinese West Tianshan orogen, which is a good example of sediments derived from juvenile materials. The turbidites, composed of sandstone, siltstone, and argillaceous siliceous rocks, are mainly Carboniferous. All the investigated samples have relatively low Chemical Index of Alteration values (35–63) and Plagioclase Index of Alteration values (34–68), indicating relatively weak weathering before erosion and deposition. The sandstone and siltstone, and slate samples display high Index of Compositional Variability values of 0.89–1.50 and 0.89–0.93, suggesting a relatively immature source. The sandstones and siltstones were mainly derived from intermediate igneous rocks, and the slates from felsic igneous rocks, formed in oceanic/continental arc settings. The investigated samples roughly display high positive εNd(t) values (mainly at +5.5 to +7.9, except one spot at +0.8), with corresponding Nd model ages at 672 Ma–522 Ma (except one at ∼1.1 Ga). Combined with the previous studies, we suggest that the turbidites in the NTAC were mainly derived from intermediate to felsic igneous rocks with juvenile arc signature, and thus the northern Chinese West Tianshan is a typical site with significant Phanerozoic crust growth.

Potassium release behavior from silicate rocks using sulfuric and citric acids media

Potassium plays a pivotal role as a critical nutrient and essential for increasing crop productivity. Recent scientific studies have been directed toward investigating silicate minerals as a promising alternative source for this element. This study presents results derived from a preliminary exploration into the release of potassium behavior, alongside other present ions, extracted from silicate rocks originating from the region of Rio de Janeiro, Brazil. The efficacy of sulfuric and citric acids as potential agents for facilitating this release was examined. Employing an incomplete factorial design, the study systematically evaluated the influential variables temperature, time, and concentration, aiming to delineate their impact on potassium release across various sample-acid systems. The discussion delves into elucidating the hierarchical order of these variables concerning potassium liberation within each sample-acid configuration. The consequential insights derived from this meticulous analysis hold considerable significance, contributing substantially to the prospective assessment of harnessing these rocks as a viable potassium resource for future agricultural applications.

Early Triassic S-Type Granitoids in the Qinzhou Bay Area, South China: Petrogenesis and Tectonic Implications

The influence of the paleo-Tethys or paleo-Pacific oceanic plate subduction on Early Triassic South China has long been debated. We have studied the zircon U-Th-Hf isotopes, trace elements, and whole-rock geochemistry of Early Triassic peraluminous granitoids in the Qinzhou Bay area, South China Block. LA–ICP–MS zircon U–Pb dating has revealed the Jiuzhou granodiorites and Dasi-Taima granite porphyries formed between 248.32 ± 0.98 and 246.6 ± 1.1 Ma. These rocks are characterized by high K2O and Al2O3, and low MgO, CaO, and P2O5 contents with A/CNK = 1.06–1.17, showing high-K calc-alkaline S-type affinities. The Early Triassic intrusive rocks and adjacent silicic volcanic rocks in the Qinzhou Bay area were found to be comagmatic and derived from a common magma pool, detached in an undifferentiated melt instead of indicating remarkable crystal—melt separation. Although the analyzed granitoids have highly enriched zircon Hf isotopic compositions (εHf(t) = −23.9 to −7.8), they cannot originate solely from metasedimentary protoliths. Source discrimination indicators have revealed enriched lithospheric mantle-derived magma was also an endmember component of the S-type silicic magma, which provided a heat source for the crustal anatectic melting as well. We inferred the studied Early Triassic granitoids formed under the paleo-Tethys tectonic regime before the collision of South China and Indochina blocks, as the oceanic plate subduction would have created an extensional setting which further caused the mantle-derived upwelling and volcanic eruption.

Sulphide petrology and ore genesis of the stratabound Sheep Creek sediment-hosted Zn–Pb–Ag–Sn prospect, and U–Pb zircon constraints on the timing of magmatism in the northern Alaska Range

The Sheep Creek prospect is a stratabound Zn–Pb–Ag–Sn massive sulfide occurrence in the Bonnifield mining district, northern Alaska Range. The prospect is within a quartz–sericite–graphite–chlorite schist unit associated with Devonian carbonaceous and siliceous metasedimentary rocks. Volcanogenic massive sulfide (VMS) deposits in the district are hosted in felsic metavolcanic rocks (362 ± 2 Ma) associated with siliciclastic and carbonaceous sedimentary rocks that overlie the stratigraphic sequence hosting the Sheep Creek prospect. Felsic metaigneous rocks in underlying units are 372 ± 4 to 366 ± 4 Ma. Sheep Creek is atypical of the other sulfide deposits in the district in (1) having Sn grades up to 1.2%; (2) being contained in fine-grained, quartz-rich rocks and quartz–pebble conglomerate that likely originated as chert and chert-clast sediment, respectively; and (3) showing minimal evidence of volcanic components in the host rocks. Comparison of immobile trace-element proportions for graphitic and siliceous rocks from the Sheep Creek area with those for argillite associated with the Bonnifield VMS deposits indicates a continental volcanic-arc provenance for the former and a within-plate and passive margin provenance for the latter. In contrast to previously published interpretations, our data analysis supports a clastic-dominated (CD) rather than a VMS affinity for the Sheep Creek prospect. In our model, Zn–Pb–Ag–Sn mineralization formed by syngenetic or early diagenetic processes on or beneath the seafloor, possibly in the shallow-water environment of an outer continental shelf setting. Potential analogues are the Paleozoic CD deposits in the Canadian Selwyn Basin outboard of the Laurentian continental margin.

A Residual Middle Triassic Oceanic Island-Seamount in the Maoershan Area, Northwest Tibet: Implications for the Evolution of the Paleo-Tethys Ocean

The assemblage of oceanic islands and seamounts, arising from the widespread presence of mature oceans, plays a crucial role in reconstructing the evolutionary history of the paleoocean. Oceanic islands or seamounts within the Longmuco-Shuanghu metamorphic complex, a remnant of the Paleo-Tethys Ocean in the central Tibetan Plateau, have seldom been reported due to their remoteness. This study has identified an oceanic island-seamount in the Maoershan area, situated to the west of the Longmuco-Shuanghu metamorphic complex, composed of basalt, diabase, limestone, and siliceous rocks. Based on field observations, petrology, zircon U-Pb dating, whole-rock geochemistry, and Sr-Nd isotopes analyses, we have identified a suite of mafic rocks with OIB affinity. The youngest zircon U-Pb age cluster was concentrated at ~243–241 Ma. The geochemical characteristics of the siliceous rocks indicate a mixture of terrigenous material, suggesting that they formed in a continental margin. In combination with regional geological data, we conclude that the Longmuco-Shuanghu Paleo-Tethys Ocean remained open during the Middle Triassic. Furthermore, a fraction of the oceanic island-seamounts underwent scraping and transformed into a metamorphic complex, while other segments experienced deep subduction, resulting in the formation of high-pressure metamorphic rocks. Collectively, these processes gave rise to the distinctive high-pressure metamorphic complex within the central Qiangtang terrane.

Contrasting sources and enrichment mechanisms in lithium-rich salt lakes: A Li-H-O isotopic and geochemical study from northern Tibetan Plateau

Lithium (Li), a crucial mineral resource for modern high-tech industries, is notably abundant in the northern Tibetan Plateau, primarily within lithium-rich salt lakes. However, the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin. Here we present results from a comprehensive study on the hydrochemical parameters, whole-rock geochemistry, H-O isotopes, and Li concentrations in surface brine, river water, geothermal springs, and associated rocks from two representative lithium-enriched salt lakes, the Laguo Co (LGC) and Cangmu Co (CMC) in Tibet to understand the genetic mechanisms. Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo (SMZB, ∼91%) and Donglong Zangbo (DLZB, ∼75%) rivers, respectively. It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources, respectively. The distinct geological characteristics reflect evolutionary differences between the two lakes, suggesting diverse lithium sources and enrichment processes. The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau. Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river. In contrast, the formation and evolution of CMC are influenced by the northern Lunggar rifts, receiving a prolonged and stable input from the DLZB, resulting in high lithium concentrations and isotopic values. The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks, such as granitic pegmatite veins containing lithium-rich beryl, widely distributed in the upstream area of DLZB. The forward modeling approach, quantifying the contribution fractions of different reservoirs (atmospheric precipitation, silicate, carbonate, and evaporite), indicates that the distinct lithium concentrations in the mainstream (>1 mg/L) and tributaries (<0.1 mg/L) are positively correlated with the ratio of silicate contributions to carbonate contributions, suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks. The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes, topographical features, hydrological factors, fundamental geological settings, and tectonic histories, despite their spatial proximity. Furthermore, our study highlights the significant role of rivers in the formation of young salt lakes, in addition to geothermal springs.

Petrology and source characteristics of the Arbarastakh alkaline ultramafic carbonatite-phoscorite complex, the Aldan-Stanovoy Shield

Late Neoproterozoic Arbarastakh alkaline ultramafic carbonatite-phoscorite complex in the southern margin of the Siberian craton (Aldan-Stanovoy shield), includes carbonatites and phoscorites closely associated with pyroxenites-ijolites and ultramafic lamprophyres. Major and trace elements data, Sr, Nd and Pb isotope compositions for the Arbarastakh rocks have been obtained to characterize the sources involved in their formation, primary melt composition and to build the petrogenetic model.All rock varieties, excluding nepheline syenites, are characterized by incompatible elements enrichments, including light rare earth elements, and strong fractionation of REEs. The initial isotope ratios of the analyzed samples, calculated at 645 Ma, display limited variations: εNd from +5.9 to +6.9 and 87Sr/86Sr from 0.70225 to 0.70272, excluding nepheline syenite with εNd +5.4. The initial Pb isotope ratios for the most studied samples overlap with each other within uncertainties. They yield an age of 642 ± 5 Ma. The Nd and Sr isotope data of the Arbarastakh rocks generally fit the patterns of the other Neoproterozoic alkaline ultramafic carbonatite complexes of the southwestern and southern margins of the Siberian craton. Observed Sr, Nd and Pb isotope variations indicate mixing of the asthenosphere and the depleted mantle components.It is supposed that the primary melts for the Arbarastakh rocks were generated directly by low-degree melting of metasomatic phlogopite‑carbonate veins with apatite and Ti-oxides in garnet peridotite, which formed shortly before the onset of melting. Ultramafic lamprophyre (aillikite) is closest to the primary melt composition in terms of high #MgO, Cr and Ni. The aillikite and latter pyroxenite crystallized from primitive melt by fractionating the olivine, phlogopite and clinopyroxene dominated mineral assemblage that was free of feldspar. This fractionation forced Na-enrichment in the magmas resulted in liquid silicate‑carbonate immiscibility. Major and trace element and isotope data indicate that the nepheline syenites are unlikely to be related with other alkaline silicate rocks through fractional crystallization and could have been formed through pre-emplacement interaction with the ambient crustal materials. Emplacement of calcite carbonatites resulted in metasomatism of surrounding pyroxenites with formation of clinopyroxene-phlogopite-calcite carbonatites. Subsequent portions of Fe-P-enriched carbonatite magmas crystallized phoscorites and apatite-dolomitic carbonatites.

Accelerated weathering of silicate rock dusts predicts the slow-release liming in soils depending on rock mineralogy, soil acidity, and test methodology

The ongoing acidification of soil poses a significant threat to the proper functioning of various ecosystems worldwide. Silicate rock dusts (RD) are increasingly amended to acid soils to restore their pH, but the acid neutralising capacity (ANC) and dissolution rate of these products are highly variable and lack proper assessment protocols. It is expected that pH-dependent RD ANCs and dissolution rates dictate the pH increase in soils depending on the initial pH and pH buffer power of the soil. This study addressed these questions by comparing and validating three accelerated weathering tests for their capacity to predict the gradual liming effects in a two-year outdoor mesocosm. Five commercial RDs (two basalts, phonolite, foidite, and trachy-andesite) were tested in four acidified forest soils varying in initial pH, in texture and associated pH buffer power. First, RD dissolution was measured in aqueous batch renewal systems during one year at various starting pH (3.5, 4.5, and 5.5) and constant temperatures (20 °C, 37 °C, and 65 °C). These showed that the ANCs of RDs exhibit a fast fraction (half-life < 1 day) followed by a slower fraction. Second, titration tests of RDs at fixed solution pH, i.e., pHstat, performed between pH 3.5 and 4.5 revealed surface normalised dissolution rates that decreased factors 10–100 per unit pH increase, the slope depending on the RD’s mineralogy. Indeed, the rate ranking of observed surface area normalised dissolution rates confirmed that of literature-based values, weighed by the XRD-derived mineralogical fractions. Third, lime-calibrated agitated soil-RD suspension tests were conducted for two months, illustrating the dependency of RD ANC on soil context, and yielding ANCs that were factor 2–5 times larger than in the batch renewal test because of pH buffering effects of soil particulates. Finally, an outdoor soil mesocosm on the four acid soils amended with RDs at 12 Mg/ha and 340 Mg/ha was established and soil pH was monitored for 2 years. The observed pH trends corresponded well for both the low dose (R2a = 0.67) and the high dose (R2a = 0.93) with model predictions made using the pH- and temperature-dependent RD dissolution rates (pHstat test) and the soil pH buffer power and RD slow ANC-fraction (soil-RD suspension test). This model predicts half-lives of RD dissolution ranging between <1 month to >100 years depending on the starting pH of the soil, its pH buffer power, the RD mineralogy (XRD based) and its specific surface area. This study shows that the dissolution and ANC of RD can be most pragmatically predicted with a series of lime-calibrated soil-RD suspension tests of maximally two months.

The Chemical Weathering of Rocks and Its Carbon Sink Effect in the Naqu River Basin of the Nujiang River Source Area, Southwest China

Carbon plays an important role in global climate change. The mechanisms of carbon sources and carbon sinks have also received wide attention from society, and the physical and chemical characteristics of riverine ions can reflect the chemical weathering of rocks and carbon sink capacity of river basins. Based on the data on river, rainwater, and rock samples from 2019, this study used various methods, such as ion ratio diagrams and ternary diagrams, to analyze the chemical characteristics of water; the chemical weathering and carbon sink effects of rocks were also calculated while assuming three scenarios based on the main sources of ions in the Naqu River. The results showed that for the whole catchment, the main ion sources in the river were: carbonate rock chemical weathering &gt; silicate rock chemical weathering &gt; evaporite dissolution &gt; atmospheric precipitation input. According to the calculations, in the three scenarios, the carbonate weathering rates were 16.84, 11.32, and 14.08 t/km2/yr, and the carbon sink capacities were 66.47, 121.13, and 93.80 mol/km2/yr, respectively; the evaporite weathering rates were 2.20, 9.63, and 5.92 t/km2/yr, respectively. The silicate chemical weathering rate and carbon sink capacity did not change significantly in either scenario, with 6.82 t/km2/yr and 248.6 mol/km2/yr, respectively. This study quantified the ion sources in the Naqu River basin and accurately analyzed their chemical genesis, which helps in understanding the role of the rivers of the Qinghai–Tibet Plateau in the global carbon cycle and global climate change, in addition to providing a reference for the scientific development of the Nujing River.

Acid-Base Buffering Assessment and Directions of Silicon Compound Transformation in Sod-Podzolic Soil when Used Various Siliceous Rocks

The variability of the main indicators of acid-base buffering of sod-podzolic light-loamy soil was investigated, and the dynamics of the content of monomers and polymers of silicic acid and acid-soluble silica compounds in the soil under conditions of reclamation doses of various siliceous rocks (diatomite, zeolite and bentonite clay 3, 6, 12 t/ha) was described. Zeolite rock and bentonite had a positive effect on the anti-acid buffering ability of the soil, shifting the H+/OH–equilibrium of the system by more than 160 and 20, respectively, depending on the applied dose of the material. The effect of diatomite was manifested in the anti-alkaline region of soil buffering, due to which the H+/OH–-equilibrium index decreased by almost 40%. Against the background of the use of diatom rock and bentonite clay, the content of silicic acid monomers in the soil increased by more than 5 and 4 times, respectively, against the background of the use of zeolite – by more than 2 times. The content of silicic acid polymers in the soil increased up to 3 and 4 times with the use of zeolite and bentonite rocks, respectively. At the same time, the introduction of diatomite into the soil contributed to an increase in the content of H4SiO4 polymers by 5–10 times, depending on the dose of the material. The content of the acid-soluble fraction of silicon compounds in the soil increased by 1.4–2.8 times against the background of different doses of the studied rocks and, in general, had a different dependence depending on the composition of each of them. Based on the revealed irregularities in the content and dynamics of mobile silicon compounds in the soil (monomers and polymers of silicic acids, acid-soluble silica fractions), the characteristic is given and the value of the first proposed indicators describing their dynamic state and directions of transformation – the potential for the formation of monomers (M-ASi) and polymers (P–ASi) is disclosed. H4SiO4, the degree of polymerization (Pm-VSi) and depolymerization (Dm-VSi) of silicic acid, the total content of the loose-amorphous silica fraction (Si-AMF) and the degree of amorphousness of the Si-containing mineral phase of the soil (AMF-VSi). The study of the influence of silicon materials in conditions of sod-podzolic soil revealed that, depending on the qualitative composition and dose of silicon rock, the M-ASi index can increase by 30–80%, and the P-ASi index can be in the range of increase from 0.3 to 3.0 or more times. The processes of polymerization of silicic acid and the decomposition of its polymers into monomers, expressed respectively by Pm-VSi and Dm-VSi, can also actively increase against the background of the interaction of soil with rocks, the measure of change of which is expressed in the order of 10–40% deviation relative to the control. The total content of loose-amorphous silica fraction in the soil, expressed by the SiAMF index, can be determined by the composition of each siliceous rock used as a meliorant. If, when using diatomite, the indicator can decrease by almost 30%, then when using zeolite and bentonite clay, it can increase by 30–100%, depending on the dose. Similarly, the indicator of the degree of amorphousness of the silicon-containing part of the soil substance (AMF-VSi) can also change.

Siliceous Rocks in the Fertilizer System of Agricultural Crops

Over the past 25 years, the influence of siliceous rocks (diatomite, zeolite, flask) on soil properties (typical chernozem, leached chernozem), yield and quality of agricultural crops (cereals, potatoes and vegetables, technical) when used both in pure form and together with mineral fertilizers and bird droppings has been studied. The possibility of creating new types of more effective fertilizers based on siliceous rocks by enriching them with elements or compounds (in particular amino acids) that most fully meet the requirements of crops has been studied. Studies have shown that the yield of grain crops when using diatomite as a fertilizer is little inferior to mineral fertilizers. Thus, the increase in grain yield of winter wheat on average over all the years of research reached 0.60–1.30, spring wheat – 0.15–0.67, barley – 0.50–0.93 t/ha. The increase in corn grain yield, depending on the dose of zeolite application, ranged from 0.93 (dose of 500 kg/ha) to 1.36 (dose of 2000 kg/ha) t/ha. Potatoes and vegetables (cucumbers, tomatoes, carrots, table beets), as well as industrial crops (sugar beet, sunflower) are highly responsive to the use of siliceous products as fertilizers. In particular, the yield of sugar beet root crops increased by 6.5 t/ha on average when diatomite was applied at a dose of 3 t/ha, and in some years – up to 8.6 t/ha. The increase in crop yield increased very significantly when combined with nitrogen fertilizers from N30 to N60 – by 11.3 and 12.5 t/ha. The high efficiency of silicon-containing rocks as fertilizers of agricultural crops is due to their complex influence on the fundamental properties of the soil: physical (structural condition, soil density, structure of the arable layer), biological (activity of soil microorganisms), chemical (nutritional regime, environmental safety), as well as on the protective properties of plants.

Structural Control of the Deposition and Subsequent Deformation of the Killary Habour-Joyce Country Silurian Succession

The Killary Harbour–Joyce Country succession of Silurian rocks forms the remnant of one of three successor basins that developed after the Grampian Orogeny and which are preserved in western Ireland. Its outcrop everywhere obscures the contact between the Dalradian rocks of Connemara and the Ordovician rocks of the South Mayo Trough. The outcrop is bisected by the prominent north-west trending Maam Valley Fault Zone that is shown to have a component of synsedimentary movement down-throwing to the southwest. The original basin margins lay well outside the current outcrop area. North-south shortening and inversion of the basin was accomplished by reactivation and inversion of earlier fault structures and was exclusively in the brittle zone. Folding of the Silurian rocks with weak to moderate cleavage and deformation of the basement rocks of Connemara was accomplished by largely vertical movements along numerous strike parallel and oblique fractures. Break-back inversion structures were developed along the southern margin of the South Mayo Trough, which include thrusting associated with footwall shortcut faults and clockwise rotation. Although the timing of deformation overlaps that of diorite sill emplacement, it remains poorly constrained in absolute terms.

New Data on the Ben Levy Anticline, With Reverse Reactivation on the Coolin Fault Giving Up-Side-Down Silurian Rocks in Joyces Country, Connemara

In Joyces Country in western Ireland, the ~ E-W striking axial plane of the D7 Ben Levy anticline folded Dalradian and unconformable Silurian rocks. The north side of the fold is mostly coincident with the contemporaneous ESE-WNW striking steeply dipping Coolin Fault close to the Dalradian-basal Silurian contact. This fault was first initiated by sinistral strike-slip motion, probably of Ordovician age, and then secondly used by post-Wenlock down throw on the north side to form the D7 anticline. Later a newly recognised third motion of reverse reactivation on the fault uplifted the north limb of the fold and locally overturned the Silurian succession against irregularities in the SSW dip of the fault. Still later, but pre-374Ma (Devonian), NE-SW faulting exposed different previous levels of the Coolin Fault zone. The superb Dalradian rock exposure provides details not generally apparent on other reactivated faults in Connemara.

Influence of Diatomite, Zeolite and Bentonite Clay on Agrochemical Indicators Sod-Podzolic Soil and Yield Agricultural Crops

In three-year microfield experiments on sod-podzolic light loam soil, the effect of reclamation doses (3, 6 and 12 t/ha) of siliceous rocks (diatomite, zeolite and bentonite clay) on the main agrochemical properties of the soil and crop productivity in the grain link of the crop rotation of winter wheat-spring barley-seed peas was studied. Among other positive effects, a significant effect of diatomite was found in reducing the concentration of exchangeable forms of aluminum in the soil (by 0.11 mg-eq/100 g), increasing the content of exchangeable forms of magnesium (by 0.33 mg-eq/100 g) and phosphates of soil solution (by 225%). Against the background of the influence of diatoms, barley gave the greatest increase in grain yield (by 38%) and straw (by 29%). The most significant effect of zeolite was revealed in a decrease in the actual, metabolic and hydrolytic acidity of the soil (a decrease of 1.11, 0.48 pH units and 0.33 mg-eq/100 g), as well as the concentration of exchange compounds of calcium (an increase of 17.7 mg-eq/100 g), magnesium (by 12.0 mg-eq/100 g) and potassium (by 46%). The introduction of zeolite rock contributed to the greatest increase in the yield of grain (by 32%) and straw (by 23%) of barley. The most significant influence of bentonite clay was established on the indicators of actual soil acidity (their decrease by 0.65 pH units), the content of exchangeable aluminum (decrease by 0.19 mg-eq /100 g) and phosphates of soil solution (increase by 175%). The introduction of clay contributed to the formation of the greatest increase in grain yield (by 33%) and straw (by 19%) of seed peas.