Quartzitic Sandstone Research Articles

Application of the Schmidt-hammer for relative-age dating of glacial and periglacial landforms in the Cantabrian Mountains (NW Spain)

A Schmidt hammer was applied for relative-age dating to 48 sites in 5 different massifs of the Cantabrian Mountains (NW Spain). The sample included glacial (moraines, erratics, and polished bedrock) and periglacial (rock glaciers, blockfields, and talus slopes) sites from the last glaciation to the present in different geomorphological contexts. The rebound (R) values agree with the morphostratigraphic reconstructions, showing progressively lower values for older deposits. Six stages from the Last Glacial Maximum to the present are inferred. The results differ according to the lithology: i) the quartzites showed higher R-values and very low weathering rates; ii) the granodiorites showed larger differences in R-values reflecting clearly age differences; iii) sandstones appear to be unsuitable for Schmidt hammer measurements in some areas; however, quartzite sandstones provide better results. The rock glaciers formed in different periods after deglaciation (i.e. just after the Last Glacial Maximum, Bölling/Allerød, Holocene), indicate a paraglacial dependence rather than climate-driven landforms. The sampled blockfields stabilized after the (almost) total deglaciation of the cirques, but their origin and significance in this mountainous area remain poorly understood.

Engineered ‘landmarks’ associated with Late Paleolithic engraved shelters

Although more than 2000 shelters with non-figurative carvings ascribed to a Mesolithic style are known within the quartzitic sandstone megaclast lag deposits in the southern Paris area, only three shelters with figurative representations of Late Paleolithic style have been recognized. Upright megaclasts are rare in the regional lag deposits but two upright quartzitic sandstone megaclasts occur close to two of these Late Paleolithic shelters. Detailed morphological surveys of these megaclasts allow us to suggest that they were erected by humans. The fortuitous conjunction of finding an upright megaclast close to two Late Paleolithic shelters is infinitesimally small in term of probabilistic considerations. Thus, the Late Paleolithic engraved shelter – upright megaclast pairs are not likely to be independent but are probably linked by culture, and so the megaclasts are expected to date from the Late Paleolithic. We suggest that they were ‘engineered landmarks’ erected to mark places that had cultural significance for Late Paleolithic hunter-gatherer people. The energy dedicated to erect the megaliths is an indication that shelter - megalith pairs probably had important spiritual and symbolic significance. We suggest that both contributed to locate and anchor stories to landscape features. Indeed, these shelter-megalith pairs were in the hinterland of the large open-air camps settled on fords on game migratory routes crossing the Seine River. These specific markers could have encompassed a storyline about landscapes as the support for learning routes through them. One possibility is that they had a timed relationship with herd migration.

Абразивные пилы Среднего Зауралья и некоторые аспекты их использования в древности

In the Middle Transurals, stones started to get sawed with abrasive saws in the Neolithic era and was widely used in the Eneolithic. The author studied 129 abrasive saws and 153 items with traces of sawing. They respectively originate from 26 and 22 archaeological sites. Usually there are one or two saws at the site (11 and 5 sites, respectively). But some sites appeared to have dozens of them (Shaitanskoye Lake I – 13; Ust-Vagilsky hill – 19; Yurino IV – 22). They are found both in settlements, sites, and in sanctuaries. Saws are mainly represented by fragments from 1.5 to 24.5 cm long. Moreover, they were broken intentionally. There are few whole saws preserved, usually their length is 10–20 cm. The thickness of the saws ranges from 0.5 to 2.5 cm. Saws up to 0.6 cm thick predominate and constitute 46.3 %. Fifteen saws have two working blades each. 30 abrasive saws are made of fragments of grinding plates and are both one-sided and two-sided. The saws cut into the processed material from 0.2 to 2.5 cm deep. Most often (56.8 %) the items were sawed 0.2 to 0.5 cm deep. The most intense deterioration (3.6 and 4.4 cm) is found in two saws. The working edges of abrasive saws were usually formed by grinding. At the same time, the opposite edge of the saws nearly always remained untreated. The deterioration of stone saws and sawing traces in various objects were analyzed and showed that sawing boiled down to mostly splitting thin blanks used to make knives and arrowheads. There are very rare traces of saws on polished chopping tools such as axes (1) and adzes (5). Abrasive saws were also used to design teeth on comb stamps or grooves on so-called ironings. Besides, saws could be used to cut out patches out of fragments of richly ornamented broken vessels. Saws were made of 8 types of mineral raw materials. It appeared possible to identify mineral raw materials for102 saws. Two-thirds of them are made of slate (41.2 %) and granodiorite (35.3 %). The next most popular material is mica slate which constitutes 11.8 %. The remaining saws are made of sandstone (5 items), quartzite, carbonaceous shale, brown ironstone (2 items each) and quartzite sandstone (1 item). The experiments made it possible to determine the sawing speed and the deterioration rate of the saw material. It is established how long and how much workforce it took to saw. The research managed to compare the efficiency of sawing different types of stone with saws made of materials with different hardness. The experiment results reveal the peculiarities of abrasive sawing of stone. The peculiarities were the methods for securing the blank and securing the saw in the intended cutting line. Sawing with a two-handed saw, as well as using fine-grained abrasive, significantly increased the processing efficiency.

Upper Riphean and Lower Paleozoic Quartzite Sandstones of the Circumpolar Urals: Geochemical Characteristics, Source Areas, and Conditions of Formation

The results of study and comparison of geochemical characteristics of quartzite sandstones of the Upper Riphean Khobeyu and Lower Paleozoic Obeiz formations of the Circumpolar Urals are presented. It has been established that the composition of quartzite sandstone of both formations was formed mainly from recycled material of ancient metaterrigenous rocks, with the participation of destruction products of igneous rocks of felsic (Obeiz Formation) and basic (Khobeyu Formation) composition and weathering crust material. The accumulation of the Lower Paleozoic psammites was accompanied by a gradual change of clastic sources, with increasing contribution of granitoid clastics.

Upper Riphean and Lower Paleozoic Quartzite Sandstones of the Circumpolar Urals: Geochemical Characteristics, Source Areas, and Conditions of Formation

Upper Riphean and Lower Paleozoic Quartzite Sandstones of the Circumpolar Urals: Geochemical Characteristics, Source Areas, and Conditions of Formation

Petrology and geochemistry of sandstone from Lower Cretaceous Kikhla Formation, NW Libya: Implications for provenance and depositional setting.

This study aims to determine and investigate the provenance of the source rocks and the depositional setting of the Kikhla Formation, northwestern Libya. It is mainly composed of mature quartzitic sandstone alternating with conglomerate and clay. The study proved that the sandstone is yellow-white in color and commonly carries quartz granular and small fragments of silicified wood. The environmental deposition is under differing fluvial conditions and by a large braided river. Texturally, the Kikhla sandstone is poorly cemented, coarse to very coarse grained and strongly unimodal and is classified as litharenite and subarkose by the modal composition, which is supported by geochemical studies. According to petrography and geochemistry, the Kikhla sandstone was deposited in a passive continental margin basin, mainly from granitic sources. On the basis of major elements ratios, and petrographic interpretation, the source rocks are most likely recognized as Proterozoic granites that were exposed via rifting. The CIA values (73.28-93.97) indicate a high degree of chemical weathering, which could be attributed to the arid climate conditions in the source area and mainly controlled by the source-rock provenance, hydraulic sorting during transport and deposition, diagenesis and depositional environment. According to chemical investigations, sandstone exhibits significant concentrations of SiO2, Na2O> K2O, and Fe2O3, which is compatible with the modal data.

Местонахождение Шапи — новый памятник энеолита в Рын-песках Северного Прикаспия

Introduction. A continental stage in the Northern Caspian geological history began with the Mangyshlak regression when sands that would shape the Ryn Desert were freed from marine waters, and the region started being actively invaded by humans, which is evidenced by numerous Stone Age sites. The bulk of the latter are represented by ‘open-air’ materials — some mixed complexes with few ceramic remains — and this does complicate chronological attributions of such archaeological collections. So, the study of monuments with preserved ‘cultural layers’ instrumental in obtaining a series of absolute dates is a primary task in understanding historical and cultural processes of the Mesolithic/Eneolithic in the Northern Caspian. Goals. The article aims to introduce into scientific circulation some materials discovered at the site of Shapi in the Ryn-Peski Desert. Materials and methods. The site of Shapi is located in the north-northwest of the Ryn Desert, 30 km south of Lake Aralsor in present-day Bokey Orda District of West Kazakhstan Region. The stone artefacts obtained are few enough, mainly of quartzitic sandstone, and number 67, e.g., 6 items are tools — arrowheads, an arrowhead fragment, a notched piece, a flake with a distinguished point, and a flake with retouch. There are 8 flint artefacts, including 5 tools — an arrowhead, fragments of blades with retouch, and two flakes with retouch. A pit was dug out on the spot abundant in finds, and it yielded bone remains of cattle, goats and sheep, a horse, a camel, and a dog (wolf). Results. Despite tool forms are few enough, one can note the presence of pieces with bifacial retouch and concave-based arrowheads with small wings. Species composition analysis of the bone remains shows those are dominated by cloven-hoofed animals, essentials of the examined bone complex attest to these are kitchen waste. Bone remains at depths of 20–40 and 40–60 cm yielded a series of calibration dates between 4048 and 3956 BCE. Conclusions. Chronologically, the site clusters with Late Eneolithic ones, and may be attributed to the late Khvalynsk and Altata cultures.

Origin and paleoenvironmental significance of Al-rich glauconite in the Ediacaran/Cambrian deposits of the Lublin Basin, Poland (SW margin of Baltica)

Geochemical and mineralogical analyses of glauconite from formations deposited at the Ediacaran – Cambrian boundary along the SW margin of Baltica, integrated with sedimentological characteristics of its host-rocks, are discussed in the study. SEM-EDS and XRD studies indicate evolved to a highly evolved stage of maturation of glauconitic grains, i.e. they are characterized by a high K2O content (>6,5%) and only a small amount of smectite within an ordered R > 1 glauconite-smectite (G-S) mixed layered structure. Despite its high K2O content, glauconite shows a low Fe2O3 and high A2O3 content. Such chemical composition is distinctive for Precambrian glauconites that originated from abiotic substrates. We have identified glauconite in fractures of K-feldspar and quartz, indicating that at least some of the evolved/highly evolved glauconite grains have been formed by the replacement of these minerals. We have also recognized a new type of substrate, i.e. clay coatings, which has not been reported in previous publications on glauconite. In our opinion, the green grains characterized by cleavage and higher-order birefringence, usually described as vermicular glauconite, result from glauconitization of clay coatings, rather than biotite or muscovite flakes as previously thought. Clay coatings composed of 2:1 clay minerals, mostly smectites, represent natural parent material for initiation of G-S evolution that does not require considerable structural changes as in case of biotite or muscovite.Results of glauconite investigation compiled with the sedimentary record of the Ediacaran – Cambrian succession of the Lublin Basin allow us to reconstruct the environment of glauconite formation and its subsequent history. Glauconite occurs in quartzitic sandstones that show evidence of deposition in shallow marine, high-energy environments (barrier islands, tidal flats and shoreface), but reveals widespread transport. It was formed in a lagoon environment, which, on the one hand, was an area with a relatively stable sedimentation rate compared to concurrent estuaries or tidal flats, and on the other hand, was close to the area of source material that provided detrital substrates, i.e., feldspars and clay coatings, formed in clay-rich soil horizons on river terrace or delta sediments. The latter substrate appears to be an essential indicator of the environment of glauconite formation, which may occur in close proximity to a river mouth or an actively eroded coastline.

REE-bearing minerals in sediment-hosted stratiform pyrite mineralization zones of the Wiśniówka area (Holy Cross Mts., Poland)

There are two arsenical pyrite (As-FeS 2 ) mineralization zones cropping out in the Podwiśniówka and Wiśniówka Duża quarries where quartzites and quartzitic sandstones have been extracted for over a century. A large amount of pyrite in the Wiśniówka siliciclastics is unusual in the hard rock mining throughout the world. The pyritiferous beds contain a variety of REE-bearing minerals, including a crandallite series of aluminum-phosphate-sulfate (APS) minerals, e.g., predominant goyazite SrHAl 3 [(PO 4 ) 2 (OH) 6 ] with subordinate gorceixite BaHAl 3 [(PO 4 ) 2 (OH) 6 ] and very occasional crandallite CaHAl 3 [(PO 4 ) 2 (OH) 6 ]. By contrast, the other REE-phosphate minerals, e.g., xenotime YPO 4 , bur particularly monazite CePO 4 occur in a lesser amount. Goyazite prevails somewhat in the Podwiśniówka beds whereas xenotime in the Wiśniówka Duża beds. Of the other REE-bearing minerals, bastnäsite REECO 3 (F,OH), florencite (REE)Al 3 (PO 4 ) 2 (OH) 6 and synchysite CaCe[CO 3 ] 2 F occur in trace amounts. Interestingly, the quite common phosphate minerals, i.e., wavellite (Al 3 [(OH,F) 3 |(PO 4 ) 2 ]×5H 2 O and variscite Al[PO 4 ]×2H 2 O) are depleted in REEs with only Ce attaining 0.09 wt.% as documented by an electron-probe microanalysis. In contrast to quartzites/quartzitic sandstones, carbonaceous clayey-silty shales and bentonites/tuffites are distinctly enriched in REE-bearing minerals. This diversity is also mirrored in the mean total REE concentrations varying from 204 to 314 mg/kg, in clayey-silty shales and bentonites, attaining 457 mg/kg in some Podwiśniówka shale beds. Results of this and the previous petrographic, mineralogical and geochemical studies have indicated that REE-bearing minerals formed generally along with As-rich pyrite, nacrite/dickite and probably TiO 2 polymorphs as a result of multiphase hydrothermal vent activity that took place in the Wiśniówka Late Cambrian sedimentary basin. This evidence is also backed up by the values of LREE NASC /HREE NASC (1.44–1.75) and Eu/Eu NASC (1.24–1.30) coefficients in the clayey-silty shales. This positive Eu anomaly (³1.20) points to the formation of REE-bearing minerals in a reducing environment.

The nothingness myth

Abstract This article analyzes the concept of “nothingness” as a part of human- resource relations in pre- and post-industrial landscapes. It addresses nothingness as a part of mythological narratives in Kvartsitnyi settlement in northwestern Russia. Kvartsitnyi was built in the 1970s near the new quartzitic sandstone quarry and was initially viewed as a modern settlement attracting workers from all around the country. However, in the early 2000s, the quarry went bankrupt and closed. The pre-industrial landscape of Kvartsitnyi is often viewed in the interviews as empty, and the quarry's closure recreated this symbolic “nothingness.” These narratives resemble mythological creation stories when a new world appears from nothing but is destroyed as a result of human mistakes. The article discusses the cosmogonic myth of Kvartsitnyi within the larger context of Soviet and post-Soviet myth-making.

Hydrothermal TiO2 polymorphs in a pyrite stratiform deposit: Lessons from a mineralogical and geochemical multiproxy record

This paper presents results of mineralogical and geochemical study of TiO2 polymorphs that occur within two hydrothermal stratiform zones of the Wiśniówka area (south-central Poland). These two mineralized zones consist primarily of alternating pyritiferous and REE-bearing sedimentary quartzites, quartzitic sandstones and silty-clayey shales. Of the TiO2 phases, anatase is a predominant type (mean of 56%) with a lesser amount of rutile (30%) and mixed rutile-anatase phases (11%) as well as rare rutile-brookite (2%) and brookite (1%) as evidenced by laser Raman microspectrometry. TiO2 polymorphs typically form interstitial euhedral to anhedral or skeleton-like grains and aggregations averaging 30–50 μm in diameter occasionally attaining 110 μm. Extremely scarce pyritiferous microfossils are infilled with needle- and lath-like anatase. Under backscattered electron microscope images, TiO2 grains are generally homogenous, in places with tiny inclusions of zircon, monazite, niobium oxide and palladium telluride. In addition, some rutile grains show oscillatory zonation or zonal-brecciated and patchy patterns. Results derived from electron microprobe examinations show enrichments of most TiO2 phases in niobium (up to 4.98 wt%), zirconium (up to 0.58 wt%) and tantalum (up to 0.57 wt%) substituting titanium in the TiO2 crystal structure. The TiNb pair shows the highest correlation (r2 = 0.98). Concentrations of these and other elements vary substantially within individual anatase/rutile grains. The lack of other potential Ti-bearing rock-forming or oxide minerals (e.g., biotite, pyroxene, hornblende, titanite, ilmenite, titanomagnetite, titanohematite) in sedimentary siliciclastic rocks of the study area also indicates that anatase and rutile may have crystallized along with prevailing pyrite, xenotime, aluminum-phosphate-sulfate (APS) minerals and most monazite directly from hydrothermal fluids at relatively low temperatures, presumably around 200 °C (range of 150 to 300 °C). Among these ore minerals, only goyazite and mixed goyazite-gorceixite aggregations contain up to 20.07 wt% Ti and 24.09 wt% Ti, respectively. Mineral and microtextural relationships show that TiO2 polymorphs may have formed in two phases under reducing and subsequently oxidizing conditions of the Wiśniówka Late Cambrian depositional basin.

ON THE TIME AND CONDITIONS OF FORMATION OF THE SHOKSHA QUARTZITE-SANDSTONES OF THE SOUTH ONEGA DEPRESSION BASED ON THE NEW DATA FROM ISOTOPE GEOCHRONOLOGY

The first results of U-Pb isotope dating of detrital zircons (dZr) from red-colored quartzitic-sandstones of the Shoksha formation (Shoksha horizon) are presented. The Shoksha formation completes the Vepsian sub-horizon (Vepsian) of the Lower Proterozoic of Karelia and is distributed within the South Onega trough. A sample (KL-555) of red-colored quartzitic sandstones was taken from the lower part of the section of the Shoksha formation in the same name deposit within the southwestern Cis-Onega Lake region. The 79 dZr grains isolated from this sample were analyzed by the staff of the Chemistry-Isotopic Analytic Laboratory of the GIN RAS using the equipment of the Shared Research Facilities of the GIN RAS. The weighted average of the three youngest U-Pb isotope dates for dZr grains is 1906±13 Ma. Taking into account the known isotopic dates of gabbro-dolerites from the Ropruchei sill, that cuts through the Shoksha formation, it makes possible to constrain the time of the Shoksha formation accumulation by ~1.90–1.75 Ga. A significant part of the carried out analyzes has yielded a high degree of discordance of the dates. The features of the distribution of the figurative points of these analyzes in the diagram with concordia suggest that the rocks of the studied section of the Shoksha formation were subjected to the alteration that disturbed the U-Pb isotope system of these zircon grains in the Phanerozoic.The set of obtained dates for dZr grains has been compared with the known ages of the crystalline complexes of the basement of the East European Platform. The age sets of dZr grains from sample KL-555 and rocks of the Ladoga group, developed along the margin of the Svecofennian accretionary orogen, are very similar (p similarity coefficient in Kolmogorov – Smirnov test is 0.27) and characterize mainly tectonic–magmatic events that had immediately preceded the manifestation of the Svecofennian orogeny (1.9–1.87 Ga). Therefore, the rocks of the Ladoga group could highly probably be a secondary source for the Shoksha quartzites. Based on a comparative analysis of ages and thorium-uranium ratios (Th/U) in dZr grains from sample KL-555, it was concluded that some of the studied dZr grains with high Th/U>1.5 originate from Ludicovian mafic rocks, but those with low Th/U<0.1 originate from ultra-high-pressure formations, such as eclogites known in the Salma, Kuru-Vaara and Gridino.A paleo-geographic scheme for the Late Vepsian is proposed, showing that the highly mature Shoksha sandstones were generated under continental conditions in a local basin due to the accumulation of clastic material carried by an extensive and branched

Selecting rock types for very-low-cost crushed rock heat storage systems with nitrate salt heat transfer

Today the demand for variable electricity is met by fossil-fuel power plants because the capital costs and the cost of storing fossil fuels are very low. A low-carbon grid requires replacements for stored fossil fuels to provide variable heat and electricity as needed. The thermal energy replacement option is to send heat from nuclear and concentrated solar power (CSP) plants operating at full capacity to heat storage with variable heat output to the power block to provide variable electricity to the grid. Very low-priced electricity from wind and solar can also be converted into stored heat. Today the lowest-cost commercial heat storage systems are in CSP plants and use nitrate salt stored in hot and cold storage tanks. Advanced heat storage systems use nitrate salt for heat transfer but replace some or all the nitrate salt with lower cost crushed rock for heat storage. These systems may lower the capital cost of heat storage by a factor of five or more to several dollars per kWh of stored heat. Locally acquired crushed rock is the lowest-cost heat-storage material but not all rock is compatible with heat storage requirements including chemical compatibility, mechanical properties, and durability under thermal cycling. Rocks have been sorted into categories likely, possibly, and unsuitable and the basis for these conclusions has been documented. Potentially suitable rock types include basalt, peridotite, taconite, quartzite, quartzitic sandstone and serpentinite. Except for taconite, sedimentary rocks are unlikely to be suitable for service.

Prospects for the use of rock crushing screenings from Karelia as a filtering medium

The aim of the research was to study the crushing screenings of gabbrodolerite, quartzite sandstone, and quartzite stored in the pit dumps in the Prionezhsky District of Karelia in order to assess their applicability as non-traditional filtering media in water treatment for the removal of various pollutants. The use of optical microscopy and X-ray diffraction analysis allowed establishing qualitative and quantitative mineral compositions of the screenings studied. According to the results of the study of physical and chemical parameters and the total specific effective activity of natural radionuclides in the screenings, the 0.5–2.0 mm fraction meets the requirements set by the standard for natural granular filtering materials. A comparison of the materials studied with quartz sand (provided by CJSC Pogranskoye Quarry Association) confirmed that their filtering media porosity and grain shape coefficient values are not inferior to those of the standard material. The bulk density of the screenings at 1307–1550 kg/m3 is comparable to the density of the sand at 1650 kg/m3. It seems reasonable to place these screenings in the lower layer of two-layer filter systems and to use them for water clarification and for the removal of mechanical impurities and iron from water. The 2–5 mm fraction of the screenings studied may be used as a loose anti-icing material for treating road surfaces in winter. Introduction of screenings as non-traditional filtering media for water treatment at local mining enterprises contributes to more comprehensive deposit development and helps solving certain economic and environmental problems in the region.

Enhancing the thermal conductivity of hot-mix asphalt

Conductive hot-mix asphalt is recommended for enhancing the solar energy collection performance of an asphalt solar collector. This type of collector consists of embedded tubes with circulating water or air inside pavement construction to generate power. This work intends to shed light on the selection of novel components for the preparation of conductive asphalt mixes. Lee's disc method was used to determine the thermal conductivity of this composite material. A comprehensive examination was conducted to prepare reference and conductive asphalt discs by manufacturing asphalt mixtures in a laboratory specified for this work. New Iraqian natural resource materials, including quartzite sandstones and silica sands, and Iraqian industrial waste materials, such as slag stones, steel wool fibres and metallic waste powder, were employed as conductive components. The results showed that the conductive materials increase the thermal conductivity of the reference asphalt mixture up to 42.75% and 66.65% for quartzite and slag combinations, respectively. Slag aggregates should not be utilized as conductive material in asphalt mixes without increasing the binder ratio. Proportions of 4% and 38% of steel wool fibres and metallic waste powder additives, respectively, were found to produce the optimal results for thermal conductivity enhancement. The air void contents and fracturing ratio of conductive discs were decreased when using conductive novel components, which is an indication of the importance of current findings in improving asphalt mixtures in heat storage and transfer applications.

Blade from the Brona Pass

Due to its landscape, dominated by hills reaching above 1000 m a.s.l., the southern part of the Western Beskids was long considered an area beyond the reach of prehistoric migrations. The small number of artefacts known from the area makes every new find significant. The article presents a stone artefact found on the Brona Pass in Beskid Żywiecki. It was made of a local raw material, quartzite sandstone. The discovery provides new evidence of the penetration of mountain landscapes by prehistoric communities.

Weathered quartite sandstones of the Kursk magnetic anomaly as a raw material for construction industry

Introduction. The features of composition and structure of quartzitic sandstones of the Kursk Magnetic Anomaly affected by weathering processes, which do not meet the requirements of normative documents for obtaining crushed rock, are considered. The reserves of these rocks have not been approved as minerals and are currently stored in the form of large-tonnage dumps on the territory of the plant.The main challenge to be solved within the framework of the work is aimed at solving the issue of expanding the raw material base of the construction industry.Materials and methods. Efficiency evaluation of the weathered quartzite sandstone use is based on the study of indicators of physical and chemical properties. The analysis of mineral rocks was carried out using digital microscopy, the method of X-ray phase analysis. The experimental studies of the kinetics of grinding raw materials have been carried out. The activity of composite binders using weathered quartzite sandstone was studied in accordance with GOST 30744-2001.Results. It is shown that genetic features of weathered quartzitic sandstones are caused by defective crystal structure of quartz, they are also characterised by low frost resistance and strength. The grinding efficiency of weathered quartzite sandstone is 4 times higher in comparison with untethered. It has been established that the use of these raw materials to produce composite binders makes it possible to reduce the proportion of Portland cement in the mixture by up to 50% and increase the strength of the composite binder by 20%.Discussion and Conclusions. In consideration of current trends in the transition of the construction industry to multicomponent compositions, it is advisable to use weathered quartzite sandstone as an unconventional quartz raw material in obtaining energy-efficient building composites of a new generation.

QUARTZITIC SANDSTONES IN THE NAMURIAN AND LOWER WESTPHALIAN SUCCESSION OF THE SOUTHERN NORTH SEA: A NEW HIGH‐PERMEABILITY CARBONIFEROUS RESERVOIR TYPE

Most of the potential sandstone reservoirs within the Namurian and lower Westphalian succession of the Southern North Sea Basin are originally feldspathic sands in which the feldspar has mainly been altered to microporous kaolinite clays. The sandstones provide a moderate porosity (typically 8‐15%, depending mainly on grain size), but permeability is severely limited owing to the microporous nature of much of the porosity. Permeability is typically 1 mD or less, rising to a few tens of millidarcies in occasional coarse‐ and very coarse‐grained sands. Predicting the presence of higher‐permeability reservoir zones is therefore a critical exploration problem in these successions.Quartzitic sands have been discovered in places, especially for example in the Trent field (block 43/24), where physical reworking of sands during the transgressions that preceded the deposition of marine bands removed much of the feldspar, so that less clay was formed during burial diagenesis. Although these sandstones display moderately elevated permeabilities, commonly several to several tens of millidarcies, they are usually fine‐grained, which limits their reservoir potential.A particular type of quartzitic sandstone reservoir has been identified quite widely within the Namurian and lower Westphalian succession of the Southern North Sea. This type is indistinguishable in terms of sedimentology and inferred detrital composition from the originally feldspathic facies which now form the widespread kaolinite‐rich, low‐permeability sandstones. However, it has a very low kaolinite content (commonly 1‐2%, compared with a more usual 5‐20%) so that these sandstones display permeabilities of the order of several hundred millidarcies.Wireline log data from nineteen wells within UK Quadrants 43 and 44 have been examined, and all relevant core logged in order to compare the depositional settings of the quartzitic and non‐quartzitic sandstones. Existing data from over 500 petrographic thin sections from the area have been reviewed and 78 new thin sections analysed to determine the petrographic controls on reservoir quality in both sandstone types. The diagenetic histories of each type have been interpreted. The dissolution of feldspars during diagenesis of the quartzitic sandstones, without a substantial residue of kaolinite or other aluminium‐rich mineral, is attributed to the mobilisation of aluminium within organic complexes. This is thought to require the presence of certain organic acids.

Use of palynology and thermal maturity in deformed geological units: A case study from the Permian succession in the Monte Leoni area (Middle Tuscan Ridge, inner Northern Apennines, Italy)

The reconstruction of the upper Palaeozoic sedimentary evolution of Western Mediterranean area is suffering for scarce age documentation of its stratigraphic units. This is also the consequence of the metamorphism and deformation they experienced during the Alpine tectonic events. Based on palynology and thermal maturity assessment, we contribute to this issue reporting biostratigraphic and sedimentological results in key-outcrops of the upper Palaeozoic successions of southern Tuscany (Italy), thus offering new data for the Palaeozoic units of the inner Northern Apennines, as well as for their palaeogeographic and palaeotectonic evolution predating the opening of the Alpine Neo-Tethys. This study is focused on the Falsacqua Formation mainly consisting of quartzitic phyllite, sandstone and carbonate, representing the basal succession of two tectonic units exposed in the Middle Tuscan Ridge, and which age attribution was strongly debated in literature and referred either to late Carboniferous-early Permian or Devonian. Palynological data document the first finding of a microflora of middle-late Permian age adding key chronological constraints. This age assignment permits to correlate the Falsacqua Formation with the coeval deposits of southern Tuscany (i.e., Farma and Poggio al Carpino formations) and Elba Island (Rio Marina Formation) that are all characterized by a similar microfloral content. Optical thermal maturity index as Spore Colour Index is around 9 to 10 and suggests a T peak of about 300–350 °C while the Raman spectroscopy on carbonaceous material indicates a T peak around 375 °C for both tectonic units. These data provide new constraints for the maximum T values occurred during syn-collisional metamorphism developed in this sector of the Northern Apennines.

Калиевый полевой шпат рудных щелочных метасоматитов (Средний Тиман)

Potassium feldspar (Kfeldspar), along with albite, is one of the leading minerals of alkaline ore (rare-metal-rare-earth) fenites of the Kosyu ore cluster of the Middle Timan. In the studied potassium feldspars, the data on an insignificant admixture of sodium oxide (0.19-0.38 wt.%) according to the results of microprobe analysis are confirmed by X-ray diffraction studies, which also indicate a minimal structural admixture of the albite component in KF. As determined by X-ray diffraction, potassium feldspar of ore fenites is a microcline. Several of its varieties have been established: the maximum microcline (Oktyabrskoe ore field), the low microcline (Novobobrovskoe and Verkhne-Shchugorskoe ore fields), and the intermediate microcline (Nizhne-Mezenskoe ore field). Kfeldspars of fenites were formed under the action of alkaline solutions on quartzite sandstones in a fairly wide temperature range from 375° to 510°C. The lowest temperature (375°C) is the most ordered maximum microclines of the Oktyabrskoe ore field. For low microclines, temperatures of 420°C and 455°C have been determined for the Novobo¬brovskoe and Verkhne-Shchugorskoe fields, respectively. The least ordered intermediate microcline of the Nizhne-Mezenskoe ore field was formed in the range of 485-510°C.