Miocene lacustrine clay deposits formed in the Şile region of Türkiye rest unconformably on Cretaceous andesite, basaltic andesite, basalts and rare dacites. Factors controlling the genesis of this sequence include: (1) sediment provenance, (2) tectonic uplift and climatic regimes during syn- and post-depositional times, (3) burial diagenesis and (4) changes from surface weathering alterations (i.e. oxidation and hydrolysis reactions) in the critical zone. Clay minerals are dominated by kaolinite and illite, with their relative abundances varying in relation to the proximity of coal seams, stratigraphic sequence and in an overlying sand-rich fluvial deposit. Variations in the mineral abundances reveals cyclothem-like sequences with patterns of fining upwards (i.e. increasing clay mineral abundance) capped by thin coal seams. The Clay Mineral Alteration Index values for the Şile clay sequence indicate a slight trend of decreasing chemical weathering intensity up-section, which is consistent with regional geological data for terrain uplifting and a drying climate during the Miocene. Critical zone processes have modified the mineral and chemical assemblages, as evidenced by the appearance of iron oxides putatively formed from recent oxidation of the ferrous minerals siderite and pyrite, which are not found in the upper sections. Taken together, the evidence indicates that the clay minerals are derived from a combination of prior weathering of basement rocks, diagenesis after deposition and modern critical-zone weathering. The degree of each process is dependent on depositional history, stratigraphic position and depth below the land surface, all under the changing influences of tectonic uplift and regional climate. The Şile deposits provide an economical clay resource that could be important to the ceramics industry of Türkiye.

The use of nanoparticles in the composition of drilling fluids can improve some of their properties (e.g. thermal, mechanical, electrical and rheological) due to their small size and high surface area, which can diminish the loss of fluid to the formation, thereby increasing thermal conductivity, reducing friction and improving well stability. In this work, we investigated the rheological and static filtration properties and the thermal performance of non-aqueous drilling fluids with organo-palygorskite-containing hydrophobic alumina (Al2O3) and amphiphilic strontium nickelate (SrNiO3) nanoparticles in varying concentrations. The results indicate that the fluids with nanoparticles had greater plastic viscosity and lower filtrate volumes. With regard to thermal performance, the fluids with nanoparticles absorbed more heat when subjected to higher temperatures. However, this excess energy was more easily released upon cooling. This study demonstrates the affinity of nanoparticles with the solvent phase of a drilling fluid and how this interaction affects their properties, with a particular emphasis on amphiphilic nanoparticles, which have been shown to have better performance in non-aqueous fluids with organo-palygorskite.

This study investigates the influence of interlayer cations on the thermodynamics and sorption mechanisms of water in a reference Wyoming montmorillonite. The behaviour of the montmorillonite exchanged with monovalent cations (Li+, Na+, K+, Rb+, Cs+) or divalent cations (Mg2+, Ca2+, Ba2+) is compared. The analysis combines X-ray diffraction (XRD), water sorption isotherms at various temperatures and mid-infrared spectroscopy. Li+, Mg2+ and Ca2+ promote greater water uptake and swelling, whereas K+, Rb+ and Cs+ significantly limit these processes. The behaviour of Na+ and Ba2+ stands out, demonstrating intermediate water uptake and high swelling. Mid-infrared spectral analysis supports these observations. It is shown that a cation’s effect on water uptake and swelling correlates best with the product of its elementary charge and ionic radius rather than with other properties such as the electrostatic potential, solvation enthalpy or chemical hardness. However, differences in isotherm shapes, hysteresis between adsorption and desorption and the variation of isosteric heat with water content suggest the presence of two distinct sorption mechanisms: one involving Li+, Cs+, Mg2+, Ca2+ and Ba2+, and another involving Na+, K+ and Rb+. These findings indicate that isotherm shape and swelling alone do not directly reflect water uptake capacity. These findings thus outline that the chaotropic (structure-breaking) or kosmotropic (structure-making) nature of the cations, along with the complex interplay between cation hydration and TOT layer attraction, may explain the complex observed differences.

Halloysite nanotubes (HNTs) face significant challenges in their application due to their aggregation, poor dispersion and high hydrophilicity, which limit their integration into polymer matrices. This study introduces a novel functionalization strategy for Algerian HNTs, targeting their inner and outer surfaces with triethoxy(octyl)silane (OTES) for silanization and caffeic acid (CA) for lumen loading. Comprehensive characterization techniques were used to analyse pristine and OTES-modified HNTs (O-HNTs) and CA-loaded HNTs (CA-HNTs) to evaluate the impacts of both selective agents, which successfully altered the structural, textural, chemical, morphological and thermal HNTs properties. The crystalline structure and changes in crystallite size following surface modification were determined using X-ray diffraction analysis. Brunauer–Emmett–Teller analysis showed that the surface area of O-HNTs increased to 74 m2 g–1 compared to 54 m2 g–1 for HNTs, whereas CA-HNTs experienced a surface area decrease to 42 m2 g–1 owing to pore obstruction, with the pore sizes shifting to 10–12 nm for O-HNTs and to 16 nm for CA-HNTs. Fourier-transform infrared spectroscopy and X-ray fluorescence confirmed effective surface modification through the achievement of successful chemical bonding and a shift in the elemental composition. Morphological analysis using scanning electron microscopy revealed considerable morphological changes in both treatments, and thermogravimetric analysis demonstrated that the thermal stability of HNTs modified with CA was improved, with a higher decomposition peak at 520°C. These modifications effectively improved the dispersion, thermal stability and compatibility of the HNTs, highlighting the potential of the modified Algerian HNTs as promising green nanofillers in polymer nanocomposite applications, such as active packaging and thermal insulation coatings.

Serra de Tramuntana of Mallorca is a mountain range built of a stack of thrust sheets composed mostly of Mesozoic platform carbonates, and it formed in the Oligocene and Miocene during the Alpine orogeny. Volcanic rocks, intruding the Triassic sediments, and known mostly from the bottom of the lowest thrust sheet, offer an opportunity for dating the post-sedimentary thermal history of this mountain range and for evaluating the maximum palaeotemperatures by studying the mineralogy and K–Ar dating of authigenic illite. Such a study was conducted on 16 samples from two outcrops, employing X-ray diffraction (XRD), optical microscopy, electron probe microanalysis and K–Ar dating of separated clay fractions. Illite was found in 10 samples, but only one sample was identified as pure volcanic rock, not contaminated by older detrital material. This sample yielded a K–Ar age of 133–140 Ma, which is within the experimental error for three grain-size fractions. This was confirmed by extrapolating the ages of a contaminated sample, and it is interpreted as representing the age of the maximum palaeotemperatures. These palaeotemperatures were estimated using several illite characteristics, including the Kübler Index applied to shales as below but close to the diagenesis/anchimetamorphism boundary (180–200°C). The dated pre-tectonic early Cretaceous thermal event is interpreted as recording the extremely high geothermal gradient at the end of the Mesozoic extensional phase. The maximum palaeotemperatures during the Oligocene–Miocene tectonic burial of Mallorca were not high enough to reset the Mesozoic K–Ar age of illite, thus being lower than ∼250°C, and, based on the preserved Cretaceous illite XRD characteristics, lower than 180–200°C.

Iron mining waste is produced from the iron ore mining operations of El Ouenza Mine (north-east Algeria), and it is not currently recycled to preserve the environment. The current study aims at developing sustainable clay bricks by mixing clay with different proportions of iron mining waste (ranging from 10 to 50 wt.%) and fired at 850°C and 950°C. Addition of 30 wt.% Iron mining waste had a positive effect on the physical and mechanical properties of the fired clay bricks. Linear shrinkage, water absorption and porosity were reduced, while compressive and flexural strengths were increased. Furthermore, up to 30 wt.% of iron mining waste addition to the mixtures improved compressive and flexural strengths to 59.17 and 10.06 MPa, respectively, when the bricks were fired at 950°C. According to their thermal conductivity, the bricks with 10–50 wt.% iron mining waste are considered as thermal insulators, with thermal conductivity values ranging from 0.45 to 0.56 W m–1 K–1. Adding 30 wt.% of iron mining waste can lead to the production of eco-friendly bricks with high mechanical and thermal properties, generating economic and environmental benefits.