In the Moroccan cement industry, searching for alternatives to clinker using noncalcined mineral additions has become a significant focus to reduce energy consumption and greenhouse gas emissions and produce cement with a low environmental impact. This study examines the effects of incorporating Triassic basalts and Liassic limestone on the mechanical properties of mortars, as well as cement color, water demand, setting time, and durability of cement – based composites. The pozzolanic activity of basalt, calculated from chemical composition and amorphous phase content, is proposed as an intrinsic index of pozzolanic activity. The pozzolanic activity strength index was evaluated as the ratio of the compressive strength of the blended basalt – limenstone/cement mortar to that of a control Portland cement. Mortars with 10–15% of El Hajeb basalt and 19–24% limestone exhibited optimal mechanical performance at early (2 d) and long-term (28 d) stages, while improving setting times. Additionally, these combinations offer improved environmental and economic benefits for the production of pozzolanic CEMIV and CEMII composite cements, which comply with international standards (ASTM C618, 2022; EN 197-5, 2021; and NM 10, 01, 004, 2019).
En este trabajo se presenta una caracterización, a partir de técnicas de microscopía y microanálisis, de la fracción densa de los minerales presentes en una serie de retazos de sedimentos detríticos miocenos que se conservan en las cotas más altas del corredor Navelgas-Pola de Allande-Linares, en el límite oriental de la Zona Asturoccidental-Leonesa (NW de España). La especie más frecuente son los óxidos de Fe (tanto hematites como magnetita), a los que habitualmente acompañan los óxidos de Fe-Ti (principalmente ilmenita), circón, cromo-espinela, monacita, xenotima y oro nativo. El oro es de carácter secundario depositado en un medio fluvial y de tamaño de grano fino (0,01-0,5 mm). Con relación a la espinela cromífera, el interés del estudio radica en que se trata de la primera referencia a la presencia de esta variedad mineral en la parte asturiana del dominio del Navia-Alto Sil. La monacita es rica en tierras raras ligeras, sobre todo en Ce (Ce>La>Nd), y en ocasiones presenta niveles elevados de Th. La xenotima, por su parte, contiene cantidades de Dy, Gd e Yb que superan el umbral de elemento mayor (1-4% en peso).
Photogrammetric techniques and 3D modelling are useful tools for obtaining morphological data, such as size, volume, and surface area, in paleontological studies, and its use is becoming increasingly simple, even with common devices such as mobile phones and tablets. This work takes as an example the skull of some of the largest theropods, Allosaurus fragilis (Carnosauria, Allosauroidea), Giganotosaurus carolinii (Carnosauria, Allosauroidea) and Tyrannosaurus rex (Coelurosauria, Tyrannosauroidea), for the elaboration of 3D models with the use of different photogrammetric and laser techniques. The study confirms that Tyrannosaurus head was shorter than that of Giganotosaurus but more robust with skull length/skull width ratio for T. rex (2.42) lower than for Giganotosaurus (2.98). The skull volume/lower jaw volume is higher in Giganotosaurus (3.68) than in Tyrannosaurus (3.31) also pointing to more robust head for T. rex. In addition, the mandible of Tyrannosaurus is deeper than that of other large theropods and robust thick pachydont dentition was probably adapted to develop high bite force. These features allowed T. rex to keep large prey and bite across meat and bone equally. Giganotosaurus is hypothesized to have had powerful slicing bites, based on its ziphodont dentition, and the capacity to manipulate relatively smaller preys compared with Tyrannosaurus, as inferred from its flattened lower jaw. Allosaurus, also from clade Allosauroidea like Giganotosaurus, had a narrow skull (skull length/skull width 3.24) equipped with straight pachydont teeth. Although the Allosaurus’ mandible was adapted to slice, capture and manipulate small preys, the skull volume/lower jaw volume ratio (3.53), lower than in Giganotosaurus, confirm that probably was also prepared to support high torsional stress when attacking larger preys.
A study of Coniacian-Santonian (Upper Cretaceous) gastropod fauna was carried out on two sections of the Cap-Estérias region, which belongs to the Gabonese Coastal Basin. This study led to the identification of eight gastropod genera, including four species, that were previously unknown in this region. The genera Akera Müller, 1776, Latirus Montfort, 1810, and Fasciolaria Lamarck, 1799, as well as the species Turritella aff. rigida Sowerby, 1835, and ?Voluta (Aulica) stromboides Munier-Chalmas, 1881 are reported for the first time from the Gabonese Coastal Basin. Similarly, the stratigraphic range of the genera Voluta and ?Nerita in the Gabonese Coastal Basin is extended to the Santonian.
