Geosciences

Particle size distribution (PSD), also referred to as grain-size distribution (GSD), is a fundamental characteristic of granular materials, influencing packing density, porosity, permeability, and mechanical behavior across soils, sediments, and industrial powders. Accurate and reproducible representation of PSD is essential for computational modeling, digital twin development (i.e., virtual replicas of physical systems), and machine learning applications in geosciences and engineering. Despite the widespread use of classical distributions (log-normal, Weibull, Gamma), there remains a lack of systematic frameworks for generating synthetic datasets with controlled statistical properties and reproducibility. This paper introduces a unified computational framework for generating virtual PSDs/GSDs with predefined statistical characteristics and a specified number of grain-size fractions. The approach integrates parametric modeling with two histogram-based allocation strategies: the equal-width method, maintaining uniform bin spacing, and the equal-probability method, distributing grains according to quantiles of the target distribution. Both methods ensure statistical representativeness, reproducibility, and scalability across material classes. The framework is demonstrated on representative cases of soils (Weibull), sedimentary and industrial materials (Gamma), and food powders (log-normal), showing its generality and adaptability. The generated datasets can support sensitivity analyses, experimental validation, and integration with discrete element modeling, computational fluid dynamics, or geostatistical simulations.

In many gold–antimony deposits throughout the world, the sequence of Au and Sb precipitation varies significantly. In high-temperature systems such as hydrothermal Au deposits, gold typically precipitates prior to antimony, whereas in lower-temperature systems (e.g., Carlin-type deposits), no consistent depositional sequence is observed. The Gutaishan Au-Sb deposit, located in the Xiangzhong Basin of the Jiangnan Orogenic Belt, South China, exhibits a distinct spatial segregation within a continuously evolving system of gold and antimony mineralization—a pattern commonly observed in many Au-Sb deposits throughout the region. To elucidate the mechanisms controlling Au-Sb co-occurrence and segregation, we conducted electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) major and trace element analyses of stibnite and pyrite from quartz veins across different ore zones within the Gutaishan deposit. Trace element signatures—such as Cu-Pb correlations and Hg/(Cu + Pb) ratios which classify stibnite into Woxi-type and Xikuangshan-type, and Co/Ni ratios classifies pyrite into magmatic–hydrothermal and sedimentary types—suggest that the ore-forming fluids were predominantly magmatic–hydrothermal in origin, with minor contributions from metamorphic basement fluids. The occurrence of low-temperature trace element signatures in the Au-Sb deposit indicates that temperature is the primary control on Au-Sb segregation. The thermodynamic model further confirms that high-temperature fluids favored the precipitation of Au veins, while lower-temperature fluids facilitated the co-precipitation of stibnite and gold in Sb-Au veins. Therefore, we propose a metallogenic model for the Gutaishan deposit that highlights temperature-driven Au-Sb segregation, resulting from the progressive cooling of the ore-forming fluids.

A combination of fault and fracture analyses, paleostress reconstructions from calcite twins, and U-Pb dating of syn-kinematic calcite mineralization provides new insights into the Cretaceous–Tertiary tectonic evolution of the Provence fold-and-thrust belt. This approach helped unravel 90 million years of polyphase deformation in this belt, which represents the eastward continuation of the northern Pyrenees. Focusing on three main targets along an NNE-SSW transect oriented roughly parallel to the regional Pyrenean shortening (the southernmost Nerthe range, the Bimont Lake area, and the northern Rians syncline), we date a wide range of scales and natures of deformation structures such as stylolites, veins, mesoscale faults, and major thrust fault zones. The reconstructed long-lasting tectonic history includes (1) the Durancian uplift and related NNE-SSW extension (~110 to 90 Ma); (2) the ~N-S Pyrenean compression related to the convergence then collision between Eurasia and Iberia and the Corsica–Sardinia block (~80 to 34 Ma); the Oligocene E-W to WNW-ESE extension related to the West European Cenozoic Rift System (ECRIS) and the Oligo–Miocene NW-SE to NNW-SSE extension related to the Liguro-Provençal Rifting (LPR); and a middle-late (?) N-S to NW-SE Alpine compression. We show that the Pyrenean shortening in Provence occurred during two main phases, 81–69 Ma and 59–34 Ma, coeval with the inversion of the pre-Pyrenean rift and the main Pyrenean collision, separated by a tectonic quiescence as described in the Pyrenees. Together with the published literature, our U-Pb ages also support the overall northward (forelandward) in sequence propagation of Pyrenean shortening across Provence. Our U-Pb results further allow us to refine the interpretation of local and regional fracture sets and reveal unsuspected polyphase development of fractures sharing a common strike. Beyond regional implications, our study shows that sampling structures of various natures and scales for U-Pb geochronology is probably the most efficient strategy to encompass the entire time interval of deformation in fold-and-thrust belts.