Geology Of Deposits Research Articles

Geology, mineralogy, geochemistry, and fluid characteristics of barite deposits in southern Nuevo Leon (NE Mexico): Implications to the evolution of the mineralization

AbstractBarite ore deposits are common in the southern region of the state of Nuevo León (Sierra Madre Oriental, NE Mexico), which has proven to have an important economic potential. This contribution provides new insights into the ore‐forming conditions and geological controls that produced the barite deposits in Nuevo León. It is based on petrography, geochemical analyses (major and trace‐elements, 87Sr/86Sr, δ34S, δ18O‐ isotopic data and Sr. concentration) of the barite and fluid inclusions microthermometry. The mineralization (veins, beds, and breccias) is associated with calcite, dolomite, quartz, pyrite, and chalcopyrite. In the barite deposits, the isotopic values of barite 87Sr/86Sr vary from 0.70710 to 0.71350, the δ34S values are 13.8‰–25.5‰ and δ18O ranges from 14.1‰ to 18.7‰. Microthermometric measurements on barite, quartz, and carbonate hosted, two‐phase (liquid–vapor) liquid‐rich fluid inclusions indicate that the mineralization may have taken place between 100 and 269°C, and salinities between 3 and 4 wt.% and 9–10 wt.% NaCl equivalent, that suggest a relationship with comparable fluids of seawater and other basinal type. The latter fluid may have been generated (with values variability in 87Sr/86Sr ratios, Sr. and δ34S, as well as Th and salinity) during the tectonic evolution of the Sierra Madre Oriental. We interpret the deposits as Mississippi‐Valley Type by a sequence of the following events. The Event A‐thin‐skinned deformation with Type I fluids: (i) deposit hosted in lithological units stratigraphically close to the Jurassic evaporites. It is characterized by relatively low values of 87Sr/86Sr ratios, δ34S, Sr. and salinity; and (ii) barites hosted in carbonate units with high salinity and δ34S, and values of 87Sr/86Sr ratios and Sr. variable. The Event B‐thick‐skinned deformation: the barite deposits occurred in the red beds unit linked to a fluid Type II, characterized by relatively high values of 87Sr/86Sr ratios, Sr., and low δ34S, and a combined high and low salinity. The new results offer a better understanding of the origin and evolution of barite deposits, allow for the development of increasingly successful exploration plans.

A FEM‐DEM Coupling Analysis on Bearing Capacity of Sandy Soil Foundation Considering Fabric Anisotropy

ABSTRACTWith the acceleration of urbanization, the stability of the foundation is being more crucial to the performance and service of the superstructure. As our understanding of the factors influencing soil's physical and mechanical behavior deepens, it becomes increasingly challenging for traditional limit equilibrium and limit analysis methods to accurately consider the complex factors affecting foundation stability, such as initial fabric anisotropy caused by the particle morphology and geological deposition in sand. Although some scholars had used advanced constitutive models in the finite element method (FEM) to investigate the influence of initial fabric anisotropy on mechanical responses of foundations, this approach failed to reveal the microscopic information underlying the shear failure of sandy soil foundations. In this study, the influence of the initial fabric anisotropy of sandy soil on the ultimate bearing capacity and shear failure mode of shallow foundation is studied using the hierarchical FEM and discrete element method (DEM) coupling analysis method. Four representative volume elements (RVEs) with varying initial bedding plane angles are constructed in DEM for characterizing different initial fabric anisotropies, and the specific stress–strain information of DEM RVEs is directly passed into the corresponding Gauss points in FEM to replace the conventional constitutive model. Numerical results show that the initial fabric anisotropy affects the ultimate bearing capacity and shear failure mode of shallow foundations significantly, and the corresponding micromechanical behaviors at different local Gauss points have been explored, which advances our understanding of the micromechanisms underlying the progressive shear failure of sandy soil foundations significantly.

Geology and genesis of the Takht-Gonbad porphyry Cu deposit in the Kerman belt, SW Iran

Geology and genesis of the Takht-Gonbad porphyry Cu deposit in the Kerman belt, SW Iran

Ore geology, mineralogy and geochemistry of a fault-controlled hydrothermal clay-Li deposit hosted by Precambrian metasedimentary rocks in south China

Ore geology, mineralogy and geochemistry of a fault-controlled hydrothermal clay-Li deposit hosted by Precambrian metasedimentary rocks in south China

Advancements in Understanding Beryllium Contamination: Novel Insights Into Environmental Risk Assessment

ABSTRACTBeryllium (Be), a lightweight metal with significant industrial applications, poses notable environmental and health risks due to its toxicity and persistence, and widespread use, particularly in the mechanical, aerospace, and electronics sectors. It is commonly alloyed with other heavy metals to enhance material properties. The primary environmental pathways for Be release include emissions from coal and fossil fuels combustion, as well as the incineration of solid wastes. Once introduced into the natural environment, primarily Be associated with soil particles and sediments, particularly in terrestrial and aquatic ecosystems. This review examined the pathways through which Be enters the environment, including atmospheric deposition, industrial discharge, and leaching from natural geologic deposits. The paper highlights the bioavailability and mobility of Be in soil and water systems, emphasizing the geochemical and physical factors influencing its persistence and potential for bioaccumulation. Risk appraisal methodologies are evaluated, with a focus on human exposure routes, including inhalation of airborne particulates and ingestion of contaminated water and food. The toxicological impacts on human health are critically analyzed, detailing both acute and chronic effects, such as respiratory diseases and carcinogenicity. This review evaluates existing regulatory frameworks and remediation strategies, assessing their efficacy in mitigating environmental contamination and exposure to Be. By integrating interdisciplinary research, this paper provides an in‐depth understanding of the environmental behavior and toxicology of beryllium, offering insights that can inform robust policy frameworks and shape future research directions.

Rare earth elements enrichment and extraction potential of bauxite deposits in Samar, Philippines

Abstract Rare earth elements (REE) play an integral part of modern life, from smartphones to satellites. Dubbed ‘critical metals’, the demand for REE has significantly increased, driven by the growth in global production for green technologies such as e-vehicles, solar panels, wind turbines, and other energy-economic infrastructure. Therefore, there is a need to explore alternative REE sources to ensure continued development of emerging green technologies. A possible alternative REE source is bauxite, which is soil that forms from intense weathering of aluminum oxide-rich rocks exposed to tropical climate. This paper investigates the REE enrichment and extraction potential from bauxite deposits in Paranas, Samar, Philippines. The sampling survey included collection of rock and soil on surface exposures, test pits, and drill cores from accessible portions of the bauxite mineral reservation site. The soil and parent rock samples collected were then subjected to various geochemical and mineralogical analyses. The main ore minerals of aluminum are gibbsite and boehmite; with minor goethite, hematite, and magnetite. Investigation of the geochemical composition of the bauxite reveals a total REE content of up to ~300 ppm, which is one of the highest REE and critical metal content among geological deposits in the country. These results will provide inputs in the design of a green and economical process to recover REE from bauxites. If the bauxite deposits prove to be a valuable REE resource, this study will help maximize the economic potential of the mineral resource in the Philippines and contribute to an economically efficient and environment-friendly way to produce e-tech elements for the country.

Rundqvistite-(Ce), Na3(Sr3Ce)(Zn2Si8O24), a new mineral from the Darai-Pioz alkaline massif, Tien-Shan Mountains, Tajikistan: mineral description and crystal structure

AbstractRundqvistite-(Ce), ideally Na3(Sr3Ce)(Zn2Si8O24), is a new mineral from the Darai-Pioz alkaline massif, Tien-Shan Mountains, Tajikistan. The mineral occurs as elongated grains up to 0.1 mm long and up to 0.03 mm thick embedded in quartz–pectolite aggregate in a silexite-like peralkaline pegmatite. Associated minerals are quartz, fluorite, pectolite, baratovite, aegirine, leucosphenite, neptunite, reedmergnerite, orlovite, sokolovaite, mendeleevite-(Ce), odigitriaite, pekovite, zeravshanite, kirchhoffite and garmite. The mineral is colourless with a vitreous lustre and a white streak, brittle, Dmeas. is 3.70(2) and Dcalc. is 3.709 g/cm3. Rundqvistite-(Ce) is monoclinic, space group P21/c, a = 5.1934(16), b = 7.8934(16), c = 26.011(5) Å, β = 90.02(3)° and V = 1066.3(4) Å3. The chemical composition of rundqvistite-(Ce) is SiO2 40.17, La2O3 2.64, Ce2O3 7.55, Pr2O3 0.80, Nd2O3 2.43, Sm2O3 0.33, Eu2O3 0.09, Gd2O3 0.24, Tb2O3 0.18, Dy2O3 0.21, PbO 1.03, SrO 19.83, FeO 0.37, ZnO 13.08, CaO 2.55, Na2O 8.04, total 99.54 wt.%. The empirical formula calculated on 24 O apfu (atoms per formula unit) is Na3.10Sr2.29Ca0.54Pb0.06(Ce0.55La0.19Nd0.17Pr0.06Sm0.02Gd0.02Eu0.01Tb0.01Dy0.01)Σ1.04Zn1.92Fe0.06 Si8.00O24Z = 2. The structural formula based on refined site-occupancies is (Na2.94Sr0.06)Σ3.00 [(Sr2.23Ca0.54Pb0.06Na0.13)Σ2.96Ln3+1.04]Σ4.00[(Zn1.92Fe2+0.06)Σ1.98Si8O24], where Ln3+1.04 = (Ce0.55La0.19Nd0.17Pr0.06Sm0.02Gd0.02Eu0.01Tb0.01Dy0.01)Σ1.04. The crystal structure of rundqvistite-(Ce) was refined to R1 = 2.76% on the basis of 3184 unique reflections [F > 4σ|F|]. In rundqvistite-(Ce), the main structural unit is a (Zn2Si8O24)12– sheet parallel to (100). In the sheet, the Si and Zn tetrahedra form four-, five- and eight-membered rings. The interstitial cations at the Na and M(1–3) sites sum to [Na3(Sr3Ce)]12– apfu. The Na and M(1–3) polyhedra share common edges to form a layer. Rundqvistite-(Ce) is a structural analogue of vladykinite, ideally Na3Sr4(Fe2+Fe3+)Si8O24. Rundqvistite-(Ce) and vladykinite are related by the following substitution: [8]Ce3+ + [4](Zn2+)2 ↔ [8]Sr2+ + [4](Fe2+Fe3+). The mineral is named after Dmitry Vasilievich Rundqvist (1930–2022), a prominent Russian geologist and an expert on the geology of ore deposits, metallogeny and mineralogy of Precambrian rocks.

Изучение геологии Северо-Тянь-Шаньского трагического оползня

The method of reconstruction and investigation of the pre-landslide condition of the tragic landslide «Ak-Kain» of the Northern Tien Shan is proposed. Information about the study of this mountain slope located along the Almaty – Talgar highway above the sanatorium of the same name is presented. The results of a geological study of the structure and composition of ground sediments from the ceiling to the foot of the Northern slope, along which the landslide occurred, are presented. Also, visual studies of the remains of landslide masses have established the layers of the initial position of the cover soils and the underlying layers. A geometric model of the initial to landslide structure of the slope with its geological deposits both along the slope and in depth towards the basalt-granite rock surface has been developed. The results of the study are shown in the form of pictures of the exact zones and layers from the top of the slope to the bottom. The meaning of the proposed methodology consists in purposeful step-by-step scientific research, starting with the study of the geology, tectonics of the region, structure, composition of soils, taking into account the eluvial-deluvial-proluvial zones, their physico-mechanical, strength properties, especially attention is paid to the real anisotropy of the composition of soil deposits and their properties. The developed algorithms for studying infiltration movements of rainwater are described. In general, the results of this work make it possible to conduct targeted research by methods of mechanical and mathematical modeling to assess and determine the critical condition for predicting the place of the beginning of soil separation from the slope.

Applying geotechnical borehole databases in the search for interglacial deposits in Denmark

Geotechnical investigations conducted in preparation for infrastructure development provide high-quality borehole data in standardised digital formats. In Denmark, such geotechnical borehole data are not required to be reported to the national well database (Jupiter) and are mainly archived in privately owned databases. Accessible interglacial and interstadial terrestrial deposits are rare in Denmark, and these borehole data have the potential to identify interglacial and interstadial deposits, with significant implications for ongoing palaeoclimate, palaeoenvironmental and archaeological research. In this study, we compiled data from six major geotechnical companies, resulting in a database with over 550 000 boreholes. From this database, we identified 1850 boreholes containing samples associated with interglacial and interstadial ages. Through extensive filtering for well-documented lacustrine or palustrine deposits, we selected 161 boreholes and referenced them to 39 different geographical occurrences. Of these 39 occurrences, 36 were either new terrestrial deposits or provided substantial new records to known interglacial and interstadial sites. Our findings demonstrate that access to these privately owned geotechnical borehole data can be a valuable resource for identifying rare near-surface geological deposits, allowing the discovery of several new Pleistocene sedimentary archives that warrant further investigation.

Determination of Water Quality Index of Drinking Water in Aligarh District, UP, India

Water is perhaps the most precious natural resource after air. Though the surface of the earth is mostly consists of water, only a small part of it is usable, which makes this resource very limited. This precious and limited resource, therefore, must be used with prudence. As water is required for different purposes, the suitability of it must be checked before use. Nowadays fresh water cannot be used directly for drinking purposes due to contamination and pollution. So treatment is used before it is used for drinking or for industrial processes. Also, sources of water must be monitored regularly to determine whether they are in sound health or not. Poor condition of water bodies are not only the indictor of environmental degradation, it is also a threat to the ecosystem. In industries, improper quality of water may cause hazards and severe economic loss. Thus, the quality of water is very important in both environmental and economic aspects. Thus, water quality analysis is essential for using it in any purpose. The quality of water depends upon its source of history. The history of water signifies the terrain through which water is flowing, its origin and most important the extent to which it is contaminated on its way by impurities, sediments and industrial waste. The solubilisation and fragmentation of the terrain through which it flows determines its quality. The extent of dissolved solid materials present in water decides its quality. Such quality is also decided by the solubility of the geological deposits, contact of water with sediments, time of interaction and special factors related to environment. To ascertain suitability of water for consumption, it is necessary to undertake examination of quality of water. . Major information on the quality of water is obtained by physical examination. considered in the present paper for calculating the WQI such as pH, Total alkalinity, Calcium, Magnesium, Chloride, Sulphate, Nitrate and also calculated the seasonal variations of physio- chemical parameters of water quality of Aligarh District.

Ore Characteristics and Distribution Based on Geological and Geophysical Features of the Tambang Sawah Low Sulfidation Epithermal Gold Prospect in Lebong District, Sumatra Island, Indonesia

Sumatra is recognized as one of the Indonesian islands with a big potential for mineral deposits particularly along the belt known as Neogene Sumatra gold axis. However, the publication of the gold resources is still restricted as regional/district scale maps or limited in some locations and internal company reports, hence, a detailed study on deposit scale remains limited. This study aims to document the deposit geology, ore characteristics and geophysical features of the Tambang Sawah prospect at Lebong district, Sumatra Island. The study was done by geological mapping, sampling, and analyzing of selected samples by petrographic, ore microscopic, X-Ray Diffraction, micro X-Ray Fluorescence and various geochemical analyses to identify ore characteristics. The geophysical survey was carried out using geomagnetic and induced polarization. Ore mineralization is manifested by various alteration types such as argillic, propylitic, and silicification, which suffered andesitic breccia and granite host-rocks. Gold mineralization is in the form of quartz veins with typical opening space filling textures such as colloform, crustiform, cockade, moss, comb, and brecciated. The main sulfides consist of pyrite, chalcopyrite, covelite, sphalerite and galena. Gold commonly occurs as free grains. Highest grade gold of up to 21.3 ppm is associated with colloform and cockade-crustiform quartz veins. Geophysical surveys indicate that gold mineralization is associated with low geomagnetic anomaly areas. The 3D modelling of the IP survey reveals that the ore mineralization may occur at 75m depth. Two target areas located at the northeastern and southwestern portions are recommended for a follow-up detailed exploration based on the mapped ore geology, ore characteristics, and geophysical anomalies.

Soil cover on complex glacial terrain and challenges for large-scale soil mapping using the World Reference Base (WRB) classification system

In conditions of complex glacial topography, large-scale soil mapping (1:10 000) according to the World reference base for soil resources (WRB) 2022 classification faces significant challenges. High diversity of reference soil groups (RSG) and qualifiers can be found in a small area, and this diversity is not related to the influence of a single but rather to a set of soil-forming factors. As a part of the study, the classification of soils on postglacial landscape was conducted using the WRB 2022 classification system. The analysis was focused on examining relationships between RSG and qualifiers, and also with type of geological deposits, location on the terrain, human activities (drainage of agricultural land, soil tillage and erosion). Survey showed that, in a relatively small area, soil cover consisted of WRB RSG such as Luvisols, Retisols, Regosols, Stagnosols, Gleysols Phaeozems, Planosols, Podzols, Histosols and Anthrosols, with the respective sets of qualifiers. Soils corresponding to the Anthrosol RSG were formed during the construction of a drainage system by burying the former soil with deeper material and later by translocation of colluvium by soil erosion. In the complex glacial topography, the distribution of RSG and their qualifiers is specific, which poses a number of challenges for soil mapping. The study confirmed the possibility of WRB classification for large-scale mapping of agricultural soils on postglacial landscape at the RSG level. The use of qualifiers for definition of mapping units in similar conditions of complex terrain and geological deposits (when mapping on a scale of 1:10 000) is possible only by increasing sampling density.

LEAD-LEAD DATING REVEALS PERMIAN REMOBILIZATION OF NIOBIUM MINERALIZATION AT BAYAN OBO

Abstract The Bayan Obo deposit hosted by the H8 unit is a world-class rare earth element (REE) deposit with considerable niobium (Nb) and iron (Fe). Permian granites are widely exposed in the mining area and have a close spatial association with the Nb mineralization. Whether the granites contributed Nb or only remobilized existing mineralization is important for understanding the controls of ore formation. Previous studies have mostly focused on the REEs, whereas research on Nb has been limited. This is due mainly to the difficulty of accurately determining the age of the Nb mineralization because of the fine-grained and texturally complex nature of the Nb-bearing minerals and their exceptionally low U content. Although microbeam techniques show promise in tackling the aforementioned challenges, their application is hampered by matrix effects caused by the diverse composition of Nb-bearing minerals. Here we report the application of a high-precision secondary ion mass spectrometry (SIMS) Pb-Pb isochron approach that enables young samples (i.e., <500 Ma) to be dated without matrix-matched reference materials. A variety of Nb-bearing minerals from eastern Bayan Obo were analyzed, yielding Pb-Pb isochron ages of 276 ± 10 Ma (pyrochlore, 394–6,864 ppm U in the rim and 6,563–19,858 ppm in the core), 277 ± 36 Ma (fersmite, 18–61 ppm U; fergusonite-Ce, 45–95 ppm U), and 257 ± 46 Ma (aeschynite, 342–1,006 ppm U). In combination with the deposit geology and petrographic observations, these ages link the Nb mineralization to ~270 Ma granites. As these granites are not particularly rich in Nb, skarn formation during granite emplacement is interpreted to have remobilized the existing Nb mineralization, which increased the grain size of the Nb-bearing minerals—a key factor facilitating their extraction. Our study shows that high-precision SIMS Pb-Pb analysis holds promise for directly dating mineralization without matrix-matched reference materials. It also emphasizes the need to consider the role of the Nb remobilization at Bayan Obo and elsewhere.

Ore Geology, H-O-C Isotopes and 40Ar-39Ar Dating of the Wutonggou Iron Deposit, Eastern Tianshan, NW China: Implications for the Source, Timing, and Genesis of Hydrothermal Mineralization in a Sedimentary Iron Deposit

Ore Geology, H-O-C Isotopes and 40Ar-39Ar Dating of the Wutonggou Iron Deposit, Eastern Tianshan, NW China: Implications for the Source, Timing, and Genesis of Hydrothermal Mineralization in a Sedimentary Iron Deposit

Compound criticality of bauxite production: implications for sustainability and trade neo-colonialism

We describe bauxite as having compound criticality. (1) It is a critical raw material (CRM) from which alumina and thereby aluminium are produced, and aluminium has the highest production levels of all metals deemed significant to the Clean Energy Transition. (2) Gallium is a by-product CRM, extracted during alumina refining. (3) Multiple other CRM by-products could be extracted during alumina refining: scandium, lithium, cobalt, titanium and REE. (4) Production is profoundly influenced by price inelasticity (for by-products), regime instability of bauxite production and supply chain bottlenecks. We review the geology of bauxite ore deposits as a function of complex CRM supply potential, and interrogate the trait of criticality using four of the world's dominant producer nations of bauxite and potential patterns of value addition from raw materials to refined products. Trade agreements and mitigation strategies to ensure security of supply in consumer regions prioritize removal of low-cost bauxite by large-scale mining operations and shipping of unprocessed ore at high CO 2 footprint from producer nations. Ore-refining nations have investments that are deemed extractive because they remove large quantities of raw material for export with minimal or no in-country processing and they can also place producer nations in debt. Opposition to neo-colonial debt-trap policies and extractive practices increases regime instability and thereby criticality. We highlight how societal-environmental-political interactions and the mineral-energy nexus in the bauxite-aluminium supply chain are subject to increasing turbulence, which may reshape the geographies of supply chains.

Fluid inclusion and He-Ar-Pb isotope studies of the Dabie-type Leimengou giant porphyry Mo deposit, Qinling Orogen

The Leimengou deposit is a Dabie-type porphyry Mo system in the Leimengou-Qiyugou orefield of Qinling Orogen. Orebodies host within the porphyry and the metasedimentary Taihua Supergroup. However, the characteristics and sources of ore-forming fluid, metal precipitation mechanism, and the sources of mineralizing substances remain unclear. In this contribution, by a comprehensive study comprising an investigation of deposit geology, fluid inclusion microthermometry, and He-Ar-Pb isotope, we discuss the source and evolution of ore-forming fluids and the molybdenum precipitation mechanism of the Leimengou deposit. The mineralizing process is divided into the Stage I quartz ± K-feldspar vein in potassic altered zone, Stage IIa molybdenite ± quartz vein, and Stage IIb molybdenite + quartz + pyrite ± purple fluorite vein in silicification-phyllic altered zone, Stage III quartz + pyrite + sphalerite + galena ± chalcopyrite ± green fluorite ± pink calcite in prophylitic altered zone and Stage IV quartz ± calcite vein in carbonatization zone based on cross-relationship. The Stage IIa and IIb veins characterize the main molybdenum mineralization stages. By microthermometry, CO2-bearing (C-), Water (WV- and WL-), and daughter minerals-bearing (S-) types of inclusions were recognized. The Stage I quartz contains C-type fluid inclusion assemblages (FIAs) with a salinity of 6.3 ± 1.4 wt% NaCl equiv., and a total homogenization temperature (Th, total) of 473 ± 3 °C. This suggests that the early fluids show characteristics of high temperature, CO2-rich, and moderate salinity, distinguishing them from those of Endako-type and Climax-type deposits. C-type and coexisting W-type FIAs from Stage IIa show similar salinity, ranging from 1.9 to 13.0 wt% NaCl equiv. and 1.9 to 14.1 wt% NaCl equiv., with Th, total of 349–376 °C and 327–392 °C, respectively. Moreover, C-type FIAs homogenize to distinct phases and also show similar homogenization temperatures, indicating fluid immiscibility. The FIAs in Stage IIb show an average salinity of 8.3 ± 7.4 wt% NaCl equiv. and a Th, total of 302 ± 14 °C. WL-type and WV-type FIAs coexist, with similar temperatures varying from 308 to 310 °C during this stage, indicating significant fluid boiling. These observations indicate that the decrease in temperature, fluid immiscibility, and decompression boiling collectively led to the precipitation of molybdenite. Trapping pressures are estimated to be 82–231 MPa for Stage IIa and 43–115 MPa for Stage IIb, corresponding to ore-forming depths of approximately 8.4 km and 4.3 km, respectively. Additionally, the He-Ar isotopes obtained from pyrite indicate a clear mixing trend of crustal fluids with mantle fluids at Stage IIb, with mantle-derived fluid components increasing during Stage III. This coincides with the tectonic shift from regional compression to extension, leading to the formation of many Dabie-type Mo deposits, alongside crustal thinning and the upwelling of asthenospheric mantle materials. Futhermore, Pb isotopes from the ore, ore-hosted gneiss, and ore-causative granitoids demonstrate that the Taihua Supergroup gneiss supplied ore-forming materials, suggesting a crustal origin for the Leimengou Mo deposit.

A MaxEnt predictive model for palaeontological sites in the Siwalik Hills: A case study from the Pinjor Formation of the Upper Siwalik Hills near Chandigarh, northern India

This study presents application of the MaxEnt predictive model to identify potential palaeontological sites in the Siwalik Hills, focusing on the Pinjor Formation near Chandigarh, northern India. The Siwalik region holds rich vertebrate palaeontological records, yet lacks comprehensive site prediction models. This research employs MaxEnt (3.4.0) software, to predict areas suitable for fossil occurrences. Georeferenced presence data was derived from literature and field surveys, for training the model. Environmental predictors including Pinjor geological deposit boundary, Vegetation Index (NDVI), and Slope and Aspect were from a digital elevation model. Furthermore, model development involved parameter tuning, for developing a potentially useful model. Field validation of the model through pedestrian surveys identified new fossil localities, demonstrating the model's practical applicability. This research emphasizes the importance of MaxEnt in developing site predictive models, offering a valuable tool for optimizing palaeontological field surveys. While highlighting the model's success, the study also recognizes its limitations, especially concerning landscape and vegetation changes over time. Overall, this work establishes a foundation for further research in predictive modelling for palaeontological exploration in the Siwalik region and emphasizes the need for multidisciplinary efforts in salvage palaeontology to mitigate anthropogenic threats.

Ultrasonic velocity anisotropy of Jurassic shales with different lithofacies

AbstractGiven the growing importance of organic-rich shale as unconventional reservoirs, a thorough understanding of the elastic and anisotropic behavior of shales is of great concern. However, for lacustrine shales, the complex lithofacies assemblage with geological deposition makes it challenging. Four lithofacies (argillaceous, mixed, siliceous, and calcareous) are recognized for 40 lacustrine shale samples from Jurassic formation in Sichuan Basin on the basis of their mineral compositions. We perform ultrasonic velocity measurements on 40 pairs of shale plugs at varied confining pressures, attempting to uncover the controls on the anisotropic properties of different lithofacies. The experimental results reveal that the total porosity, clay, and organic matter would positively contribute to velocity anisotropy of Jurassic shales. Combined with microstructure and pressure-dependent velocity analysis, the preferred orientations of platy clay particles and lenticular kerogen, the development of clay pores along clay fabric, and the sub-parallel micro-cracks induced by hydrocarbon expulsion are treated to be the controlling mechanisms. We add the total porosity, clay content, and kerogen volume together, intending to distinguish the elastic and anisotropic properties of four lithofacies. Generally, argillaceous shales, the dominant lithofacies in Jurassic formation, could be characterized by the highest clay and total organic content (TOC), the lowest bedding-normal velocities, and the strongest velocity anisotropy. Finally, with the laboratory data, two rock-physics-driven exponential relationships are proposed to predict the P- and S-wave velocity anisotropy with the bedding-normal velocities.

Missing phosphorus legacy of the Anthropocene: Quantifying residual phosphorus in the biosphere.

A defining feature of the Anthropocene is the distortion of the biosphere phosphorus (P) cycle. A relatively sudden acceleration of input fluxes without a concomitant increase in output fluxes has led to net accumulation of P in the terrestrial-aquatic continuum. Over the past century, P has been mined from geological deposits to produce crop fertilizers. When P inputs are not fully removed with harvest of crop biomass, the remaining P accumulates in soils. This residual P is a uniquely anthropogenic pool of P, and its management is critical for agronomic and environmental sustainability. Managing residual P first requires its quantification-but measuring residual P is challenging. In this review, we synthesize approaches to quantifying residual P, with emphasis on advantages, disadvantages, and complementarity. Common approaches to estimate residual P are mass balances, long-term experiments, soil test P trends and chronosequences, with varying suitability or even limitations to distinct spatiotemporal scales. We demonstrate that individual quantification approaches are (i) constrained, (ii) often complementary, and (iii) may be feasible at only certain time-space scales. While some of these challenges are inherent to the quantification approach, in many cases there are surmountable challenges that can be addressed by unifying existing P pool and flux datasets, standardizing and synchronizing data collection on pools and fluxes, and quantifying uncertainty. Though defined as a magnitude, the distribution and speciation of residual P is relatively less understood but shapes its utilization and environmental impacts. The form of residual P will vary by agroecosystem context due to edaphoclimatic-specific transformation of the accumulated P, which has implications for management (e.g., crop usage) and future policies (e.g., lag times in P loading from non-point sources). Quantifying the uncertainty in measuring residual P holds value beyond scientific understanding, as it supports prioritization of monitoring and management resources and inform policy.

Genesis of Hongqiling Sn-W polymetallic deposit in Dongpo ore concentration field, southern Hunan: Evidences from U-Pb chronology and trace element geochemistry of cassiterite

Hongqiling deposit is one of the most typical hydrothermal vein type Sn-W polymetallic deposits in the Dongpo ore field, southern Hunan. It is an ideal object to study the Sn-W mineralization in the Nanling metallogenic belt and even in the whole South China Block, and to reveal the regional metallogenetic regularity. Based on the detailed investigation of the deposit geology, this paper discusses the mineralization age and processes of the Hongqiling hydrothermal vein type Sn-W polymetallic deposit by LA-MC-ICP-MS in-situ U-Pb dating and trace element geochemistry of cassiterite from the quartz vein type Sn-W ore body. Cathodoluminescence (CL) imaging shows that cassiterite in Hongqiling deposit can be divided into two generations.primary cassiterite (Cst-I) and altered cassiterite (Cst-II). The LA-MC-ICP-MS in-situ U-Pb age of the two groups of Cst-I samples are 158.9 ± 0.7 Ma and 158.4 ± 0.8 Ma, respectively, which are well consistent with the mineralization ages of most Sn-W deposits in the Nanling metallogenic belt, and are also consistent with the ages of middle to late Jurassic magmatic activity represented by the Qianlishan intrusion. This indicates that the Hongqiling deposit, like many Sn-W deposits in the Nanling metallogenic belt, is genetically related to the regional Middle to Late Jurassic granitic magmatic activities. LA-ICP-MS trace element analysis shows that trace elements such as Na and Cs are mainly distributed in fluid inclusions in cassiterite, while the major elements such as Mg, Al, and Si are mainly distributed in the mineral inclusions, and other elements such as W, U, Zr, Hf and Ti are mainly distributed in the cassiterite by isomorphic substitution. The high Fe and W contents in both primary and altered cassiterite indicate that the ore-forming fluid of Hongqiling deposit is mainly derived from granitic magma. The fluctuating variation of Fe, V, Sc, Ti, Zr, Hf, Nb and Ta in the primary cassiterite with the crystalline bands indicates that there are two large-scale pulses of magmatic hydrothermal fluid during the mineralization process, while the altered cassiterite is relatively depleted of Ti, Sc, Zr and U elements, and enriched in Pb which may represent the compositional characteristics of the late-stage fluid. In summary, the Hongqiling hydrothermal vein type Sn-W polymetallic deposit was formed by the pulsating exsolution of magmatic hydrothermal fluid of late Jurassic granitic magmatism. The trace elemental compositions of primary cassiterite are generally controlled by the compositions of ore-forming fluid and the rate of crystallization.