Geological Journal最新文献

The paleogeography and kinematic evolution of the Lhasa terrane during the Cenozoic time are key aspects to understanding the tectonic evolution of the Tibetan Plateau. Previous studies have focused on the paleolatitude reconstruction of the Lhasa terrane before and during the onset of the initial India–Asia collision. However, there exists an important gap between the period immediately after the onset of the India–Asia collision and the precise time at which the Lhasa terrane reached its present-day latitude in terms of its kinematic evolution throughout the Cenozoic time. To this end, we performed an integrated study including paleomagnetism and isotopic geochronology on the Paleogene sediments of the Niubao (NB) Formation to provide a new constraint on the late Eocene paleolatitude of the Lhasa terrane. In combination with rock magnetic and petrographic results, our obtained results show that 91 inclination-shallowing corrected characteristic remanent magnetizations (ChRM) are of pre-folding origin and have passed the reversal test, indicating their primary nature. Based on these inclination-shallowing corrected 91 filtered ChRM directions from sediments, the paleopole was calculated as λ_p = 77.2° N, φ_p = 308.2° E, with dp/dm = 3.0°/5.1°. This new result indicates that the Lhasa terrane was at 21.7° ± 3.0° N for the reference site at ca. 38 Ma, suggesting that the Lhasa terrane was still underway to its northward motion before its final arrival at present-day latitude. This further suggests that a total magnitude of ca. 1700 km crustal shortening was partitioned within Asia since 38 Ma to the present day.

Solar saltworks often face challenging production conditions, including drastic thermodynamic condition changes. The major ionic evolution of the inland brine in Chott Melrhir saltwork has been studied with an indoor polythermal and isothermal at 35°C evaporation simulation, using phase diagrams and forward geochemical modelling. Hydrochemical and mineralogical analysis indicated that the brine under investigation exhibits an oceanic chemical character and follows a metastable evaporation path similar to that of seawater at 35°C. During the transport to the surface, the brine undergoes a drastic concentration, depositing major calcium content as gypsum. Evaporation yields significant quantities of kainite, magnesium sulphate salts and halite, the latter of which precipitates predominantly at the outset of the process along with minimal gypsum contents. Raw salt and washing brine analysis indicated that the interstitial brine was the source of the major ionic impurity, along with clay and sand, while gypsum and calcium ions were identified as solar evaporation impurities. The use of PHREEQC (pH-Redox Equilibrium C-programme) geochemical simulation software and Pitzer's database has enabled the precise proposal of a shift in pumping densities for solar evaporation feed brine of approximately 1.221 and for washing brine of approximately 1.227. This methodology may be tested for the purpose of overcoming significant challenges posed by major ionic impurities that producers may encounter during production in such environments. Moreover, the results have the potential to facilitate the expansion of production through the separation of other salts that may possess greater economic value, such as kainite in this case.

The potential resources of potassium and lithium in the underground brine of the Qaidam Mahai Basin are considerable. However, the research on the mineralization regularity of lithium-rich clay layer brine lacks a theoretical basis. This article takes the shallow intercrystalline brine of Dezong Mahai as the research object and employs hydrochemical and isotope geochemical methods to discuss the salinization and mineralization characteristics, evolution patterns, and the sources of brine-forming fluids of the underground brine. The shallow intercrystalline brine deposits in the study area belong to alkaline brines with high salinity, and the hydrochemical type is mainly the magnesium sulfate subtype. The contents of K⁺ and Li⁺ are relatively high, attaining the minimum industrial grade and the boundary grade respectively, and thus possess mining value. The Hydrochemical analysis reveals that the water chemical composition of the shallow intergranular brine in the study area is dominated by evaporation and crystallisation. Under the effect of evaporation and crystallisation, minerals such as gypsum, rock salt, mirabilite, glauberite, sylvite, carnallite and bischofite are precipitated. Under the water-rock interaction, carbonate rock precipitates are generated, evaporite and silicate rock minerals are dissolved, and the main ion sources of the brine are enriched. The hydrogen and oxygen isotope analysis indicates that the shallow intergranular brine in the study area has a meteoric water origin, with a recharge elevation of approximately 3440 m, and is replenished by the meteoric water and snowmelt water from the Seshten Mountain and Nanbaxian Mountain. The strontium isotope analysis demonstrates that the material source of the shallow intergranular brine in the study area is multi-sourced, and there are certain supplies of rock salt leachate water, deep fluid, and water from the Yuqia River. There exists a close relationship between the genesis of the shallow intercrystalline brine in the study area and factors such as atmospheric precipitation, infiltration of surface water, admixture of deep fluids, evaporation and concentration, and water-rock interaction.

The increasing demand for heavy metals has led to extensive excavation of their ore deposits. The leaching of heavy metals from active and abandoned mines can contaminate the water resources available nearby. The present study evaluates the extent and spatio-temporal variability of heavy metal concentrations in groundwater and surface water resources around the chromite mining regions of the Sukinda Valley, Odisha, India. Twelve surface water samples were collected from the major stream flowing through the region, and 30 tube wells located close to the mining regions were also sampled for groundwater. The samples from the same sites were collected twice, once during pre-monsoon and again in post-monsoon seasons. All samples were analysed for major ion and heavy metal concentrations. Major ion chemistry indicates that the water is of Ca-Mg-HCO₃ type during both seasons. There are no large-scale seasonal variations in the groundwater chemistry; however, a significant seasonal change in the hydrochemistry of surface water has been observed. Heavy metals such as Cr, Fe, Mn, Ni and Zn were detected (> 5 μg/L) in more than 30% of samples, out of which Fe and Cr were identified as the major contaminants. Iron concentrations above the WHO prescribed limit in drinking water have been found in more than 70% of groundwater samples, while higher Cr concentrations were observed in 20%–23% of groundwater samples. Heavy metal pollution indices suggested around 50%–60% of groundwater samples were contaminated with heavy metals, while the surface waters were close to critical condition. Groundwater contaminations with these heavy metals are prominent mainly in the densely populated central regions of the study area. Bivariate cross-plots of major ions indicated the hydrochemistry of the area to be controlled by sediment–water interactions, especially silicate weathering and carbonate dissolution. Multivariate analyses combined the measured water quality parameters based on their analogous behaviour and confirmed the above processes controlling the water chemistry. From a combined statistical analysis and pollution indices, it has been confirmed that geogenic and mining-related activities are responsible for heavy metal contaminations both in groundwater and surface water resources of the region. Weathering of the local lithology, leaching and discharges from the mines were identified as the dominant contributors of heavy metals to the water resources.

The Abiod carbonate reservoir of the Campanian-Early Maastrichtian age represents a major oil reservoir In the Pelagian block of eastern Tunisia, forming complex fractured networks that are poorly understood. Given the total absence of geological outcrops of Campanian-Maastrichtian age in the study area, 2D seismic reflection, geological modelling and well log datasets were integrated to characterise the subsurface geodynamic structures, investigate the petrophysical characteristics, the relationship between fault systems and fracturing and define their implications for petroleum exploration. Analysis of seismic profiles, lithostratigraphic logs, borehole data and geological modelling has shown the prevalence of three major fault networks: northwest–southeast (NW–SE), E–W and northeast-southwest (NE–SW). These faults have controlled the thickness of the limestones of the Abiod reservoir, favouring highly subsiding NW–SE trending zones where the thickness has exceeded 500 m. Based on responses of the Gamma Ray (GR) and Sonic curves, this formation is made up of four different lithological units (U1–U4). The wireline log analyses concluded that the gross thickness of the Abiod reservoir includes good reservoir property intervals with average effective porosity ranging from 8.6% to 20.6% and average shale volume ranging from 2% to 17%. Furthermore, analysis of the fracturing affecting the Abiod reservoir, based on oil well FMS image logs, has shown the presence of open and partially open fractures that are key to hydrocarbon accumulations. The rose diagrams of fracture directions at the wells and the rose diagram of major fault directions of the map are in perfect agreement with the clear predominance of the NW–SE directions. Beyond the main uplift faults, the structural features that impact the studied area's stratigraphy are divided into three main categories. This study showed that the brittle tectonics play a role in the enhancement of the petrophysical characteristics of the studied limestone reservoir and controlled the charge access of the hydrocarbons into the reservoir. The majority of the fractures affecting the Abiod reservoir are parallel to the large fault and have the same direction of movement, while the others are distributed in a conjugate family close to perpendicular to the large fault and with complementary directions of movement. The combination of geological factors and logging parameters indicates that the tectonic legacy and structural inversions play an important role in the structuring of the cover and the evolution of the petroleum system, which have made this chalk one of the most important oil reservoirs in eastern Tunisia. Finally, the developed 3D structural model suggests favourable locations for high-potential areas in the studied region and provides insights for the reservoir development.

Landslide is one of the most sought-after research areas in the current multidisciplinary geoscience studies. In this study, a landslide susceptibility map was developed using a Multi-Criteria Decision Analysis (MCDM) framework with the Analytical Hierarchy Process (AHP) in the Dima Hasao district of Assam, India. The region is located in the western extent of the Assam–Arakan fold belt. It is characterised by extensively folded and faulted mountainous terrain. The region is highly susceptible to landslide hazard due to several factors including climatic factors, weak lithologic conditions, anthropogenic activity and so forth. This study utilised a GIS-based approach of mapping landslide susceptibility zones; geoprocessing of 12 landslide causative factors was considered, namely slope, rainfall, elevation, geology, distance from fault, drainage density, distance from drainage, curvature (Cu), distance from road, Land Use/Land Cover, Topographic Wetness Index and aspect were utilised by the AHP algorithm. Weightage criteria are assigned to all the 12 factors on a scale of 1–5 based on the significance of landslide occurrence. The AHP algorithm classified four landslide susceptible zones of different hazard, that is, low, moderate, high and very high susceptible zones. The obtained landslide susceptibility model was validated using the area under the curve (AUC) of the receiver operating characteristics (ROC) with an accuracy of 0.864, which confirmed its reliability.

The present-day structure of the southern Izu-Bonin arc-trench system appears to have been influenced by the partial subduction of the Ogasawara Plateau beneath the Philippine Sea Plate, which has significant tectonic consequences. Unfortunately, there is insufficient information regarding the effects of the Ogasawara Plateau collision on the geophysical and seismic characteristics of the region. Therefore, we employ the geophysical and seismic analysis on the gravity and bathymetry datasets, seismic events and earthquake moment tensors to examine the geophysical and seismic patterns of the southern Izu-Bonin subduction zone, thereby uncovering the effects of the Ogasawara Plateau subduction. The results show that the Ogasawara Plateau forms uplift/upthrusts and large fractures/faults in the outer rise region at its subduction area. Several uplifted tectonic features are observed along the southern Izu-Bonin Trench axis at the area of the Ogasawara Plateau collision, where also the bathymetry is approximately 3 km elevated compared to other sections of the trench. Several conspicuous seamounts, uplifts, depressions and ridges are visible in the outer forearc region affected by the collision of the Ogasawara Plateau. Moreover, abnormal low Bouguer gravity anomalies are detected in both the outer and inner forearc regions around the area associated with the Ogasawara Plateau subduction. An area with a scarcity of earthquakes is observed to the west of the Ogasawara Plateau, suggesting a density contrast within the subducting Pacific Plate beneath this region. A seismic gap (moderate to great magnitude [Mw > 4]) is observed in the subducting Pacific Plate at depths ranging from 200 to 500 km around the Ogasawara Plateau subduction area. This study shows that the Ogasawara Plateau subduction influences geophysical properties, seismic activity and faulting in the southern Izu-Bonin subduction system. It also improves understanding of subduction dynamics and the seismic effects associated with the subduction of large bathymetric highs.

China's rapid industrialization and economic development have significantly contributed to rising CO₂ emissions, posing a direct challenge to sustainable development objectives. This study investigates the relationship between aquaculture production, renewable energy consumption, energy intensity, and CO₂ emissions in China, with a particular focus on the role of aquaculture production and renewable energy consumption in shaping emission patterns. Employing the Method of Moments Quantile Regression (MMQREG) and Bootstrap Quantile Regression (BSQREG) approaches, the analysis explores the nonlinear dynamics across various quantiles of CO₂ emissions. The findings reveal that renewable energy consumption and energy intensity exert varying effects on CO₂ emissions across different emission levels, with the most pronounced impact observed in the lower quantiles. The study underscores the necessity of considering regional and sectoral disparities when formulating emission mitigation policies. It highlights the importance of China's ongoing transition toward renewable energy, enhanced efficiency, and region-specific policy interventions, particularly in high-emission areas. These insights contribute to the discourse on sustainable development in emerging economies, offering practical implications for policymakers and avenues for future research, particularly in regional variations and economic determinants of CO₂ emissions.