Geological Journal最新文献

The Daying, Tarangaole and Nalinggou uranium deposits in the northern Ordos Basin form a world-class uranium field, with complex uranium mineralisation processes. Key ore-controlling factors of these deposits have contributed to the uranium enrichment in different ore-bearing strata. The paper presents an overview of the relationships among the tectonics, fluids, paleoclimate of ore-controlling factors and mineralisation in these sandstone-type deposits. The shape of uranium ore bodies is influenced by the tectonic features of the Zhiluo Formation's base. The Daying uranium deposit located in a flat area benefits from a stable hydrodynamic environment, resulting in elongated ore bodies, In contrast, the Tarangaole and Nalinggou deposits situated on an uplifted slope have shorter ore bodies due to a stronger hydrodynamic setting. Previous studies on fluid inclusions, sulphur isotopes of pyrite, carbon and oxygen isotopes of carbonation indicate the following: (1) the homogenisation temperature and salinity of fluid inclusions in the calcareous colluvium increase from east to west of the study. (2) Sulphur in pyrite from the Daying area originates from organic matter in Zhiluo and Yan'an Formation coals; sulphur in pyrite from the Nalinggou and Tarangaole area originates from the Upper Palaeoproterozoic coals. (3) Carbon in the carbonate minerals primarily originates from the decarboxylation of sedimentary organic matters. The paleoclimate and sedimentary environment analyses indicate that from the southeast to the northwest of the north basin, the uranium-bearing horizon gradually transitioned from the lower sub-member to the upper sub-member of the lower Zhiluo Formation, showing obvious migration regularity. The development characteristics of coal line and carbonaceous mudstone in the lower member of the Zhiluo Formation restrict the spatial distribution of uranium deposits. As depth and reducing fluid pressure increase, the reducing fluid moved upward and mixed with oxygenated fluids, resulting in uranium enrichment. Consequently, the multi-stage and multi-layered uranium mineralisation process occurred in the northern Ordos Basin, which is indicative of a complex interplay among tectonic, ore-forming fluid and paleoclimate.

This study is the first to examine the carbon and oxygen isotopic composition of Upper Cretaceous marine sediments from the Muti Formation, exposed in the northern Oman Mountains. As the earliest depositional unit within the Oman foreland basin, the Muti Formation is a key component of the Aruma Group, providing valuable insights into the basin's early sedimentary and geochemical history. Two sections of the Muti Formation, located in the Sayga and Nakhal areas around the Jabal Akhdar dome, were selected for analysis. A total of 79 whole-rock samples were prepared for isotopic analysis aiming to investigate the relationship between the lithofacies and isotopic values, analyse the influence of depositional environments on isotopic signatures and examine the effects of sea-level fluctuations during the deposition of the Muti Formation. Additionally, it aims to establish both local correlations between the Sayga and Nakhal sections and broader global correlations between the study area and other published Upper Cretaceous sections. The results suggest that the oxygen isotopic values are nearly similar for both Sayga (avg. −7.35‰) and Nakhal (avg. −7.64‰) sections, possibly reflecting warm conditions. This study suggests that the lower part of the Nakhal section was deposited in a more proximal setting, whereas the Sayga section represents a more distal environment. This interpretation is supported by isotopic data, with negative carbon isotope values in the Nakhal section (avg. −0.95‰) attributed to meteoric water influence driven by sea-level fluctuations and positive carbon isotope values in the Sayga section (avg. +1.32‰) associated with seawater influence. Furthermore, a range of carbon isotopic values was observed within the same lithofacies, indicating no straightforward relationship between the lithofacies and carbon isotopic composition. The Sayga and Nakhal sections exhibit consistent patterns and show a strong carbon isotopic match with other sections globally from the base of the Coniacian to the upper Campanian age.

The newly discovered Telaaobao uranium deposit, hosted within Lower Cretaceous sandstones in the north-western Ordos Basin, represents a significant new stratigraphic target for uranium exploration. This study offers detailed petrological and geochemical analyses of different types of rocks from the Huanhe Formation, aiming to investigate the factors controlling uranium mineralisation in this deposit. The Huanhe Formation is generally characterised by low to moderate concentrations of total rare earth element (∑REE) (70–213 ppm) and Y (7.5–30.1 ppm), right-inclined REE patterns and slightly negative Eu anomalies, which resemble those of the upper continental crust (UCC). The trace element characteristics further reveal that the sedimentary sources have an average composition typical of intermediate-felsic rocks, with the addition of some old sediments. The U content in sediments is mostly higher than that of the average UCC, even in non-mineralised rocks from both the oxidised (2.5–58.8 ppm) and reduced zones (2.0–49.6 ppm), indicating that the provenance rocks and the sedimentary strata can serve as enriched uranium sources for the deposit. The Lower Cretaceous strata in the north-west margin of the Ordos Basin, which were formed in an arid depositional environment and lacked organic matter and other reducing agents, restricted the formation of uranium deposits. Nevertheless, influenced by multiple stages of tectonic activity, the release of deep-seated reducing fluids, such as oil and gas, greatly enhanced the reducing capacity of the sandstone, creating an extensive green reduction zone. The current development of uranium ore bodies is mainly controlled by the oxidation–reduction transition zone. Additionally, high U (591–4080 ppm) enrichment has also been found in the oxidised zone, where mineralised rocks display distinct petrological and geochemical characteristics from those in the transition zone. These rocks exhibit anomalous increases in REEs (∑REE = 168–722 ppm), with bell or flat shape REE patterns and high Y concentration (147–866 ppm). These features resemble the uranium minerals that are typically formed in deep-originated hydrothermal fluids, especially in unconformity-related uranium deposits. In this case, the hydrothermal fluids may have also introduced uranium into the Telaaobao deposit as a potential source.

To accurately evaluate seismic risk and comprehend the tectonic activity in the Himalayan region, it is essential to have comprehensive knowledge of the structure of the crust and shear-wave velocity contrast across Moho (δβ_M). Measurements of δβ_M are conducted using seismological data recorded at 26 BBS located in the Himalayan region. To estimate δβ_M, a novel technique that utilises P-to-s converted wave amplitude data was applied. The values of δβ_M range from 0.7 to 1.3 km/s across the area under investigation. The δβ_M values beneath the Himalaya region vary from 0.7 to 1.0 km/s, whereas with the presence of sedimentary layers, it jumps up to 1.3 km/s. This indicates that the presence of sediments influences the δβ_M values. The Moho depth has been taken from the published results below these stations. The crustal thickness (H) varies in the Himalayan region from 44 to 63 km. In the presence of sediments, H varies from 44 to 54 km below the 5 stations. The scaling relation between δβ_M and H is positive, which indicates the thick crust associated with a high δβ_M meaning that the presence of a low-velocity material may be fluid at the lower crust beneath the Himalayan region. It is proposed that the fluid, connected with the weak zone, may have activated pre-existing faults, leading to the generation of earthquakes. It is suggested that the accumulation of strain in the crust–mantle transition zone, which is rich in fluid, might be sufficient to generate seismicity in the lower crust. The identification of such a velocity contrast could allow tracking of temperature–pressure conditions responsible for the genesis of the crust–mantle boundary and their evolution.

The geothermal regime of a sedimentary basin plays a critical role in the formation and distribution of hydrocarbon resources. However, the lack of measured temperature data has hindered a comprehensive understanding of the geothermal regime, complicating the analysis of hydrocarbon accumulation processes in the northern Junggar Basin. This study validated and applied a predictive method based on mantle and crustal heat flow to estimate heat flow in regions without measured temperature data. By integrating data from existing and pseudo boreholes, the present geothermal regime of the northern Junggar Basin was analysed. Thermal histories were reconstructed for different regions, and the maturation processes of source rocks were further examined. Correlation analysis confirmed that the mantle and crustal heat flow method provides a reliable approach for predicting heat flow in areas lacking direct measurements. The heat flow of the northern Junggar Basin varies between 31 and 59 mW/m², with an average of 43 mW/m². Spatially, the highest heat flow values were found in the southeast, followed by the west, with the lowest in the north. The spatial distribution of the geothermal gradient and deep formation temperatures aligns with heat flow patterns and is primarily influenced by basement topography and orogenic activity. Basin modelling results revealed that the southeastern region experienced higher temperatures, leading to the maturation of source rocks during the Permian and their progression into the gas generation stage. In contrast, source rocks in the western region remain in the oil generation stage. Similarly, lower temperatures in the northern region have preserved source rocks in the oil generation stage. This study provides a detailed understanding of the thermal regime in the north of Junggar Basin and its impact on hydrocarbon accumulation processes, offering valuable insights for future hydrocarbon resource exploration and evaluation.

The evolution of the Bangong Meso-Tethys Ocean is a hot topic, not only because the Lhasa–Qiangtang collision, following its closure possibly during the Late Cretaceous, resulted in the initial elevation of the Tibetan Plateau, but also because world-class Cu–Au polymetallic deposits discovered in central Tibet are closely related to the subduction of the Bangong Meso-Tethys Ocean. However, many fundamental aspects regarding the Bangong Meso-Tethys Ocean are still intensely debated. Here, we conducted a study on the Jiangco composite pluton of diorite porphyry (DP) and quartz monzonite porphyry (QMP) that was emplaced in the accreted Early Jurassic oceanic plateau on the southern margin of the Qiangtang block of central Tibet. Our research thus probes into how the Bangong Meso-Tethys oceanic plateau interacted with the southern Qiangtang margin and how the Bangong Meso-Tethys subduction zone evolved during and after its accretion to the continental margin in the Late Mesozoic. The DP samples were dated at ~170 Ma by the zircon U–Pb method and show low K and Rb but high Na and Fe contents. They have low Nb and Y contents and show a positive correlation between the P₂O₅ contents and SiO₂ contents, exhibiting distinct S-type granite characteristics. Their high Zr contents of 194–282 ppm and intermediate (Nb/Zr)_PM ratios of 0.95–1.17 (averaging 1.1) are consistent with the magmatic rocks emplaced in a crust-thickened orogen. Their high initial ⁸⁷Sr/⁸⁶Sr (0.7104–0.7105) and low ε _Nd(t) (−13 to −12) and zircon ε _Hf(t) (−12 to −8) values suggest a derivation from crustal sources. Therefore, we argue that they were produced by partial melting of the thickened southern Qiangtang lower continental crust in an accretionary orogeny triggered by the subduction of the ~185 Ma Meso-Tethys oceanic plateau. The QMP samples have zircon U–Pb ages of 113–116 Ma. They exhibit a distinct calc-alkaline affinity and are depleted in Nb and Ta but enriched in large-ion lithophile elements (LILEs), Th and Pb, indicative of a continental arc environment. They have a broad ε _Hf(t) range (−3.1 to 2.2) but low ε _Nd(t) (−4.4 to −3.8) values, demonstrating strong Nd–Hf decoupling (Δε _Hf(t) = 2.1 to 8.1). They were produced most likely by partial melting of mélange diapir raised from the Bangong Meso-Tethys subduction channel. These results indicate that the southern margin of the Qiangtang block underwent significant crustal thickening during the Middle Jurassic accretionary orogeny and switched to normal oceanic subduction during the late Early Cretaceous.

The South Yellow Sea Rift basin (SYSB), located in the lower Yangtze Block, has distinct geological characteristics: a low thermal regime, thick lithosphere (~100 km), and no commercial oil fields. Here, we propose a comprehensive basin analysis that combines numerical simulations of tectonic–thermal evolution with interpretations of geophysical data to elucidate the origins of the low thermal regime, geodynamic background and hydrocarbon exploration potential in the SYSB. In this study, a geodynamic model and vitrinite reflectance-depth profiles are used for basin modelling to determine the rifting stage, tectonic subsidence, stretching factor and heat flow evolution; seismic interpretation data are used to observe fault evolution, crustal detachment depth, tectonic inversion and trap formation; and deep reflection seismic profiles are used to observe crustal deformation and Moho surface morphology. The tectonic–thermal evolution history of the SYSB shows that the average maximum lithospheric extension factor is ~1.3, the tectonic subsidence is 1900–2200 m, and the average heat flow gradually increased to 76 mW/m² during the syn-rift phase, which gradually decreased to approximately 66 mW/m² during the post-rift phase. Compared with the petroliferous rift basins in eastern China, the SYSB has the lowest degree of tectonic subsidence, the lowest peak heat flow, and the lowest present geothermal field. Simple shear deformation controlled by crustal-scale detachment faults dominated the continental lithosphere extension of the Lower Yangtze Block, and the evolution of the fault system suggests that these crustal-scale detachment faults may have been formed by the reactivation of pre-existing faults. The flat Moho morphology, continuous low thermal regime, and continental lithospheric extension dominated by simple shear of the crust imply that after the significant thinning of the Lower Yangtze Block in the Early Cretaceous, large-scale thermal upwelling of the asthenosphere and pure shear deformation of the lithospheric mantle did not occur beneath the Lower Yangtze Block in the Late Cretaceous–Cenozoic. The hydrocarbon generation history suggests that the thermal evolution of the source rocks ended in the Oligocene tectonic inversion, and seismic interpretation reveals that the drilled traps were driven by the Oligocene tectonic inversion, indicating that these traps have no hydrocarbon accumulation potential. Future hydrocarbon exploration should focus on palaeogeothermal and palaeoburial methods to find mature hydrocarbon kitchens and evaluate the effectiveness of traps.

This study examines the relationship between environmental innovation and digital integration in improving sustainability performance within China's mining industry, a key global resource supplier facing significant environmental challenges. Using firm-level panel data from 2020 to 2022, sourced from the China National Bureau of Statistics, the Ministry of Industry and Information Technology, corporate sustainability disclosures and patent databases, we employ a dynamic panel model estimated via the generalised method of moments (GMM) to address endogeneity concerns. The findings reveal that environmental innovation significantly enhances sustainability performance by reducing emissions, improving energy efficiency and optimising waste management. However, digital integration alone shows a negative impact, suggesting that its benefits may not inherently align with environmental objectives. Notably, the interaction between environmental innovation and digital integration demonstrates a synergistic effect, where digital tools enhance the effectiveness of green innovations. Policy support further strengthens this relationship, highlighting the importance of subsidies, tax incentives and regulatory measures in driving sustainability. These insights provide valuable guidance for policymakers and industry stakeholders to align digital transformation with environmental goals, ensuring long-term sustainability in resource-intensive industries. Our study contributes to the theoretical and empirical understanding of innovation-technology interactions in the mining sector, offering broader implications for global sustainability transitions.

Organic matter types, abundance, and thermal maturity were assessed based on organic geochemical data. Then, we provided insights into the source rocks' hydrocarbon-generating capacity and described the favourable reservoir types in the Ordovician units of the Sichuan Basin. The cross-plot of hydrogen Index (HI, mg HC/g Total Organic Carbon (TOC)) versus temperature of maximum generation (T _max, °C) shows that samples from the Houtan and Sanhui sections have very low HI values (12.05 < HI < 7.75 mg HC/g TOC). These samples suggest kerogen type IV, which does not generate hydrocarbons and is considered inert. Outcrop and core samples from the southeastern part of the Sichuan Basin have HI values ranging from 450 to 68.29 mg HC/g TOC and suggesting type II_b kerogens, which are oil and gas-prone. Tongzi-Honghuayuan section samples have TOC, vitrinite reflectance (VRo), and T _max values ranging from 0.76 to 1.54 wt.%, 0.98% to 1.96%, and 398°C to 559°C, respectively, which are above the defined lower TOC limit of effective source rock and in the dry gas window. Samples from the Late Ordovician Wufeng Formation have TOC values varying from 0.85 to 3.16 wt.%, in the dry gas generation window. The potential source rocks are mainly type II_b kerogens with TOC values higher than 0.5 wt.% and are in the oil window and dry gas window. In the investigated region, favourable source rocks are mainly from the Early/Middle Ordovician Meitan and the Late Ordovician Wufeng formations. Favourable reservoir areas are developed in three facies zones of the Tongzi, Honghuayuan, and Baota formations, including intra-platform shoal, platform marginal shoal, and palaeokarst areas around the Central Sichuan Uplift. The main reservoir spaces comprise intergranular pores, residual intergranular pores, dissolution pores, intergranular dissolution pores, and karst caves.

It has become important to understand the dynamic nature of hydro-meteorological phenomena, especially rainfall, as rainfall is considered to be the principal source of water in the hydrological cycle. Purulia, the westernmost district of West Bengal, India, is part of the Chotanagpur Plateau fringe with its undulating topography, varying slope, hard rock aquifer, limited surface and subsurface water resources, and sub-humid dry climate. Drought has been a recurring phenomenon for years, and the majority of its residents practise rain-fed agriculture, solely relying on the monsoonal rain. Therefore, it is crucial to study the nature and pattern of annual and seasonal rainfall. The objective of the study is to bring out the long-term nature of the rainfall trend along with the short term and to understand the characteristics of the rainfall over the region. This study has used the India Meteorological Department (IMD) provided daily gridded rainfall dataset for 1961 to 2020, non-parametric Mann-Kendal (M-K) test, Modified version of M-K test, and Sen's slope estimator to determine the trend of rainfall in long-term and short-term time series; the recently developed approach, i.e., innovative trend analysis (ITA) is also applied to determine the underlying trend and its stability in the long-term time series. For the purpose of change point identification, this paper has applied the sequential version of M-K test (SQMK). Both the long term (1961–2020) and two short term (1961–1990 and 1991–2020) time series have been analysed annually and seasonally. To understand the long-term variation in the character of rainfall temporally and spatially, three indices, i.e., precipitation concentration index (PCI), rainfall deviation index (RDI) and modified Fournier index (MFI) have also been implemented. The ITA approach provides a better understanding of the trend as it can determine the trend whilst the M-K test failed to determine it in some cases. In contrast to the long-term (1961–2020) and first-half (1961–1990) series, the second half of the time step (1991–2020) had the largest falling trend; i.e., 90% of the total stations have recorded a downward trend during the monsoon season. PCI and RDI, as well as SSE, identified the western half of the district as being the driest, and MFI revealed that the eastern section of the district has high rainfall intensity. This study may help the planners and policymakers to frame policies for its people and their livelihood; the comprehension of the previous hints will be used to predict the future.