Geological Journal最新文献

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.

The mafic magmatism during the Middle-late Early Neoproterozoic period (ca. 830–720 Ma) is frequently construed as indicative of plume magmatism, facilitating the breakup of the supercontinent Rodinia and establishing a climatic backdrop conducive to the onset of the Sturtian glaciation. Nevertheless, the tectonic models proposed to explain the formation of the latest Tonian magmatism in the Yangtze Block remain a subject of debate. In this study, four mafic dyke samples yielded weighted mean ²⁰⁶Pb/²³⁸U ages of 733 ± 14 Ma, 722 ± 8 Ma and 734 ± 6 Ma, 733 ± 5 Ma, respectively, indicating their crystallisation age in the Neoproterozoic era. These mafic dykes are characterised by a subalkaline tholeiitic composition, with relatively low concentrations of SiO₂ (43.04–46.75 wt%) and MgO (5.50–7.86 wt%), and Mg^# values ranging from 48 to 64. Furthermore, the mafic dykes are also marked by relatively high FeO^T (9.26–12.28 wt%), TiO₂ (1.20–1.62 wt%). They exhibit a slight enrichment in LREE with (La/Yb)_N ratios of 2.99–3.35 and demonstrate trace element patterns that are typical of continental tholeiite. Moreover, the mafic dykes display εNd (t) values ranging from −3.7 to +4.4, εHf(t) values ranging from −12.33 to 4.41, along with low ratios of (²⁰⁶Pb/²⁰⁴Pb)_i (16.70–17.46), (²⁰⁷Pb/²⁰⁴Pb)_i (15.37–15.70) and (²⁰⁸Pb/²⁰⁴Pb)_i (36.67–38.00). The combination of these characteristics and clinopyroxene compositions provides evidence that the source region of the mafic dykes was created through the partial melting of the depleted asthenosphere mantle mixed with subduction fluid metasomatic lithospheric mantle during the transition of the spinel-garnet facies peridotite within an extensional setting. The congruities in formation chronology, petrogenesis, source attributes and tectonic settings among the mafic rock samples within the Douling Complex, the Yaolinghe Group and the Wudang Block suggest that the South Qinling Belt was in an extension setting during the Middle-late Early Neoproterozoic, and presumably witnessed the rifting of the Rodinia supercontinent.

Potassic–ultrapotassic volcanic rocks are the products of post-collisional magmatism in the Tibetan Plateau and can reveal the deep lithospheric processes and subduction dynamics of the Tethys oceanic crust and Indian continent. To better understand the genesis and tectonic setting of potassic magmatic rocks, this study presents zircon U–Pb ages, Sr–Nd–Pb and Hf isotope data, and whole-rock major and trace element data for the Konglong potassic–ultrapotassic volcanic rocks in the central Lhasa terrane. The Konglong volcanic rocks mainly consist of low-silica trachyte and high-silica rhyolite. Zircon U–Pb dating reveals that the trachyte formed at 21.0 ± 0.1 Ma, while the rhyolite formed at 20.6 ± 0.1 Ma. Both rock types are characterised by relatively high potassium contents and are K-rich (K₂O = 5.81%–8.52%; K₂O/Na₂O > 1). These rocks are strongly enriched in large-ion lithophile elements (e.g., Rb, Th, U, and K) and light rare earth elements (LREEs), with noticeable depletions in high-field-strength elements (e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs) can be observed in these samples. The rhyolite contains comparatively low concentrations of Ba, Sr, and δEu, and the trachyte features glomeroporphyritic aggregates. The isotopic signature shows relatively high radiogenic ⁸⁷Sr/⁸⁶Sr_(t) ratios (0.71–0.72), low εNd_(t) values (−11.1 to −9.8) and zircon εHf_(t) values (−12.2 to −10.0) and more uniform radiogenic Pb isotope ratios (²⁰⁶Pb/²⁰⁴Pb_(t) = 18.79–18.95, ²⁰⁷Pb/²⁰⁴Pb_(t) = 15.76–15.81, ²⁰⁸Pb/²⁰⁴Pb_(t) = 39.51–40.00). These findings suggest that the enriched lithospheric mantle source region in the Konglong area has experienced two episodes of metasomatism. During the oceanic slab subduction stage, the enrichment was primarily derived from oceanic crustal sediments, whereas during the Indian continental crust subduction, it was dominated by melts and fluids produced by metamorphism of the Indian crust. During the Miocene, delamination of the lithospheric mantle slab led to asthenospheric mantle flow upwelling, with high heat flow triggering partial melting of the enriched lithospheric mantle and mixing with magma of Lhasa crustal origin. The mixed magma underwent differentiation through crystal-melt separation, with the trachyte representing a crystal-enriched and melt-depleted cumulate and the rhyolite representing the resultant high-silica, crystal-poor melt.

This paper aims to provide an overview of the geochemistry and mineralogical characterisation of coal within the Sohagpur coalfield, located in the Burhar–Amlai Sub Basin of Madhya Pradesh, India. The study involves the determination of proximate and ultimate analysis components, major elements, and trace elements by using various techniques, including x-ray diffraction (XRD), x-ray fluorescence (XRF), oranic petrography, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy–Energy Dispersive Spectroscopy (SEM-EDS). Petrological studies identify the types of macerals and minerals associated in coals, assess their concentration, and examine their association with elements found in the coal samples. Our research also delves into the environmental implications of these elements, particularly those considered environmentally sensitive, such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. These findings are crucial for understanding the potential environmental impact associated with the utilisation of coal. This study identified several major sources of these elements within the coal, including silicate minerals (Quartz and Feldspar), oxides (Haematite, Rutile and Anatase), sulphides (Pyrite and Marcasite), sulphates (Gypsum) and carbonates (Calcite). Recognising these sensitive components is vital as they require mitigation or elimination before coal utilisation to minimise environmental risks. Our study delivers a valuable understanding of the geochemical composition and mineralogical characteristics of coal in the Sohagpur coalfield, highlighting the importance of environmental considerations in the utilisation of these resources.

Systematic investigations into the deep diagenetic fluid environment, diagenetic evolution and their effects on reservoir properties in the deep layers of the Pinghu Formation within the N structural belt of the Xihu Sag in the East China Sea Shelf Basin remain scarce. Drawing upon petrographic thin sections, scanning electron microscopy (SEM), whole-rock and clay mineral X-ray diffraction (XRD), fluid inclusion analyses, well logging and other analytical data—integrated with burial and thermal history modelling—this study elucidates the alternating acidic and alkaline fluid conditions, their diagenetic evolutionary pathways and their consequent influence on reservoir performance. The results indicate that the deep Pinghu Formation reservoirs experienced multiple episodes of acid-alkaline diagenetic environments during their geological evolution. Presently, they are at the mid-diagenetic stage A₂, characterised by a transition from weakly alkaline to acidic and then to alkaline conditions. Acidic environments are primarily marked by the dissolution of feldspar and lithic fragments, precipitation of authigenic kaolinite, development of secondary quartz overgrowths and minor calcite dissolution. Alkaline environments are recognised by quartz dissolution, illite and chlorite cementation, carbonate precipitation and replacement, as well as albite precipitation. We establish a pore evolution model featuring ‘early compaction, intermediate dissolution and late cementation’. Four fluid environment types can be identified: weakly alkaline–weakly acidic, weakly acidic–moderately to strongly acidic, acidic–weakly alkaline and weakly alkaline–alkaline. Acidic fluids derive mainly from organic acids, complemented by humic acids, whereas alkaline conditions arise when acidic fluids are extensively consumed and metal cation enrichment elevates the pH of formation waters. Repeated cycles of acidic and alkaline diagenesis foster multi-phase carbonate cementation and clay mineral transformations. Overall, acidic fluids enhance reservoir quality, while alkaline fluids exert both constructive and destructive influences. Compaction-related porosity loss is largely depth-dependent, cementation-related porosity loss correlates with alkaline diagenesis and dissolution-related porosity gain hinges upon the intensity of acidic fluid supply.