Geological Journal最新文献

The Late Jurassic to Early Cretaceous was a critical transformative period for the North China Craton (NCC), marked by a tectonic shift from compression to extension and the formation of numerous Yanshanian magmatic intrusions across Shanxi Province. This article presents zircon U–Pb geochronology and Hf isotope, whole-rock geochemistry and Sr–Nd isotopic compositions of Late Jurassic to Early Cretaceous intrusive rocks from the Hunyuan area in northern Shanxi Province. The Chakou, Liulengshan and Zhongzhuangpu intrusions yield zircon U–Pb ages of 150.9 ± 1.7 Ma, 137.9 ± 2.0 Ma and 115.4 ± 0.6 Ma, respectively. The Chakou monzogranites exhibit typical features of high-K calc-alkaline I-type granites, and they are enriched in Rb, Ba, K and U, and depleted in Nb and Ta. The Sr and Nd isotopes of these samples show (⁸⁷Sr/⁸⁶Sr)_i values ranging from 0.7062 to 0.7103 and ε _Nd(t) values between −8.8 and −8.7. Additionally, zircon rims show highly variable ε _Hf(t) values, spanning from −12.7 to −8.1. Geochemistry and isotopes suggest that the Chakou monzogranites originated primarily from the partial melting of the lower crust. The Liulengshan quartz syenites exhibit low SiO₂ and high K₂O contents, classifying them as shoshonitic I-type quartz syenites. They are enriched in LREE and LILE, depleted in HFSE with a weak negative Eu anomaly, and display moderate ε _Nd(t) values between −17.1 and −17.0. Zircon Hf isotope composition is relatively uniform, with ε _Hf(t) values ranging from −22.6 to −20.4. We propose that the quartz syenites from Liulengshan were formed by mixed products of mantle-derived and crust-derived magmas, with the latter being dominant. The Zhongzhuangpu biotite monzogranites are petrologically and geochemically uniform, showing enrichment in Pb and Ta, and strong depletion in Sr, Ba and Eu. We consider that they originated from the partial melting of crustal materials. Collectively, our data indicate that continuous crustal extension, thinning and asthenospheric upwelling facilitated partial melting of both lithospheric mantle and crustal materials. These processes were the primary drivers behind the formation of intrusions in the NCC during the Late Jurassic to Early Cretaceous.

In the digital age, using digital tools to promote environmental governance has gained significant attention. Digital finance (DF) integrates financial systems with digital technologies, offering a new financing channel and mechanism for collaboratively reducing pollutants and carbon emissions (RPCEs). This paper explores the multifaceted impact of DF on RPCE, using China as a case study. Utilising panel data from 30 provinces in China from 2011 to 2021, the study applies benchmark regression, mediation, moderation and spatial econometric models to empirically analyse DF's effects and mechanisms on RPCE. The findings revealed that: (1) DF positively influences RPCE, with industrial structure upgrading playing a key role in this process. (2) DF's impact on RPCE varies across regions and e-government demonstration zones in China, showing stronger effects in central China and e-government zones. (3) DF's impact on RPCE can be strengthened by increasing green fiscal expenditure. (4) The negative spillover effect of DF on RPCE in neighbouring areas was witnessed, where local DF development inhibited DF growth in adjacent areas through a ‘siphon effect’. As a result, the modern financial system should be tailored to regional characteristics while accelerating industrial structure upgrading. By leveraging green fiscal expenditure regulations, DF's potential can be fully realised, creating a synergistic effect on RPCE.

Coastal areas are increasingly susceptible to frequent cyclones driven by climate change. This leads to severe flooding, habitat loss, economic damage and community displacement, necessitating urgent adaptation measures. In this context, the present study aims to assess the impact of tropical cyclone Yaas on the coastal districts of Odisha and West Bengal combining SAR and optical satellite data. The Sentinel-1 data was used for flood inundation analysis, allowing for the identification and mapping of areas affected by the cyclonic flooding. In addition, Sentinel-2 data was employed for land use and land cover (LULC) analysis, enabling the evaluation of the cyclone's impact on various land cover classes. A fuzzy Analytic Hierarchy Process (AHP) was applied to analyse the changes in forest canopy cover. By integrating these diverse datasets and analyses, the study provides a holistic understanding of the cyclone's impact on the coastal region's environment and land cover. The findings reveal that the Yaas cyclonic flood affected an area of 2528.70 sq. km, accounting for 6.8% of the total region. In the coastal areas of West Bengal, more than 24% of cropland was affected particularly in the districts of Purba Medinipur, North 24 Parganas, Hoogly, Howrah and South 24 Parganas. In Odisha state, the most affected cropland areas were Bhadrak (945.11 sq. km) and Kendrapara (557.90 sq. km), while the districts of Bhadrak, Balasore, Jajpur, Khordha and Cuttack experienced the greatest impact on built-up areas. The findings of this comprehensive study contribute to a deeper understanding of the magnitude and extent of tropical cyclone Yaas's impacts. This study can be useful for the development of effective mitigation and adaptation strategies that is, restoration of mangrove forests, introduction of salt-tolerant crops and upgrading of existing embankments and levees to enhance the resilience of the coastal communities.

Creating accurate and effective Landslide Susceptibility (LS) maps can aid disaster prevention and mitigation efforts and provide sufficient public safety. The primary aim of this study is to develop an LS map for the Garo Hills region in Meghalaya, India, using the weight of evidence (WoE), frequency ratio (FR), and Shannon entropy (SE) methods. A comprehensive landslide inventory catalogued 98 events from 2000 to 2023 for the analysis, and nine key geographical and environmental parameters were prepared. Conducted multicollinearity and correlation analysis to identify and mitigate collinearity issues between factors. The model's performance was analysed through the area under the curve (AUC) value of receiver operating characteristic (ROC) curves and three recent landslides. The results showed that FR method achieved the highest accuracy, with successive rate curve (SRC) AUC and predictive rate curve (PRC) AUC values of 0.860 and 0.940, respectively, and classified susceptibility at three sites as high, moderate, and low. The WoE method effectively identified three landslides site in high and very high susceptibility zones, achieving SRC AUC and PRC AUC values of 0.844 and 0.915, respectively. The SE method showed robust performance in predicting landslide-prone areas, with PRC AUC comparable to other methods (0.913), though its SRC AUC (0.771) was lower. Developed maps revealed that high and very high susceptibility zones account for approximately 10% and 3% of the study area, predominantly near roads, steep slopes, and higher elevations. The information in this study is valuable for civilians and the government authorities involved in hazard monitoring and management.

The Lengjimanda Plate in the central Da Hinggan Mountains is mainly composed of a series of acid volcanic rocks such as rhyolites and rhyolitic crystal tuffs of the Early Cretaceous Baiyingaolao and Guanghua formations. LA-ICP-MS zircon U–Pb dating indicates that rhyolites of the Baiyingaolao Formation formed between 140 and 137 Ma, while rhyolites of the Guanghua Formation formed between 129 and 128 Ma. Rocks of the Baiyingaolao Formation exhibit the characteristics of high silica contents, alkali enrichment and aluminium depletion, thus resembling A-type granites. They show significant fractionation of light and heavy rare earth elements with a pronounced negative Eu anomaly. They zircon ¹⁷⁶Hf/¹⁷⁷Hf ratios range from 0.282932 to 0.252800, with an average ε _Hf(t) value of +1.28; (⁸⁷Sr/⁸⁶Sr) _i ranges from 0.68848 to 0.70068, with ε_Nd(t) ranging from +1.4 to +3.7; and t _DM2 ranges from 629 to 817 Ma, indicating magma derived from newly formed young crustal material after the closure of the Mongolian-Okhotsk Ocean. The volcanic rocks of the Guanghua Formation have characteristics that are similar to I-Type granites, with silica and alkali enrichment and Ca and Mg depletion. They also show a right-skewed “V”-shaped pattern in their REE distribution curves, with a strong negative Eu anomaly. The zircon ¹⁷⁶Hf/¹⁷⁷Hf ratios range from 0.282887 to 0.282986, with an average ε _Hf(t) value of +8.78; (⁸⁷Sr/⁸⁶Sr)_i ranges from 0.70060 to 0.70096, with ε _Nd(t) ranging from +3.0 to +3.8; and t _DM2 ranges from 616 to 677 Ma, indicating the partial melting of depleted mantle-derived mafic lower crustal material, influenced by the closure of the Mongolian-Okhotsk Ocean and subduction of the ancient Pacific Plate.

This study examines the oil storage capacity and controlling factors of organic-rich Chang 7 shale in the Ordos Basin, using multistep Rock-Eval pyrolysis (MREP) and liquid hydrocarbon vapour adsorption (LHVA) techniques. The research evaluates the effectiveness of these techniques in determining oil content and identifies key geological and geochemical factors impacting free and adsorbed oil. Analyses of geochemical, mineralogical, and pore structure characteristics reveal that Chang 7 shale, with high total organic carbon (TOC) content and oil-prone kerogen, along with moderate thermal maturity, is a high-quality hydrocarbon source rock. A strong linear correlation between MREP and LHVA results demonstrate the reliability of both methods for assessing adsorbed oil content, though discrepancies emphasise the impact of hydrocarbon loss during sample preparation. Statistical analysis indicates TOC content (> 2%, with > 4% especially favourable) and thermal maturity (R _o = 0.7%–1.0%) as the critical factors for shale oil accumulation and key indicators for identifying sweet spots. These findings improve the understanding of oil occurrence processes in shale and offer practical insights for optimising shale oil exploration and development.

The Cuddapah Basin located in the southern part of India, is one of the largest Proterozoic basins in the world. This basin witnessed multi-stage growth that involved sedimentation, magmatism and tectonism. This region has been studied geophysically for over nine decades, nevertheless, its subsurface structural configuration, underlying crust–mantle structure and its evolutionary relationship with east Antarctica during the Columbia and Rodinia supercontinental assembly periods, remain an enigma. In the present study, we provide a 3-D crustal structural configuration of this basin based on gravity modelling along 13 east–west and 3 north–south profiles, utilising density and subsurface depth constraints from crustal seismic studies. We have delineated the presence of a 15–20 km anomalously thick, high density differentiated magmatic layer above the Moho, which varies widely from 32 km below the Eastern Ghats Belt to about 50 km below the Nellore Schist Belt. It is invariably shallower at 37–38 km north of 14°45'N, compared with 43 to 46 km south of it, indicating possible tilting of the basin from north to south. Importantly, we also notice a high order translational movement of the crustal column across the Nallamalai Basin as revealed by conspicuous change in the Moho trend, which correlates with the absence of Eastern Ghats Belt for a distance of about 400 km south of Ongole, mimicking the translational movement. We infer that the Napier complex of east Antarctica, may form the missing part of Eastern Ghats Belt of India's east coast. Similarly, a high gravity over the Nellore Schist Belt region would possibly indicate presence of remanent slab material (or magmatic material) underneath which may be related to erstwhile supra-subduction during the Rodinia supercontinental assembly period. The present study further suggests that the Iswarakuppam dome, located in northern part of the Nallamalai Basin, contains a thin veneer of Cumbum shale (5.10 km/s) followed by a high velocity (Vp: 5.70 km/s) sequences containing Bairenkonda quartzites and possibly mantle derived mafic rocks that may be correlatable with the sills of southwestern part of the Cuddapah Basin. This domal structure probably formed due to underthrusting of the western Cuddapah Basin and the collision of Nellore Schist Belt/Eastern Ghats Belt terrains after the cessation of supra-subduction below eastern Dharwar Craton at the end of the Rodinia period (around 950 Ma).

The Central Indian Tectonic Zone (CITZ) runs across peninsular India and includes Proterozoic bimodal volcanics (basalt-rhyolite), quartzite, mafic-ultramafic rocks, volcanic sediments and Banded Iron Formation (BIF). The bimodal volcanic rocks of Betul–Chhindwara belt have been subjected to upper greenschist to lower amphibolite-grade metamorphism and have well-preserved remnants of pillow structures. Total alkali vs. silica diagram clearly discriminates all the samples into subalkaline basalts and rhyolites which corresponds to their bimodal nature. Mafic volcanic sequence of Betul–Chhindwara belt is represented by high Ti and low Ti Groups. I. High Ti basalt has undergone low degree of partial melting (~5%), whereas low Ti basalt has undergone a high degree of partial melting (~20%) of the same source rock. Fe and Ca decrease with decreasing Ti indicating clinopyroxene and iron-titanium oxide fractionation in both the groups of basalt. These basalts are generally enriched in incompatible trace elements such as Rb and Ba and depleted in Nb, P and Ti, which collectively are good indicators of continental crust/lithosphere involvement in their genesis. The basalts show no Eu anomaly, which indicates little role of plagioclase during fractionation process. Positive anomalies of U–Th–Zr for the basalts indicate crustal involvement. Whole-rock Sm–Nd isochrons for the mafic volcanic rocks indicate an age of crystallisation for these volcanic rocks at about 1232 ± 37 Ma (initial ¹⁴³Nd/¹⁴⁴Nd = 0.510752 ± 0.000035, mean square weighted deviate [MSWD] = 1.20) which is much younger than the basement rocks ca. 1500 Ma. The ε _Ndt (t = 1232 Ma) vary from −5.93 to −3.1 for the mafic volcanic rocks and between −5.81 and +0.14 for felsic volcanic rocks. Depleted mantle model ages of basalts vary from 2204 to 3040 Ma, and for rhyolites, these vary from 2174 to 2863 Ma, respectively. The ε _Nd value for all the basaltic samples includes both the groups of basalts plot away from the CHUR line indicating their derivation from a depleted source and evolves to lower values, indicating longer crustal residence or more crustal contribution. Mafic magma might have been produced at the subduction zone interacted with the lower continental crust while ascending to the surface. This lowered the melting point of the continental crust which led to the production of felsic melt. Episodic mafic magma could have led to the production of rhyolite, produced at different levels of the continental crust.

The northeast margin of Ordos Basin, China has a large area with ‘bleached sandstone’, a unique rock characterised by a low diagenetic degree and poor cementation degree. Long-term wind and hydraulic erosion have led to significant soil erosion, vegetation degradation and low ecological carrying capacity in this region, with huge amounts of sediments being transported to the Yellow River. Therefore, it is critical to investigate the weathering mechanism and physicochemical characteristics of bleached sandstone. In this study, the pore structure, elemental composition, mineral composition and radon exhalation characteristics of the bleached sandstone were analysed using low-temperature nitrogen adsorption instrument, inductively coupled plasma mass spectrometer, polarising microscope and environmental radon detector, respectively. Moreover, the physicochemical characteristics of the bleached sandstone were analysed to determine the correlation among them. The results demonstrated that the degree of pore development in bleached sandstone is significantly higher than that in original rock, and the content of mesopores of size from 2 to 50 nm is the highest. These pores were found to be predominantly slit pores with parallel plate structure. The mineral composition is primarily quartz, feldspar, clay minerals and muscovite, with quartz being the highest. Quartz and feldspar exhibited significant weathering, broken crystals and more impurities. A large amount of biotite was altered to form muscovite. The intergranular spaces of bleached sandstone are filled with heterobase, primarily composed of clay minerals. Additionally, clay minerals formed a ring band structure around the particle skeleton. Bleached sandstone was found to be rich in P, Ba, Mn, Sr, Zr and other elements, with Ba showing the highest proportion. The bleached sandstone is enriched in toxic elements Be, As, Cd, Sb, Hg, Tl and ²³⁸U compared with the original rock, indicating that the latter has a certain degree of adsorption. Among them, Be has the highest enrichment degree. Moreover, it is enriched with light rare earth and deficient in heavy rare earth. δEu and δCe exhibit a slight deficiency. Although the rate of radon exhalation in bleached sandstone is low, it is higher than that of the original rock. The high porosity and micropore content can promote radon exhalation. High ²³⁸U content can enhance radon generation, which exhibited a positive correlation with radon exhalation rate. The research results can provide a reference for ecological management, development and utilisation of bleached sandstone in this region.

Understanding the Late Palaeozoic accretionary processes responsible for the formation of the eastern Central Asian Orogenic Belt (CAOB) is crucial for unravelling continental growth mechanisms in this region. This study systematically investigates newly identified volcanic rocks in the northern margin of the North China Block (NCB) and Bainaimiao Arc Belt (BAB), aiming to elucidate their petrogenesis, tectonic setting and implications for the evolution of the Paleo-Asian Ocean (PAO). Zircon U–Pb dating reveals that these volcanic rocks were emplaced between 278 and 260 Ma. The intermediate-mafic volcanic rocks exhibit typical subduction-related geochemical signatures, including low TiO₂ contents, enrichment in Rb, Ba, U, K, Pb and Sr., and depletion in Nb and Ta, reflecting derivation from a subduction-modified lithospheric mantle. The acidic volcanic rocks, characterised by high SiO₂ and Al₂O₃ contents and pronounced negative Eu anomalies, are interpreted as products of partial melting of the lower continental crust with fractional crystallisation. The _εHf(t) values range from highly positive in the BAB region to lower values in the NCB, highlighting the incorporation of juvenile crustal material in the north and ancient crustal components in the south. Geochemical and isotopic evidence suggests that the volcanic rocks formed in an Andean-type continental arc during the southward subduction of the PAO beneath the northern margin of the NCB. After 260 Ma, the tectonic setting transitioned to an extensional environment, as reflected in the geochemistry of younger intraplate granites. These findings suggest that the PAO continued subduction until the Late Permian, followed by slab break-off and post-collisional extension. The crustal thickening (40–66 km) and widespread magmatism indicate significant juvenile crustal growth during the Middle to Late Permian. Combined with regional tectonic data, this study provides critical insights into the geodynamic processes driving crustal evolution in the eastern CAOB.