Geological Journal最新文献

Tjörnes Transform Zone (TTZ) and Reykjanes Rift Zone (RRZ) are two transform zones connecting Icelandic rift zones with Reykjanes and Kolbeinsey spreading ridges, respectively. They are strikingly different from the majority of transform zones that develop under the strong influence of the Icelandic plume. TTZ has a complicated pattern comprising several active and inactive rift and transtensive structures. RRZ has a relatively simple structure including several en-echelon volcanic systems. The transform zones have a similar position between the spreading ridges and the Icelandic rift zones within a large igneous province, but a very different structure. We have used physical modelling with lithospheric accretion to reproduce the conditions for the evolution of the present-day structure of the TTZ and RRZ. The modelling results show that the main conditions for the TTZ include the presence of a crustal thickness gradient, the interaction of overlapping structures, structural inheritance, and the magmatic pulses of the Icelandic plume. The specific feature of TTZ is Húsavík-Flatey Fracture Zone with a transtensive pattern. We rely on it could onset from Northern Rift Zone and predefine the whole pattern of the TTZ western branch. The main conditions for the RRZ are crustal thickness and its variation with distance from the centre of the Icelandic plume, and structural control of the Reykjanes Ridge. Nowadays, its active part is an analogue of a small part of TTZ. Another method, morphometric analysis of fault scarps, has been used to reflect the current structure and activity of the transform zones. Within the TTZ, the western branch shows decreasing tectonic activity, while the eastern branch shows increasing activity. In the RRZ, the most active volcanic systems are those adjacent to the Western Rift Zone and the Reykjanes Ridge. There is currently a southward displacement of all extension centres. The current evolution trend of both transform zones supposes their structural simplification.

The late Paleogene sedimentary succession exposed in the north Sulaiman fold-thrust belt (SFTB), Pakistan, provides a critical record of the tectono-sedimentary processes associated with the transition from the remnant Tethys Sea to a foreland basin. This study integrates sedimentary facies and biostratigraphy data of these sediments to unravel the dynamics of this transition, closely linked with the early stages of the Himalayan orogenic evolution. The Pirkoh Formation, characterised by three microfacies, indicates deposition in inner to open shelf settings. The overlying Drazinda Formation comprises six microfacies and two lithofacies, indicating deposition in semi-restricted lagoon to middle shelf environments. The Chitarwatta Formation comprises five distinct lithofacies, with the lower unit reflecting deposition in tidal flat settings and the upper unit representing deposition in a fluvial floodplain. An assemblage and two taxon range larger benthic foraminiferal and two planktic foraminiferal assemblage biozones in the Pirkoh and Drazinda formations were identified. These biozones suggest a Lutetian to Bartonian (Middle Eocene) age for the Pirkoh and the lower part of the Drazinda formations, and a Priabonian (Late Eocene) age for the upper part of the Drazinda Formation. No age-diagnostic fauna was retrieved from the Chitarwatta Formation. Therefore, an Oligocene age has been retained for it based on previous studies. The integration of sedimentary facies with biostratigraphic ages reveals a final transgression of the Tethys Sea in the SFTB in the Lutetian–Bartonian following the initial India–Asia collision in the early Eocene in the region. The Tethys Sea started to gradually retreat in the Priabonian with the deposition of dominantly semi-restricted lagoonal shales in the upper part of the Drazinda Formation. The Tethys Sea further retreated at the start of the Oligocene with the deposition of the transitional marine tidal flat sediments in the lower part of the Chitarwatta Formation. The cessation of the Tethys Sea occurred in the late Oligocene, represented by the deposition of the fluvial sediments in the upper part of the Chitarwatta Formation in the SFTB. The typical Miocene Himalayan foreland basin molasse sediments overlie the Chitarwatta Formation, representing the establishment of the foreland basin sedimentation in the SFTB by the late Oligocene to Miocene. This transition from remnant Tethys Sea to Himalayan foreland basin sedimentation in the SFTB can be linked with the southward migration of the Himalayan deformation front.

The Late Permian sedimentary sequences of the Northern Qiangtang Terrane are closely related to the formation of late Palaeozoic basins and the sub-duction of the Paleo-Tethys Ocean. Here we present new insights into the paleoenvironment and provenance of the southern margin of the Northern Qiangtang Terrane (NQT) during the Late Permian to Middle Triassic, integrating existing petrological, geochemical and detrital zircon U–Pb age data. The Chemical Index of Alteration (CIA) and Ln (Al²O³/Na²O) ratio indicate that the Late Permian sediments experienced moderate chemical weathering under warm and humid conditions, while the Early to Middle Triassic sediments underwent weak chemical weathering under cold and arid conditions. Paleo-salinity indicators (Sr/Ba, CaO/(CaO + Fe)), suggest that the Northern Qiangtang Terrane transitioned from brackish to saline marine environments. Redox-sensitive indicators, including V/(V + Ni) and Ce/La, reveal that the anoxic conditions persisted from the Late Permian to the Middle Triassic, with a significant increase in the degree of anoxia. Provenance-sensitive geochemical indicators (La/Th vs. Hf, La/Sc vs. Co/Th, TiO²/Al²O³ vs. TiO²/Zr), along with tectonic setting discrimination diagrams based on zircon trace elements, indicate that the clastic contributions to the Northern Qiangtang Basin during the Late Permian to Middle Triassic were dominated by felsic volcanic arc-derived sources. Detrital zircon age spectra show a notable shift in provenance from the Late Permian to Early Triassic, with Late Devonian to Early Carboniferous volcanic rocks from the western Northern Qiangtang Terrane contributing partially to the southern Northern Qiangtang Terrane, while Late Permian to Early Triassic continental arc magmatism provided proximal volcanic sources. We conclude that the development of the Late Permian to Middle Triassic sedimentary sequences in the southern Northern Qiangtang Terrane was closely linked to the subduction of oceanic crust beneath the Northern Qiangtang Terrane and subsequent closure of the Paleo–Tethys Ocean. These findings provide an improved understanding of the climatic, depositional and tectonic evolution of the NQT during the Permian–Triassic transition and have significant implications for further exploration of the early evolution of the Paleo-Tethys Ocean and regional tectonic frameworks.

The Cretaceous-Paleogene (K/Pg) transition is a global mass extinction event that affected the paleoenvironment, palaeogeography, and biota of the Earth. In this study, we investigated the sedimentary record of the K/Pg transition in the Hazara Basin, a part of Eastern Tethys in Pakistan, using an integrated approach of sedimentology, micropaleontology, geochemistry, and mineralogy. We identified eight biozones based on benthic and planktonic foraminifera, ranging from Middle Cenomanian to Thanetian in age. We also recognised 10 microfacies, reflecting different depositional settings from middle-outer ramp to inner ramp and shoreface environments across the K/Pg transition. We used geochemical proxies and indices to infer the paleoredox conditions, paleosalinity, paleotemperature, detrital input, and paleoproductivity of the basin. We found that oxygenated conditions prevailed across the K/Pg transition, with normal salinity in marine settings and lower salinity in continental settings. The Sr/Ca and Mn/Ca ratios indicated moderate paleotemperature and low terrigenous input, except for shale intervals with higher detrital input. The chemical weathering proxies showed moderate to intense weathering in the source area. The organic matter was mainly of type-III and type-IV, with low total organic carbon and hydrogen index values. The clay mineralogy was dominated by kaolinite, indicating warm and humid conditions, followed by smectite, chlorite, and illite. The K/Pg boundary could not be constrained by the fossil record due to the absence of Late Maastrichtian and Danian fauna in the Hazara region, which may be attributed to tectonic uplift, erosion, and non-deposition of sediments during the collision of the Indian Plate and Kohistan Island Arc. However, the boundary could be recognised by the facies change corresponding to lateritic and oolitic haematite at the base of the early Palaeocene Hangu Formation.

Early Cretaceous and Paleogene shale and limestone sediments in the southern Indus Basin were investigated by geochemical data and 1-D basin modelling. Most of the shales from the Early Cretaceous and Paleogene formations exhibit total organic carbon (TOC) content between 0.51 wt. % and 6.06 wt. %, overall, indicating organic matter richness capable of generating hydrocarbons. However, the limestone samples of the Paleogene formations have lower TOC values in the range of 0.36–0.97 wt.%, inferring poor to fair petroleum source rock. The studied shale and limestone sections exhibit also varying hydrogen indices (HI) ranging from 27 to 430 mg HC/g TOC and different kerogen pathways, ranging from Type II to Type IV. Generally, most of the samples with the Lower Cretaceous and Paleogene formations consist mainly of hydrogen-poor Type III and IV kerogens, with HI values range from 27 to 206 mg HC/g TOC, while some other samples belonging to the Paleogene formations exhibit Types II and II/III kerogen (HI from 219 to 430 mg HC/g TOC). The dominance of such kerogen shows the presence of oil- and gas-prone source rocks, with high potential for gas generation. Maturity-related indicator of Rock-Eval T_max shows different thermal maturity levels, ranging from immature to post-mature. Most of the Lower Cretaceous Goru shales are more mature than other Paleogene sediments, and rank from main oil to gas generation windows, reaching the generation efficiency. This is probably attributed to the deep burial of the Goru Formation reaching a depth up to 4050 m. Therefore, the preliminary geochemical results of the Goru shale unit were integrated into a basin modelling analysis using three exploratory wells to simulate the timing of oil and gas generation. In this case, the simulated basin models reveal that the Goru source rock system currently attained the main oil and gas generation windows, with computed vitrinite reflectance values between 0.75 and 2.00 Easy %Ro. The simulated models indicate that commercial amounts of oil have been generated from the Goru source rock system since the early Palaeocene, as demonstrated by the TR ratio of up to 62%. Moreover, oil was cracked into thermogenic gas during the late Eocene to present-day, with computed vitrinite reflectance of up to 2.00 Easy %Ro. The oil and gas generation was increased with increasing the burial depth, thus, an intensive hydrocarbon exploration and production program is highly recommended in the deeper stratigraphic succession of the Goru source rock system in the southern Indus Basin.

This study delves into the low-permeability sandstone uranium deposits in China's Ordos Basin, examining the Daying and Bayinqinggeli deposits. Employing x-ray diffraction, clay mineral analysis, x-ray fluorescence, core porosity, gas permeability tests, micrometre computed tomography (CT), and scanning electron microscopy (SEM), the research reveals the low-permeability genesis of these uranium deposits. The findings highlight a high presence of clay minerals, with Daying from 11.5% to 31.5%, and Bayinqinggeli at about 10%. Dense calcareous interlayers are common, with carbonate minerals like calcite and dolomite filling pore spaces and cementing rock-forming minerals, reducing pore sizes and ineffective connectivity, creating dead pore spaces and lowered permeability. The study concludes that the high montmorillonite content and calcareous cementation are the main causes of low permeability, providing a theoretical basis for future permeability enhancement and sustainable exploitation of uranium resources.

This paper investigates the global influence of Earth's pole motion on CO₂ emissions through global warming. Empirical evidence is provided using cointegration techniques and the Vector Error-Correction estimator, covering 1962–2022. Additionally, panel Autoregressive Distributed Lag models are utilised, incorporating data from 1990 to 2020 across 144 countries to bolster the findings. The first set of results evidences that Earth's pole motion positively influences global warming dynamics in the short-term, particularly in the X coordinate, on global warming dynamics. Further, the pole motion shock can be indirectly transmitted to CO₂ emissions, with global warming mediating. EKC effect and renewable energy are also considered. The second set of findings refers to the influence of global warming on CO₂ emissions. Herein, global warming reduces CO₂ emissions in the short-term, especially during sinusoidal periods of pole motion. In contrast, long-term trends show a positive relationship between global warming and CO₂ emissions, highlighting ecosystem modifications like sea-level rise and the non-linear relationship between economic growth and emissions. Moreover, the study identifies indirect pathways linking Earth's pole motion, global warming, and CO₂ emissions, underscoring the role of factors like the Coriolis Effect and pole motion in influencing ecosystem responses across hemispheres. In summary, the pole motion shock boosts global warming in the short term, mitigating CO₂ emissions, but has an expansive emissions tendency in the long term. The policy implications primarily involve adaptive frameworks to address dynamic geo-environmental conditions, the development of renewable energy to reduce dependence on fossil fuels by fostering a low-carbon economy through innovation and cost reduction, long-term climate resilience measures, and the implementation of effective monitoring systems to track pole motion and CO₂ emissions.

This study presents a comprehensive approach to flood risk assessment and mapping in the Uttarakhand region, India, by integrating geographic information system (GIS) and multi-criteria decision-making (MCDM). The methodology involves using digital elevation models (DEMs) to categorise elevation into five classes, slope analysis to evaluate the role of terrain steepness and drainage density assessment to identify areas less susceptible to flooding. Average annual rainfall data, classified from meteorological stations, land use/land cover patterns and distances from rivers and roads, were analysed within a GIS framework to assess flood susceptibility. The analytic hierarchy process (AHP) was employed to assign weights to these criteria and generate a flood risk index (FRI) map. Key findings indicate that extensive moderate-to-high-risk zones are present, particularly in the lower regions of Uttarakhand. The weighted overlay analysis using GIS and AHP effectively identified areas at greater risk of flooding. The results offer valuable insights for flood risk management, land-use planning and disaster preparedness, highlighting the need for targeted interventions to enhance flood resilience in the region.

This paper takes 277 Chinese cities data from 2011 to 2020 and measures the quality of green innovation and efficiency of green innovation based on super-efficiency SBM model. This paper uses the fixed effect model to analyse the digital economy on the influence of the quality and efficiency of urban green innovation, and uses the threshold effect model to test the threshold effect gathered in this effect. This paper found that the digital economy can promote urban green innovation quality and efficiency. The conclusion is still valid after robustness tests, such as recalculating the level of the digital economy and adjusting the sample time interval. Heterogeneity test shows that digital economy has a more obvious effect on improving the quality of green innovation in central and western cities, non-resource cities, cities with high-level innovation and cities with low-level enterprise density, while it has a more obvious effect on improving the efficiency of green innovation in eastern cities, non-resource cities, cities with high-level innovation and cities with high-level enterprise density. Furthermore, digital economy can enhance the quality and efficiency of urban green innovation by increasing the degree of urban economic agglomeration, talent agglomeration, industrial agglomeration and financial agglomeration. Additionally, the quality of green innovation, the improvement effect of the digital economy is stronger when the degree of economic agglomeration exceeds the threshold. Finally, when the degree of economic and financial agglomeration exceeds the threshold, the improvement of green innovation efficiency caused by the digital economy is stronger. Therefore, the government should improve the infrastructure of the digital economy, pay attention to the role of agglomeration, develop the digital economy according to local conditions and promote urban green innovation.

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.