Geological Journal最新文献

This contribution reports two graptolite assemblages from the Puna Turbidite Complex, outcropping in Sierra de Lina and Cauchari locality, western Puna, Jujuy and Salta provinces, Argentina. In Sierra de Lina, the graptolite assemblage comprises Didymograptus sp., Glossograptus fimbriatus, Cryptograptus schaeferi, Archiclimacograptus sp., Pseudamplexograptus distichus, Pseudamplexograptus latus, ?Urbanekograptus retioloides and Hustedograptus sp. The graptolite fauna collected from Cauchari locality includes Didymograptus spp., Archiclimacograptus caelatus, Archiclimacograptus sp. cf. A. micidus, scarce and incomplete specimens doubtfully referred to the genera Archiclimacograptus and Acrograptus and scarce siculae of Cryptograptus sp. The associations allow us to identify the Pseudamplexograptus distichus Zone in Sierra de Lina and possibly the Pterograptus elegans Zone at Cauchari locality. Graptolite assemblages recorded in both zones allow assigning a middle-late Darriwilian (Middle Ordovician) age for the bearer levels.

The Early-Middle Jurassic is one of the crucial coal-forming geologic periods in the world and an important target for hydrocarbon exploration in the Turpan-Hami Basin, China. The paleoenvironment and vegetation reconstruction of the Early-Middle Jurassic have been investigated using elemental geochemistry and palynological analysis to reveal paleoclimate evolution. A total of 48 genera of pteridophyte spore and 35 genera of gymnosperm pollen were identified, and 5 palynological assemblages were longitudinally divided, which showed significant differences in geochemical behaviours. The paleoenvironment was a transition from suboxidation to anoxia and then to an oxidation environment under freshwater conditions. The paleowater in the northern Taibei Sag was deeper than that in the southern part during the Middle Jurassic, which coincided with the sedimentary background of the sublacustrine fan in the north and the shallow braided river delta in the south. The paleovegetation evolved from mixed lowland–upland forest in the Hettangian-Toarcian, to lowland fern forest in the Aalenian-Bajocian, to upland conifers forest in the early Bathonian, to upland Cheirolepidiaceae forest in the late Bathonian-Callovian. The Toarcian and Bathonian-Callovian arid climate and the Hettangian-Pliensbachian and Aalenian-Bajocian warm-humid climate were responses to the continued global warming events and the intensification of the East Asian monsoon circulation, respectively. The influence of the Bathonian-Callovian aridification event on the sedimentary response in the southern Taibei Sag will be delayed due to the gradual southward migration of the depositional centre.

The Lower Cretaceous Dabeigou Formation (135–130 Ma) in the Luanping Basin, associated with its contemporary strata in northeastern China, contains the earliest documented fossils of the Jehol Biota. This includes the Luanpingella—Eoparacypris—Ocrocypris ostracod assemblage, referred to in this study as the Dabeigou-type ostracod fauna (DOF). Ostracods, which are small (0.5–2 mm) aquatic crustaceans, are abundant and easily preserved as fossils. Outlining a clear palaeobiogeographic range of the DOF can help expand the distribution range of the early Jehol Biota, providing valuable information on its origin. Results show that the DOF is mainly distributed in a series of rift basins along the Yanliao area of China to the eastern Transbaikal region of Russia, with a roughly narrow north-south distribution. Rift basin development in the eastern part of the North China Craton, combined with humid climatic conditions, provided a suitable environment (e.g., fluvial-lacustrine systems) for the emergence of the Jehol Biota.

Carbon emissions, ecological pollution and a steadily rising global temperature have been widely acknowledged as the most severe risks to human survival in the last few decades. Alarming increases in global temperature and sudden climatic shifts are nature's way of warning us to curb the use of fossil fuels and adopt more sustainable practices. Therefore, the present study investigates the impact of financial stability, environmental regulations and uncertain economic policies on carbon emissions and investment in renewable energy. The study used a nonparametric DEA-DDF technique to fulfil this objective using a balanced panel dataset comprising 28 Chinese provinces from 2011 to 2021. Overall results demonstrated that financial stability reduces carbon emissions and accelerates investment in renewable energy projects. The findings imply that a financially stable economy like China encourages businesses to invest in cutting-edge, environmentally friendly technology to boost productivity while reducing carbon emissions. Likewise, results show that stringent ecological regulations decrease carbon emissions and promote investment in renewable energy. Hence, stakeholders are keen to comply with environmental regulations in China to reduce carbon emissions by investing in renewable energy resources to avoid penalties. Finally, results suggest that uncertain economic policies increase carbon emissions and restrict access to credit from financial institutions for investment in renewable energy purposes in China. Findings imply that uncertainty in economic policies could lead to less environmentally friendly production practices that may increase carbon emissions and reduce the demand for renewable energy products.

Large igneous provinces (LIPs) are often the surface expressions of mantle plume process. Intensive magma could occur in the continental crust when a mantle plume penetrates the Moho. How magmas migrate in the crust, forming LIPs, remains debated. In this study, we employ 2D thermo-mechanical numerical modelling to study the dynamics of magma intrusion and migration within the continental crust affected by a mantle plume. Our results suggest that (1) lateral magma migration dominates crustal deformation, promoting the possible formation of metamorphic core complexes; (2) two distinct crustal deformation modes are recognized regarding the presence or absence of crustal break-up, affected by whether a significant vertical magma migration occurs; (3) the crustal thickness, Moho temperature and the length of the preset weak crust–mantle decoupling zone are the three key parameters controlling crustal magma migration. This study highlights the importance of lateral magma migration in the lower crust and provides physical mechanisms for the interpretation of magma migration under LIPs.

The Kutch Basin of western India exposes one of the most complete, fossiliferous marine Cenozoic sedimentary sequences of India. Precise depositional ages of these sequences are of great importance in the reconstruction of palaeoclimatic and palaeobiogeographic histories of the basin. Due to the poorly constrained foraminiferal biostratigraphic ages, we conducted high-resolution ⁸⁷Sr/⁸⁶Sr chronology of the various fossiliferous, stratigraphically continuous units of Oligocene–Miocene strata in Kutch Basin. Besides updating the previously determined ⁸⁷Sr/⁸⁶Sr chronology, we report new numerical depositional ages for Oligocene–Miocene formations and members, and correlated these ages to the existing biostratigraphic schemes. The new ⁸⁷Sr/⁸⁶Sr data indicates a depositional age range between 28.64 + 0.29/-1.11 and 23.51 + 1.53/-1.85 Ma (Rupelian-Chattian) for the Maniyara Fort Formation, between 23.07 + 0.94/1.39 and 18.09 + 0.24/-0.57 Ma (Chattian-Burdigalian) for the Khari Nadi Formation, and between 15.11 + 0.56/-2.87 and 12.29 + 1.22/-1.9 Ma (Langhian-Serravallian) for the Chhasra Formation. The sedimentation rate, determined through numerical ages derived from ⁸⁷Sr/⁸⁶Sr, indicates an increase in sedimentation for the Khari Nadi (0.23 ± 0.04 cm/kyr) and Chhasra (0.12 ± 0.04 cm/kyr) formations, likely related to uplift of the Himalaya-Tibetan plateau and intensification of the Indian Summer Monsoon. The bulk sediment element ratios (V/Ni, Ni/Co and V/Cr) indicate oxic to suboxic palaeo-redox conditions during deposition of the Oligocene–Miocene successions of the basin. Based on new and updated ⁸⁷Sr/⁸⁶Sr chronology, the depositional environments and sedimentation rates of the Kutch sequence are correlated with changes in sea-level, sedimentation rates in the Arabian Sea and Bay of Bengal, and the global climate changes across the Oligocene–Miocene boundary.

The tectonic deformation reaction to multi-plate convergence in the northern Guizhong Depression, as well as its geodynamic process, remain poorly understood. Two phases of intracontinental deformation are identified using field geological investigations, paleo-stress inversion and seismic reflection sections: (1) early NE–SW-directed compression during the Middle Triassic to Early Jurassic; (2) later NW–SE-directed compression during the Middle Jurassic to Early Cretaceous. The reconstruction of paleo-stress provides robust constraints on the spatiotemporal evolution of stress within the Guizhong Depression. The regional SW–NE-directed compression during the Middle Triassic to Early Jurassic was driven by the collision and convergence between the Indochina and South China blocks, resulting in the formation of NW–SE-directed compressional structures during the Indosinian Period. The later SE–NW-directed paleo-stress field was probably driven by the NW-directed subduction of the Paleo–Pacific Plate during the Middle Jurassic to Early Cretaceous.

The northeastern periphery of the Qaidam Basin is a crucial region for comprehending the northeastward growth of the Tibetan Plateau, as it documents Late Cenozoic crustal deformation that elucidates the plateau's growth process. In this study, we reconstruct three stages of crustal deformation in the northeastern periphery of the Qaidam Basin during the Late Cenozoic based on interpretation of growth strata from five seismic profiles, structural mapping of the typical superimposed folds and detailed detrital zircon analysis within the study area. (1) During the Early Miocene to Late Miocene period (23–8.6 Ma), there was NW–SE extensional deformation in the northeast margin of the Qaidam Basin, which exerted control over the deposition of the Youshashan Formation. (2) The NW–SE shortening occurred during the Late Miocene period (8.6–8.1 Ma), subsequent to the deposition of the Youshashan Formation and preceding the deposition of the Shizigou Formation, resulting in a parallel unconformity between these two geological units. (3) The intense shortening of the NE–SW direction occurred during the Late Miocene and Pliocene epochs (8.1–2.5 Ma). The timing of this deformation aligns with the sedimentary age of the Shizigou Formation, suggesting that the initial deformation age may represent the onset of NE extrusion from the Tibetan Plateau towards the northeast margin of the Qaidam Basin. The present study not only delineates a Late Cenozoic structural dome resulting from two-stage crustal shortening in the northeastern periphery of the Tibetan Plateau, but also provides a crucial evidence for reconstructing the Late Cenozoic intracontinental deformation process in this region.

Liquefaction-induced lateral spread is a kind of ground deformation caused by soil liquefaction, which is a danger to houses, roads and other infrastructures. In order to systematically investigate the influence law of different parameters on lateral displacement, this paper establishes a numerical model of the seismic responses of gently sloping grounds through the open-source finite element software OpenSees and carries out a large number of calculations considering various working conditions. Based on the calculation results, eXtreme Gradient Boosting (XGBoost) and random forest (RF) regression are used to build the proxy models for lateral spread displacement prediction. The finite element model was verified by using the multiple VELACS No. 2 centrifuge experiments. Finally, the model was interpreted using SHapley Additive exPlanation (SHAP) method. The results of the model training showed that both models were able to achieve a good fit to the numerical calculation results, with the RF model having a smaller prediction error for the centrifuge experiments. The model interpretation results showed that the modified cumulative absolute velocity (CAV₅) was the most important input variable in the model, and the importance of ground slope (S), relative density (D_r) and thickness of liquefiable soil layer (H_L) was relatively high. In addition, the influence of each parameter on the lateral displacement is consistent with the actual situation, reflecting the rationality of the model prediction process. In addition, the results showed that there is a threshold for the modified cumulative absolute velocity (CAV₅) and Arias intensity (I_a) that leads to a significant increase in lateral displacement. The thresholds of CAV₅ and I_a are 1.3 g s and 1.0 m/s, respectively. These thresholds are in good agreement with the thresholds for triggering the overall initial liquefaction of the soil layer determined by related studies, which provides a reference for the evaluation of liquefaction-induced lateral displacement.

The central Inner Mongolia, located at the intersection of the northern margin of the North China Craton (NCC) and the Central Asian Orogenic Belt, is crucial for deciphering the Late Palaeozoic tectonic evolution associated with the subduction and closure of the Palaeo-Asian Ocean (PAO). Our study focused on petrology, detrital zircon LA–ICP–MS U–Pb geochronology and whole-rock geochemistry for the Late Carboniferous to Permian sandstones within the Shuanmazhuang, Dahongshan, Naobaogou, and Laowopu formations in Siziwang Banner, central Inner Mongolia. This comprehensive analysis shed light on the dynamic interplay between the NCC and the South Mongolia Block. Detrital zircon U–Pb ages in investigated samples mainly cluster between 250 and 2650 Ma, with significant peaks at 2.4–2.5 Ga, 1.8–2.0 Ga, 400–430 Ma, and 250–320 Ma, respectively. The geochemistry data are characterized by SiO₂ contents (56.29–77.95 wt. %), Na₂O / K₂O ratios (0.45–1.58) and SiO₂/Al₂O₃ ratios between 4.33 and 7.44. Moreover, they exhibit the slight enrichment in large ion lithophile elements (Rb and Ba) and the depletion in high field strength elements (Nb, Ta, Th, and U). These facts indicate that the sedimentary detritus predominantly originates from felsic sources, probably deriving from the Late Carboniferous–Permian continental island arc-related intermediate-acid igneous rocks, the Late Ordovician-Silurian magmatic rocks in the Bainaimiao arc and the basements of the NCC. Furthermore, our present results also suggest that during the Early–Middle Permian, accelerating oceanic crust subduction triggered significant magmatic events in Siziwang Banner, leading to rapid uplift and the erosion of arc magmatic rocks, as well as the abundant corresponding sediments. Subsequently, the gradual convergence and eventual collision between the NCC and the Southern Mongolian Block took place at the end of the Permian, representing final closure of the PAO.