Geological Journal最新文献

Over the past two decades, the frequency of natural hazard incidents has steadily risen, leading to substantial human casualties, infrastructure destruction, societal and economic disruption. The occurrence of disasters, both of natural and human origin, has exhibited an upward trend in frequency over the past few decades on a global scale, posing a significant threat to diverse populations. Over time, remote sensing technologies have proven to be effective in analysing and monitoring diverse natural disasters, including but not limited to droughts, earthquakes, tsunamis, landslides and cyclones. The significant extent of its coverage capacity and the ability to repeat observations make its application economically efficient. This paper aims to elucidate the fundamental contributions and role of remote sensing in disaster management applications. In a comprehensive analysis, this study explores recent practical applications in the context of disaster events. The utilisation of diverse methodologies and functions of remote sensing in disaster monitoring and control is further expanded to encompass the domain of disaster risk management, employing cutting-edge sensors and satellites from emerging technological advancements. This paper also addresses challenges related to disaster monitoring, detection and management. Emergencies, particularly during typical catastrophe scenarios, often witness partial disruptions in communication networks. Consequently, the role of alternative networks becomes paramount in enabling effective disaster detection and management strategies. Emerging issues are highlighted, and potential directions for future research are outlined and also support sustainable development goal 13 (climate action).

This is a comment on the paper of Singh et al. (Geological Journal, 2024:1–20) on Strontium isotope stratigraphy of marine Oligocene–Miocene sedimentary successions of Kutch Basin, western India. Kutch hosts stratotypes of some lithostratigraphic and chronostratigraphic units of India. In this study, the Sr-isotope estimated ages of the studied formations deviate significantly from their known ages based on biostratigraphy. The authors have not validated the interpreted ages with biostratigraphy. We believe a scrupulous screening of samples and validation of Sr-isotope data with biostratigraphy are two essential requirements of Sr-isotope stratigraphy. Unfortunately, Singh et al. made a new contribution to Kutch stratigraphy that falls short of meeting both conditions, leading to incorrect ages of the regional chronostratigraphic units of India.

The connection between the Ordovician bentonites on the southern margin of the Ordos Basin and the Early Palaeozoic volcanic rocks of the North Qinling Orogenic Belt is crucial for understanding the subduction and collisional closure of the Shangdan Ocean during the Early Palaeozoic. This paper investigates zircon U–Pb ages, geochemistry and Lu–Hf isotopic compositions of zircons in the Upper Ordovician Zhaolaoyu Formation bentonites located on the southern margin of the Ordos Basin. U–Pb dating of zircon indicates a coeval age of 453.3 ± 1.4 Ma (MSWD = 0.99), which represents the crystallisation age during the Late Ordovician Katian stage. The bentonites exhibit higher SiO₂ (57.94–77.95 wt.%) and Al₂O₃ (9.21–14.33 wt.%), classifying them within the low-potassium alkali basalt to medium-potassium calc-alkaline series. The parent rock of the bentonites is likely intermediate to felsic volcanic rocks. The rare earth element partitioning curves of the bentonites are right-dipping, with a more pronounced negative Eu anomaly (δEu = 0.48–0.67). The zircons in the bentonites yield two-stage model ages ranging from 546 to 956 Ma, along with ε _Hf(t) values between 5.56 and 13.55. These results indicate that the bentonites are products of volcanic arc magma formed in a subduction–collision environment. The interbedded bentonites in the Upper Ordovician limestones of the southern margin of the Ordos Basin may be associated with the northward subduction of the Shangdan Oceanic crust, reflecting the subduction and consumption of the Proto-Tethys Ocean along the southern margin of the North China Block.

The northern continental margin of the South China Sea (SCS) is an important component of deep-water circulation, providing excellent conditions for studying bottom currents in a marginal sea. Seismic data were employed to discern the sedimentary patterns prevalent in the deep-water continental slope sediments on the northern continental margin of the SCS, encompassing gravity flow, contourite and mixed depositional systems. The contourite depositional system includes various types of deposits (such as separated mounded drifts, patch or channel-related drifts, deformed sheeted drifts, composite drifts, bottom current sediment waves, plastered contourite drifts) and various morphologic erosional features eroded by the bottom current (such as moats, non-depositional surfaces, troughs and scarps). These contourite features are related to the continental slope's morphology and its sources. The Dongsha slope exhibits distinctive characteristics marked by intense bottom current erosion and deposition, featuring separated mounded drifts and deformed sheeted drifts along its lower slope. The lower slope of the Pearl River showcases a spectrum of bottom current-induced features, including sediment wave fields, erosion fields and contourite drifts. The southern flank of the Shenhu slope is characterised by a bottom current erosion field, a non-depositional surface, a sediment wave field and isolated mounded drifts. On the Yingqiong slope, the contourite drifts are limited to its southern flank where gravity flow action is absent, and the complex geomorphology interacts with the bottom current, forming a complex contourite depositional system. The results of this study serve as a foundational framework for further global research on bottom current circulation and hydrodynamics.

This research focuses on the field observations, petrography, mineral chemistry and geochemistry of the serpentinised peridotite of Al-Barramiya ophiolitic sequence to place constraints on their magmatic history and their geodynamic evolution. Al-Barramiya ophiolitic rocks are a dismembered ophiolite which was strongly deformed and metamorphosed under greenschist to lower amphibolite facies. They comprise a mantle section dominated by highly serpentinised peridotite with less metapyroxenite and chromitite, as well as a crustal portion represented by metagabbros. Along shear zones, the ophiolite sequence was affected by several types of alteration. Extensive carbonate alteration is common in the ultramafic section, resulted in talc carbonates, listvenites and magnesite, while rodingitisation is common in the metagabbro resulted in rodingite. Despite the extensive serpentinisation, some fresh relics of primary mantle minerals such as Cr-spinel, olivine and pyroxenes are preserved sporadically in the serpentinised peridotite. Few Cr-spinel crystals are sometimes surrounded by subhedral flakes of Cr-chlorite (kämmererite) that was formed due to replacement of Cr-spinel during later alteration or regional metamorphism. The serpentinite samples are depleted in the total REE (0.56–1.19 ppm) with slightly negative to slightly positive Eu anomalies (0.89–1.28). The fresh cores of Cr-spinel have Cr# mostly > 60, and the relics of pyroxenes and olivine are Mg-rich suggesting that the Al-Barramiya serpentinites are residual to high degrees of melt extraction. The estimated degrees of partial melting range between 18.2% and 20.7%. All the mineralogical and geochemical characteristics of the ultramafic section of the Al-Barramiya ophiolites are most consistent with its formation in a fore-arc setting.

The Permian shales in the Kaijiang-Liangping Trough within the Sichuan Basin represent a promising frontier for marine shale gas exploration, whereas there has been limited systematic research on their sedimentary environment and organic matter (OM) enrichment mechanisms. Therefore, we present total organic carbon (TOC) analysis, major/trace element analyses and scanning electron microscope experiments for the Permian marine shales from the trough to determine their paleoenvironmental conditions and influencing factors of OM enrichment. The results show that the paleoclimate changed from dry climate to humid and warm climate (P₃w¹ [the first member of the Wujiaping Formation]) and semi-humid to semi-arid climate (P₃w² [the second member of the Wujiaping Formation]) and P₃d-I (Dalong Formation-I) and then to arid climate again during the shale deposition period from the P₂g (Gufeng Formation) to the P₃d-II. The shales with the highest TOC contents (TOC > 3%, P₃d-I and P₂g), lower TOC contents (TOC < 1%, P₃w¹ and P₃w²) and higher TOC contents (1% < TOC < 2%, P₃d-II) were formed under the control of anoxic environment and high paleoproductivity, oxic-suboxic environment and high paleoproductivity, anoxic-euxinic environment and lower productivity, respectively. Only appropriate sedimentation rates promote OM enrichment. Terrestrial input, paleoclimate, volcanic activity and hydrothermal upwelling mainly indirectly affect OM accumulation by influencing paleoproductivity. The degree of redox conditions is the primary factor affecting OM enrichment, followed by paleoproductivity. Nonetheless, anoxic to euxinic environments are most appropriate for OM preservation. Weak volcanic activity can boost paleoproductivity, but severe volcanic activity might introduce excessive harmful compounds that limit organism survival, resulting in a fall in paleoproductivity. Additionally, element P brought by volcanic ashes doesn't contribute to OM accumulation.