Geological Journal最新文献

Iron speciation has emerged as a robust proxy for discerning oceanic redox conditions; nonetheless, it is subject to certain limitations. Specifically, the applicability of the degree of pyritization is contingent upon the presence of unequivocal evidence of an anoxic water column and its discriminatory capacity is limited to distinguish between ferruginous (anoxic) and euxinic conditions. This study highlights that through the integration of redox-sensitive trace metal enrichment data with Fe-speciation data, the depositional redox conditions for marine sediments can be established with greater certainty. Recently, a set of dedicated geological reference materials (BHW and WHIT) have been developed for validating the Fe-speciation analytical results for redox reconstruction studies; however, to the best of our knowledge, these reference materials are not characterized for trace and rare earth elements (REEs). In this connection, the BHW (oxic) and WHIT (anoxic) reference materials are measured for major, trace and REEs. After careful statistical considerations for these reference standards, a complete set of trace and REEs is reported. Furthermore, considering BHW and WHIT as oxic and anoxic end-members, respectively, the utility of trace metal enrichment and Fe-speciation data in combination has been discussed. The trace and REE concentrations of BHW and WHIT reported in this study will enhance their applicability as a reference material to understand ocean chemistry and the oxidation state of the ancient oceans.

Spodumene-bearing pegmatite dyke swarms have recently been discovered in the Chaqiabeishan area, at the northeastern margin of the Qinghai-Tibet Plateau in northwest China. In order to elucidate the connection between the Chaqiabeishan lithium pegmatites and Triassic magmatism and mineralization within the West Kunlun – Songpan -Garzê rare-metal belt, this study presents new columbite-group mineral and monazite U–Pb dating results, mineral chemistry, monazite in situ Nd isotope analyses and gamma-ray spectrometric measurements. Magmatism and mineralization at Chaqiabeishan mainly occurred ca. 216 Ma, and the mineralized pegmatites (Mn-rich columbite-group minerals, highly evolved monazite compositions and high effective uranium contents in the gamma-ray survey) were generated from the high degree of the fractional crystallization in a volatile-rich granitic magma. The source material of the Chaqiabeishan lithium pegmatites (ε_Nd(t) values from −14.4 to −12.8) was more enriched than that of other pegmatite-type lithium deposits (Jiajika and Bailongshan) in the West Kunlun – Songpan – Garzê rare-metal belt and is ascribed to melting of ancient crustal materials in the basement. These late-Triassic mineralizing events were closely related to the collision-related tectonic setting at the northeastern margin of the Tibetan-Qinghai Plateau, a product of Paleo-Tethys Ocean closure.

Tunnels stand as indispensable pillars of transportation infrastructure, assuming a central and transformative role in fostering the sustainable evolution of urban. The excavation process of tunnels presents a spectrum of geological challenges, encompassing the potential for instability and collapse. Ensuring the stability of the tunnel is a top priority in tunnel construction. The destabilization leading to collapse in certain tunnels is intricately connected to the structural planes of the rock mass. Accurately obtaining the distribution of structural planes within the rock mass is the necessary basis for maintaining the stability of the tunnel. The conventional Monte Carlo method generates each parameter of stochastic structural planes separately without considering the correlations between the parameters. To address this limitation, we propose a stochastic structural plane generation method based on deep generative model (DGM). The model takes the measured factual structural plane data as input, and the neural network realizes the generation of structural plane data with automatic learning of the distribution law of structural planes and the correlations between each parameters without assuming the probability distribution of stochastic structural planes in advance. This method has been used for stochastic structural plane generation of the rock mass in the Yuelongmen tunnel located in Mianyang City, Sichuan Province. The validation results show that the proposed DGM-based method automatically captures the correlation between structural plane parameters while ensuring the greater accuracy of the generated structural planes.

Skirted foundations are critical components in offshore applications where combined loads are common in deep-water environments. Their ultimate capacity under VH (vertical-horizontal) combined loading is traditionally determined using VH failure envelopes, which are primarily constructed using numerical methods. These methodologies, however, frequently ignore the spatial variability inherent in seabed soils due to geological formations. This paper investigates the effect of spatial variability of undrained shear strength and embedment ratio impact on the capacity of skirted foundations subjected to VH combined loading. For this, OptumG2 software is used to perform Monte Carlo simulation combined with random finite element limit analysis. This paper investigates the stochastic analysis of bearing capacity and failure envelopes, with a particular emphasis on understanding the effect of spatial correlation on undrained shear strength. The study focuses on the horizontal scale of fluctuation and the soil strength heterogeneity index, shedding insight on previously undiscovered areas. Novel findings highlight how a rigid base affects VH failure envelopes and offer insights into evaluating the vertical bearing capacity of skirted foundations. [Correction added on 8 July 2024, after first online publication: The above statement has been updated in this version.]

The Neotethyan Sanandaj–Sirjan Zone of western Iran has recorded major magmatic activities due to its continental arc tectonic setting during the Mesozoic. The Varcheh mafic intrusions were less-studied plutons in the northern Sanandaj–Sirjan Zone (SSZ). Field evidence, petrography, geochemistry and U–Pb geochronological data were used to determine petrographic composition, geochemical nature, crystallization age and also to suggest a conceptual tectonomagmatic model for their emplacement. Small plutonic bodies are dominantly composed of monzogabbro that have intruded into the Cretaceous sedimentary rocks. Based on U–Pb zircon datings, these rocks have crystallized at 125–118 Ma in late Early Cretaceous (Barremian–Aptian), and are older than the supposed ages reported on geological maps. Varcheh rocks are not just typical calc-alkaline rocks and some show alkaline affinity. Negative anomalies in Nb–Ta–Ti and enrichments in some large-ion lithophile elements on spider diagrams are consistent with a subduction-zone setting. Potential deep source for magma generation is partial melting of subcontinental lithospheric mantle wedge above a subducting slab of oceanic lithosphere. The spaces for the Varcheh mafic intrusions are accommodated by dominant dextral strike-slip movement in a continental arc experiencing extension during late Early Cretaceous subduction. According to the zircon U–Pb geochronology results in this paper and previous U–Pb ages in the northern part of the SSZ, the mid-Cretaceous magmatism reveals a significant NW-ward younging trend and migration of the magmatic arc from the Barremian–Aptian in south-east to the Albian–Cenomanian in the north-west.

The Tongbai complex plays an important role in the understanding of the tectonic evolution of the Tongbai-Dabie orogenic belt. By detailed structural analysis, new zircon U–Pb dating, zircon Lu–Hf analysis and whole-rock elements for the rocks in the Tongbai complex and the wrapped shear zones, we suggested that the Tongbai complex was derived from the partial melting of the basement of Yangtze Block and experienced a uniform orogen-parallel extension with a top-to-NW shearing at 142–133 Ma. The migmatites yield a migmatization age of 116 ± 2 Ma and are identical to the metamorphic age of 115–111 Ma from the L and LS tectonites in the Tongbai complex. The late Early Cretaceous migmatization may give rise to the severance of the uniform top-to-NW shear zone and lead to an antiform folding of the Tongbai complex. The similar deformation and migmatization of the complexes in both the Tongbai and Dabie orogenic belts suggest that the Tongbai-Dabie orogenic belt is likely to have a similar tectonic transformation from orogen-parallel to orogen-perpendicular extension in the Early Cretaceous, namely a uniform orogen-parallel extension of the ductile lithosphere during the early Early Cretaceous and a widespread migmatization during the late Early Cretaceous.

The present paper addresses petrography, geochemistry and Ar-Ar geochronology of a significant number of mafic dykes from the Paleo- to Neoarchean Bundelkhand Craton in central India. The majority of the dykes are NW-SE oriented (with a few NE-SW and ENE-WSW) with tholeiitic, sub-alkaline and basalt to basaltic andesite composition. The trace element geochemistry of these dykes indicates an island arc setting during emplacement. The Ar-Ar mineral dating (plagioclase) of three representative dykes reveals an emplacement age between 1.53 and 1.46 Ga. This finding and earlier reports (2.1–1.73 Ga) point to sustained mafic magmatism throughout the Bundelkhand Craton in a preferred structural orientation between 2.1 and 1.46 Ga. Mafic magmatism was episodic and can be linked to the perpetual subduction accretion processes between the central Indian Archean continents during the development of the Columbia supercontinent. The mafic dykes were emplaced at 45° to the maximum compression direction (E-W), that is, along the line of no finite longitudinal strain. This time equivalent widespread NW-SE and NE-SW trending mafic dyke system is also relatable along the adjacent continents (Singhbhum, Bastar) and thus opened up a new paradigm for the dyke's emplacement across the Indian cratons.

During the early Cenozoic, the collision and convergence between India and Eurasia resulted in the uplift of the Tibetan Plateau and continuous northward compression, forming the Circum-Tibetan Plateau Basin and Orogen System (CTPBOS). The Tarim Basin, located between the Tibetan Plateau and the Tianshan Mountains, plays a crucial role for studying the convergence-driving strain propagation mechanism intra-Asian continent during the growth processes of the Tibetan Plateau. Owing to the lack of accurate geophysical information on the deep structure of the Tarim crust，the mechanism of Cenozoic deformation in the Tarim Basin has been under debate. In this paper, the teleseismic data acquired by the broadband seismic profile across the Tarim Basin from south to north and the S-wave receiver function method were used to obtain the depth of the Moho and the discontinuities in the lithosphere beneath the Tarim Basin. The SRF result shows that the Moho geometry has an abrupt relief under the Bachu Uplift, and Moho offset under the fault zone between the Kalashayi Fault and the Tumuxiuke Fault. The regional dip of the Moho under the Bachu area can be explained by the root of the Bachu basement-involved uplift cutting across the whole crust and locally penetrating into the mantle lithosphere. The Bachu Uplift, located in the central Tarim terrane, has a relatively weak lithosphere. In the process of forming the Tarim large igneous province during the early Permian, the crust beneath the Bachu area was weakened and thinned by the thermo-mechanical erosion from upwelling mantle plume. As the collision and convergence of India and Eurasia since the early Cenozoic, the convergence-driving strain was propagated into the Tarim Basin. The pre-existing weak Bachu Uplift was reactivated. The Tarim Basin absorbs Cenozoic compressional deformation through the crustal shortening and Moho offset of the Bachu Uplift.

RETRACTION: M. Tao, B. Zhang, G.B.A. Kizi, “Measuring the management of natural resources and regional sustainable development: Mediating role of green finance in China,” Geological Journal 58, no. 9 (2023): 3278–3287, https://doi.org/10.1002/gj.4820.

The above article, published online on 13 July 2023 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal's Editors in Chief, Ian D. Somerville and Yunpeng Dong; and John Wiley & Sons Ltd. The retraction has been agreed following concerns raised by a third party. Further investigation by the publisher has found manipulation of the peer review process. The retraction is warranted due to the compromised integrity of the article's peer review.

The source of oil and gas in the Tarim Basin's platform has always been controversial. The Lower Cambrian Yurtusi Formation and the Xidashan Formation–Xishanbulak Formation argillaceous source rocks are an important set of oil source series in the basin. Based on the principle of conservation of matter, this paper calculates the hydrocarbon expulsion amount of the source rock. Using a phase state hydrocarbon expulsion amount characterization model, the paper reconstructs the evolution process of the hydrocarbon expulsion phase state of the source rock. According to the characterization model of hydrocarbon expulsion dynamics, the relative contribution of each force to hydrocarbon expulsion is evaluated. The hydrocarbon expulsion geologic model of argillaceous source rocks in the Lower Cambrian in the Tarim Basin is established. The results show that this set of source rocks can serve the main source rocks in the basin. The hydrocarbon expulsion of the Lower Cambrian argillaceous source rocks in the Tarim Basin can be divided into three stages. In the first stage, the hydrocarbon expulsion phase is dominated by the water-soluble and diffusion phases. The conversion of clay minerals into dehydration and diffusion forces is the main driving force for the hydrocarbon expulsion. In the second stage, the oil and gas expulsion present the characteristics of multiphase and multidynamic coexistence. In the third stage, the phase state of oil and gas expulsion is mainly free phase. The capillary force difference and the thermal expansion force of the fluid rock are the main driving forces for oil and gas expulsion. The research results of this paper can deepen the understanding of the hydrocarbon expulsion mechanism of the set of source rocks, and then guide oil and gas exploration.