Geoscience frontiers最新文献

The accurate identification of dinosaur egg accumulations as nests or clutches is crucial for understanding the reproductive behaviour of these extinct species. However, existing methods often rely on the presence of complete eggs and embryo remains, and sedimentological criteria that are only applicable to well-structured sediments. In this study, we introduce an innovative approach to characterize egg accumulations in structureless sediments, where traditional nest structures may not be preserved. Our methodology employs a unique combination of sedimentological, taphonomic, geochemical, and geophysical proxies for the study of egg accumulations. We applied this approach to the egg accumulation from Paimogo (Jurassic, Portugal), traditionally interpreted as a nest. Our findings reveal that the Paimogo egg assemblage is a secondary deposit, resulting from a flooding event in a fluvial plain that dismantled several allosauroid and crocodylomorph clutches. The eggshell vapor conductance results, coupled with sedimentological evidence, suggest that allosauroid dinosaurs buried their eggs in the dry terrain of overbank areas close to a main channel during the breeding season, likely during the dry season to prevent the embryos from drowning. This research underscores the necessity of multidisciplinary approaches in interpreting egg accumulations and offers a novel methodology for studying these accumulations in structureless sediments. Our findings provide new insights into the breeding behaviour and nesting preferences of these extinct organisms, contributing to our understanding of dinosaur ecology.

The energy access challenge remains a significant barrier to sustainable development, with millions of people still needing access to modern energy services. Fossil fuels have played a crucial role in meeting electricity demand, but they face challenges and drawbacks in terms of environmental sustainability, energy security, and climate change. This study examines how renewable and non-renewable energy generation capacity impacted the environment in 53 upper-middle-income countries from 1990 to 2020, using energy access and alternative energy sources as mediating variables. The findings of this study provide valuable insights into the complex relationship between renewable energy generation capacity, energy access, alternative energy sources, and environmental conditions in upper-middle-income countries. The positive relationship between renewable energy generation capacity and environmental conditions emphasizes the importance and potential of renewable energy sources in mitigating environmental degradation. Additionally, the findings indicate that energy access also plays a crucial role in shaping energy generation patterns, with higher levels of access being associated with increased renewable energy generation and decreased reliance on non-renewable energy sources. These findings highlight the urgent need for policies and measures to promote renewable energy adoption and prioritize energy access to mitigate environmental degradation and achieve sustainable development goals.

Phosphorus is one of the key elements, which determined the emergence of primordial life on our planet. The source of prebiotic phosphorus was most likely to be easily soluble compounds containing phosphorus in the negative form of oxidation (e.g., phosphides). The present paper is the first thorough investigation of phosphide-bearing mineral assemblages confined to telluric (terrestrial) native iron from volcanic rocks of Disko Island, Greenland. Phosphorus speciation in given assemblages varies from the solid solution in native iron (up to 0.3 wt.% P), different phosphides – schreibersite Fe₃P, nickelphosphide Ni₃P, barringerite Fe₂P, and phosphates, including fluorapatite, anhydrous Fe-Na phosphates, phosphoran olivine and pyroxene (up to 1 wt.% P). The diversity of observed phosphorus speciation can be explained by the steep changes of redox conditions during subsurface crystallization of iron-phosphide-bearing lavas. Based on the available data on likely redox conditions on the early Earth, we hypothesize that reactive prebiotic phosphorus may have originated from shallow crustal rocks.

The energy transition challenges faced by modern civilization have significantly enhanced the demand for critical metals like lithium resulting in improved methods to explore, extract, and utilize these metals. In this comprehensive review, we discuss the different types of lithium resources, factors, and mechanisms controlling lithium enrichment in various geological settings including terrestrial and marine environments. Diverse exploration strategies including geological, geophysical, mineralogical, geochemical, and remote sensing techniques including drone-based techniques for lithium exploration studies in different terranes are summarized. An overview of the mining techniques, including beneficiation and extraction, and their principles, mechanisms, operations, and comparison of the various approaches and compatibility with different types of lithium deposits for obtaining maximum yield are evaluated. Lithium isotopic studies are useful in understanding geological processes such as past weathering events and riverine input into the oceans, as well as in understanding the source of lithium in diverse types of deposits. We also highlight the recent developments in other areas such as recycling, environmental impact, and state-of-the-art analytical techniques for determining lithium in different lithium ore deposits and other geological materials. Our overview provides the latest developments and insights in the various sectors related to lithium and prompt further developments to meet the growing demand for this valuable metal as the world transforms to clean energy.

This study proposes an approach that considers mitigation strategies in predicting landslide susceptibility through machine learning (ML) and geographic information system (GIS) techniques. ML models, such as random forest (RF), logistic regression (LR), and support vector classification (SVC) are incorporated into GIS to predict landslide susceptibilities in Hong Kong. To consider the effect of mitigation strategies on landslide susceptibility, non-landslide samples were produced in the upgraded area and added to randomly created samples to serve as ML models in training datasets. Two scenarios were created to compare and demonstrate the efficiency of the proposed approach; Scenario I does not considering landslide control while Scenario II considers mitigation strategies for landslide control. The largest landslide susceptibilities are 0.967 (from RF), followed by 0.936 (from LR) and 0.902 (from SVC) in Scenario II; in Scenario I, they are 0.986 (from RF), 0.955 (from LR) and 0.947 (from SVC). This proves that the ML models considering mitigation strategies can decrease the current landslide susceptibilities. The comparison between the different ML models shows that RF performed better than LR and SVC, and provides the best prediction of the spatial distribution of landslide susceptibilities.

The development of laser ablation inductively coupled plasma quadrupole tandem mass spectrometry (LA-ICP-Q-MS/MS) opens new opportunities to rapidly date a variety of hydrothermal minerals. Here we present in situ Lu-Hf and Re-Os dates for hydrothermal apatite and molybdenite, respectively. We further report the first in situ Lu-Hf dates for bastnäsite, dolomite, and siderite, and assess their potential for constraining ore deposit geochronology. For method validation, we report isotope-dilution Lu-Hf dates for apatite reference material Bamble-1 (1102 ± 5 Ma) and calcite reference material ME-1 (1531 ± 7 Ma), enabling improved accuracy on matrix-matched calibration for LA-ICP-MS/MS Lu-Hf dating. The new methods are applied to the Vulcan Iron-Oxide Copper-Gold (IOCG) prospect in the Olympic Cu-Au Province of South Australia. Such deposits have been difficult to accurately date, given the general lack of reliable mineral geochronometers that are cogenetic with IOCG mineralisation. Hydrothermal apatite Lu-Hf dates and molybdenite Re-Os dates demonstrate that mineralisation at Vulcan largely occurred at ca. 1.6 Ga, contemporaneous with the world class Olympic Dam deposit. Our data also indicates that the Lu-Hf system in apatite is more robust than the U-Pb system for determining the timing of primary apatite formation in an IOCG system. We further demonstrate that dolomite can retain Lu-Hf growth ages over an extended time period (>1.5 billion years), providing constraints on the timing of primary ore mineral crystallisation during brecciation and IOCG mineralisation. Finally, late Neoproterozoic (ca. 589–544 Ma) and Carboniferous (ca. 334 ± 7 Ma) Lu-Hf dates were obtained for texturally late Cu-bearing carbonate veins, illustrating that the carbonate Lu-Hf method allows direct dating of Cu remobilisation events. This has important implications for mineral exploration as the remobilised Cu may have been transferred to younger deposits hosted in Neoproterozoic sedimentary basins overlaying the Olympic IOCG province.

Mesozoic magmatic rocks occur widely in the South China Block and are generally interpreted as the manifestations of the subduction of the Paleo-Pacific oceanic lithosphere beneath Asia. Subduction-driven magmatism in southeast (SE) China continued from the Late Permian through the Late Cretaceous with an inferred lull between 125 Ma and 115 Ma that is known in the literature as the Cretaceous “magmatic quiescence”. We report in-situ zircon U–Pb ages, Hf–O and whole-rock Sr–Nd isotopes, and whole-rock geochemistry of Cretaceous granitoids on Hainan Island and discuss their magmatic evolution within the framework of the Late Mesozoic geodynamics of SE China. We recognize two main stages of the emplacement of Cretaceous granitoids on Hainan, first around 120 Ma and then around 100–95 Ma, displaying high-K calc-alkaline, I-type geochemical affinities. Granites in both age groups are enriched in LILE and LREE, but depleted in Nb, Ta, Ba, Sr, and Eu. The 120 Ma granites have zircon ε_Hf(t) values of –2.6 to 2.3 corresponding to Hf crustal model ages, ranging from 0.79 Ga to 1.03 Ga, and δ¹⁸O values ranging from 6.9‰ to 7.7‰. Zircons from 100–95 Ma granites have ε_Hf(t) values of –4.2 to 1.1 corresponding to Hf crustal model ages of 1.08 Ga to 1.42 Ga, and δ¹⁸O values ranging from 6.7‰ to 8.4‰. Increasing ε_Hf(t) values of the Cretaceous Hainan granites with younger crystallization ages indicate addition of more juvenile components and reworking of crustal material into their melt evolution. The ε_Nd(t) values of the 120 Ma and 100–95 Ma granitoids range between –4.1 to –0.4 and –7.7 to –4.0, respectively. The calculated two–stage model age of the 100–95 Ma granitoids clusters between 1.25 Ga and 1.53 Ga. These isotopic data suggest that magmas of the Cretaceous granitoids were produced by partial melting of Mesoproterozoic metabasaltic rocks, which make up much of the crystalline basement of the southern Cathaysia block. The geochemical and isotopic characteristics of the Cretaceous granitoids on Hainan resemble those of magmatic arcs in the Circum–Pacific orogenic belts and identical to those of nearly coeval granitoid intrusions in the continental fragments within the South China Sea basin. We interpret these Cretaceous granitoids in the Peri–South China Sea region as the remnants of a once contiguous Late Mesozoic magmatic arc system that bounded the southern margin of the entire continental Southeast Asia. Our findings do not support the existence of an episode of magmatic quiescence in the geological record of SE China during the Aptian.

Kaapvaal lamproites (aka orangeites) are a group of volatile-rich (H₂O, CO₂), micaceous, ultrapotassic igneous rocks that are unique to the Kaapvaal craton in southern Africa. However, the composition of the melts that give rise to these rocks remains poorly understood due to overprinting effects of contamination by mantle and crustal material, volatile exsolution, fractional crystallisation and post-magmatic alteration. Consequently, this lack of reliable data on the initial composition of the Kaapvaal lamproite melts hampers our understanding of their source, petrogenesis and ascent mechanisms.

Olivine is a common mineral comprising the Kaapvaal lamproites that has both xenocrystic (i.e., mantle) and magmatic origins. Multiphase inclusions (melt/fluid) entrapped within olivine have been consistently demonstrated as an effective tool for gaining fundamental insights into the composition and evolution of melts that produce both kimberlites and lamproites, prior to processes, such as eruption, devolatization and syn-/post-magmatic alteration.

In this study, multiphase inclusions of both secondary and pseudosecondary origin hosted in olivine from a Kaapvaal lamproite (Silvery Home, South Africa) provide novel insights into the composition of the melt(s) that initially transported olivine to the surface and then crystallised after emplacement to form the lamproite groundmass. The inclusions in our study contain daughter mineral assemblages consisting of diverse Ca-Mg carbonates, including K-, Na-, Ba-, and Sr-bearing varieties, moderate K-rich silicates (phlogopite, tetraferriphlogopite), and subordinate oxides, phosphates, sulphides, sulphates, and halides. Based on these daughter mineral assemblages, we suggest that the composition of the melt entrapped by olivine was SiO₂-poor, Ca-Mg carbonate-rich and contained elevated concentrations of K, Na, Ba, Sr, P and Cl. The mineral and reconstructed melt compositions are in stark contrast to the mineral association of the groundmass and the bulk-rock composition of the Silvery Home lamproite, respectively. We suggest that alkali-/alkali-earth carbonates, phosphates, sulphides, sulphates, and halides represented a potentially significant, or even dominant, component of the melt that crystallised the Silvery Home lamproite but were likely removed by degassing and/or interaction with syn-/post-magmatic fluids. We show that olivine-hosted multiphase inclusions from the Silvery Home lamproite share many compositional similarities to melt inclusions hosted in olivine from kimberlites but are distinct from ‘classic’ cratonic olivine lamproites worldwide.

The trace element composition of zircon reveals information about the melt that they are derived from, as such, detrital zircon trace element compositions can be used to interrogate melt compositions, and thus the evolution of the continental crust in time and space. Here, we present a global database of detrital zircon compositions and use it to test whether average global trends for five common petrogenetic proxies truly represent secular changes in continental evolution. We demonstrate that the secular trend is broadly comparable across continental regions for Ti-in-zircon temperatures, but for other trace element ratios interrogated, secular trends are highly variable between continental regions. Because trace element ratios result from multiple petrologic variables, we argue that these petrogenetic proxies can be overinterpreted if projected to global geologic processes. In particular, we caution against the interpretation of crustal thickness from trace elements in zircon, and we argue that our results negate current hypotheses concerning secular changes in crustal thickness.