Zircon SIMS U-Pb dating of the Poshi, Hongshishan, Bijiashan, and Huangshan Ni-Cu-bearing and Xiangshan Ni-Cu-Ti-Fe-bearing mafic-ultramafic intrusions in the Eastern Tianshan and Beishan Rift yields ...a relatively restricted range of 278.6 Ma to 284.0 Ma. The histogram of compiled age data of basalts in the Tarim Basin and mafic-ultramafic intrusions in the Eastern Tianshan and Beishan Rift has a peak of 280 Ma, which probably represents the time of mantle plume activity. The basalts have lower ...(t) values in the range of -9.2 ~-1.7 and Mg# of <50, and higher TiO... contents (>2 wt.%), indicating that they were generated directly from a peripheral zone of the mantle plume by low degree of melting. The mafic-ultramafic intrusions have higher ...(t) of -1.3 ~11.2 and Mg# of 33 ~90, and lower TiO... < 1.8 weight percent, suggesting that their parental magmas were produced from lithospheric mantle source by high degree of melting due to higher temperature of the mantle plume head. A possible mantle plume model beneath lithospheric mantle of the Tarim Basin, Tianshan and Beishan and its spatial framework is suggested. (ProQuest: ... denotes formulae/symbols omitted.)
As the world shifts away from fossil fuels, we will need to produce materials for vast arrays of wind turbines, solar panels, electric vehicles, batteries, fuel cells, hydrogen and more. Demand for ...the raw materials, from aggregates to metals, needed to build these and other components of the infrastructure required for decarbonisation will skyrocket (Hund et al., 2020). Securing access to these raw materials is essential for building a sustainable low-carbon economy, but how can this be carried out responsibly and fairly? Improving the sustainability of all aspects of the extractive industries is vital, otherwise the looming supply shortage in the coming decades will lead to a range of geopolitical, economic, and environmental issues (Lee et al., 2020). This Special Issue on "Sustainability in the Extractive Industries" puts a spotlight on the important and varied role that Earth Science plays in the raw materials economy. The published papers within this special issue tackle the issues related to the sustainability of the extractive industry to ensure economic growth as well as social and environmental protection: Renn et al. shed some light on the conundrum between society's need for exploring and extracting the metals and the unsustainable perception of mining. This article reviews how the sustainability criteria can be applied to the extractive sector. This encompasses environmental, economic, and social sustainability aspects whose policies need to be homogenized worldwide. They highlight three key aspects to ensure sustainability in political instruments and investment policies in order to achieve the desired results. The article emphasizes the need for transparent and inclusive stakeholder participation as well as a holistic understanding of the impact of extractives activities. The authors propose that investors providing capital for companies operating in the extractive industries should place sustainability indicators into their decisionmaking with the aim of improving governance of the extractive industry for increased economic prosperity and environmental protection. Lawley et al. show that integrating biodiversity variables in prospectivity models is essential to ensure a responsible supply of battery metals. This article suggests that a quantitative approach bringing together machine learning tools and models with geological and ecological databases is efficient in tackling the conundrum our society faces, helping to balance areas that can be exploited and those needing to be preserved. The authors recommended the application of artificial intelligence aimed at lowering the ecological and environmental risks of the natural resources sector. Troll and Arndt focus on the European case which is characterized by an almost complete dependency on importation for critical raw materials, thus delocalizing the negative environmental impact of the extractive industry. The authors highlight that Europe has a moral responsibility to change that paradigm and regain sovereignty by initiating a
The study assesses the extent of nitrate pollution in the Densu Basin, because of its predominance in agriculture and urbanized vicinities, by employing robust techniques to estimate both the natural ...background and human-induced concentrations. Statistical methods used are the pre-selection method, graphical approach (probability plot), non-parametric approach (kernel density estimation), and parametric approach (Gaussian mixture model). The study shows that the Gaussian mixture model is robust enough in determining the spectral distribution and clustering of the NO
3
-N concentration in the basin. It estimated the natural background and human-induced concentration at 1.7 ± 1.3 and 9.8 ± 5.6 mg/L, respectively. The results show that the natural background concentration in the basin is more dominant and, hence, conducive for drinking. We found a 26% contribution from anthropogenic sources that had leaked into the natural groundwaters of the Basin. The data suggest multiple sources of NO
3
-N concentration in the groundwater.
A 3D steady state groundwater flow model has been calibrated for the Afram Plains portion of the Southern Voltaian Sedimentary Basin. The model was based on data of hydraulic parameters of the ...aquifer in the area, and regional groundwater recharge estimates conducted by various researchers using a variety of methods. Model calibration was conducted using hydraulic head data of 43 boreholes in the area. Although the groundwater system in the area appears to receive some amount of recharge from the Volta Lake, the net groundwater outflow into the lake currently outstrips the volumes received from the Lake. The net effect, as suggested by the calibrated model is that groundwater outflows into the Volta Lake amount to approximately 465 m
3
/day (169,725 m
3
/year). However, with increasing groundwater abstractions at a rate of 2.5%, consistent with annual population projections, a reversal of flow is predicted by 2030 if groundwater recharge remains at the 2015 rates. This would lead to a net lake discharge of approximately 9755 m
3
/day into the aquifer system to sustain abstraction rates by 2050. This is predicted to increase further if there is a reduction in groundwater recharge as suggested by regional hydroclimatological data. A 25% reduction in groundwater recharge rate by 2050 will induce a net lake discharge of approximately 11,000 m
3
/day into the aquifer system to sustain abstractions for domestic consumption. Lateral outward/environmental flows will reduce from 5200 m
3
/day to 2700 m
3
/day under the 2015 recharge conditions, and 1300 m
3
/day under conditions of reduced recharge by 2050. Groundwater in the area does not appear to hold promise for commercial abstraction for irrigation purposes, especially under climate change conditions.
The Chinese Altai is renowned for its rich rare-element resources. Nine representative rare-element (REL) pegmatites were dated using LA-ICP-MS and 40Ar–39Ar methods. The columbite grains yield a ...weighted mean 206Pb/238U age of 239.6±3.8 Ma for the Dakalasu (Be-Nb-Ta) pegmatite and concordia U–Pb ages of 258.1±3.1 Ma and 262.3±2.5 Ma for the Xiaokalasu (Li-Nb-Ta) pegmatite. The zircons display a weighted mean 206Pb/238U age of 198.5±2.5 Ma for the Husite (Be) pegmatite and concordia U–Pb ages of 194.3±1.6 Ma and 248.2±2.2 Ma for the Qunkuer (Be) and Taerlang (barren) pegmatites. The muscovite 40Ar–39Ar dating gives plateau ages of 286.4±1.6 Ma, 297.0±2.6 Ma, 265.2±1.5 Ma, 178.8±1.0 Ma, 162.2±0.9 Ma, 237.7±1.3 Ma, 237.4±1.2 Ma and 231.9±1.2 Ma for the Talate (Li-Be-Nb-Ta), Baicheng (Nb-Ta), Kangmunagong (barren), Husite (Be), Qunkuer (Be-Nb-Ta), Xiaokalasu (Li-Nb-Ta), Weizigou (Be) and Taerlang (barren) pegmatites, respectively. These new ages coupled with previous geochronological work suggest that the REL pegmatites in the Chinese Altai formed during early Permain – Late Jurassic time. The REL pegmatites located in the Central Altaishan terrane are younger than those in the Qiongkuer–Abagong terrane, showing a correlation with the coeval and adjacent granites. The formation of the REL pegmatites and these granites indicates frequent and strong magmatic activity in the post-orogenic and anorogenic setting. The spatial and temporal distribution of pegmatites and granites reveals a magmatism path from the SE (of age early–middle Permian), to the NW (middle Permian – Middle Triassic) and finally to the central part (Middle Triassic – Jurassic) of the Chinese Altai.
An innovative technique of measuring the intensities of major sources of variation in the hydrochemistry of (ground) water in a basin has been developed. This technique, which is based on the ...combination of R-mode factor and multiple regression analyses, can be used to measure the degrees of influence of the major sources of variation in the hydrochemistry without measuring the concentrations of the entire set of physico-chemical parameters which are often used to characterize water systems. R-mode factor analysis was applied to the data of 13 physico-chemical parameters and 50 samples in order to determine the major sources of variation in the hydrochemistry of some aquifers in the western region of Ghana. In this study, three sources of variation in the hydrochemistry were distinguished: the dissolution of chlorides and sulfates of the major cations, carbonate mineral dissolution, and silicate mineral weathering. Two key parameters were identified with each of the processes and multiple regression models were developed for each process. These models were tested and found to predict these processes quite accurately, and can be applied anywhere within the terrain. This technique can be reliably applied in areas where logistical constraints limit water sampling for whole basin hydrochemical characterization. Q-mode hierarchical cluster analysis (HCA) applied to the data revealed three major groundwater associations distinguished on the basis of the major causes of variation in the hydrochemistry. The three groundwater types represent Na–HCO
3
, Ca–HCO
3
, and Na–Cl groundwater types. Silicate stability diagrams suggest that all these groundwater types are mainly stable in the kaolinite and montmorillonite fields suggesting moderately restricted flow conditions.
Dislocation textures of olivine grains and Pb isotopic compositions (207Pb/206Pb and 208Pb/206Pb) of olivine-hosted melt inclusions in basaltic lavas from three Hawaiian volcanoes (Kilauea, Mauna ...Loa, and Koolau) were examined. More than 70% of the blocky olivine grains in the studied samples have a regular-shaped dislocation texture with their dislocation densities exceeding 106cm−2, and can be considered as deformed olivine. The size distribution of blocky olivine grains shows that more than 99% of blocky olivines coarser than 1.2mm are identified as deformed olivine. These deformed olivine grains are identified as antecrysts, which originally crystallized from previous stages of magmatism in the same shield, followed by plastic deformation prior to entrainment in the erupted host magmas. This study revealed that entrainment of mantle-derived crystallization products by younger batches of magma is an important part of the evolution of magnesium-rich Hawaiian magma. Lead isotopic compositions of melt inclusions hosted in the olivine antecrysts provide information of the evolutionary history of Hawaiian volcanoes which could not have been accessed if only whole rock analyses were carried out. Antecryst-hosted melt inclusions in Kilauea and Koolau lavas demonstrate that the source components in the melting region changed during shield formation. In particular, evidence of interaction of plume-derived melts and upper mantle was observed in the earliest stage of Koolau magmatism.
Contrary to what is currently known, archetypal zircon samples from gneisses and intrusive leucogranites in the Palaeoproterozoic Suhum Basin, SE Ghana, suggest the involvement of Neoarchean crustal ...material in the formation of the Palaeoproterozoic juvenile crust of the Birimian terranes in Ghana. The zircons dated using U–Pb dating methods and subjected to Lu–Hf isotopic analysis suggest that crustal‐forming events from different contemporaneous magmatic episodes within the Suhum Basin took place over a time interval of 139 Ma from 2224 to 2085 Ma. Whole‐rock Lu–Hf data obtained for the gneissic and leucogranitic rocks gave model ages (T
DM2
) ranging from 2789 to 2456 Ma with ɛHf(t) values ranging from −1.1 to +5.4. These model ages imply that the magmas that formed these rocks were sourced from the early Palaeoproterozoic juvenile mantle with substantial Neoarchean crustal reworking.
To investigate the petrogenesis of cyclic units in layered intrusions, we examined chromitite, dunite, poikilitic harzburgite and bronzitite from the Ultramafic Zone of the Stillwater Complex and ...measured stable isotopes of Li and O in their major minerals. The Li isotopes in olivine range from 4 to 26‰ in δ
7
Li with uniform Li contents of 1–3 ppm, whereas orthopyroxene and clinopyroxene have Li contents of 0.5–5 ppm and 4–8 ppm, and δ
7
Li ranges of −13 to 7‰ and −14 to −6‰, respectively. The δ
18
O values vary from 4.91 to 5.72‰ in olivine, from 5.11 to 5.87‰ in orthopyroxene, and from 4.64 to 5.86‰ in clinopyroxene. For a given sample, olivine displays more variable and higher δ
7
Li but lower δ
18
O values than orthopyroxene, indicating that olivine experienced more extensive compositional modification after crystallization relative to orthopyroxene. The general Li and O isotopic compositions are interpreted as the result of re-equilibration between interstitial liquids, from which pyroxenes crystallized, and cumulus minerals. The inter-mineral and inter-sample isotopic variations correlate with mineral assemblages, crystal sizes and major and trace element compositions, revealing that the interstitial liquids varied compositionally mainly due to mixing between fractionated magma and newly injected primitive magma. Abrupt mineralogical and geochemical changes from silicate rocks to chromitites imply that hydrous fluids, which collected on chromite surfaces and were later released from chromite seams, played an additional, critical medium of chemical exchange between minerals in the chromitites.
Extensive late Paleozoic mafic–ultramafic complexes in the Eastern Tianshan and Beishan regions in the southern Central Asian Orogenic Belt (CAOB) represent an ideal opportunity to assess the ...characteristics of the mantle in this area. Whole-rock Nd–Sr and zircon Hf–O isotopic data from the mafic–ultramafic complexes of the Jueluotage Belt, Middle Tianshan Massif and Beishan Rift were compiled for isotopic mapping. εNd(t) and (87Sr/86Sr)i values range from +5.5 to +9.5 and 0.702 to 0.706 respectively in the Jueluotage Belt, and from −2 to +11 and 0.703 to 0.710 respectively in the Middle Tianshan and Beishan. Zircon εHf (t) and δ18O values are in the range of +6.0–+17.0 and 4.14‰–8.00‰ respectively in the Jueluotage Belt, +1–+8 and 5.17‰–6.30‰ respectively in the Middle Tianshan, and show large variations of −1–+17 and 4‰–12‰ respectively in the Beishan. Spatially, the (87Sr/86Sr)i ratios of mafic–ultramafic complexes increase from the Jueluotage Belt and Beishan to the Middle Tianshan, while the εNd(t) values show an opposite trend and reflect a mixing character between depleted mantle and EM-II reservoirs. Zircon εHf (t) and δ18O values exhibit an apparent southward decreasing and increasing trends respectively, from the Jueluotage Belt, through Middle Tianshan, to Beishan Rift. Their corresponding Hf model ages increase continuously from north to south. These observations demonstrate that the mantle sources beneath the Eastern Tianshan and Beishan are compositionally heterogeneous, which presumably result from significant and variable degrees of subduction-related modification. We therefore suggest that the late Paleozoic subcontinental lithospheric mantle beneath the Jueluotage Belt was modified by slab-derived melts and fluids during the subduction of the Junggar Ocean, whereas the mantle beneath the Beishan Rift was influenced mainly by slab-derived fluids during the subduction of the South Tianshan Ocean. The unique similarities of the Middle Tianshan mafic–ultramafic complexes reflect a two-stage modification of their mantle source, namely the sequential subduction of the early South Tianshan Ocean, followed by subduction of the Junggar Ocean. Thus, the subduction-induced mantle heterogeneity beneath the CAOB is probably regional in scope.
► Systematic Nd–Sr–Hf–O isotopic mapping of the mafic–ultramafic complexes from the southern CAOB. ► Compositional heterogeneity of mantle sources beneath Eastern Tianshan and Beishan. ► Two subduction-related modifications from South Tianshan Ocean and subsequent Junggar Ocean induced mantle heterogeneity. ► The generation of mafic–ultramafic intrusions related to post-orogenic extension and ~280Ma mantle plume.
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