Types Of Deposits Research Articles

Recent Trends and Future Challenges for Lichen Biomonitoring in Forests

Currently, forest ecosystems are often located in remote areas, far from direct sources of air pollution. Nonetheless, they may be affected by different types of atmospheric deposition, which can compromise their health and inner balance. Epiphytic lichens respond to air pollution and climate change, and they have been widely adopted as ecological indicators, mainly in urban and industrial areas, while forest ecosystems are still underrepresented. However, in recent years, their use has become increasingly widespread, especially in the context of long-term monitoring programs for air pollution in forests. In this review, we provide a critical analysis of the topic from the point of view of the different methodological approaches based on lichen responses adopted in forest ecosystems. Further, we discuss the main challenges posed by the current global change scenario.

Geology and geochemistry of Zn-Pb(-Ge-Ag) deposits in the Sichuan-Yunnan-Guizhou Triangle area, China: A review and a new type

Mississippi Valley Type (MVT)1 deposits represent the majority of carbonate-hosted Zn–Pb deposits globally. They typically form in an extensional tectonic setting along passive margins. However, studies on carbonate-hosted Zn–Pb deposits in the Sichuan–Yunnan–Guizhou Triangle area (SYGT) reveal differences in terms of the essential features of typical MVT deposits. We discuss the main features of these deposits, controlled by folds and faults, high-grade Zn–Pb ores and symbiotic or associated elements (i.e., abundant Ag and dispersed amounts of Ge, Ga, and Cd) of significant economic value. Based on a comparison of Pb-Zn deposits in SYGT and classical MVT deposits formed in an extensional tectonic setting, as well as a subsequent discussion on deposit classification, we propose that the Huize-style Zn–Pb deposits are a new deposit style, whose basic features can guide future ore exploration. We define the Huize-style deposits based on four factors: i) Hierarchical ore-controlling system of strike-slip fault-fold structures, ii) litho-facies associated with typical alternation and mineralisation, iii) ore-forming geochemical features revealed by typical mineral assemblages, mineralisation alteration zoning, fluid-inclusion, isotope geochemistry and metallogenic acid–alkali geochemical barriers, and iv) different prospecting methods to those typically used for MVT deposits. The Huize-style and typical MVT deposits constitute the carbonate-hosted non-magmatic epigenetic hydrothermal-type (CNHT) Zn–Pb deposits.

Texture and geochemistry of sphalerite from the Chitudian Pb-Zn-Ag deposit, southern margin of the North China Craton: Implications for the enrichments of Cd, Ga, and In

The Chitudian Pb-Zn-Ag deposit, located in the southern margin of the North China Craton (SNCC), is a typical magmatic-hydrothermal deposit, where sphalerite is the predominate ore mineral with significant concentrations of critical metals, including Ga, In, and Cd. However, previous studies paid little attention to the critical metals in the deposit. This study carried out in-suit elemental analysis on the sphalerite from the Chitudian deposit, aiming to constrain the spatial distribution and enrichment mechanism of critical metals. In the Chitudian deposit, five types of sphalerite were identified (Z-Sp, Y-Sp1, Y-Sp2, X-Sp1, and X-Sp2), which differ in color, texture, and chemical composition. The concentrations of Cd, Ga, and In of these sphalerites range from 1440 to 5145 ppm, 0.53 to 528 ppm, and 0.75 to 2113 ppm, respectively. In detail, Cd is mainly concentrated in the sphalerites from the hydrothermal vein-type orebodies relative to skarn-type orebodies. Indium is progressively depleted from granite-proximal locations to granite-distal locations, and the Fe-rich sphalerite is an excellent host of In. Gallium enrichment is only observed in the tectonically deformed location of the sulfide ore vein, where the Ga-rich sphalerite is poor in Fe and shows a complex texture. Microanalysis conducted on the Ga-rich sphalerite suggested that Ga, together with In, Sn, and Cu, are removed from the deformed sphalerite by mineral-fluid interaction and subsequently sequestered by the late sphalerite cement. Considering that the Ga-rich sphalerite is close to the Ga-bearing coal bed of the Meiyaogou Formation, it is likely that the coal bed could be a potential source for Ga. These results highlight that tectonic deformation followed by hydrothermal fluid overprinting is favorable for the enrichment of critical metals in sphalerite-rich deposits.

Pyrite as a Microtextural and Geochemical Tracer of Ore-Forming Processes, Central Zone Orogenic Gold Deposit, Gabgaba District, Sudan

Abstract Gold deposition in structurally controlled deposits is triggered by changes in the mineralizing fluid conditions. Recent research has demonstrated that in deposits with a well-established paragenesis, the processes that control the ore-forming fluid conditions, and thus the gold timing and deposition, can be inferred from the study of both textural and chemical characteristics of ore-bearing minerals such as sulfides, which are ubiquitous in almost every gold deposit type. In this contribution, we carried out a coupled investigation of (1) microscopic-scale expression of regional deformation, (2) textures of mineralized veins and pyrite generations, and (3) laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace element concentrations in pyrite from the Neoproterozoic Central Zone gold deposit, located in the poorly studied Gabgaba gold district, central Keraf suture, Sudanese Nubian shield. The Central Zone gold mineralization is associated with late-collisional Keraf strike-slip shearing. It is expressed by visible gold-bearing quartz-ankerite-(albite) conjugate veins hosted by metagranitoids surrounded by metasediments. Some structurally lattice-bound gold occurs in proximal As-Au-Ni–enriched pyrite associated with sericite-albite-ankerite alteration. Vein textures and proximal pyrite oscillatory zoning and geochemical signatures indicate that vein infilling occurred as a response to sudden pressure drops and boiling of the mineralizing fluid. We therefore interpret the Central Zone deposit as a typical orogenic gold deposit, with microtextural evidence and geochemical data supporting the existence of earthquake-induced fault-valve processes.

Origin of Disseminated Gold-Sulfide Mineralization from Proximal Alteration in Orogenic Gold Deposits in the Central Sector of the Yana–Kolyma Metallogenic Belt, NE Russia

The Yana–Kolyma metallogenic belt, NE Russia, is a world-class gold belt with resources numbering ~8300 tons of gold. The belt is localized in the central part of the Verkhoyansk–Kolyma orogen, formed by a collage of diverse terranes. The Tithonian-to-Early-Cretaceous orogenic gold deposits are hosted in a sequence of Permian–Triassic and Jurassic clastic rocks and altered Late Jurassic andesite, dacite, granodiorite, trachyandesite, and trachybasalt dykes. High-fineness gold (800–900‰) in quartz veins and invisible gold in disseminated arsenian pyrite-3 (Py3) and arsenopyrite-1 (Apy1) are present in ores. Here, we present new data about microtextures; the chemical composition and stable sulfur isotopes of auriferous pyrite-3 and arsenopyrite-1 from proximal alterations in sediment-hosted (Malo–Taryn, Badran, Khangalas); and intrusion-hosted (V’yun, Shumniy) orogenic Au deposits in the central sector of the Yana–Kolyma metallogenic belt to better constrain the ore-forming process and tracking their evolution. Detailed petrography defined the following generations of pyrite: syn-sedimentary/diagenetic Py1, metamorphic Py2 and hydrothermal Py3, and Apy1. Hydrothermal Py3 and Apy1 are localized in the proximal pyrite–arsenopyrite–sericite–carbonate–quartz alteration in ore zones and make a major contribution to the economic value of the veinlet-disseminated mineralization with “invisible” gold in the orogenic deposits of the Yana–Kolyma metallogenic belt. Electron microprobe analysis (EMPA) of Py3 in both types of deposits shows concentrations of As (up to 3.16 wt%), Co, Ni, Cu, Sb, and Pb. Py3 in intrusion-hosted orogenic gold deposits reveals elevated concentrations of Co (up to 0.87 wt%), Ni (up to 3.52 wt%), and Cu (up to 2.31 wt%). The identified negative correlation between S and As indicates an isomorphic substitution of sulfur by As1−. Py3 from igneous rocks is characterized by a high degree of correlation for the pairs Fe2+→ Co2+ and Fe2+→ Ni2+. For hydrothermal Apy1, Co (up to 0.27 wt%), Ni (up to 0.30 wt%), Cu (up to 0.04 wt%), and Sb (up to 0.76 wt%) are typomorphic. According to atomic absorption spectrometry, the concentration of Au in Py3 reaches 159.5 ppm; in Apy1, it reaches 168.5 ppm. The determination of the precise site of the invisible gold within Py3 and Apy1 showed the predominance of solid-solution Au+ in the crystal lattice. The values of δ34S in Py3 and Apy1 (from −6.4 to +5.6‰, mean value of about +0.6‰), both from sediment-hosted and from intrusion-hosted deposits, display a relatively narrow range and are characteristic of the hydrothermal ore stage. Our analytical results showed no systematic differences between the chemical and stable sulfur isotope compositions of both auriferous pyrite-3 and arsenopyrite-1 from the proximal alteration in sediment-hosted (Malo–Taryn, Badran, Khangalas) and intrusion-hosted (V’yun, Shumniy) orogenic Au deposits, indicating that the primary source of sulfur, gold, and mineralizing fluids was likely from subcrustal and metamorphic systems in the Late-Jurassic-to-Early-Cretaceous Verkhoyansk–Kolyma orogen.

Apatite records metamorphic and hydrothermal fluid evolution at the large Shuangqishan orogenic gold deposit, SE China

Orogenic gold deposits are currently the world’s major source of Au, but uncertainty exists in the timing of mineralization relative to the ages of host rocks, metamorphism, and magmatism. Consequently, the origin and detailed evolution of ore-forming fluids have long been elusive. Apatite occurs widespread in various types of mineral deposits and can provide valuable information on ore genesis. Here, we present textural, high-precision in situ U-Pb geochronological, trace elements, and Sr isotope data for metamorphic and hydrothermal apatite in the Shuangqishan gold deposit in southeastern China. These data, together with U-Pb dates of metavolcanic host rocks, granitic and mafic intrusive rocks, allow us to precisely constrain the timing of mineralization and reconstruct the history of the ore-forming fluids there. The apatite crystals within metamorphic and auriferous quartz veins can be grouped into three generations according to cathodoluminescence imaging and trace element concentrations: Ap1 precipitated in the pre-mineralization metamorphic stage, whereas Ap2 and Ap3 formed in the auriferous hydrothermal stage. Metamorphic Ap1 displays a negative Eu anomaly, indicating a predominance of Eu2+ and crystallization under relatively reduced conditions. On the other hand, syn-gold hydrothermal Ap2 and Ap3 have marked positive Eu anomalies. Radiometric ages for metamorphic Ap1 are at ca. 461 Ma, whereas hydrothermal Ap2 and xenotime from auriferous quartz gave U-Pb ages of 425 ± 15 Ma and 416 ± 15 Ma, interpreted as the time of gold mineralization. Emplacement ages determined by U-Pb zircon data are 439 ± 2 Ma for granitic intrusion and 427 ± 2 Ma for a mafic dike in the mining district. Mineralization, therefore, postdates the metamorphism of local host rocks and granitic magmatism by ∼35 ± 24 m.y. and ∼14 ± 17 m.y., respectively. The synchronism of gold genesis and mafic magmatism provides additional evidence for a mantle derivation of the ore-forming fluids. The highly radiogenic 87Sr/86Sr ratios obtained for Ap1 (0.7178−0.7302) are consistent with its precipitation from a metamorphic fluid. Higher Sr concentrations (Ap2 = 1228−2884 ppm, Ap3 = 2325−3169 ppm) and positive Eu anomalies (Eu/Eu*: Ap2 = 1.03−2.84, Ap3 = 2.00−4.30) but lower and variable 87Sr/86Sr ratios in hydrothermal Ap2 (0.7100−0.7165) and Ap3 (0.7086−0.7116) are mainly ascribed to extensive fluid-wall rock exchange of Sr during mineralization. It is therefore suggested that fluid-rock reaction played a vital role in the observed positive Eu anomalies of hydrothermal apatite. Our study highlights the usefulness of apatite as a novel and robust geochronological, geochemical, and isotopic indicator of complex mineralization processes in hydrothermal gold deposits.

Origin and metal-enrichment mechanism of sedimentary rare earth element deposits in Yunnan and Guizhou provinces, western Yangtze Block, China

In southwest China, claystone layers occur in the lower part of the late Permian Xuanwei Formation, immediately overlying the Permian Emeishan flood basalts. The lowermost claystone layers are characterised by high contents of rare earth elements (REEs; 1100–16,000 ppm, average 2700 ppm), indicating a new type of REE deposit. However, the origin of this deposit and the enrichment mechanisms are unclear. We collected samples from 10 sections of the Xuanwei Formation, including REE-rich claystones, siltstones, iron claystones, and tuff. Detrital zircons gave U–Pb ages of 275–245 Ma, εHf(t) values of –16.7 to 8.9, and TDM2 model ages of 0.70–2.32 Ga. The field, petrological, geochemical, and isotopic data suggest: (i) the REE-rich claystones were deposited over 2.6 Myr in the period 257.22–254.62 Ma at a very low average rate of deposition (0.076–0.61 cm/ka), and (ii) the REE-rich claystones were derived from a region of denudation in the inner zone of the Emeishan Large Igneous Province, with the ore metals sourced mainly from syenite but with minor contributions from high-Ti basalts and felsic igneous rocks. The siltstones near the base of the Xuanwei Formation were derived mainly from felsic volcanic rocks with minor contributions from basalt. The iron-bearing claystones resulted from weathering of the Emeishan flood basalts. Our study shows a surface REE migration pattern of “weathering of REE-rich matrix → fluid migration → physical or chemical precipitation”, which is consistent with the origin of the REE-rich claystones.

Primary Exploration, Mining and Metal Supply Scenario (PEMMSS) model: Towards a stochastic understanding of the mineral discovery, mine development and co-product recovery requirements to meet demand in a low-carbon future

Existing scenario models of future material flows often exclude or place a ‘black-box’ around the mining industry and disregard important industry dynamics such as mineral exploration. This lack of sophistication prevents formation of knowledge required to answer key questions pertaining to future mining output, the amount of companion metals that can be supplied and the investments and lead times needed to fulfil future metal demand. To address this, we introduce the Primary Exploration, Mining and Metal Supply Scenario (PEMMSS) model, which allows for mine-by-mine modelling with full regionalisation and linkages to geological deposit types. PEMMSS allows for the assessment of required rates of mineral deposit discovery, mine development and co-product recovery overtime for a range of socio-economic and sustainable development linked primary material demand scenarios. The model can be calibrated using mineral resource grade, tonnage and density probability distribution functions for regions and deposit types to stochastically model scenarios for future greenfield discoveries and understand uncertainities. Applying PEMMSS will facilitate improved understanding of how future urbanisation across the globe and low-carbon transitions will translate into altered requirements for the exploration and primary mineral and metal supply sectors and their associated environmental impacts. A hypothetical case study is presented for a four co-product commodity system to highlight potential model behaviours and key drivers of model sensitivity.

Spatial-temporal distribution, metallogenic mechanisms and genetic types of nephrite jade deposits in China

The nephrite jade deposits of different tectonic units in China exert significant commercial quality, which have attracted wide attention. However, these deposits have not been systematically summarized to date. Here, we investigate the major nephrite jade deposits in China to decipher their gemological and mineralogical characteristics, spatial-temporal distribution, and mineralization processes as well as to identify their geological settings and gemological properties, via integrating published geochronology, major and trace elements as well as H-O isotopes. The compiled data suggest that the major nephrite jade deposits in China can also be generally divided into green jade-type (GJ-type) and white jade-type (WJ-type) which covers different species, but most of them belong to the latter. The GJ-type nephrite deposits predominantly occur in ophiolite/ophiolitic mélange suites or are embedded into ultramafic serpentine jade orebodies. This type of nephrite jade mainly formed through the late auto-metamorphic metasomatism of serpentine or the spontaneous crystallization/precipitation along suture/shear zones that acted as pathways to migrate Ca-rich fluids during orogeny. In contrast, the orebodies of WJ-type nephrite jade are usually hosted at the contact zones between the dolomitic marbles and intermediate-felsic or mafic intrusive rocks, which were produced through metamorphism-metasomatism during post continent-continent collision, such as the Kunlun orogenic belt with about ∼1,300 km Hetian nephrite belt, and the eastern nephrite jade deposits along the Pacific Ocean. Our study highlights that the nephrite jade deposits in China originally formed during multiple tectonic stages related to the interactions between hydrothermal fluids and metamorphism under subduction accretion- and collision orogenesis-related settings. In addition, this study also provides insights into the genetic discrimination, mineral exploration, and occurrence characteristics of nephrite jade deposits as well as the evaluation and identification of nephrite jade quality.

Sedimentologika: a community-driven diamond open access journal in sedimentology

Sedimentologika is a community-driven Diamond Open Access scientific journal for the publication of work in the broad area of sedimentology and stratigraphy. The journal aims to provide a platform to the academic community and broader society, offering and guaranteeing permanent free publication and free access to peer-reviewed scientific studies focusing on all types of sedimentary processes, deposits, and environments across all spatial and temporal scales, on Earth or any other planetary body. It will publish high-quality research that will advance the field of sedimentary science (through multidisciplinarity, new teaching practices, tools and methods, and progress in accessibility to science). Sedimentologika is part of an ongoing broader Diamond Open Access movement in geosciences aspiring freedom from the financial barriers and pressures of private publishing houses, to provide direct and equal access to science for all citizens, scientists, and institutions worldwide. The published material will include research, review, methodology and opinion articles, which will be free to share, as the authors will retain the copyright on all the submitted material. Manuscripts will be published in English. Authors can attach a second abstract in the language of their choice, further allowing local communities, students, or decisional bodies to access, at least, a summary of the latest research, thus reducing potential language barriers. Sedimentologika follows Open Science principles to promote ethical dissemination and accessibility of science and knowledge, following high equity, diversity and inclusion standards. Sedimentologika emerged as a solution for the scientific community to sidestep structural inequality of the academic publishing system that is becoming financially unsustainable to its payers (authors, funding agencies), and to commit to bibliodiversity. The objective is to ensure that scientific findings remain accessible to all in order to keep advancing research and informing society on how we understand sedimentology and stratigraphy in the world around us. Sedimentologika is driven by the academic and scientific community for the community and society, promoting self-governance and adapting to the needs expressed by the community.

First record of Jacobsoniidae (Coleoptera) on the African continent in Holocene copal from Tanzania: biogeography since the Cretaceous

Neither fossil nor living Jacobsoniidae are found in abundance. Derolathrus cavernicolus Peck, 2010 is recorded here preserved in Holocene copal from Tanzania with an age of 210 ± 30 BP years. This leads us to three interesting conclusions: (1) This is the first time the family was found on the African continent, extending the family’s distribution range to hitherto unknown localities. Derolathrus cavernicolus in Holocene copal from Tanzania expands the known distribution of the species, previously only recorded in the USA (Hawaii and Florida), Barbados, and Japan, both spatially and temporally. (2) All fossil specimens of the family have been found preserved in amber, which might be due to the small size of the specimens that prevents their discovery in other types of deposits. However, we here add a second aspect, namely the occurrence of this cryptic and currently scarce family of beetles in resinous environments, where they live in relationship with resin-producing trees. (3) The discovery of a new specimen from a family unknown on the African continent supports the relevance of these younger resins in preserving arthropods that lived in pre-Anthropocene times. Although we cannot demonstrate their extinction in the region, since it is possible that the family still survives in the already fragmented coastal forests of East Africa, we are detecting a loss of local biodiversity during the so-called Anthropocene, probably due to human activity.

Critical metals and minerals in the Nordic countries of Europe: diversity of mineralization and green energy potential

Abstract Europe relies mainly on imports of critical raw materials (CRMs) for its industry, not least the vital ones for emerging green energy technologies. Among the main metal and mineral producers in Europe today, the Nordic countries (specifically, Greenland, Norway, Sweden and Finland) share a diverse geology with various deposit types formed over a long geological time span. This has led to large near-future potential with regard to CRM production. Based on current knowledge and datasets, we assess the Nordic geological potential for CRMs that are specifically relevant for green technologies, namely cobalt, graphite, hafnium, lithium, niobium, platinum-group metals, rare earth elements (REEs), silicon, tantalum, titanium and vanadium, describing the most important deposits, their setting and characteristics. Several Nordic CRM resources stand out in a European and even global context, such as the giant REE(–Nb–Ta–Hf) deposits in Greenland, while the REE–Nb–(Hf) deposits at Fen (Norway) and Norra Kärr (Sweden) are very significant for Europe; Finland is the only major cobalt producer, while Norway has very significant graphite and titanium resources and production. Furthermore, Sweden, Finland and Greenland have very large vanadium resources. In addition, we conclude that the Nordic research and exploration potential for most CRMs is large.

Interaction Between Mineralization and Rock Magnetization: New Constraints From a Silurian‐Lower Devonian Volcanogenic Massive Sulfide (VMS) Deposit

AbstractThe unclear relationship between mineralization, hydrothermal alteration, and rock magnetization in volcanogenic massive sulfide (VMS) deposits limits us from fully understanding the magnetic anomalies and remagnetization process in this type of deposit. We address the issue by conducting systemic paleomagnetic, rock magnetic, petrographic, and X‐Ray diffraction studies in the Dapingzhang VMS deposit on the northwestern Indochina Block. Magnetite is the dominant magnetic carrier of hydrothermally altered surrounding rocks and orebody. Magnetite consumption and secondary magnetite formation occurred at different stages and types of hydrothermal alteration. The overall decrease in magnetite concentration from chloritization via silicification to mineralization implies that the magnetite was mostly consumed during hydrothermal alterations. Secondary single domain magnetite, which can carry a remagnetization direction, is proposed to be formed during illitization via the smectite‐to‐illite transformation. Secondary superparamagnetic magnetite, which was most likely formed during the late stage of chloritization, is unable to carry the stable characteristic remanent magnetization. The site‐mean direction of high‐temperature and high‐coercivity components is Dg/Ig = 324.5°/43.1°, and kg = 35.1, with α95 = 6.8° before tilt correction, and Ds/Is = 316.2°/37.6°, and ks = 16.4, with α95 = 10.1° after tilt correction, with a negative fold test. However, plate reconstruction is limited by the uncertainty of the tilting process following mineralization and the possibility of remagnetization during burial alteration. Therefore, this study provides a mechanism for rock magnetic variation and remagnetization during VMS mineralization.

Automatic Damage Segmentation Framework for Buried Sewer Pipes Based on Machine Vision: Case Study of Sewer Pipes in Zhengzhou, China

Aging buried sewer pipes are at risk of rupture, corrosion, scaling, and other damages, and they may cause urban waterlogging, road collapse, environmental pollution, and other urban safety problems. Therefore, it is very important to accurately detect and segment sewer pipe damages regularly for safety evaluation. This paper proposes an intelligent damage detection method to segment and measure five types of sewer pipe damages, namely, staggered joints, deposits, corrosion, scaling, and fracture, leveraging a fine-tuned fully convolutional network (FCN) algorithm. A case study on Zhengzhou’s sewer pipes is conducted. Then, a dataset of 3,558 images is built, and the images are collected from Zhengzhou’s sewer pipes. Subsequently, the encoder of the FCN is replaced with a pretrained VGG-19, and the upsampling part has spatial and channel squeeze and excitation (SCSE) modules added. The evaluation matrix of the pixel accuracy (PA), mean pixel accuracy (MPA), mean intersection over union (MIoU), and frequency weighted intersection over union (FWIoU) of the proposed method is 91.42%, 81.44%, 73.65%, and 87.16%, respectively. Subsequently, damage areas are measured at a pixel level to quantify the pipe damage. Compared with the existing mask region-based convolutional neural networks (RCNN) method, the proposed FCN-based method shows effective performance for multiple and similar sewer pipe damage detection under complex backgrounds. Moreover, a real-time damage detection platform for sewer pipes is proposed, realizing the data uploading, data storage, data analysis, and data visualization.

Grain Shape Evolution of Sand‐Sized Sediments During Transport From Mountains to Dune Fields

AbstractGrain shape is used less frequently in identifying the origin of sediments than grain size distributions and/or surface microtextures because of technological limitations. In addition, systematic studies on grain shape change of sand‐sized sediments from a source‐to‐sink perspective are lacking, and yet the evolutionary mechanism of grain shape along the sediment transport pathway remains poorly understood. Here, we investigated grain shape changes in sand‐sized sediments ranging from mountains to dune fields using an efficient and quantitative dynamic image analysis technique. By means of the detailed hydro‐geomorphic analysis and field sampling in a quasi‐closed sedimentary system, we collected 41 samples from the Hulunbeier Sandy Land (HSL) in northern China and its potential source region. Also, 21 typical fluvial deposit samples from different river systems in China were collected for comparison. We identify that the sphericity, symmetry, aspect ratio, and mineralogical maturity of the fluvial deposits from mountains are significantly lower than the eolian sand in dune fields. Despite the apparent inheritance of sediments from the mountains to the dune fields, the abrupt changes in the sedimentological and geochemical properties along their pathway suggest that multiple cycles of eolian abrasion within the HSL modify the sediments significantly after they are transported away from the fluvial environments. The well‐defined separation between eolian sand and fluvial deposits by grain shape parameters such as sphericity and symmetry underscores that grain shape can be a powerful tool for tracing sediment transport history in paleoenvironmental or extraterrestrial studies.

A Geo-Data Science Method for Assessing Unconventional Rare-Earth Element Resources in Sedimentary Systems

Rare-earth elements (REEs) supply raw materials that constitute many of our modern critical infrastructure, defense, technology, and electrification needs. Despite REE accumulations occurring in conventional bedrock and ion-adsorption deposits sourced from weathering of igneous rocks, unconventional host materials such as coal and related sedimentary strata have been identified as promising sources of REEs to meet growing demand. To maximize the potential of unconventional resources such as REE-coal systems, new approaches are needed overcome challenges from mineral systems with no known deposits and areas with sparse geochemical data. This article presents a systematic knowledge-data resource assessment method for predicting and identifying REE resource potential and occurrence in these unconventional systems. The method utilizes a geologic and geospatial knowledge-data approach informed and guided by REE accumulation mechanisms to systematically assess and identify areas of higher enrichment. An assessment of the Powder River Basin is presented as a test case to demonstrate the method workflow and results. The key output is a potential enrichment score map reported with varying confidence levels based on the amount of supporting evidence. Results from the test case indicate several locations with promising potential for different types of coal-REE deposits, demonstrating the viability of the method for exploration and assessment of unconventional REE resources. The method is flexible by design and, with sufficient applicable knowledge and data, can be adapted for assessing critical mineral systems in other sedimentary systems as well.

Quaternary palaeoecology and the historic environment: Challenges and opportunities for preserving England's wetlands

Palaeoecological records can provide important information on past cultural and economic activities and landscape change. Wetland sites in particular provide remarkable depository opportunities for such remains. Yet these deposit and site types are often not fully appreciated and are undervalued in terms of their place in our culture and history. This article explores reasons for this and suggests ways in which better collaboration between disciplines and sectors can be achieved. We also highlight the work that Historic England has been carrying out and funding, signposting the organisation's publications and guidance. In doing so, we demonstrate that Historic England is an advocate of wetlands and their heritage values, and is concerned with their protection, rather than only historic buildings, scheduled monuments and other designated sites, as it is commonly perceived. Through this we hope to establish partnerships and develop networks across sectors with those who are interested in wetlands, leading to better integrated working practices.

An Insight into Investment and Deposit Products Offered by Islamic Banks in Malaysia

The aim of this paper is to understand the practical application of investment and deposit products in comparison with the guidelines offered by the Islamic Financial Services Act (IFSA). Here, the products’ features and benefits of the banks’ deposit and investment products are highlighted. A performance analysis of both products is conducted among different banks in Malaysia, and their results are used to draw conclusions on the effects of IFSA on banks. The data was based on two banks in Malaysia: one was a fully-fledged Islamic bank, and the other was a subsidiary bank offering Islamic banking products. The information was obtained from the banks’ websites, annual reports, and Bank Negara Malaysia’s (BNM) website. The findings of the research are that the two banks analyzed all conform to the guidelines issued by IFSA. The volumes of investment products have significantly decreased after the introduction of IFSA compared to the volumes of deposit products. Bank Islam and CIMB Islamic both provide items that are suitable for use with an IFSA. Customers have a thorough understanding of the benefits of various types of deposits and investments.

Spatial Relationship between Eclogite and Copper-Nickel Mineralization in East Kunlun, China

In recent years, Cu-Ni deposits have been discovered at different localities in the Eastern part of the Kunlun orogenic belt such as Xiarihamu, Langmuri, Shitoukengde, and Wenquan. Eclogites are usually exposed in the areas associated with these deposits, thereby implying a certain coupling relationship between the Cu-Ni deposits and eclogite distribution. In this study, eclogite samples from the Xiarihamu and Langmuri areas were analyzed using petrogeochemistry, U-Pb zircon geochronology, and electron probe microanalysis (EPMA). Further, eclogite protolith properties, the formation environment, and the metallogenic mechanism were also investigated. Geochemically, eclogite is rich in MgO and FeO and low in alkali and SiO2. Its m/f ratios are 0.72 to 1.53 and Mg# values of 42 to 61. Overall, the chondrite-normalized rare-earth elements (REE) patterns showed characteristics of weak enrichment with LREE, weak negative Eu anomalies, relative enrichment of large-ion lithophile elements such as K and Rb, active incompatible element Th, the depletion of high-field strength elements Nb, Ta, Zr, and Hf, and V-shaped valleys caused by depletion in Sr, P, and Ti. These geochemical characteristics indicated that the protolith is highly differentiated Fe gabbro that formed in a continental margin type of rift environment. The EPMA analyses showed that the composition of garnet consists of almandite and grossularite, and omphacite often contains augite. Geochronological investigations showed that the peak metamorphic age of eclogite in Xiarihamu and Langmuri is 415.6 ± 2.7 Ma (MSWD = 0.43, n = 16) and 449.1 ± 8.5 Ma (MSWD = 0.88, n = 19), which are related to the early Paleozoic orogenic cycle and formed slightly earlier than the formation of the magmatic liquation type of Cu-Ni deposits in this area. On the basis of spatial coupling, formation age approximation, and geochemical correlation between eclogite and mafic rock masses, in combination with the previous research results of earlier work, it has been considered that the Cu-Ni ore deposits in the East Kunlun Range were formed in the post-collisional extension environment after the deep subduction of the continental crust. The ultra-high-pressure metamorphic melange formed by continental deep subduction or the enriched mantle formed by crust-mantle metasomatism was partially melted to form sulfur-rich mafic–ultramafic magmas in the post-collision extension environment. During the deep subduction of the continental crust, a large amount of crust-derived sulfur was brought into the mantle, which is the key factor for the mineralization of Cu-Ni ore in the region.

Study of the Deposition Characteristics of Particles on the Slag Wall of a Gasifier

In this work, the behavior of coal char particles adhering to the slag wall was studied. The effects of slag thickness and particle size on the restitution coefficient and probability of deposition were mainly discussed. In addition, the types of particle deposition were also classified. The results of exploring the effect of particle size on the coefficient of restitution show that the restitution coefficient of coal char particles hitting the slag wall surface has a complex dimensional effect, with a maximum and minimum coefficient of restitution occurring at the same particle size, a phenomenon referred to in this paper as the discrete effect. The minimum restitution coefficient greater than 0 is regarded as the critical restitution coefficient (εf), and it is considered that particles with theoretical restitution coefficient higher than εf will bounce off the slag wall. With the particle diameter of 600 μm as the boundary, εf first decreases and then increases. The maximum restitution coefficient increases with an increasing particle size of less than 600 μm and stays at a maximum value of 0.62 when the particle size is more than 600 μm. Moreover, the fragmentation of particles occurs at the particle size of 840–1600 μm. The discrete effect was also observed in the experimental data for the investigation of slag thickness, εf increases with the increase of the slag thickness, and the maximum possible restitution coefficient does not change with the thickness of the slag. In addition, according to the statistics of the deposition probability, it is found that the smaller the particle size, the greater the deposition probability, the thicker the slag thickness, and the easier it is to deposit.