Characteristics Of Deposits Research Articles

Sedimentary exhalative Pb-Zn deposit model of the Ban Lin – Phia Dam ore range, Vietnam

Purpose. The aim of this study is to construct a typical ore model for Pb-Zn ore range in Ban Lin – Phia Dam and to compare it with the existing ones. The model is constructed based on three main elements of the mineral generation process, such as formation environment, generated-ore fluid source, and deposited-ore mechanism. The obtained results are aimed at determining and predicting the resource of sedimentary exhalative (SEDEX) Pb-Zn ore deposit in Vietnam. Methods. To comprehend the characteristics of the SEDEX Pb-Zn ore deposits in the Ban Lin – Phia Dam area, we employ a combination of approaches that include mineralography to determine the composition and tectonic structure of rocks and ore, inclusion analysis to determine the temperature and inclusion composition, Pb isotopic analysis and stable S isotopic analysis to explore the environment and sources of ore-forming materials. Findings. The sedimentary exhalative (SEDEX) Pb-Zn ore deposit arises from the dissolution of metal-rich salt deposits due to heating at shallow depths (several kilometers). Subsequently, this fluid migrates through faults and fractures to preferred locations where galena and sphalerite precipitate alongside sedimentary basin deposition. Originality. SEDEX ore deposits have been extensively studied in various regions of the world. Although there are multiple theories regarding their origin, including explosion, biological debris accumulation, and surface replacement, each model has its own distinct advantages and limitations in explaining the genesis and development of SEDEX ore deposits. Practical implications. The acquired findings are intended to identify and predict the resources of sedimentary exhalative Pb-Zn ore deposits in Vietnam.

Characteristics of Lithium Deposits in Mongolia

Characteristics of Lithium Deposits in Mongolia

Comparative Study of the Coastal Geomorphology of Kajirbhati Sand-Spit Using Google Earth Pro Images (2005, 2011, 2023) and Landsat Satellite Data (2009, 2016, 2023): An Approach Towards the Impact of the Casuarina Plantation

Coastal geomorphology undergoes constant transformation due to a combination of coastal and fluvial processes and human intervention. Remote sensing and GIS tools are invaluable in identifying and studying these changes. Due to the dynamic interaction between land and sea, the coastline requires careful monitoring to detect hotspots and understand the spatial and temporal impacts of climate change on the coastal environment. Remote sensing data offers a comprehensive means of studying coastal landform changes. In a recent study, the focus was to analyze the impact of the Casuarina plantation on the coastal geomorphology of Kajirbhati spit. This involved studying various depositional features such as sand bars, sand spits, dunes, and beaches. The study utilized Google Earth Pro images from 2005, 2011, and 2023 to digitize 13 classes each year, enabling the identification of changing geomorphic classes. These include agriculture, swash zones, dunes on sand spits, berm lines, Casuarina and coconut plantations, estuary, mangroves, mudflats, open land, sea, settlement, and vegetation. The results revealed dramatic changes in land use and land cover classes from 2005 to 2023. In the years from 2011 to 2023, the area of sandspit covered by Casuarina plants expanded rapidly. To analyze the changes, Landsat 5, 8, and 9 data were used to check the intensity of NDVI (Normalized Difference Vegetation Index) in 2009, 2016, and 2023. NDVI is a critical factor in this research. The mean NDVI values for 2009, 2016, and 2023 were -0.002, 0.02, and 0.04 respectively. The changes in higher NDVI values from 2009 to 2023 were -0.10, 0.27, and 0.28, while the lower values were -0.10, -0.10, and -0.07 for the same years. The correlation calculation between the mean NDVI values and the years indicates a strong positive correlation with an R-value of 0.99. Casuarina plants play a crucial role in protecting the coast from strong winds and dynamic sea waves. They help protect mudflats, mangroves, settlements, and estuary land use and cover classes along the coast of Kajirbhati.

Genesis of Yongping copper deposit in the Qin-Hang Metallogenic Belt, SE China: Insights from sulfide geochemistry and sulfur isotopic data

Yongping copper deposit is a large-scale polymetallic mine that contains 1.6 Mt of proven Cu metal reserves with an average grade of 0.74 % and contributes significantly to China’s production of copper. This deposit is situated in the eastern part of the Qin-Hang Metallogenic Belt (Jiangxi province, SE China) at the contact zone between the Yangtze Cu–Mo metallogenic belt and the Jiangxi W–Sn–REE metallogenic belt. The thick stratiform and lenticular-shaped orebodies are hosted in the Carboniferous Yejiawan Formation, consisting of sandstone, limestone, mudstone, and chert-rich clastic rocks. Dominant metal-bearing minerals are chalcopyrite and pyrite with a minor amount of sphalerite, tetrahedrite, galena, molybdenite, pyrrhotite, magnetite, hematite, and scheelite. Although intensive research has been done on its geological setting, geochemical characteristics, and geodynamic evolution over the past thirty years, the origin and depositional environments have remained controversial. In the current research, in situ trace element geochemistry and sulfur isotope analyses, coupled with microscopic investigation, were conducted on sulfide minerals using the LA-ICP-MS technique. The results display that Yongping pyrite rich in Co, As, Ni, Zn, Cu, and Te and deplete in other trace elements. Sphalerite rich in Fe, Mn, Cu, and Cd, followed by In, Co and Ga. The calculation results of formula T(°C) = (Fe/Zn + 0.2953)/(0.0013) reveal that sphalerite was formed in medium–high temperature conditions (262 °C–377 °C). The δ34SV-CDT values of studied sulfides (pyrite, chalcopyrite, sphalerite, and tetrahedrite) varied from −1.52 ‰ to 5.13 ‰ with an average of 2.36 ‰, which are highly consistent with those recorded from porphyritic biotite granite stock of Shizitou (from 2.20 ‰ to 4.5 ‰), suggesting a dominantly magmatic origin. Collectively, trace element compositions of analyzed sphalerite and pyrite from the Yongping area exhibit characteristics of typical skarn deposits. Combined with previous studies, we can conclude that the Yongping Cu deposit is a skarn deposit that was most likely formed by contact metasomatism after the intrusion of the Jurassic Huoshaogang-Shizitou granitic stock into the Carboniferous Yejiawan Formation.

Classification of volcanogenic massive sulfide deposits in North Qilian, China: Evidenced from lithostratigraphy and geodynamic setting

Volcanogenic massive sulfide (VMS) deposits are widely distributed both geographically and temporally, occurring from ancient Archean cratons to modern submarine volcanic environments, with a notable surge during the Paleozoic era. The North Qilian orogenic belt in China is a prominent Paleozoic VMS metallogenic province, shaped by complex geological processes such as the opening of the Qilian Ocean, oceanic subduction, and arc-continent collision. Previous research has constrained the timing of VMS mineralization in the North Qilian to between 440 and 470 Ma, identifying two primary deposit types: Kuroko-type and Cyprus-type. However, ongoing debates persist regarding the classification and geodynamic framework of these VMS deposits. The recent surge in international research on VMS deposit classification and tectonic settings has prompted a reassessment of VMS mineralization within the North Qilian belt. This study revisits the geological and geochemical characteristics of VMS deposits in the region, identifying two distinct types: Mafic VMS deposits and Bimodal-Felsic VMS deposits. Furthermore, the metallogenic dynamics of the Shijuli, Jiugequan, and Baiyinchang deposits have been re-evaluated in the context of the structural evolution and contemporary interpretations in this area.

Wax Deposition of Diesel Oil and Consequent Contamination of Gasoline in Sequential Transportation of Product Oil Pipeline

Wax deposition of diesel oil and contamination of gasoline by diesel wax deposit is a severe problem in sequential transportation of product oil in pipes. However, it has long been neglected by the pipeline transportation industry. In response, this work aims to present a unique perspective on wax deposition of diesel oil and consequent contamination of gasoline. A cold finger apparatus was designed and constructed. Model oil composed of diesel and refined wax was prepared for wax deposition. Shear dispersion was excluded for wax deposition of diesel oil. Moreover, dissolution experiments of diesel wax deposit in gasoline were conducted. It was found that the dissolution rate increases with oil temperature and decreases with cold finger temperature and shear stress. Analysis on gasoline quality after diesel wax deposit dissolution indicated that contamination of gasoline caused by diesel wax deposit severely deteriorates its distillation range, but the octane number remains acceptable. This work features an interesting investigation on the wax-deposition mechanism of diesel oil, dissolution characteristics of diesel wax deposit, as well as quality deterioration of subsequent gasoline. It would be helpful in scheduling a product oil-transportation program.

Sedimentary dynamics and depositional model for mud accumulation in deep lake basins: A case study in the Upper Triassic Chang-7 Member, Ordos Basin, northern China

Shales in deep lake basins have become the main focus of continental shale oil and gas exploration. In order to highlight the sedimentary dynamics of mud deposition in deep lake basins, a combination of core observation, thin section examination, X-ray diffraction, and QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy) was used to analyze the depositional characteristics of mudrocks in the Chang-7 Member from the Yanchang Formation (Upper Triassic) in Ordos Basin, and to establish a depositional model for mud accumulation in deep lake basins. This study recognizes four mudrock lithofacies in the Chang-7 Member: (1) the laminated silt-bearing mudstone, which generally develops a binary composition of “silt–clay” or a ternary composition of “silt–clay–organic matter”; (2) the graded mudstone, mainly composed of dark gray and gray-black mudstone sandwiched by silt-bearing mudstone; (3) the massive mudstone, internally showing a uniform distribution of quartz, clay, and carbonate minerals, with also a small amount of organic detritus; and (4) the laminated shale, which is generally composed of clay laminae, and organic laminae of the former two. Sediment supply, topographic slope, and flood intensity combine to control the evolution of gravity flows and the transport and deposition of the mudrock in the Chang-7 Member. The influence of orogeny provides terrain gradient, water depth, abundant sediments at source areas, and triggering mechanism for the formation of gravity flows. Floods triggered by wetting events provide the impetus for sediment transport. Mud deposition in the Chang-7 Member was mainly related to the transport and sedimentation of mud by hyperpycnal flows and rapid sedimentation by buoyant plume flocculation. A comprehensive evolutionary model for shale accumulation in the deep lake basin is established by integrating various triggering mechanisms and mud transport sedimentary processes.

Evidence of a Large Debris Avalanche Event (22.0 Ma) from the Comondú Group on the Baja California Sur Peninsula, Mexico

The morphological, sedimentological, and microtextural characteristics of Miocene debris avalanche deposits which extend from the Punta Coyote to the vicinity of the city of La Paz, were studied along the eastern of the Baja California Peninsula. The debris avalanche deposits studied include a mixture of angular mega blocks whose composition comes from the deposits that make up the Comondú Group: pre-Comondú (red sandstones and conglomerates with intercalated ignimbrites), the Upper Unit (brownish sandstones, shales, and conglomerate), and breccia, with a predominance of jigsaw cracks, injection structures, and fault structures. These deposits were studied and analyzed considering the stratigraphic relationships between the rock formations present in the mega-blocks. Six stratigraphic sections were measured to describe the composition and morphology of the clastic components present in the mega-blocks of the debris avalanche. Two different units (m1 and m2), were identified in the debris avalanche deposits. Unit m1 is the oldest, with a thickness of 100m, and consists of a chaotic set of mega-blocks up to 100 m in diameter derived from the pre-Comondú Group, and Upper Unit. The deposits are highly heterolithic, with angular and highly fractured clasts at different scales. While the unit m2 consists principally of 20-100 m thick volcaniclastic layers dominated by poorly sorted, breccias and minor epiclastic deposits. According to stratigraphic relationships, the collapse occurred at 22.0 Ma. The debris deposit covers an area of 150 km2 and has an estimated volume of 1.3 km3. The characteristic suggests a transport mechanism with a disintegration of the mega-blocks and a contact/collision interaction. Where mega-blocks moved within a dense flow in a buffered manner, remaining consistent over long distances. The observed structures and textures suggest that the mega-blocks were mainly produced by the alteration and ingestion of older substrates by the avalanche of moving debris. The avalanche flowed over pre-existing topography excavated in the Comondú Group sequence, and flow indicators reveal a west-southwest direction, exhibiting a typical mountainous avalanche topography. The study of ancient debris avalanche events not only provides a deeper understanding of these natural phenomena but also contributes to the development of tools to predict, mitigate, and manage risk areas.

Research on Sediment Deposition Characteristics and the Vegetation Restoration of Ecological Riverbanks in the Deep Waterway Regulation Scheme of Yangtze River

In order to explore the sediment deposition characteristic of ecological riverbanks associated with vegetation restoration in the deep waterway regulation scheme of Yangtze River, two kinds of typical ecological riverbanks and a traditional riprap riverbank (TRR) in engineering areas were investigated. The vegetation community characteristics, sediment aggregate compositions, nutrient contents, total organic carbon (TOC), sediment microbial biomass carbon (MBC), sediment microbial biomass nitrogen (MBN), and sediment microbial biomass phosphorus (MBP) were determined. The results indicated that the ecological restoration effect of the lattice gabion ballasted vegetation mat riverbank (LGBVR) was best, followed by the mesh grid riverbank (MGR), and that of the TRR was relatively poor. In different ecological riverbanks, the sediment aggregated compositions were not significantly varied. The sediment contents of NH4+-N, available phosphorus (AP), and TOC in ecological riverbank areas were relatively higher than those of the TRR. In the LGBVR, the sediment contents of MBC were relatively higher than those of the others. The sediment deposition characteristics and ecological restoration effects in the study area should be monitored for a long time.

A global database of tsunami deposits

AbstractGeomorphic environments play a crucial role in influencing the preservation and characteristics of tsunami deposits. This paper introduces a global database of tsunami deposits, encompassing information on deposit locations, thematic data such as geomorphic environments and proxies and bibliographic details. Additionally, the database features maps incorporating environmental parameters and the precise locations of tsunami deposits. The primary utility of this database lies in assessing progress and identifying gaps in knowledge. It also involves analysing the relationship between environmental parameters and interpreting areas with varying probabilities of tsunami deposit preservation. The files are readily compatible with GIS software and can seamlessly integrate into spatial databases associated with tsunamis or other hazards. This contributes significantly to disaster risk management, enhancing preparedness and response efforts by providing a comprehensive historical dataset on tsunamis. Future applications of the database include the incorporation of modern deposits, boulders and new data from paleotsunami and historical studies. By enhancing data with thematic information, such as dating techniques and creating timelines, the database facilitates a more comprehensive understanding. The correlation between geomorphic environments and proxies aids in selecting sampling sites and identifying suitable proxies for analysis. Encouraging an open‐access approach, this database invites all interested researchers to include and modify additional information. The information compiled for this database serves multiple purposes: (1) assessing the global distribution of tsunami deposits; (2) identifying knowledge gaps in tsunami deposits; (3) guiding the selection of study areas for further research and finally; (4) enabling a meta‐analysis of the information gathered.

Experimental Investigation of Sulfur and Nitrogen Oxide Emissions and Corrosion Propensity During the Combustion of Coals and Biomass Fuels

ABSTRACT The increasing use of biomass in Indonesian coal-fired power plants, mainly through co-firing, presents challenges due to different fuel characteristics, which can affect gas emissions, ash deposition, and combustion efficiency. This study assesses flue gas emissions (SO2 and NOx) and corrosion tendencies of various biomass types and coal. The study begins with characteristic testing and ash analysis of coal and biomass samples, including proximate, ultimate, and calorific value analyses, to determine their suitability as fuels. Preliminary calculations predict flue gas emissions and ash deposit formation, followed by laboratory-scale combustion experiments using a DTF to assess flue gas and ash deposit characteristics. The results show that sulfur in biomass is converted to the gas phase up to 99%, while in coal, it is converted up to 95% at high temperatures. NOx levels are primarily affected by the nitrogen contents of the fuels; for instance, Coal-B at 0.88 wt% produces less NOx than solid recovered fuel (SRF) and refused derived fuel (RDF) with 1.73 wt% and 1.51 wt%, respectively, yet still generates higher emissions than the other three biomass types. In general, wood chips (WC), rise husk (RH), and palm kernel shell (PKS) emit 30–80% less flue gas compared to coal. However, ash deposition results indicate that PKS, SRF, and RDF exhibit corrosion tendencies due to the dominance of albite (NaAlSi3O8) in the mineral phase. Additionally, the high chlorine content in SRF (0.544 wt%) and RDF (0.224 wt%) leads to the formation of sticky ash deposits, which potentially impact heat transfer surfaces. These findings contribute to identifying suitable biomass types for both co-firing or dedicated combustion in coal-fired power plants.

Audio magnetotelluric view of the giant carbonatite-hosted Bayan Obo REE deposit, Inner Mongolia, northern China

As critical minerals in low-carbon economies, rare-earth elements (REEs) are crucial for modern industry, technology, and medicine. The largest known REE resource in the world is the Bayan Obo (BO) deposit in northern China. However, BO features as complicated mineral compositions and has experienced several geological events. As a reuslt, controversy remains about the BO REE genesis and enrichment mechanism, and debates are also ongoing about the controlling structure of this giant deposit. We carried out an multiscale electromagnetism study on BO mineral deposits. The multiscale study consists a microscale on samples, a small scale targeting mineral deposits and a mid scale concerning the mine field. The small and mid scale study were conducted using audio-magnetotelluric (AMT). This study revealed the controlling structure using geoelectrical characteristics. AMT data were acquired from more than 590 stations, and the petro-electromagnetism of several samples was analyzed to understand the geoelectrical features of the ore deposits and their surrounding rocks. The data were interpreted using Bostick transformation and generalized least-squares inversions. We obtained the geoelectrical structure of the BO complex down to a maximum depth of 3500 m, and we present two-dimensional imaging based on the AMT conversion results. The results show that the BO deposit developed at the transition of the high- and low-resistivity geoelectrical structure from south to north. Our AMT results indicate that the tectonic setting of the BO deposit is the transition zone between the rift edge and craton margin slope. The ore geology is presently controlled by the complex slope and the rift remnant, the ore-bearing dolostone in the profiles is Y-shaped. It goes downward from south to north and potentially features a great mineral prospect deep in the BO deposit.

Case study of a cluster of simple and complex monogenetic volcanoes in the north‐east part of the Michoacan–Guanajuato Volcanic Field, Central Mexico: Nomenclature implications

With the advent of new terminologies to categorize and characterize the simple and complex monogenetic volcanoes, also came the semantic issues, which caused a predicament for the usage of terms like simple, complex, polycyclic, polymagmatic, complex monogenetic volcanoes with polygenetic inheritance. To analyse and validate this nomenclature, we studied an overlapping volcanic structure located south of the present‐day town of Irapuato, Central Mexico, that appears to be a monogenetic complex at first sight. Field observations, tephra stratigraphy, petrography and geochemistry of the tephra deposits confirms that the structure is in fact a cluster of three simple (San Joaquin tuff ring and two scoria mounds) and one complex, polycyclic, polymagmatic (La Sanabria‐San Roque tuff ring) monogenetic volcanoes formed by independent events, governed by distinct conduits and magma bodies of different origin (subduction‐related, OIB and E‐MORB origin) and separated by different tephra sequences of dissimilar components and depositional characteristics. We estimate the magma volumes (using the juvenile content and their vesicularity percentage) to be at 0.40–1.31 × 108, 0.25 × 108 and 0.42–0.90 × 108 m3 for San Joaquin, La Sanabria and San Roque, reckoning an eruption duration of 77 and 48 and 81 days, respectively (considering an average eruption rate of 6 m3/s from the well‐documented shallow crater (<30 m), Ukinrek maars in Alaska) occurring within the age range of 40–70 k years (crater diameter and depth ratio). This study not only aided to validate the above‐mentioned terms for monogenetic volcanoes, but also reconsider a few of them and avoid confusion with the polygenetic counterparts.

Deterministic modelling for driving factors of mineralization in Shanggong gold deposit (China)

1. Three-dimensional (3D) deterministic modeling is crucial for analyzing the controlling factors of mineralization. The Shanggong gold deposit, situated in the southern margin of North China Craton, represents a magmatic hydrothermal deposit. To construct the 3D deterministic model, boreholes, cross-sections, and geochemistry assays are integrated based on the geological characteristics of the Shanggong gold deposit. This paper summarizes its contents as follows: 1) GoCAD software can be utilized to build a 3D geology model encompassing faults and ore bodies; 2) Geostatistics and discrete smooth interpolation (DSI) can be employed to create a 3D attribute model involving grade and Au/Pb ratio. The findings reveal that: 1) High-value zones are associated with NE and NNE trending cross faults; 2) Deterministic modeling, such as grade model and Au/Pb ratio model, effectively elucidates the metallogenic process mechanism.

Uncertainty Quantification in Mineral Resource Estimation

AbstractMineral resources are estimated to establish potential orebody with acceptable quality (grade) and quantity (tonnage) to validate investment. Estimating mineral resources is associated with uncertainty from sampling, geological heterogeneity, shortage of knowledge and application of mathematical models at sampled and unsampled locations. The uncertainty causes overestimation or underestimation of mineral deposit quality and/or quantity, affecting the anticipated value of a mining project. Therefore, uncertainty is assessed to avoid any likely risks, establish areas more prone to uncertainty and allocate resources to scale down potential consequences. Kriging, probabilistic, geostatistical simulation and machine learning methods are used to estimate mineral resources and assess uncertainty, and their applicability depends on deposit characteristics, amount of data available and expertise of technical personnel. These methods are scattered in the literature making them challenging to access when needed for uncertainty quantification. Therefore, this review aims to compile information about uncertainties in mineral resource estimation scatted in the literature and develop a knowledge base of methodologies for uncertainty quantification. In addition, mineral resource estimation comprises different interdependent steps, in and through which uncertainty accumulates and propagates toward the final estimate. Hence, this review demonstrates stepwise uncertainty propagation and assessment through various phases of the estimation process. This can broaden knowledge about mineral resource estimation and uncertainty assessment in each step and increase the accuracy of mineral resource estimates and mining project viability.

Accumulation of Environmental Radioactivity on the Surface of a High Arctic Ice Cap (Flade Isblink, NE Greenland).

Under climatic warming, glaciers are becoming a secondary source of atmospheric contaminants originally released into the environment decades ago. This phenomenon has been well-documented for glaciers near emission sources. However, less is known about polar ice sheets and ice caps. Radionuclides are one of the contaminants that can be remobilised through ice melting and accumulate in cryoconite material on the surface of glaciers. To understand the cycling of radionuclides in polar glacial contexts, we evaluate the radioactivity of cryoconite samples from Flade Isblink, a High Arctic ice cap in northeast Greenland. The measured radioactivity is among the highest reported across the High Arctic and the highest from Greenland. The high variability observed among the samples is explained by considering the different macroscopic features of single cryoconite deposits. The radioactivity source is compatible with the stratospheric reservoir established during atmospheric nuclear tests and with weapons-grade fissile fuel, likely originating from Novaya Zemlya proving grounds. This study shows that the ability of cryoconite to accumulate radioactivity in remote areas is undisputed, highlighting the need for a deeper understanding of the remobilisation of radioactive species in polar glacial contexts.

The characteristics of modern flood deposits in the lower reaches of a small watershed and the significance of paleo-flood identification

The mountainous region of central Shandong Province in eastern China is renowned for its high frequency of rainstorms, which often result in devastating flood disasters and have profoundly affected the evolution of local ancient civilizations. To identify ancient flood disaster events, recognizing sediment signatures via multiple indices is important. Here, we investigated the 2018 flood deposits in the Danhe River Basin and sampled short core DH2, on which the grain size, total organic matter (TOM) content, carbonate content, magnetic susceptibility (MS) and pollen were measured. The fine grain size of the flood sedimentary layer reveals that the flood energy in the alluvial plain area is usually weak. The pollen species and concentration and the tree pollen content in the flood layer are significantly greater than those in the soil layer, suggesting that the flood sediment mainly originates from the mountainous areas in the upper reaches of the river, which provides more forest vegetation information. The MS of flood deposits is lower than that of the soil layer, which is mainly related to the intensity of pedogenesis. The research results indicate that the flood sediments in the downstream floodplain areas of small watersheds are predominantly composed of fine-grained components, with characteristics of high loss on ignition, low magnetic susceptibility, high pollen abundance and diverse species. These findings establish a multi-index identification system for paleoflood sedimentation, which has important reference significance for the study of paleoflood sedimentology and hydrology.

Architecture and dynamics of Precambrian linear megadunes: Galho do Miguel Formation, Mesoproterozoic, South-East Brazil

Recognizing the deposits of linear megadunes in ancient aeolian successions is challenging when the original bedform topography is not preserved. The present study provides a detailed analysis of the depositional architecture of an ∼ 80 m-thick interval of the Mesoproterozoic Galho do Miguel Formation (SE Brazil) to reconstruct the original morphologies of linear megadunes and to understand their dynamics. The depositional architecture reveals compound cross-bedded sets, which transition laterally into thick low-angle cross-stratified sets and planar-parallel sandstone beds. The depositional features indicate the presence of complex megadunes separated by adjoining wide dry inter-megadune areas, which were themselves flooded seasonally by a water table that rose above the depositional surface. Linear megadunes experienced two phases of development: vertical accretion and subsequent episode of lateral migration. During the vertical accretion phase, high sediment supply, typical of Precambrian aeolian systems, and the convergence of winds from two distinct directions promoted high rates of megadune growth, bedform elongation, and the formation of superimposed dunes. The lateral migration phase was characterised by a component of lateral bedform shift relative to the main along-crest sediment transport direction; this prevented preservation of a bimodal pattern of dune cross-strata azimuths. The accumulation of these deposits occurred via a combination of megadune climbing that occurred with progressive rise of the water-table level. The water-table rise hindered cannibalization of the lower parts of the migrating megadunes, allowing the accumulation and subsequent preservation of megadune sandstone packages. The rise of the water table was also responsible for the accumulation of thick dry inter-megadune strata. The unusual thickness of linear megadune and inter-megadune deposits of the Galho do Miguel Formation, as compared with Phanerozoic examples, are attributed to the interplay between the barren conditions of the early Earth, the morphodynamics of the linear megadunes, and the seasonal impact of the water table at the accumulation surface. Without a water-table control, opportunities for megadune accumulation and preservation were likely limited in Precambrian ergs.

Ambient noise tomography of an iron-oxide copper–gold (IOCG) deposit under thick cover

As most outcropping and shallow mineral deposits have been found, new technology is imperative to finding the hidden critical mineral deposits required for the renewable energy transition. One such seismic technique, called ambient noise tomography (ANT), has shown promise in recent years as a low cost and low environmental impact passive method of three-dimensional (3D) imaging of shear-wave velocity structure of the Earth. Over the last twenty years the method has been well-established in academia to image crustal and regional scale geological features but has seldom been used at the mineral exploration deposit-scale. In this paper we show the application of seismic ANT at an IOCG deposit in South Australia under more than 750 m of sedimentary cover. A 100-site survey in a 10 by 10 grid with site spacing of 1 km, using 3-component nodal seismometers with a natural-frequency of 5 Hz, was conducted over a two-week period. Data were inverted to generate a 3D velocity model to a depth of 2 km. When compared to drillholes in the survey area, the tomographic model delineates cover sequence lithologies and the depth of crystalline basement. A velocity anomaly in the basement has characteristics of a potential IOCG deposit and is aligned with a gravity anomaly due to brecciated haematite. The results of the paper indicate that ANT is a useful tool for deep cover mineral exploration that can potentially expedite the discovery of new deposits.

What Factors Influence the Increasing Dependency on Mobile Banking in Bangladesh? A Quantitative Study in Bangladesh

Mobile Banking has expanded in Bangladesh at a rapid pace for the last two decades in Bangladesh. Mobile service providers have introduced this magical financial innovation. It’s significant to understand what factors may motivate individuals to use online banking in Bangladesh. The study aims to identify influential factors of rapid growing M-banking in Bangladesh. A quantitative study based on a survey was adopted with 200 mobile banking users was selected as participants for the study. Participants think a wide variety of m-banking features with easy access and use plays a significant role in surging the system. The covid-19 pandemic has also increased people's dependency on m-banking. Apart from that, m-banking authorities have no direct contact with its customers. Safety, large amount of money transactions, deposit and profit limit features and reduced charges are all factors that would attract more customers in the coming days. Banks can presently provide managing an account administration to the country and unbanked populaces through portable phones. Around 54% of respondents opinioned that this framework is less exorbitant and timesaving and 63% of respondents felt believe in this benefit. 83% of respondents consider it is simpler to get to, but this benefit isn't accessible for interbred transactions, as well as the nonattendance of an administrative system may lead to cash washing exercises.