Source Of Supply Research Articles

Geomorphic evolution of a tropical river basin in the Deccan Volcanic Province: a critical water supply source to Mumbai metropolitan region (MMR), India

ABSTRACT Reservoir siltation lowers a dam’s effective storage capacity, which is mostly determined by the sediment discharge from soil erosion in the watersheds. The morphometric parameters are significant in determining erosional susceptibility of watersheds. In the present study, morpho-hypsometric aspects of the Surya sub-basin, a major tributary of Vaitarna river, has been considered. This river system and associated dams provide the major source of drinking water supply to the Mumbai Metropolitan Region (MMR). A major part of the river flows through the Deccan Volcanic Province (comprising basalts) and Quaternary alluvial deposits. The seven sub-watersheds (SWs) of Surya sub-basin were analysed using the morphological parameters (linear, areal, and basin shape aspects), along with ratio factors and hypsometric integral (HI) values. The HI values for the SWs range from 0.11 (SW-1) to 0.51 (SW-6) with a HI value of 0.21 for the whole Surya sub-basin. The relatively high HI values of SW-6 (0.51) and SW-7 (0.31) indicate that these SWs are relatively prone to high erosion and sediment discharge resulting in dam siltation, and will be a great threat to livelihood of millions of people in the MMR. Therefore, prioritizing these SWs for proper engineering measures could reduce erosion and improve recharge.

CO2 microbubbling system for lithium carbonate precipitation

Lithium carbonate (Li2CO3) is becoming increasingly valuable with the growth of the lithium-ion battery industry. For effective Li2CO3 production, the efficient supply of the carbonate source to the solution is crucial. Conventionally, sodium carbonate has been used as the carbonate source; however, the importance of CO2 utilization has been recently recognized. Conventional CO2-based carbonate sourcing exhibits limited efficiency. In this study, we propose a CO2 microbubbling system based on a rotating nozzle for Li2CO3 precipitation. The CO2 micro-bubbling system demonstrated a 1.6 to 1.9 times greater precipitation reaction rate than that of the conventional CO2 bubbling system. This rate enhancement could be attributed to the increased gas-liquid contact surface and greater residence time due to the generation of CO2 microbubbles. Additionally, the Li2CO3 reaction terminated when the pH of the solution dropped below 9.4–9.7 approximately. The re-dissolution of precipitated Li2CO3 occurred below this pH range as bicarbonate ions became the dominant species over carbonate ions. This study successfully demonstrated that CO2 microbubbling technology could be an excellent alternative for carbonate sourcing systems in the Li2CO3 production industry.

Evolving research on groundwater governance and collective action for water security: A Global bibliometric analysis

Groundwater is a significant source of freshwater supply globally. State-mandated groundwater regulatory frameworks are often pervasive and have failed to reap tangible outcomes. The participatory approach of groundwater governance has surfaced to understand human-groundwater relations through collective action going beyond the techno-managerial paradigm. Hence, the study is carried out to provide a comprehensive and systematic review of the evolution and trends of research in groundwater governance and collective action deploying bibliometric analysis to understand the political economy of groundwater. A total of 356 scholarly peer-reviewed and grey literature published from 2000 to 2022 was compiled. A substantial increase in publications after 2013 was observed. USA and India lead in publication contributions in terms of geographical distribution. Three peer-reviewed journals were prominent publishing outlets: Hydrogeology, Water, and Water Alternatives. The analysis of 814 keywords co-occurrence shows that "groundwater," "governance," and "collective action" were the most extensively used keywords. The emerging themes observed are governance and institutions, cooperative management, and policy. Our findings signify that cooperative management or collective action will be prioritised to understand human-groundwater relations by making the invisible resource visible integrating socio-cultural perspectives.

Solar‐Driven Lithium Extraction by a Floating Felt

AbstractOceans/brine offers a massive supply of lithium sources that can support the renewable energy storage system. However, the current lithium extraction processes from seawater are complicated for scalable production. Here, a high‐performance solar‐driven, direct lithium‐extraction felt (DEF) is developed. DEF consists of a reasonable addition of Li1.6Mn1.6O4 particles on polypropylene/polyethylene core‐sheath fibers, which are dark‐colored and can float on top of bodies of water. Compared with the conventional method, DEF shows improved Li‐ion adsorption rate and capacity by solar‐driven. Meanwhile, the fibers’ hydrophilicity promotes spontaneous upward transport of water/ions, avoiding concentration polarization. Even for the test using simulated seawater (≈100 kg) with low Li‐ion concentration outdoors, DEF demonstrates high efficiency under natural sunlight. DEF shows good salt‐rejection performance in outdoor real‐time evaporation experiments to ensure working stability. In addition, this method saves the steps of liquid storage, liquid transportation, and pump drive. This work provides an easy, highly efficient, and low‐cost strategy to extract lithium directly from seawater/brine with the assistance of solar energy.

Evaluation of the efficiency of energy complexes with the production of hydrogen, oxygen, heat and electricity

RELEVANCE of the research. The global trend of decarbonization of the national economies of the leading countries of the world implies an increase in energy production due to renewable energy sources and hydrogen. The most environmentally friendly way to produce hydrogen is the electrolysis of water using wind and solar energy. Combined production of thermal, electric energy, hydrogen and oxygen carried out by energy complexes ensures reduction of harmful emissions and increase of their economic efficiency.METHODS. In solving this problem, the method of computational experiment was used, taking into account the geographical and climatic data of the location of the energy complex, as well as the nature of consumption of thermal, electric energy and hydrogen. The calculation was implemented in Visual Basic.RESULTS. The article describes the relevance of the topic, examines the influence of the installed capacity of photovoltaic converters, geographical, climatic and cost characteristics on the efficiency of the energy complex.CONCLUSION. The structure is determined and a schematic diagram of a multi-purpose energy complex is proposed. A methodology for calculating quantitative and economic indicators of the installation has been developed. In the course of the study, it was noted that there is an optimal value of the installed capacity of a photovoltaic installation, further increase of which is inexpedient from an economic point of view. It was also determined that the combination of hydrogen gas stations based on solar installations with traditional sources of energy supply can reduce the cost of hydrogen produced, which in the future may be a solution to the problem of creating a hydrogen infrastructure.

Coupling relationship and genetic mechanisms of shelf-edge delta and deep-water fan source-to-sink: A case study in Paleogene Zhuhai Formation in south subsag of Baiyun Sag, Pearl River Mouth Basin, China

The coupling relationship between shelf-edge deltas and deep-water fan sand bodies is a hot and cutting-edge field of international sedimentology and deep-water oil and gas exploration. Based on the newly acquired high-resolution 3D seismic, logging and core data of Pearl River Mouth Basin (PRMB), this paper dissected the shelf-edge delta to deep-water fan (SEDDF) depositional system in the Oligocene Zhuhai Formation of Paleogene in south subsag of Baiyun Sag, and revealed the complex coupling relationship from the continental shelf edge to deep-water fan sedimentation and its genetic mechanisms. The results show that during the deposition of the fourth to first members of the Zhuhai Formation, the scale of the SEDDF depositional system in the study area showed a pattern of first increasing and then decreasing, with deep-water fan developed in the third to first members and the largest plane distribution scale developed in the late stage of the second member. Based on the development of SEDDF depositional system along the source direction, three types of coupling relationships are divided, namely, deltas that are linked downdip to fans, deltas that lack downdip fans and fans that lack updip coeval deltas, with different depositional characteristics and genetic mechanisms. (1) Deltas that are linked downdip to fans: with the development of shelf-edge deltas in the shelf area and deep-water fans in the downdip slope area, and the strong source supply and relative sea level decline are the two key factors which control the development of this type of source-to-sink (S2S). The development of channels on the continental shelf edge is conducive to the formation of this type of S2S system even with weak source supply and high sea level. (2) Deltas that lack downdip fans: with the development of shelf edge deltas in shelf area, while deep water fans are not developed in the downdip slope area. The lack of “sources” and “channels”, and fluid transformation are the three main reasons for the formation of this type of S2S system. (3) Fans that lack updip coeval deltas: with the development of deep-water fans in continental slope area and the absence of updip coeval shelf edge deltas, which is jointly controlled by the coupling of fluid transformation at the shelf edge and the “channels” in the continental slope area.

Navigating supply chain financing and supplier sourcing

This paper shares perspectives on key challenges businesses face when working with international suppliers and how to overcome them. The paper presents real-world examples of companies that have fallen into the trap of using too few suppliers or those that have not done the necessary due diligence before engaging with international suppliers.

Deciphering Multi‐Scale Submarine Groundwater Discharge in a Typical Eutrophic Bay

AbstractAs a significant source of nutrients and other components into the coastal ocean, submarine groundwater discharge (SGD) is a combination of multiple spatial‐temporal scale processes, including fresh terrestrial groundwater (FSGD), recirculating seawater (RSGD), and porewater exchange (PEX). Quantifying the different types of SGD is extremely important for understanding the coastal biogeochemical cycles of various materials. The green tide bloom in the southern Yellow Sea (China) has attracted increasing attention during the past decade. Haizhou Bay is thought to be an important green tide proliferating area, but the source of an apparent high supply of nutrients has not been identified yet. We report here on our investigations of the distribution patterns of Ra and Rn isotopes in groundwater and seawater in Haizhou Bay. By solving a combined mass balance for 224Ra, 223Ra, 226Ra, and 222Rn, we estimated that the bay's water residence time is 28.8 days, FSGD is highest at 3.6 cm d−1, RSGD is 2.7 cm d−1, and PEX is lowest at 0.6 cm d−1. The total SGD into Haizhou Bay is estimated at 9.40 × 107 m3 d−1 (6.9 cm d−1), about 12 times that of the local river discharge into the bay. SGD‐derived nutrients are shown to play an important role when considered among all known nutrient sources. Our results suggest that dissolved inorganic nitrogen (DIN) and silicate (DSi) are transported by SGD mainly via FSGD. We also note that the phosphorus (DIP) budget is heavily influenced by RSGD.

Geographic Information Systems for Water Quality Modeling in the Zhytomyr District Communities

Abstract To ensure safe and quality drinking water for residents of rural settlements who use their own wells, boreholes, and natural sources for domestic water supply, a comprehensive approach to evaluating the quality of underground drinking water using geographic information system (GIS) technologies is necessary. The purpose of the study was to assess the quality of drinking water sources of noncentralized water supply in rural settlements of the united territorial communities (UTCs) of Zhytomyr district and to create geoinformation models based on the research results. The following research methods were used during the research: analytical, field, laboratory, statistical, calculation, and cartographic. The research was conducted in 129 settlements of 12 UTCs of Zhytomyr district, where drinking water samples were collected from noncentralized water supply sources for further analysis in the Measurement Laboratory of Polissia National University, and the creation of geoinformation models using the ArcGIS Pro software package. It has been proven that the average pH level in none of the studied settlements exceeded the norm. The average nitrate concentration in the drinking water from noncentralized water sources exceeded the norm by 1.4–3.5 times, specifically in the water of the Pulyny, Cherniakhiv, Vilshanka, Volytsia, and Oliivka communities, exceeding the maximum acceptable concentration (MAC) limit by more than two times. Only in rural settlements in the Liubar community was the average iron content found to be above the norm by more than 1.9 times. Overall, it was established that the calculated value of the overall water quality class in the Zhytomyr district was 2.03, which is determined as “good,” clean water of acceptable quality. The best water quality was found in the Vilshanka, Cherniakhiv, and Stanyshivka communities, with a quality class range of 1.85–1.93, while the worst water quality was recorded in the Oliivka, Teterivka, and Liubar communities, with a quality class range of 2.13–2.31. It was determined that the highest contribution to the overall water quality was made by nitrate and iron content. The obtained research results and models based on them can be used by local governments of the studied communities to inform the population about the quality of drinking water and to develop a plan for improving the state of drinking water supply with the aim of increasing the level of environmental safety of drinking water.

ASSESSING THE CHALLENGES IN USING DIGITAL TECHNOLOGIES IN TEACHING AND LEARNING IN STATE UNIVERSITIES IN CAMEROON

This study on assessing the challenges in using digital technologies in teaching and learning in state universities in Cameroon had as objective to find out the challenges faculty and students face in the use of digital technologies in teaching and learning in state universities in Cameroon. Four specific research questions guided the study – What challenges do faculty and students face in the use of LMS in state universities in Cameroon? What challenges do faculty and students face in the use of Video Conference Platforms in state universities in Cameroon? What challenges do faculty members face in the use of Microsoft PowerPoint in teaching in state universities in Cameroon? What challenges do faculty and students face in the use of smart devices in state universities in Cameroon? The study based on Rogers’ (1962) diffusion of innovation theory, supposing that the adoption of a new idea, behaviour or product does not happen simultaneous in a social system; rather it is a process whereby some people are more apt to adopt the innovation than others and Davis’ (1986) technology acceptance model, which posits that the more a technology is perceived as useful and easy to use; its actual usage increases. The researcher adopted a survey design in a qualitative study method. The accessible population consisted of 3666 teachers and final year undergraduate students of eight long existing state universities in Cameroon. Using Kothari and Garg (2014), 406 participants from professional faculties in five of the eight universities were selected to make up the sample size comprising 386 final year undergraduate students and 20 teachers. Stratified purposive sampling and purposive sampling techniques were used in the study. An online Google form alongside an interview guide were adopted as the study instruments. The qualitative data collected were analyzed thematically. The findings of the study showed that Poor internet connection, distractions, and frequent power cuts, were the dominant challenges reported by teachers and students in the use of digital technologies in teaching in state universities in Cameroon. Based on these findings, it was recommended that Government could cause telecommunications companies to improve on their quality of services rendered, as well as reduce the cost of internet. The Government can also diversify energy supply sources to include solar energy in universities Campuses to mitigate the effects of frequent power outages.

Improving Supply Security: Guidelines and Policy Proposals

Abstract Supply security is threatened by technical, business, natural and policy shocks, as well as geopolitical tensions. Is there a rationale for policy intervention? If yes, what are efficient and effective measures that achieve de-risking? This article first explains why private incentives do not generally lead to an optimal diversification of supply sources, and then discusses measures that strengthen protection against and resilience in the face of shocks. Governments should refrain from policies that further disincentivise diversification such as the ex post skimming of excess profits when adverse shocks force the halt of production and should work on framework conditions that facilitate diversification. Importantly, most measures are best taken at the EU level.

THERAPEUTIC BIOLOGICAL ACTIVITIES OF Balanites aegyptiaca (L.) Delile: A REVIEW

Medicinal plants continue to be a crucial source of safe, less toxic, economical, available, and reliable natural medicine supplies all over the world. Balanites aegyptiaca Del. (Zygophyllaceae), commonly known as the "desert date", is a thorny shrub or tree found in arid parts of Africa and South Asia. It has traditionally been used to cure a variety of maladies such as wounds, haemorrhoids, jaundice, syphilis, intestinal worm infection, malaria, dysentery, constipation, diarrhoea, stomachaches, asthma, and fever. The fruits of B. aegyptiaca are highly effective as antioxidants, anti-inflammatory, antibacterial, antifungal, antiparasitic, antidiabetic, and anticancer. However, the safety and effectiveness of B. aegyptiaca have not beencompletely studied in humans, so additional well-planned clinical trials are required to corroborate preclinical findings. The WHO has stressed on continued research on medical plants since products derived from plants will continue to be in demand. Searches were conducted on Google Scholar, Science Direct, Google.com, Wiley, PubMed, Hindawi, Springer, and other relevant databases for research publications on B. aegyptiaca. Duplicate publications including thesis papers, and reviews of B. aegyptiaca were excluded This review presents a thorough overview of current information on the therapeutic characteristics of B. aegyptiaca with a focus on its biological activities. It briefly examines its traditional usage, taxonomy, and biological evaluation.

Physicochemical characterization of wastewater from the Niamey National Hospital (NNH) (Niger) and assessment of its impact on the environment

The Niamey National Hospital (NNH) is among the reference hospital in the Niamey region (Niger) to after the quality of care it offers to the population. However, these activities have a negative impact on the quality of the water of the river constituting one of the main sources of water supply for the population of Niamey and gardening activities. This study aims to determine the physicochemical quality of wastewater from the NNH activated sludge treatment plant and its impact on the environment. To carry out this study, twenty (20) wastewater samples were taken at the outlet of the NNH treatment station. The sampling lasted five (5) weeks to take into count fluctuations. The results obtained indicate that the average values of physicochemical parameters such as: the pH (6,91), temperature (27.825°C), conductivity (574.80 µS/cm) and certain heavy metals of this hospital are compliance with national and international standards for wastewater discharge. However, it was noted that the average values ​​obtained at the HNN for copper (1.982 mg/L); zinc (1.077 mg/L); in phosphorus (18.065 mg/L); DCO (808 mgO2/L) and DBO5 (442.5 mgO2/L) do not comply with national and international wastewater discharge standards. These abnormal levels must be treated before being released into the river.

Cordycepin in the fruiting body of Cordyceps militaris cultured from 5 different materials in Vietnam: Analysis and comparison

Cordyceps militaris is frequently employed in pharmacology and nutrition for its well-documented health benefits. The advancement of Cordyceps militaris farming technology has facilitated the establishment of a reliable supply source capable of effectively meeting the expanding market demand. This study aimed to analyze and compare cordycepin concentrations in the fruiting bodies of Cordyceps militaris cultivated from five raw material sources in Vietnam. The results revealed significant variations in cordycepin concentrations among the samples, with average concentrations (measured in mg/g) as follows: Sample 1 (0.8), Sample 2 (1.2), Sample 3 (0.6), Sample 4 (1.0), and Sample 5 (0.9). Notably, Cordyceps militaris from Sample 2 exhibited the highest cordycepin concentration, while Sample 3 had the lowest. Differences in cordycepin content between Cordyceps militaris samples from different raw material sources may be attributed to variations in manufacturing technology. The results of this study provided the necessary information to evaluate the quality of Cordyceps militaris products on the market and propose quality standards for raw materials in the food and pharmaceutical industries.

Assessment of Water Quality of Tighra Reservoir using Weighted Arithmetic Water Quality Index (WA-WQI)

Water is a natural resource used for drinking, agriculture, and industry. Being a vital source of life for living beings, its quality needs to be assessed regularly and the environmental health of water resources should be maintained accordingly. This study assessed the water quality of Tighra reservoir, which is the primary source of water supply in Gwalior, M.P. For this task, the water sampling was carried out during Jun-Sep, 2023. Total 32 samples were collected to cover pre & post monsoon and monsoon season. Subsequently, the water quality parameters such as pH, Turbidity, Acidity, Alkalinity, Chloride, Hardness, Total solids (TS), Total dissolved solids (TDS), Total suspended solids (TSS), Dissolved solid (DS), Iron (Fe), MPN were determined to assess weighted arithmetic water quality index (WA-WQI). Consequently, the WQI ranges from 15.91 to 121.76 respectively. Furthermore, poor water quality was observed at SS7 followed by SS6, and SS5. However, good quality of water was observed at SS1 followed by SS2, SS3, and SS8. The seasonal distribution of WQI reveals that June (19.38-121.75) with SS7 and SS6 have poor water quality, July (16.74-66.87) with SS5, SS6, and SS7 have poor water quality, August (38.08-79.28) with SS4, SS5, SS6, and SS7 have poor water quality, September (15.91-101.11) with SS4, SS5, SS6, and SS7 have poor water quality. The aforementioned findings will surely help to local authorities to take suitable action for the upgradation water quality of Tighra reservoir.

Distribution, source identification, water quality, and risk assessment of trace elements in the surface-groundwater-sediments multifunctional system in Guohe River Basin

Within the Huaihe River Basin, Guohe River, as its second-largest tributary, serves as a critical water supply source. Recent industrial and agricultural advancements have led to increased trace element contamination, adversely impacting the water quality within Guohe River Basin. Therefore, this study aimed to investigate the distribution characteristics, sources, water quality and risk assessment of trace elements in the surface water, groundwater, and sediments across the basin. The results showed that the spatial distribution of trace elements in the surface water and groundwater of Guohe River Basin was that most of the high concentrations appeared in Qiaocheng District of Bozhou City, the mean concentration of Fe in Guohe River sediments was the highest, the mean concentration of Sb was the lowest. The PMF source analysis results showed that the main source of trace elements in Guohe River Basin was natural geological processes, followed by human activities. The sodium adsorption ratio (SAR) indicated that the surface water samples of Guohe River in two seasons had high sodium and salinity hazards. The water quality index (WQI) showed that surface water and groundwater samples in the northwestern of Guohe River Basin had poor water quality. The results of the risk assessment showed that As and Mn posed great ecological risks to surface water and groundwater, respectively, and that F− was the pollutant with the most potential health risk hazard in the basin. The Geo-accumulation index (Igeo) results showed that Cd, Se and As should be taken seriously as the main contaminants of the sediments in Guohe River Basin. KeywardsTrace elements; Source analysis; Sodium adsorption ratio; Water quality index; Risk assessment; Geo-accumulation index.

Remediation of heavy metal-contaminated estuarine sediments by strengthening microbial in-situ mineralization

The production of in-situ iron-sulfide minerals through sulfate reduction is commonly used to immobilize heavy metals in sediments and waste residues from abandoned non-ferrous mines. Ensuring a consistent supply of organic carbon sources, such as small molecular organic acids, under optimal reduction conditions, is essential for effective biomineralization. In this study, we developed a technique to enhance the biomineralization (iron-sulfide minerals) capacity of native sulfate-reducing bacteria to immobilize heavy metals, using the facultative anaerobic fermentation bacterium Bacillus coagulans to bind to waste olivine, providing small molecular organic acids required by sulfate-reducing bacteria while providing more reduction conditions for remediation systems.Our results showed that, compared with the control group (Control) and the group added with medium (Cul), the groups added with Bacillus coagulans (Cul + Bio) and the combination of Bacillus coagulans and olivine (Cul + Bio + Oli), significantly increased the overlying water pH value, pH remained above 8 in the final stage of remediation, and decreased the redox potential and sulfate concentration, ORP remained −80 mV, SO42− concentration below 600 mg/L at the end of remediation. The addition of Bacillus coagulans and olivine helped stabilize heavy metals Cu, Pb, Zn, and Cd by reducing their release into the liquid phase. Cd and Pb were found to be in more stable forms within the solid phase. In the Cul + Bio and Cul + Bio + Oli groups, sulfur primarily existed as more reductive FeS, accounting for 55% and 75% of the sulfur speciations, respectively. Desulfuromonadia, Desulfuromonas, Desulfofustis, and Geothermobacter have been identified in the Cul + Bio + Oli experimental group in high abundance and are capable of dissimilatory sulfate reduction. The combined application of microorganisms and waste olivine offers an effective strategy for remediating in-situ heavy metal-contaminated soils/sediments, thereby establishing a theoretical and practical foundation for employing microbial mineralization in the in-situ remediation of heavy metals in sediment.

Analysis of the Dairy Milk Supply Chain at Sapi Juara Farm, Bogor Regency

Pamijahan District in Bogor Regency, West Java, is known as one of the main sources of milk supply for dairy cows in the region. Dairy cow's milk is a product that has high and stable demand and selling value. Supply Chain Management (SCM) at Sapi Juara Farm in Pamijahan District involves the distribution of dairy cow's milk which includes product flow, information and finance. This study aims to understand the SCM of dairy milk at Sapi Juara Farm, including product flow, information and finance, as well as efficiency as measured through marketing margin and farmer's share. This research uses quantitative descriptive methods with primary data obtained from interviews. The results of the analysis show that there is a flow of dairy milk products, a flow of information from farmers to various actors in the supply chain, and a flow of funds that includes costs and profits from nine distribution channels that influence the performance of the supply chain based on the payment system. From the analysis of the profit share value, it can be seen that the SCM for dairy cow milk in Pamijahan District is running efficiently. It is hoped that SCM in Pamijahan District can be more efficient to avoid losses at each stage or link in the chain and stabilize milk prices in the market, while improving the welfare of farmers, especially at Sapi Juara Farm.

The role of storage in energy security performance based on diversification and concentration for distributed energy systems

This work addresses the use of diversification and deconcentration strategies of primary sources of energy supply for the multi-objective design of distributed generation systems based on renewable sources. The Shannon–Wiener and Herfindahl–Hirschman indices are proposed as optimal design objectives. The utopia-tracking method is used to identify trade-offs between the total annual cost of the system and the efficiency of the storage system. The storage system is included in the assessment of diversification and deconcentration due to its functions as a backup unit in the event of adverse system operating conditions. Cases of interconnected and off-grid systems are addressed. The results show that, by including the storage system, an over-diversification of supply sources is generated and that, in the absence of various sources, as occurs in off-grid systems, storage generates sufficient flexibility to reach a trade-off among economic performance, diversification of supply sources and energy efficiency. The robust nonlinear programming model is fed with real data from a residential building.

Late Carboniferous–Early Permian sedimentary–tectonic evolution in the eastern Qaidam Basin, Western China: Insight into the zircon U–Pb geochronology of ash-fall tuffs and sandstones

The Late Carboniferous–Early Permian period is a significant transitional phase within the late Paleozoic ice age and to investigate the sedimentary–tectonic evolution of the Qaidam Basin in this period is crucial for comprehensively understanding the tectonic history of the northeastern Paleo-Tethys Ocean and the related response to energy and mineral resources. This paper focuses on the Carboniferous–Permian strata of the Wanggaxiu-Dongdagou outcrop that was taken to represent the southern Oulongbruk terrane in the eastern Qaidam Basin. We determined the ages of tuff interbeds within the Zhabusagaxiu Formation originally identified as the upper Carboniferous and obtained the crystallization age spectra of detrital zircon grains from Carboniferous to lower Permian sandstones using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) isotope geochemical techniques. The origin of the volcanic ash and the sedimentary–tectonic evolution in this period were analyzed. The results indicate that the original Zhabusagaxiu Formation can be divided into two chronostratigraphic units: the upper Carboniferous Zhabusagaxiu Formation and the lower Permian. The earliest age obtained from tuffaceous layers within the dark shale interval is 297.8 ± 3.0 Ma (mean square weighted deviation (MSWD) = 0.87), which suggests a stratigraphic boundary between the Carboniferous and Permian periods. Detrital zircons from Carboniferous–Permian samples in the southern Oulongbruk terrane predominantly originated from the Qaidam block-North Qaidam ultrahigh-pressure belt continental island arc to the south. The ultrahigh-pressure belt had a significantly increased contribution to the detrital source supply system from the Late Carboniferous to Early Permian, while the Qaidam block experienced frequent volcanic eruptions from 298 to 293 Ma, dispersing volcanic ash only northward to the Oulongbruk back-arc basin and the Zongwulong Trough. The upper Carboniferous Zhabusagaxiu Formation was marked by siliceous clastic rock–carbonate rock interbedding in an epicontinental sea, while the lower Permian was characterized by shallow to bathyal marine shelf to subaqueous sedimentation. The Early Permian transgression potentially represents the largest transgression during the late Paleozoic ice age, indicating an enriched hydrocarbon-generating interval.