Types,characteristics and implication for hydrocarbon exploration of the Middle Miocene deep-water sediments in Beikang Basin,southern South China Sea

The internal seismic architectures of the Middle Miocene in Beikang Basin, southern South China Sea, were investigated and described using regional 2D seismic data from Guangzhou Marine Geology Survey. In particular, five typical seismic facies were identified based on an integrated analysis of the amplitude, continuity, contact relationship, and morphologies of seismic reflections. Bathyal-abyssal fine-grained sediments, deltaic front sandy bodies, turbidites, and small-scale turbidite channels were developed in the Middle Miocene according to the tectonic-sedimentary evolution of the sedimentary basins in the southern South China Sea. The findings of this study suggest that deltaic front sandy bodies and turbidites can be considered as the two major types of deep-water clastic reservoirs for the depression stage of Beikang Basin. A well-developed source-reservoir-cap assemblage was composed by deep rift-stage source rocks, deep-water clastic reservoirs of the Middle Miocene, and bathyal-abyssal deep-water fine-grained sediments after the Middle Miocene, implying a good potential for hydrocarbon exploration.

Provenance and depositional setting of the Late MiocenePleistocene clastic sediments in the eastern Arabian Peninsula and western Iraq using rare earth elements geochemistry

The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements(REE) and trace elements(Sc, Co, V, and Th) concentrations in these sandstones revealed that they likely derived from a single source. The steep light rare earth elements(LREE) and flat, heavy rare earth element(HREE) patterns, negative Eu anomaly, and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks. The average concentration of ΣREE is 93.5 ppm, which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale. The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source. The Th/Co, Th/Sc, La/Sc, La/Co, Eu/Eu*and(La/Lu)cn elemental ratios indicated that these Late Miocene–Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.

Tracing suspended and bed sediments during high and low water periods using geochemical characteristics-Case study:Vazrood watershed,northern Iran

Complete and comprehensive information about sediment dynamic and identification of hotspots of sediment production and transport are necessary for understanding the erosion processes and increasing the efficiency of soil and water conservation practices.Numerous studies used the sediment fingerprint techniques to investigate the contribution of different sources in suspended and bed sediment yield of the watersheds.However,the contribution of various land use/land covers in suspended and bed sediment yield for the great Caspian Sea basin is in an aura of ambiguity and the present study was conducted to gather information about an important part of this area in northern Iran,where rangelands are located upstream of Hyrcanian forests and dense agricultural lands are located downstream.The surface soil of different land use/land covers including forest,rangeland,agriculture and streambank lands were sampled in 30 points.Suspended and bed sediments were sampled in the watershed outlet in two high and low water periods.Geochemical characteristics of soil and sediment samples containing 59 elements were measured using ICP-OES GBC Integra.The reliable and suitable tracers from 59 elements were then selected using Range test,Kruskal-Wallis and Discriminant Function Analysis,respectively,in FingerPro package of R software.The results showed that for suspended sediment,streambank and rangeland had the highest contributions of 86.2%and 47.5%,respectively,in two high and low water periods.For bed sediment,in two high and low water periods,rangeland and streambank had the highest contributions of 73.8%and 84.4%,respectively.Land use change and especially human activities such as agriculture,road construction and development of residential areas along the main river riparian zone has led to a significant increase in suspended and bed sediments.

Diversity, Ecology, and Environmental Significance of Foraminifera in Al Hamama and Susah Coastal Regions, Northeastern Libya: Insights from Holocene Sediments

This research initiative, conducted along the coastal zones of Al Hamama and Susah in northeastern Libya, aimed to enhance our understanding of Holocene benthic foraminifera assemblages and the paleoenvironmental parameters in the region. We meticulously gathered five sediment samples to analyze the composition of foraminifera populations within the unconsolidated sedimentary deposits adjacent to these locations. We successfully identified nine distinct benthic foraminifera species, including Amphistegina lobifera, Eliphidium crispum, Sigmoilinita tenuis, Sorites orbiculus, Stomatorbina concentrica, Peneroplis planatus, Pseudotriloculina rotunda, Pyrgoella sphaera, and Triloculina schreberiana. Notably, Eliphidium crispum and Amphistegina lobifera emerged as the most prevalent species. These foraminifera species exhibited distinct ecological preferences, shedding light on paleoenvironmental conditions and climatic fluctuations during the Quaternary Period in the Susah and Al Hamama coastal regions. The presence of Orbulina universa, a planktonic foraminifera species, further enriched our understanding of the paleoenvironment by providing insights into specific water depths and temperature ranges. This research significantly contributes to paleoceanography and environmental reconstruction, highlighting the invaluable use of foraminifera as proxies for exploring past environmental changes. Additionally, the study investigated the impacts of anthropogenic influences on benthic ecosystems in the Al Hamama and Susah coastal areas. These influences included reworked foraminifera specimens and the effects of karst formations, acid rain, and eutrophication. Notably, human-induced factors have visibly affected biogenic fauna and ecosystem dynamics in the study area. Consequently, this research provides valuable insights into paleoenvironmental conditions and ecological dynamics within the Susah and Al Hamama coastal regions, emphasizing the crucial role of foraminifera in reconstructing historical environmental fluctuations.

Assessment of Selenium Contamination in Sediments of the Aby and Tendo Lagoons in Côte d’Ivoire

Selenium is a trace element that can have both beneficial and harmful effects on aquatic life. The Aby Lagoon is a coastal environment in Côte d’Ivoire that receives selenium inputs from various natural and anthropogenic sources. The aim of this study was to assess the levels of selenium in the sediments of the Aby Lagoon and its tributaries, the Tanoe River and the Tendo Lagoon, and to examine the spatial and seasonal variations of selenium concentrations. Sediment samples were collected from different sites and seasons, and selenium concentrations were measured by atomic fluorescence spectrometry. The results showed that the average concentration of selenium in the sediments of the Aby Lagoon was 0.82 mg/kg, indicating moderate contamination. The concentration of selenium varied between sites and seasons, with higher values in the channel of the Tendo Lagoon and during the dry season. The study highlighted the complexity of selenium dynamics in aquatic ecosystems, and the need to take into account seasonal and spatial variability as well as interactions between environmental factors. The study also suggested potential ecotoxicological risks for some sensitive organisms in certain areas of the lagoon. This study contributes to the knowledge of the dynamics of selenium in lagoon ecosystems and to the assessment of the environmental risks associated with its presence.

Assessment of Radiological Hazards of Sedimentary, Igneous and Sediments Natural Rocks

Gamma-ray spectroscopy based on a 100% efficiency hyper-pure germanium detector was used to evaluate the activity concentrations of 226Ra, 232Th, and 40K natural radionuclides in sedimentary, conglomerate, igneous and sedi-ments rock samples collected from four different locations in Eastern desert in Egypt. The obtained activity concentrations are used to evaluate the radi-ological hazards indices, absorbed dose rate, annual effective dose equivalent in air, radium equivalent, external and internal hazard index, radiation level index, annual gonadal dose equivalent, excess lifetime cancer risk and expo-sure rate. The results show that 1) the absorbed dose rate depends on the rock type, 2) the annual effective dose equivalent in air in 71% of sample below 20 mSvy-1 (permissible limit for workers), 3) the conglomerate rocks show low radioactivity level, 4) sedimentary rocks are rich in radium while igneous rocks are rich in thorium and the sediments rocks are rich in both radium and thorium.

Evaluation of Agricultural Contamination Level by Heavy Metals and Pesticides in Sediments of Rivers and Water Bodies for Shrimp Fishing in the Lower Ouémé: Case of the Aguigadji, Ahlan and Sele Stations in Benin

This study assessed sediment contamination by heavy metals and pesticide active ingredients linked to chemical inputs used in agricultural activities in the lower Ouémé. Pesticide residues from the organochlorine, pyrethroid and organophosphorus families were investigated by gas chromatography, and heavy metals (Cd, Pb, As, Ni, Zn, Fe, Mg, Cr and Hg) by atomic absorption spectrophotometry. The metallic pollution indices, the contamination factor (CF) and the ecological risk index were calculated. The results revealed 8 active ingredients in the rainy season and 9 in the dry season. Glyphosate was the active ingredient with the highest concentration at all stations, 9.65 ± 0.84 mg/kg recorded in the dry season at the Aguigadji station. All glyphosate values were above the EQS. DDT, Atrazine and Endosulfan also showed high concentrations in the dry and rainy seasons. Emamectin, Abamectin and Lambda Cyhalothrin also showed high concentrations in the dry season at Aguigadji, Ahlan and Sele. Only glyphosate was recorded at the control station (Toho), but in very low concentrations. Lead showed the highest concentrations at all the stations, 265.96 ± 21.02 mg/Kg in the rainy season and 255.38 ± 79.09 mg/Kg in the dry season, all detected at the Aguigadji station and above the EQS. Zn, Ni, Fe, Cu and Cr were all representative in both the dry and rainy seasons at the contaminated stations. Manganese showed high concentrations in the rainy season. Pb showed very high contamination (FC ≥ 6) at the Aguigadji and Ahlan stations and significant contamination (3 ≤ FC 6) at the Sele station in both the rainy and dry seasons. Ni, Hg and Cd, showed either moderate or significant contamination at the contaminated stations. The risk values showed a considerable ecological Ri (190 ≤ Ri < 380) in the rainy season and a moderate ecological Ri (95 ≤ Ri < 190) in the dry season at these contaminated stations.

Features of sampling stream sediments of large river valleys under cryolithogenesis conditions in the Balygychan-Sugoy trough,North-East of Russia

Comprehensive research has been implemented to raise the efficiency of the geochemical survey of stream sediments(SSs)that formed under the cryolithogenesis conditions.The authors analysed the composition,structure and specific features of the formation of exogenous anomalous geochemical fields(AGFs)identified through SSs of large river valleys of IV order.In our case,these were the valleys of Maly Ken,Ken and Tap Rivers.These rivers are located in the central and southern parts of the Balygychan-Sugoy trough enclosed in the Magadan region,North-East of Russia.The authors proposed a new technique to sample loose alluvium of SSs in the large river valleys along the profiles.The profiles were located across the valleys.The AGFs of Au,Ag,Pb,Zn,Sn,Bi,Mo and W were studied.Correlations between elements have been established.These elements are the main indicator elements of Au-Ag,Ag-Pb,Sn-Ag,Mo-W and Sn-W mineralization occurring on the sites under study.The results obtained were compared with the results of geochemical surveys of SSs.It is concluded that the AGFs recognized along the profiles reflect the composition and structure of eroded and drained ore zones,uncover completely and precisely the pattern of element distribution in loose sediments of large water flows.The alluvium fraction<0.25 mm seems to be most significant in a practical sense,as it concentrated numerous ore elements.Sampling of this fraction in the river valleys of IV order does not cause any difficulty,for this kind of material is plentiful.The developed technique of alluvium sampling within large river valleys is efficient in searching for diverse mineralization at all stages of prognostic prospecting.It is applicable for geochemical survey of SSs performed at different scales both in the North-East of Russia,as well as other regions with similar climatic conditions,where the SSs are formed under the cryolithogenesis conditions.

Environmental dynamics of nitrogen and phosphorus release from river sediments of arid areas

Human activities lead to the accumulation of a large amount of nitrogen and phosphorus in sediments in rivers.Simultaneously,nitrogen and phosphorus can be affected by environment and re-enter the upper water body,causing secondary pollution of the river water.In this study,laboratory simulation experiments were conducted initially to investigate the release of nitrogen and phosphorus from river sediments in Urumqi City and the surrounding areas in Xinjiang Uygur Autonomous Region of China and determine the factors that influence their release.The results of this study showed significant short-term differences in nitrogen and phosphorus release characteristics from sediments at different sampling points.The proposed secondary kinetics model(i.e.,pseudo-second-order kinetics model)better fitted the release process of sediment nitrogen and phosphorus.The release of nitrogen and phosphorus from sediments is a complex process driven by multiple factors,therefore,we tested the influence of three factors(pH,temperature,and disturbance intensity)on the release of nitrogen and phosphorus from sediments in this study.The most amount of nitrate nitrogen(NO_(3)^(–)-N)was released under neutral conditions,while the most significant release of ammonia nitrogen(NH_(4)^(+)-N)occurred under acidic and alkaline conditions.The release of nitrite nitrogen(NO_(2)^(-)-N)was less affected by pH.The dissolved total phosphorus(DTP)released significantly in the alkaline water environment,while the release of dissolved organic phosphorus(DOP)was more significant in acidic water.The release amount of soluble reactive phosphorus(SRP)increased with an increase in pH.The sediments released nitrogen and phosphorus at higher temperatures,particularly NH_(4)^(+)-N,NO_(3)^(–)-N,and SRP.The highest amount of DOP was released at 15.0℃.An increase in disturbance intensity exacerbated the release of nitrogen and phosphorus from sediments.NH_(4)^(+)-N,DTP,and SRP levels increased linearly with the intensity of disturbance,while NO_(3)^(–)-N and NO_(2)^(–)-N were more stable.This study provides valuable information for protecting and restoring the water environment in arid areas and has significant practical reference value.

Saturation Estimation with Complex Electrical Conductivity for Hydrate-Bearing Clayey Sediments:An Experimental Study

Clays have considerable influence on the electrical properties of hydrate-bearing sediments.It is desirable to understand the electrical properties of hydrate-bearing clayey sediments and to build hydrate saturation(S_(h))models for reservoir evaluation and monitoring.The electrical properties of tetrahydrofuran-hydrate-bearing sediments with montmorillonite are characterized by complex conductivity at frequencies from 0.01 Hz to 1 kHz.The effects of clay and Sh on the complex conductivity were analyzed.A decrease and increase in electrical conductance result from the clay-swelling-induced blockage and ion migration in the electrical double layer(EDL),respectively.The quadrature conductivity increases with the clay content up to 10%because of the increased surface site density of counterions in EDL.Both the in-phase conductivity and quadrature conductivity decrease consistently with increasing Sh from 0.50 to 0.90.Three sets of models for Sh evaluation were developed.The model based on the Simandoux equation outperforms Archie’s formula,with a root-mean-square error(E_(RMS))of 1.8%and 3.9%,respectively,highlighting the clay effects on the in-phase conductivity.The fre-quency effect correlations based on in-phase and quadrature conductivities exhibit inferior performance(E_(RMS)=11.6%and 13.2%,re-spectively)due to the challenge of choosing an appropriate pair of frequencies and intrinsic uncertainties from two measurements.The second-order Cole-Cole formula can be used to fit the complex-conductivity spectra.One pair of inverted Cole-Cole parameters,i.e.,characteristic time and chargeability,is employed to predict S_(h) with an E_(RMS) of 5.05%and 9.05%,respectively.

Chemical Determination of Base Status Metals in Soil Sediments and Particulate Matter in Wellington Industrial Estate Location

This research study explored the levels of base status metals in soil sediments and particulate matter in the wellington industrial estate location;the main objectives were to: 1) determine sodium and potassium, 2) determine calcium and magnesium, 3) determine available iron. The following hypotheses were put forward;H0a: there is no significant difference in the concentration levels between Ca and Mg in the study area, H1a: there is significant difference in the concentration levels between Ca and Mg in the study area, H0b: there is no significant difference in the concentration levels between Na and K in the study area, H1b: there is significant difference in the concentration levels between Na and K in the study area. Six locations were used to collect samples with the aid of scoop and gravel free auger (at varying depths of 0 - 5 cm and 5 - 10 cm) which are Wellington Industrial Estate Area 1 (WIEL 1), (WIEL 2), (WIEL 3), (WIEL 4), (WIEL 5), (WIEL 6);the samples were given laboratory treatment. Flame photometer, EDTA, and Spectrophotometer were used in the determinations of sodium and potassium, calcium and magnesium, and available iron respectively. The results indicated that levels of potassium were in medium range (moderately high);sodium levels were generally low when compared to Brook’s classification table. Levels of calcium were generally low and those of magnesium were moderate based on Brook’s table of classification. Levels of available iron which fall within the range of Quijano-Guerta (2003) were high;this implies such levels can lead to toxicity. In all locations, there was decrease in the levels of each metal in the samples with (5 - 10 cm) depth.

Eco-toxicity and health risk assessment of polycyclic aromatic hydrocarbons in surface sediments of Burullus Lake in Egypt

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous environmental contaminants of growing concern due to their potential ecological and human health risks.This study presents a comprehensive assessment of PAHs contamination in the surface sediments of Burullus Lake,a vital and second largest delta lake in Egypt.The aim was to evaluate the eco-toxicity and potential health risks associated with the presence of these compounds.Surface seven sediment samples were collected from various drains in the southern part of Burullus Lake.Soxhlet extraction method was employed to extract PAHs(16PAHs)from the sediment sample.Analytically,target compounds were located using HPLC.The results showed that samples contained PAHs levels ranging from 0.038×10^(-6)to 0.459×10^(-6),which is considered heavily polluted by the European standard for PAHs pollution.Additionally,there was no apparent source of PAHs in the ElKhashah drain or the Brinbal Canal,as HPLC found none of the compounds.The most prevalent compound in sediment samples along the study area was fluoranthene.The diagnostic indices in the present study indicated that the hydrocarbons in the region originated from pyrolytic and man-made sources along the drains of Burullus Lake.The principal component analysis(PCA)and diagnostic ratios revealed that coal combustion and pyrolytic sources were responsible for the PAHs contamination in the surface sediments.The non-carcinogenic risk(HI),which is the product of the HQs for the adult and child populations,respectively,was calculated.HI values under 1,therefore,demonstrated that they had no carcinogenic effects on human health.TEQs and MEQs in the sediments of Burullus Lake do not have a cancer-causing impact on people.For the safety of nearby wildlife,aquatic life,and people,all activities that raise petroleum hydrocarbon levels in Burullus Lake must be adequately regulated and controlled.According to the ecological risk assessment,there is little chance that PAHs will be found in the sediments of Burullus Lake.This study underscores the urgent need for effective pollution control measures and regular monitoring of PAHs levels in Burullus Lake sediments to protect the aquatic ecosystem and public health.It also highlights the importance of considering eco-toxicity and human health risks in integrated risk assessments of PAHs-contaminated environments.

Granulometry Assessment of Lom Pangar Dam Sediments (East-Cameroon)

The Lom Pangar dam, the largest reservoir in Cameroon with a storage capacity of 6 km3 and a 30 MW hydropower plant, primarily regulates the hydrologic regime of the Sanaga River to maintain hydropower efficiency during dry seasons and enhance downstream hydropower plant performance. Understanding and managing sediments are crucial for the sustainability of dams, as indicated by numerous studies. This study assessed the granulometry of the sediments transported across the reservoir. For that purpose, 6 samples of fresh sediments were collected in the lacustrine and transitional sections of the reservoir using the standard method. Particles size was assessed using the laser diffusion technic after a 3 mm sieving. Various granulometric parameters were derived from the literature to analyze and characterize those sediments. Results show that silts are more than 70% of particles size and range between 2.19 - 60.26 µm. Size distribution also shows the same trend with D75 less than 51 µm. This is confirmed by the low values of Inman Skewness SkΦ (−0.168 to 0.303). The Sorting index S0 ranges from 0.31 to 0.53 µm, showing a very well-sorted sediments, aligning with low values of Krumbein index (0.906 - 1.683) that express the low heterometry of the particles. The consequence on the dam will be a quick clogging of the bottom of the reservoir. Their pH varies from 7.0 to 7.5. It also appears that the sandy fraction trend is higher in the right bank of the dam and reaches 22% on the right bank of Pangar River due to crystalline geology. Fraction greater than 3000 µm is negligible. The management of the dam has to keep attention to these results as siltation may close the safety outlet of the dam, damage turbines, and provoke recurrent technical and safety issues. Further, the clogging of the bottom of the reservoir may lead to an ecological problem with the limitation of hyporheic flow. Thus, water exchange with the underground water table and the natural purification of water reduce, while increasing sediments deposits change the biogeochemistry processes.

Sedimentary elements,evolutions and controlling factors of the Miocene channel system:a case study of the deep-water Taranaki Basin in New Zealand

Deep-water channel systems are important petroleum reservoirs,and many have been discovered worldwide.Understanding deep-water channel sedimentary elements and evolution is helpful for deep-sea petroleum exploration and development.Based on high-resolution 3D seismic data,the Miocene channel system in the deep-water Taranaki Basin,New Zealand,was analyzed by using seismic interpretation techniques such as interlayer attribute extraction and strata slicing.The channel system was divided into five composite channels(CC-I to CC-V)according to four secondary level channel boundaries,and sedimentary elements such as channels,slump deposits,inner levees,mass transport deposits,and hemipelagic drape deposits were identified in the channel system.The morphological characteristics of several composite channels exhibited stark variances,and the overall morphology of the composite channels changed from relatively straight to highly sinuous to relatively straight.The evolution of the composite channels involved a gradual and repeated process of erosion and filling,and the composite channels could be divided into three evolutionary stages:initial erosion-filling,later erosion-filling(multistage),and channel abandonment.The middle Miocene channel system may have formed as a consequence of combined regional tectonic activity and global climatic change,and its intricate morphological alterations may have been influenced by the channel's ability to self-regulate and gravity flow properties.When studying the sedimentary evolution of a large-scale deep-water channel system in the Taranaki Basin during the Oligocene-Miocene,which transitioned from a passive margin to plate convergence,it can be understood how tectonic activity affected the channel and can also provide a theoretical reference for the evolution of the deepwater channels in areas with similar tectonic conversion environments around the world.

Paleocene deep-water sediments and radiolarian faunas: Implications for evolution of Yarlung-Zangbo foreland basin, southern Tibet

This is the first report on the Paleocene deep-water sequences and radiolarian faunas, which are distributed along the southern side of the Yarlung-Zangbo suture zone. The Zheba group is coined to indicate these Paleocene sequences which are subsequently divided into two lithostratigraphic units based on the lithology observed in the field. The lower unit characterized by the rhythmic cherts and siliceous shales is named the Sangdanlin formation, and the upper one composed mainly of flysches is termed the Zheya formation. The radiolarian faunas from the Zheba group are assigned to the RP1-RP6 zones of the Paleocene age. The Early Paleocene ra- diolarian assemblages have the potential to be established into the low latitude radiolarian zones and to fill in the gap between the Late Cretaceous and the Late Paleocene radiolarian zonations. The radiolarian dating provides a valuable tool for the regional correlation and reconstruction of the sedimentary environment of the Neo-Tethyan Ocean. The preliminary work shows that the Paleo- cene sequences accumulated in a foreland basin resulted from the southern Asian margin loading onto the northern Indian passive continental margin. The Yarlung-Zangbo foreland basin se- quences deposited on the Indian passive continental margin also resulted in many good source- reservoir-covering assemblages for oil and gas resources.

Structural characteristics and deep-water hydrocarbon accumulation model of the Scotian Basin, Eastern Canada

Commercial hydrocarbon reservoirs have been discovered in shallow-water areas of the Scotian Basin, Eastern Canada. However, knowledge about the structure and hydrocarbon accumulation characteristics of the basin is still insufficient, which constrains the oil and gas exploration in deep-water areas. Based on comprehensive data of magnetic anomalies, seismic survey, and drilling, this study determines the structure characteristics of the Scotian Basin and its hydrocarbon accumulation conditions in deep waters and evaluates the deep-water hydrocarbon exploration potential. The transform faults and basement structures in the northern basin control the sedimentary framework showing thick strata in east and thin strata in west of the basin. The bowl-shaped depression formed by thermal subsidence during the transitional phase and the confined environment (micro basins) caused by salt tectonics provide favorable conditions for the development of source rocks during the depression stage (also referred to as the depression period sequence) of the basin. The progradation of large shelf-margin deltas during the drift phase and steep continental slope provide favorable conditions for the deposition of slope-floor fans on continental margins of the basin. Moreover, the source-reservoir assemblage comprising the source rocks within the depression stage and the turbidite sandstones on the continental margin in the deep waters may form large deep-water turbidite sandstone reservoirs. This study will provide a valuable reference for the deep-water hydrocarbon exploration in the Scotian Basin.

Quantitative morphometric analysis of a deep-water channel in the Taranaki Basin, New Zealand

The morphological changes of deep-water channels have an important influence on the distributions of channel sand reservoirs,so it is important to explore the morphological change process of deep-water channel for the exploration and development of deep-water oil and gas.Based on a typical sinuous Quaternary channel(Channel I)in the Taranaki Basin,New Zealand,a variety of seismic interpretation techniques were applied to quantitatively characterize the morphological characteristics of the Channel I,and the relationships between the quantitative parameters and the morphological changes of the Channel I,as well as the controlling factors affecting those morphological changes,were discussed.The results are as follows:(1)in the quantitative analysis,six parameters were selected:the channel depth,width,sinuosity,and aspect ratio(width/depth),the channel swing amplitude(λ)and the channel bend frequency(ω);(2)according to the quantitative morphological parameters of the channel(mainly including three parameters such as channel sinuosity,ωandλ),the Channel I was divided into three types:the low-sinuous channel(LSC),the high-sinuous channel(HSC),the moderate-sinuous channel(MSC).U-shaped channel cross-sections developed in the LSC,V-shaped channel cross-sections developed in the HSC,including inclined-V and symmetric-V cross-sections,and dish-shaped channel cross-sections developed in the MSC;(3)the morphological characteristics of the LSC and MSC were related to their widths and depths,while the morphology of the HSC was greatly affected by the channel width,a change in depth did not affect the HSC morphology;(4)the morphological changes of the Channel I were controlled mainly by the slope gradient,the restricted capacity of the channel and the differential in fluid properties.

Heavy metal pollution assessment in marine sediments in the Northwest coast of Sabah,Malaysia

Heavy metal contents along the Northwest coast of Sabah were determined to interpret the pollution level in the marine sediment. The metal abundance is regulated by the physico-chemical properties such as the average sediment pH(7.82, 9.00 and 8.99), organic matter(0.62%, 1.60%, and 2.27%), moisture content(25.00%, 29.70%, and 15.00%) and sandy texture in Kota Belud, Kudat and Mantanani Island,respectively. The major elements show Ca>Fe>Mg>Al>Mn for all study sites, while the heavy metals show Ni>Cr>Zn>Cu>Co>Pb, Cr>Ni>Zn>Cu>Pb>Co and Zn>Pb>Cr>Ni, for Kota Belud, Kudat and Mantanani Island, respectively. The pollution degree of heavy metals was evaluated by using the Sediment Quality Assessment(SQA). The SQA parameters indicated none to moderate pollution in Kota Belud that shows Class 0, Class 1 and Class 2 pollution. The parameters also indicated none to low pollution in Kudat and Mantanani Island that show only Class 0 pollution. The enrichment factor(EF) suggested minor to moderately severe metal enrichment by anthropogenic sources in Kota Belud, whereas only minor enrichment in Kudat and Mantanani Island. The modified pollution degree(MCD<1.5) and pollution load index(0 PLI<1) indicating only low pollution level in the marine sediments for all study sites. The objectives of this study are:(1) to determine the physico-chemical parameters of sediments,(2) interpret the heavy metal contents and(3) evaluate the sediment quality.

Geochemistry and sedimentology of sediments in a short fluvial system,NW China:implications to the provenance and tectonic setting

Six outcrop sections in Fenghe River,Northwestern China,were sampled and analyzed.This study aims to determine provenance,tectonic setting,and source-area paleoweathering of the sediments of Fenghe River in combination of lithofacies analysis and bulk-rock geochemical data.The lithofacies in the studied area were classified as gravel,sand,and fine-grained clastic lithofacies,reflecting generally channel fill deposits,channel bar deposits,and over-bank deposits,respectively.The Chemical Index of Alteration(CIA),Plagioclase Index of Alteration(PIA),and Chemical Index of Weathering(CIW)values ranged 50.10–62.29,50.13–66.35,56.52–71.12,respectively,together with element ratios such as Rb/Sr,K/Na,Rb/K,Th/K,Rb/Ti,and Cs/Ti indicate that the source area was under a low to moderate chemical weathering condition probably in cold and semi-arid climates.Moreover,plot of SiO_(2)vs.(Al_(2)O_(3)+K_(2)O+Na_(2)O)suggests that the sediments were deposited in a semi-arid climate.Plots of Cr/Th vs.Th/Sc,TiO_(2)vs.Zr,La/Yb vs.rare earth element(REE),and La-Th-Sc ternary diagrams,along with the lithology,indicate that the sediments in Fenghe River were mainly originated from felsic igneous rocks.Major elements-based discrimination diagrams and Th-Sc-Zr/10 and La-Th-Sc ternary diagram of the samples indicates that the source rocks of Fenghe River developed in a composite active continental margin and continental island arc field.

Geochemical Exploration of Sediments in the Toumodi Region: Origin of Metasediments, Geological Dynamics, and Perspectives for Regional Geological History

The region of Toumodi, located in the heart of the West African Craton, is renowned for its geological complexity. This geochemical study delves into the origin of siliciclastic sediments and the geodynamic context of their formation. The study reveals that Toumodi’s sediments exhibit an intriguing mineralogical composition, with indications of a dual source of parent rocks, one rich in quartz and the other poor in quartz. Furthermore, geochemical analysis highlights a variation in sediment maturity from west to east, indicating the coexistence of distinct geotectonic environments in the region. In the eastern part of the Toumodi region, a passive margin is defined characterized by sediments with an abundance of quartz, while to the west, an active margin is observed with sediments having a lower quartz content. This arrangement suggests the presence of a potential suture zone in the region. This geological complexity underscores the importance of further research to better understand the origin of sediments and the processes that have shaped them. Moreover, this study sheds new light on the fascinating geology of Toumodi, but many questions remain to be explored.