Average Shale Research Articles

Evaluation of trace elements concentration in surface sediments of Parishan International Wetland (Fars Province, SW Iran) by using geochemical and sedimentological analysis

This study investigated the concentration of trace metals in surface sediments of Parishan Lake. Parishan Lake is one of the biggest freshwater lakes in the Middle East, situated in Kazerun area (Fars Province, Iran). This preliminary study concerns the mineralogy, enrichment level, and trace elements source identification in surface sediment of this lake. The geochemical Enrichment Factor (EF) and Geo-accumulation index (Igeo) and sedimentological approaches were applied to characterize the contamination by heavy metals, comparing with Average Shale. Multivariate statistical analysis was also used to identify probable studied elements sources in collected samples. The XRD and microscopic analysis show that main mineral of surface sediments is aragonite with small amounts quartz and nepheline. Chemical analysis of sediments showed that the mean concentrations of As, Cd, Cr, Cu, Ni, Pb, Zn, and Sr were 1.88, 27.2, 32.4, 18.6, 8.1, 38.4, and 3934.9 mg/kg, respectively, and average concentrations of Cd, Cu, and Sr exceeded the corresponding values of upper continental crust (UCC) values. The outcomes of this study indicate that geochemical indices (EF and Igeo) revealed an extremely high enrichment for Sr, whereas other elements had minimal enrichment. The levels of potential ecological risk index (RI) for studied trace elements in all sampling locations were 41.13 and 23.76, lower than baseline value (150), signifying that ecological risks displayed by those elements in sediments were moderate. The multivariate statistical analysis indicated that Sr had a geogenic source (natural source), while As and Cd came probably from Industrial source (chemical fertilizers), Ni and Cr were likely derived from vehicle emissions, particularly agricultural machinery, and Pb originated from exhaust and non-exhaust traffic emissions.

Environmental impact of fuel stations on some heavy metal concentrations in nearby surface crust soils in urban areas: A case study of soil heavy metal contamination

In the present study, the chemical analysis, related to heavy metals (Pb, Ni, Zn, Mn, and Fe) which considered the main source of pollution in soils that come from several sources, was carried out near a three fuel stations to reveal their effect on heavy metals in the nearby soils. Samples were collected from soils which are near to three Fuel stations in Al Hilla city, as a case study, it was found that the concentrations of these metals are all below the value that should be available in average shale, except that for Pb. The average concentration of metals in samples was Pb (25.47 ppm), Ni (86.65 ppm), Zn (84.38 ppm), Mn (96.71 ppm), and Fe (112.38 ppm), and a statistical analysis is done for these results to find correlations coefficients among studied elements, and the results suggested that the fuel station may compromise the nearby soils by increasing Pb concentrations in them.

Geophysical appraisal and oil potential for Rudeis Formation at West Hurghada area, southern Gulf of Suez: detection of stratigraphic trap

This study suggests a suitable stratigraphic trap in West Hurghada area at the southwest Gulf of Suez Basin based on the interpretation of seismic and well logging data. This stratigraphic trap formed by lateral and vertical facies change from porous limestone to massive marl within Rudeis Formation. The examination of the available mud logs revealed that Rabeh East-22 Well displays positive criteria opposite a thick limestone interval between depths 4550 and 4630 ft (zone 1) to be considered a potential oil-bearing zone. This thick limestone bed did not appear in the other examined wells (Nageh-1, Rabeh East-8, and Rabeh East-25) which are so close to Rabeh East-22 Well confirming the lateral facies change. The expected stratigraphic trap on seismic data extends for about 1.5 km in north-south direction and for 0.75 km in east-west direction throughout the study area. The quantitative petrophysical analysis for this thick limestone interval (zone 1) in Rabeh East-22 Well indicated that the interval between 4569 and 4595 ft (26-ft thick) represents the most promising interval within zone 1. This promising interval reflects good reservoir characteristics with average hydrocarbon saturation of 53%, average shale volume of 21%, average total porosity of 20%, average effective porosity of 15%, and average bulk volume of water of 0.07.

Rare earth elements distribution and geochemical behaviour in the volcanic groundwaters of Mount Vulture, southern Italy

The Mount Vulture basin, which mainly consists of pyroclastic and subordinate lava flow layers, is one of the most important aquifers for drinking water and irrigation supply in southern Italy. In this study, we investigated the geochemical behaviour of the rare earth elements (REEs) in the groundwater of this aquatic system, assessing fractionation patterns and performing speciation calculations to elucidate the geochemical processes affecting the REEs' distribution.The groundwater collected was separated into two subsets corresponding to recharge and discharge water. Overall, the groundwater exhibited REE concentrations well below 1000 ng/l, and the average content measured in the discharge water is approximately three times higher than that of the recharge water. In the recharge water, the shale normalised patterns are characterised by a more negative average Ce anomaly, a more positive average Eu anomaly, and a larger average (La/Yb)PAAS.The observed relationship between Ce anomalies and dissolved oxygen (DO) supports the idea that Ce oxidative scavenging has a role in determining the size and shape of the Ce anomaly. Further, the less negative average size of the Ce anomaly in the discharge zone also suggests Ce desorption due to changes in redox conditions.As for the Eu anomalies, the largest Eu* are associated with the recharge zone, characterised by higher average Eh and DO values. The volcanics in the Mt. Vulture lithologies have post-Archean average shale (PAAS) normalised patterns showing positive Eu anomalies due to feldspars occurrence. This indicates that the Eu* of groundwater in the recharge zone is mostly produced by the dissolution of feldspars. In the discharge zone, most samples are in equilibrium with smectite and Eu2+ adsorption onto the clay phase surface or its inclusion in the mineral structure as exchangeable cations likely lead to the smaller average size of Eu*. The possible occurrence of secondary minerals preferentially scavenging light REEs may also explain the difference in the (La/Yb)PAAS index observed between the recharge and discharge zones.Speciation calculations indicate that dissolved REEs consist mainly of carbonato complexes (LnCO3+) whereas the percentage of dicarbonato complexes (Ln(CO3)2−) increases in samples with circa-neutral pH. At acidic pH, the Ln3+ species are numerous and, in samples with large amounts of dissolved sulphate, derived by feldspathoids dissolution, from the discharge zone, the percentage of LnSO4+ species is not negligible.

Geochemistry and mineralogy of the shallow subsurface Red Sea coastal sediments, Rabigh, Saudi Arabia: provenance and paleoenvironmental implications

Mineralogical and geochemical characteristics of the shallow subsurface sediments retrieved from a short sediment core (2.05 m long) collected from the tidal flat south of Al-Kharrar Lagoon, Rabigh area, Saudi Arabia, are presented to determine the impact of temporal change of depositional environment and distinguish the principal control(s) on their chemical composition. The sediments are dominantly siliciclastic, consisting of two vertically stacked sedimentary facies: lagoonal (LG) gray silt-rich mud to argillaceous very fine sand at the base and intertidal flat (TF) brown mud and argillaceous very fine-grained sands at the top. The sediments of the two facies are similar in their mineralogical and chemical composition except for slight vertical variations in the relative abundance of minerals and concentrations of major oxides and trace elements. The mineralogical composition is dominated by quartz, feldspars, and plagioclase with less abundant clay minerals and hornblende, all of detrital origin. In addition, traces of high and low Mg-calcite, dolomite, and gypsum were recognized. Geochemically, the sediments are first-cycle and compositionally immature. The Al2O3/ TiO2 ratios range from 9.4 to 17 and from 13 to 15.4 for the sediments of the LG and TF facies, respectively. These values suggest an intermediate igneous source rock of the Birak group that belongs to the oceanic island arc of the Hijaz Terrane, western Arabian Shield. The average values of paleoweathering indices CIA, CIW, and PIA are <50, suggesting unweathered to poorly weathered source rock that is consistent with the late Holocene arid climate. Although the redox-sensitive V and Cr in the sediments of LG facies are slightly enriched relative to the average shale, the values of the V/Cr ratio are generally <2, suggesting deposition under oxic conditions. The chemical characteristics of the sediments are primarily controlled by the composition of source rock and to a lesser extent by hydraulic sorting during transportation and deposition.

Mineralogy and geochemistry of alluvial sediments from the Kadey plain, eastern Cameroon: Implications for provenance, weathering, and tectonic setting

Mineralogical analyses by X-ray diffraction and geochemical analyses by X-ray fluorescence and inductively coupled plasma-mass spectrometry were performed on the Kadey Plain clastic sediments in order to determine their provenance and weathering. The Kadey Plain has four types of clastic sediments, shales, wackes, litharenites, and Fe-sands. The shales and wackes consist of kaolinite, quartz, muscovite, gibbsite, illite, anatase, and goethite. In the litharenites, minerals found are quartz, illite, kaolinite, gibbsite, muscovite, and goethite. Fe-sands consist of quartz, muscovite, and kaolinite, whereas gibbsite, illite, iron oxyhydroxides and anatase occur as traces. The U/Th (0.11–0.37) and V/Cr (0.99–1.73) ratios indicate an oxidising deposition environment. The behavior of trace elements is the same in these sediments, except for U content which is depleted in Fe-sands. Rare earth elements (REE) normalized with chondrite for the studied clastic sediments, demonstrate a slightly light REE enrichment (3.74 < (La/Sm)n < 5.80) and comparatively flat heavy REE patterns (1.12 < (Gd/Yb)n < 1.78) associated to negative Eu anomaly (0.51 < Eu/Eu* < 0.67). These materials disclose less fractionation of REE [7.10 ≤ (La/Yb)n ≤ 18.41]. These ratios are higher than that of Post-Archean Australian Average Shale [(La/Yb)n = 9.15], except for wackes. Al2O3/TiO2 vs. (SiO2)adj diagram, Eu/Eu*, La/Sc, Th/Sc, La/Co, Th/Co, and Th/Cr ratios suggest that the studied clastic sediments were derived from felsic sources. The REE patterns for sediments from the Kadey Plain disclosed closer resemblance to those of granites, quartzites, migmatites, and chlorite schists found relatively near to the study area. The tectonic discrimination diagrams indicate chiefly passive margin setting for these alluvial sediments.

Assessment of Heavy Metals Concentration and Enrichment Levels in Soils around Quarries and Barite Mine Sites in Part of Akamkpa and Biase Area, Southeastern Nigeria

Geochemical investigation of the soils around quarry and barite mine sites in part of Akamkpa and Biase area of Southeastern Nigeria, was carried out to assess the concentration and enrichment levels of some heavy metals and trace elements in the soils. The investigation involved the collection of fifteen (15) soil samples between the depth of 15 - 30 cm. The samples were dried at room temperature, prepared and analyzed for heavy metals using inductively couple plasma mass spectrometer. The result shows that the concentration of Co, Cr, Nb, Pb and Sn were higher than the average shale values around the quarries while Ba, Pb and Sn were higher around the barite mines. The contamination factor indicates low to minimal contamination and low to considerable contamination around the quarries and barite mines respectively. While the Enrichment factor indicates minimal to significant enrichment around the quarries and minimal to extremely high enrichments around the barite mines. The result of the factor analysis and spatial distribution of the heavy metals suggests that the metal concentration and enrichment were controlled by the rock types, weathering and anthropogenic activities around the mine sites.

EVALUATION THE CALCULATION OF WATERSATURATION WITH SIMANDOUX AND INDONESIA METHOD IN THE P LAYER R FIELD

Logging Interpretation aims to determine petrophysical parameters such as volume shale, porosity, formation water resistivity used to calculate water saturation values. In this study the wells analyzed were four exploration wells. Log analysis carried out in this well is in the form of qualitative analysis and quantitative analysis. The average shale volume in KML-1, KML-2, KML-3 and KML-4 wells is respectively 0.172, 0.132, 0.167 and 0.115. The average effective porosity of KML-1, KML-2, KML-3 and KML-4 wells is 0.236, 0.268, 0.219 and 0.225 respectively. The values of a, m and n follow the lithology of the well, namely limestone (carbonate) with a value of 1, 2 and 2. The value of Rw is obtained from the Pickett Plot Method that is equal to 1.52 Ωm on KML-1, 1.52 Ωm on KML-2, 1 , 52 Ωm on KML-3 and 0.5 Ωm on KML-4. The average water saturation with the Simandoux Method in KML-1, KML-2, KML-3 and KML-4 wells is 0.336, 0.434, 0.670 and 0.397. While the average water saturation value with the Indonesian Method in KML-1, KML-2, KML-3 and KML-4 wells is 0.439, 0.488, 0.723 and 0.440 respectively. From the comparison with Sw Core, the Simandoux method is better used in calculating water saturation because the result is closer to the value of Sw Core.

Geochemical fractionation pattern and environmental behaviour of rare earth elements (REEs) in mine wastes and mining contaminated sediments; Sarcheshmeh mine, SE of Iran

The geochemical fractionation pattern and environmental behaviour of rare earth elements (REEs) were investigated in the mining/processing wastes and contaminated sediments associated with the Sarcheshmeh mine, one of the largest Oligo-Miocene Cu-porphyry deposits in the world. For this purpose, the total concentration and the fractionation pattern of REEs were determined using microwave-assisted multi-acid digestion (HCl + HNO3 + HF) and BCR (Community Bureau of Reference, European Commission) sequential extraction methods, respectively. The normalizing patterns of the total concentration of REEs based on the world average shale (WAS) and average chondrite (AC) for the samples composed of primary lithogenic minerals have corresponded with the higher enrichment of LREEs than HREEs, a pattern that was similar to the Sarcheshmeh porphyry rocks. The BCR fractionation pattern of REEs in theses samples was mainly dominated by the residual fraction. By contrast, the normalizing patterns of the total concentration of REEs in the samples composed of secondary minerals or amorphous solid phases showed higher enrichment of HREEs than the LREEs. Surprisingly, depending on the mineralogy and environmental conditions, the BCR fractionation pattern of REEs in these samples was mainly associated with the both readily acid-soluble and reducible fractions. For example, the BCR fractionation pattern of REEs in the Sarcheshmeh mine pit sediments, which were enriched in amorphous Fe oxides, was mainly controlled by the reducible fraction (>46%), while these elements were mainly related to the acid-soluble fraction (>80%) in the sediment sample collected from the surface evaporative layer formed on top of the old weathered tailings. On the other hand, the BCR fractionation pattern of REEs was controlled by the both acid-soluble (>32%) and reducible fractions (>43%) in the samples collected from sediments and efflorescence salts formed along the waste rock drainages. These results showed that statement any general geochemical pattern and environmental behaviour for the REEs without considering the key environmental factors may lead to miss-understanding or even contrasting interpretations. This study emphasizes on the importance of the mineralogy, the conditions of weathering and oxidation reactions, and even the climate and topography on the BCR fractionation pattern and geochemical behaviour of REEs in the environment.

Spatial Distribution and Contamination Assessment of Trace Metals in the Coral Reef Sediments of Kavaratti Island in Lakshadweep Archipelago, Indian Ocean

ABSTRACT Surficial coral reef sediments collected from 17 sampling stations (shore, lagoons, and outer lagoons) of Kavaratti, Island belonging to Lakshadweep Archipelago were analyzed for trace metal concentration, total organic carbon and sediment grain size composition. The predominant grain size constituent of sediments from the sampling stations was medium sand with low organic carbon content. Except Cd and Pb, all the other trace metals selected for the study were below their global average shale concentration. The sediment contamination was assessed on the basis of geochemical and ecological risk indices. Considerable contamination and significantly high ecological risk were reported from all stations and the serious threat was from Cadmium. Diesel-based power generation, untreated sewage, activities related to shipping, fishing, agriculture, and tourism are the main anthropogenic sources contributing to trace metal pollution in Kavaratti. Statistical analysis of the data also supported the anthropogenic sources of origin of trace metals.

Textural, Mineralogical and Geochemical Assessment of the Pikrolimni Lake Sediments (Kilkis District, Northern Greece) and Suitability for use in Pelotherapy

Pelotherapy is the application of thermal muds (peloids) for recovering muscle, bone and skin pathologies. Specific criteria were established for the evaluation of the therapeutic suitability of peloids. Critical factors ruling the quality of the solid phase of peloids include granulometry, mineralogy, and physical-chemical properties. The aim of the present study was to investigate the textural, mineralogical and geochemical characteristics of the Pikrolimni Lake sediments (PLS), Kilkis district (N. Greece) in order to assess their suitability for application as raw material into mud therapy technologies. Representative PLS samples were collected and analyzed by means of different techniques at the analytical laboratories of the Hellenic Survey of Geology and Mineral Exploration (HSGME). Results showed that, texturally, the PLS were classified as sandy loam sediments. X-ray diffraction (XRD) study revealed that the PLS consist mainly of quartz, clay minerals (kaolinite, montmorillonite, illite), and muscovite, with minor feldspar and calcite. X-ray fluorescence (XFR) analysis showed that PLS samples have higher SiO2 and lower Al2O3 contents compared to the average shale composition. Among the analyzed, by means of inductively coupled plasma mass spectrometry (ICP-MS) technique, potentially toxic elements only As and Pb contents were found significantly higher than those of the average shale. Based on the calculated mean values of enrichment factor (EF) and geo-accumulation index (Igeo) PLS displayed minor enrichment and moderate contamination by Pb and As, respectively. In conclusion, an improvement of the grain size composition of PLS by means of a sieving process is needed. Besides, the study of the concentration and behavior of toxic elements in peloids formed by the mixing of the processed PLS with salty thermo-mineral water is proposed.

Contamination and risk assessment of heavy metals, and uranium of sediments in two watersheds in Abiete-Toko gold district, Southern Cameroon

In this investigation, the level of toxic metals (Cd, Pb, Hg, Cu, Ni, Al, Zn and U) was determined in sediment samples from two watersheds (Kienké and Tchangué) in the Abiete-Toko gold district, southern Cameroon. The potential contamination and toxicity of studied metals was determined by evaluating enrichment factor (EF), geo-accumulation index (Igeo) and ecological risk assessment (ERA). Considering the spatial distribution patterns, metal concentrations were lower than the average shale values, except for Cu and Ni of site 4 in the Kienké watershed and only Ni in the Tchangué watershed. In this study, the EF and Igeo values revealed that sediments were moderately polluted by Ni and Cu and unpolluted by other metals. The evaluation of the ERA based on ecological risk index (RI), ecological risk factor (Er), contamination factor (CF) and pollution load index (PLI) revealed that the sediments from the Abiete-Toko watersheds have significant to very high ecological risk assessment and are generally unpolluted by trace metals and U, except for Ni and Cu. Little quantities of heavy metals with low U levels and distribution were found at the sites close to the vicinity of artisanal mining and peri-urban areas. This proximity reveals that artisanal gold mining activities, agricultural runoff, and other anthropogenic inputs in the study area are probable sources of slight metal contamination. However, the non-use of toxic effluents for gold mining and pesticides for agriculture can be an advantage of the unpolluted status of the watersheds. The physical degradation of the ecosystem through excavations, wells and other stream diversion methods is expanding in the zone. Appropriate measures should be taken by artisans to rehabilitate the gold mining sites, to ensure appropriate treatment of wastewater and non-use of toxic effluents into nearby tributaries.

Trace elements geochemistry in high-incidence areas of liver-related diseases, northwestern Ethiopia

This paper reports the results of trace elements geochemistry from Tigray national state, northwestern Ethiopia. The area is part of the Arabian-Nubian Shield, where the dominant exposure is low-grade metamorphic rocks and has a long history of liver-related diseases. The increase in the number of liver-related disease patients of the area has been an environmental health issue of national concern. The aim of the study is to determine the level of trace element concentrations and distributions in water and stream sediments of the area and identify the possible sources in relation to human health. Water, stream sediment and rocks samples (20 water, 20 stream sediments, and 6 rock samples) were collected in March 2011 and analyzed for major and trace element contents using ICP-MS, ICP-OES, ion Chromatography, and XRF methods. Bromine, aluminum, fluorine, arsenic, and nitrate values exceed the WHO maximum acceptable concentration (MAC) for drinking purpose. Bromine ranges from 0.11 to 1.48 mg/l show higher values in all samples, and fluorine ranges from 0.21 to 16.49 mg/l show higher values in 20% of the samples. Other trace elements are aluminum—30%, arsenic—10%, and nitrate (NO3)—10%, and they are examples of elements which have above MAC for drinking water. Selenium deficiency may be the other problematic element in the area for which its deficiency is associated with liver damage and heart muscle disorder. The concentration of cobalt and chromium exceeded world geochemical background value in average shale at most sample stations indicated that these stations were in potential risk.

The heavy metal contamination history during ca 1839–2003 AD from Renuka Lake of Lesser Himalaya, Himachal Pradesh, India

The Himalayan lakes are facing an acute problem of survival due to increased concentration of toxic elements in water and sediments. In the present study, the heavy metal contamination history of Renuka Lake during the calendar year (ca) 1839–2003 AD has been performed using 137Cs and 210Pb radionuclide-dated core sediment sample and Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). The concentration of heavy metals (Mn, Cr, Cu, Zn, Ni, Pb and Co) during the said time period is found to have significant variations and suggested a contribution of both natural and anthropogenic factors like surrounding rocks, burning of fossil fuels, sewage and agro-chemicals. The highest concentration of Mn is observed during ca 1847, which is 4–5 times more than ca 2003. The Cr is found to be highest during ca 1962; whereas Cu, Zn, Ni and Pb are observed highest during 1883. Similarly, Co is determined highest during ca 1939. The contamination factor (Cf) indicated low to the considerable level of contamination, whereas the degree of contamination (Cd) revealed a low level of contamination in the lake. However, the geo-accumulation index (Igeo) marked the lake uncontaminated to moderately contaminated and on the other hand, the pollution load index (PLI) showed some signs of contamination in the Renuka Lake. The present study has been compared with other lakes and the background concentration of average shale, upper crust, crustal average and carbonate rocks. Although, keeping in view historical contamination, there is a need of stringent steps for the preservation of the Renuka Lake.

Mobilisation of arsenic, selenium and uranium from Carboniferous black shales in west Ireland

The fixation and accumulation of critical elements in the near surface environment is an important factor in understanding elemental cycling through the crust, both for exploration of new resources and environmental management strategies. Carbonaceous black shales are commonly rich in trace elements relative to global crustal averages, many of which have potential environmental impacts depending on their speciation and mobility at surface. This trace element mobility can be investigated by studying the secondary mineralisation (regolith) associated with black shales at surface. In this study, Carboniferous shales on the west coast of Ireland are found to have higher than average shale concentrations of As, Cd, Cu, Co, Mo, Ni, Se, Te and U, similar to the laterally equivalent Bowland Shales, UK. Groundwater penetration and oxidative weathering of these pyritic black shales produces oxide deposits, dominated by goethite and jarosite, which are significantly enriched in As (44–468 ppm), Se (12–184 ppm), U (6–158 ppm) and other trace elements, compared to concentrations in the parent shales. Major elemental abundances vary in composition from 3.5 to 29.4% sulphate, 0.6–9.1% phosphate and 36.6–47.2% iron-oxide. Phosphate substitution within jarosite is observed in these samples, formed under ambient pressure and temperature conditions.The major and trace elements forming these secondary deposits are predominantly sourced from the underlying black shales through mobilisation by groundwater. This discovery is critical for the environmental assessment of black shale lithologies during shale gas exploration and production, where the demonstrated mobility of in situ elemental enrichments may indicate a significant source of produced- and groundwater contamination during and after hydraulic fracturing processes. The proportions of the major oxide phases exhibit a clear control on the trace elemental enrichments within the secondary deposits, where increasing Se and As concentrations correlate with increasing phosphate content of the jarosite mineralisation. This has implications for the remediation of acid mine drainage seeps, where phosphate-rich jarosite phases could be utilised for more efficient trace element removal.

Reconstruction of a 3700 Ma transgressive marine environment from Isua (Greenland): Sedimentology, stratigraphy and geochemical signatures

The rare preservation of a stratigraphy in the northwest of the Eoarchean Isua supracrustal belt (Greenland) demonstrates the world's earliest-recognised marine transgression. Stratigraphically lowest is the ~3710 Ma Solvang Volcanic Formation of picrites, basalts and basaltic-andesites with arc-like geochemical signatures. Close to its erosional top, this formation's volcanic rocks show increase in K2O with depletion of Na2O, depletion in Sr with no alteration in Eu abundance and δ18OVSMOW increase to +16‰, interpreted as subaerial weathering at ~3700 Ma. The sedimentary Snowpatch Formation was deposited unconformably on the Solvang Volcanic Formation. Locally, the unconformity is marked by the laterally discontinuous Conglomerate Member dominated by rounded quartz clasts, but also with clasts of basalt and andesite up to >10 cm across, layered chert and ultramafic rocks. The Conglomerate Member carries sparse detrital zircons, the youngest of which are ~3710 Ma. The conglomerates are succeeded by the Sandstone and Dolostone Member of layered quartz and dolomite clastic sandstones that locally preserve relict shallow marine cross-bedding with scoured layers, tempestite breccia beds and very rare stromatolite horizons. The Sandstone and Dolostone Member is succeeded by the ~3695 Ma BIF Member.The Snowpatch Formation quartz-dolomite sandstones and interlayered stromatolites have seawater-like REE + Y trace element patterns variably modified by a negligible to significant influx of a terrigenous component. Trace element signatures such as Ti/V ratios and normalising REE + Y data to a 3710 Ma weathered volcanic rock (rather than Post Archean Average Shale) suggest this component was derived from a juvenile arc source, resembling the basement Solvang Volcanic Formation. The detailed field and geochemical evidence such as positive correlation between Fe/Mg and Pr/Yb* in the Snowpatch Formation dolostones and BIF (banded iron formation) indicates that the dolomitic lithologies developed in a shallow water setting with clastic sedimentation, during a marine transgression over a weathered ~3710 Ma volcanic arc basement, followed by BIF deposition in deeper water. Thus by 3700 Ma, shallow-water, exposed, settings had already been established, which were the site of stromatolite development.

The geochemical behavior of F and Cl during the weathering–diagenesis–metamorphism–anatexis cycle. Insights from the clay fraction of fine sands from the Amazon River mouth and metapelititic rocks from the Seridó Belt, Brazil

The average contents F = 788 ppm and Cl < 45 ppm of the clay fraction from Amazon River mouth sediments represent the composition of a large portion of weathered South American continental crust prior to any contact with high salinity formation waters. The data show a large fractionation between F and Cl with the latter being strongly leached during weathering along with Na and Ca. The one-order-of-magnitude fractionation is comparable to Cl fractionation from degassing during early Earth accretion. In contrast, F is strongly retained in the hydroxyl sites of neoformed clay minerals, mainly illite, as well as in detrital apatite and muscovite. The high average ratio F/Cl >10 of the clay fraction from Amazon River sediments are comparable only to Cl-poor MORB and evolved granite and rhyolite. The high content Cl = 180 ppm and low F/Cl = 3 of average shale is due to interaction of the sediments with high salinity diagenetic fluids. The Seridó schist belt is used to assess the behavior of F and Cl during shale metamorphism and anatexis. Its ratio F/Cl >10 ppm is high compared to average shale and is related to the strong partitioning of Cl into metamorphic fluids. The obtained data suggest that the Cl partitioned into shales during diageneses is released back into fluids produced during metamorphic conditions. The experimental data indicate that anatexis of mica schist significantly fractionates F/Cl ratios producing schist residue with F/Cl > 38 and peraluminous melts with F/Cl = 6.

Harmful and nutrient elements in paddy soils and their transfer into rice grains (Oryza sativa) along two river systems in northern and central Vietnam.

Thirty soil samples and 24 corresponding unpolished rice samples along the Red and Huong Rivers in northern and central Vietnam respectively, were analyzed in order to evaluate (a) soil geochemistry, (b) factors that determine the transfer of harmful and nutrient elements from soils into rice grains, (c) health risk to the local population through rice consumption. The concentrations of As, Bi, and U in the soils of this area are higher relative to those of average shale probably due to natural redox-related processes. Also, Zn, Ce, Th, La, Sn, Pb, and Cd are accumulated in some soils because of mining activities or industrial wastewater application. Arsenic concentrations exceed the Vietnamese allowable limit of 15mgkg-1 in 80% of the tested soils. Twelve percent of the unpolished rice grains surpass the permissible maximum concentration of 0.2mgCdkg-1 grain dry matter by FAO/WHO and European Union, and all samples are below the Pb limit. The daily intake of As is within the range of the tolerable intake levels proposed by the European Food Safety Authority. Influences of soil parameters such as pH value, contents of soil organic matter, oxides/hydroxides of Al, Fe, and Mn cause a broad spread of transfer factors from soil to grains. Positive trends exist between the transfer factors within the groups (a) As, Sb, and U, (b) Co, Cu, Ni, and Zn, (c) Cd and Mn which indicate similar influences of soil parameters on their uptake. We propose that the allowable Cd maximum concentration for rice should be set to less than 0.2mgkg-1. The analysis of As and Cd concentrations in soils and corresponding rice grains as well as the soil pH value should be made obligatory in order to prevent intoxication. In addition, critical elements from nonferrous metal mining and industrial areas should also be evaluated.

Trace elements characterisation in floodplain soils underlain by crystalline rocks, akure, southwestern Nigeria

The results of the floodplain soils study on the spatial distribution of selected trace elements in top soils (0 – 30 cm) and sub soils (&gt; 30 – 100 cm) near Ala River, Akure metropolis, are reported. The objectives of this study are to determine the concentration of trace elements in the top and bottom soils, and identify the possible enrichment sources of these elements in the floodplain area. Forty two samples (top soil 21; sub soil 21) were collected for the study. The samples were air dried at room temperature, disaggregated and sieved using 53 µg mesh size. The prepared samples were further digested using modified aqua regia of (1:1:1 HNO3: HCL: H2O). The digests were subjected to elemental analysis using Inductively Coupled Plasma-Emission Spectrometry (ICP-MS). The trace elements concentration in ppm exhibited the following distribution pattern. Cu range in ppm from 6.0 – 53.0 mean 27.43; Pb, 10.0 – 165.0, mean 58.43; Zn, 29.0 – 479.0 mean 223.1; Ni, 10.0 – 20.0, mean 14.86; Co, 16.0 – 33.0, mean 24.29; Mn, 250.0 – 1615.0, mean 983.29; Th 9.0 – 19.0, mean 14.43; V, 35.0 – 89.0, mean 73.05; La 26.0 – 84.0, mean 56.76 and Cr 11.0 – 60.0 mean 40.43. While the result for the sub soils range in ppm, Cu from 3.0 – 51.0, mean 21.24; Pb, 7.0 – 208.0, mean 56.33; Zn, 21.0 - 460.0. mean 149.14; Ni, 8.0 – 29.0, mean 13.76; Co, 12.0 – 37.0, mean 23.95; Mn, 138.0 – 2283.0, mean 806.43; Th 9.0 – 28.0, mean 17.48; V, 40.0 – 105.0, mean 68.71; La 25.0 – 96.0, mean 61.00 and Cr 12.0 – 58.0 mean 35.38. The results of both the top soils and sub soils showed higher concentration metal enrichment than the average shale values. The relative elemental mean concentration is such that Mn&gt; Zn &gt; V &gt; La &gt; Pb &gt; Cr &gt; Co &gt; Cu &gt; Th &gt; Ni in that order. Elements such as Cu, Zn, Pb, V, Mn, Th and Cr had relatively moderate to very strong correlation coefficient (r = 0.54 0.97) with each other, which apparently indicate that these elements are of same source of enrichment in the floodplain. Pb, Zn, V, La, Th and Cr are elements that are of significant environmental concerns.

Provenance and tectonic setting of the Lower Cambrian Niutitang formation shales in the Yangtze platform, South China: Implications for depositional setting of shales

Geochemical compositions of the Lower Cambrian Niutitang Formation shales in the southeastern Yangtze Platform margin were investigated for provenance, tectonic setting, and depositional environment. The shale samples are characterized by higher abundances of large ion lithophile elements (Cs, Ba, and Pb), lower abundances of high field strength elements (Cr, Sc, and Co) and transition elements (Th, Zr, Hf, Nb, and Ta) relative to average shale. North American shale composition (NASC) -normalized rare earth element (REE) patterns are observed, with negative Ce anomalies, negative Eu anomalies, and positive Y anomalies. The chemical index of alteration (CIA) varies from 68.67–74.93. Alkali and alkaline element contents and CIA values suggest that the source rocks have undergone moderate weathering. The index of compositional variability (ICV), Zr/Sc and Th/Sc ratios vary from 0.53 to 1.07, 5.31 to 8.18 and 0.52–1.02, respectively. ICV values and relationships between Zr/Sc and Th/Sc ratios indicate negligible sedimentary recycling. The Al2O3/TiO2 (14–26) and TiO2/Zr (56–77) ratios imply that the source rocks of the investigated shales had intermediate igneous compositions. However, Cr/V ratios and a La/Th–Hf discrimination diagram suggest that the intermediate compositional signal of the source rocks was derived from a mixture of 75% mafic and 25% felsic igneous rocks rather than intermediate igneous rocks. The major source was the Jiangnan continental island arc with bimodal igneous rocks, lying to the south of the study area, together with a contribution from granites and gneisses uplifted and eroded in the Yangtze Block. Discrimination of tectonic setting using major and trace elements indicates that the source rocks originated in a transitional setting from active continental to passive margin, consistent with the failed intracontinental rift model for the evolution of the South China plate. The Niutitang Formation shales were deposited in a rift basin setting under conditions of anoxic bottom water in a redox-stratified water column, with organic-rich shales prospective for shale-gas production being found in deep-water downslope and basin environments rather than the shallow-water shelf.