Heavy-mineral Concentrates Research Articles

Evaluation of nutrient composition of selected small indigenous fish species in Bangladesh and potential contribution to nutrient intakes

Small indigenous fish (SIF) are recognized as easily available, and abundant source of macronutrients and micronutrients in Bangladesh. The current investigation was undertaken to assess the existing heavy metal, mineral, vitamin, and others nutrient content of small indigenous freshwater fish in Bangladesh. Eight indigenous fish (Mola, Tengra, Baim, Punti, Chanda, Guchi, Koi, and Taki) were selected for this study. The AAS (Atomic Absorption Spectrophotometer), ICP-MS (Inductively Coupled Plasma-Mass Spectrometry), and the Association of Official Analytical Chemists methods outlined were used to determine the proximate compositional analysis of fish. The highest fat content was found in koi fish. Protein was highest in both baim and taki fish. Iron, zinc, vitamin A, and vitamin B12 content were highest in mola fish. Highest calcium and phosphorus were found in the chanda and taki fish. The study concludes that small indigenous fish are valuable sources of fat, protein, ash, iron, zinc, calcium, phosphorus, potassium, vitamin A, and vitamin B12, which are important for maintaining good health. Our findings suggest that small indigenous fish could serve as a viable option for addressing the nutritional needs for the children (6–23 m age), and Pregnant and lactating women in Bangladesh as a tool to fight malnutrition.

A comparative study of the elevated radioactivity in beach placer deposits of Bangladesh.

Beach sediments are mineral deposits formed through weathering and erosion of either igneous or metamorphic rocks. Among the rock constituent minerals are some natural radionuclides that contribute to ionizing radiation exposure on Earth. Kolatoli and Kuakata are the two major beaches with heavy mineral deposits and important tourist sites in Bangladesh. Natural radioactivity in Kolatoli and Kuakata beach sand deposits along the southern coast of Bangladesh was assessed and compared to identify the sources, causes, and possible environmental impact. Result shows most of the radionuclides have higher activity concentrations than the background level, and the activity varies with the sample locations. The dominant radionuclides were found to be the radionuclides of thorium series i.e. Th-232 and Ra-228 followed by uranium series and K-40. The radioactivity in Kolatoli beach sands was observed to be much higher than Kuakata beach due to the presence of a higher content of heavy minerals i.e. illmenite, rutile, zircon, garnet and monazite. Furthermore, monazite and zircon are the two radioactive minerals that are considered to be the main contributors to the radioactivity in Kolatoli beach sand. These minerals are dominated by the activity of thorium series radionuclides i.e. Th-232 and Ra-228 surpass the activity of all other radionuclides such as U-238, U-234, Th-230, Ra-226, Po-210, and K-40. However, major contribution of radioactivity in Kuakata beach sand comes from uranium series radionuclides such as U-238, U-234, Ra-226, and Po-210. Beach morphology, sedimentological, and geochemical evolution of those minerals might be important areas of further study for the radioactivity monitoring activity in those areas.

Geochemical characterization and reserve estimation of the economic heavy minerals of Sonadia Island, Bangladesh

The goal of the current study is to understand the elemental concentration, reserve assessment, mineralogical composition, and distribution of heavy minerals in the dune sands, foreshore, and backshore of Sonadia Island, Southeast Bangladesh. The study area yielded a number of drill hole composite sand samples that were used for density and magnetic separation of heavy minerals. These samples were then subjected to petrographic characterization, grain counting, mineralogical analyses using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX), x-ray diffraction (XRD), and bulk sand geochemistry using X-ray fluorescence (XRF). The results of heavy liquid separation show that the total heavy mineral (THM) enrichments in foreshore sand (about 4.86%), backshore sand (about 9.03%), and dune sand (about 22.28%) are significantly higher. After characterizing the sand samples from Sonadia Island based on the abundance of each mineral species, the average content values relative to total economic heavy minerals (TEHM) were determined to be 38.14% ilmenite, 5.74% magnetite, 51.52% garnet, 1.01% zircon, 3.57% rutile, and 0.01% monazite. An SEM–EDX examination reveals that the elemental concentration of ZrO2 in zircon is 66.60%, while the average TiO2 content in rutile is ~ 95%, whereas TiO2 is 45% and the total Fe2O3 is 45.70% in ilmenite. Major phases including amphibole (tremolite) 45.9%, muscovite 15.6%, quartz 12.6%, garnet (almandine) 10.9%, dolomite 7.9%, ilmenite 4.1%, and kaolinite 1.3% are also identified by the XRD pattern. There are an estimated 19,794 tons of garnet in the foreshore sand, 47,324 tons in the backshore sand, and 276,868 tons in the dune sand within the reserve, making it the most prevalent heavy mineral. Ilmenite is the second most common heavy mineral, with quantities detected in the foreshore (15,016 tons), backshore (30,487 tons), and dune sand (215,092 tons).

Concentration of heavy minerals in Padma-river bar sediments from Bheramara to Ruppur using multispectral satellite data and petrographic analysis

Concentration of heavy minerals in Padma-river bar sediments from Bheramara to Ruppur using multispectral satellite data and petrographic analysis

The Influence of Sandstones with a High Concentration of Heavy Minerals on the Distribution of Hydrocarbons in a Reservoir Using the Example of a Field in Western Siberia

The Influence of Sandstones with a High Concentration of Heavy Minerals on the Distribution of Hydrocarbons in a Reservoir Using the Example of a Field in Western Siberia

Mercury in river samples with artisanal and small-scale gold mining influence: The case of the upper Madeira River Basin (Brazil/Bolivia)

The issue of mercury (Hg) is becoming a growing concern in the Amazon basin. The Madeira River is known for intense artisanal and small-scale gold mining (ASGM), and Hg poses a significant issue for public health and ecosystems. In this study, we analyzed Hg riverine concentrations in water samples, suspended particulate matter (SPM) and sediments in the Upper Madeira River Basin. We also examined mineralogical and elemental compositions of the solid phase to enhance our understanding of Hg behavior in the environment. Dissolved Hg was not detected in water, and Hg concentrations in solids remained in the same order of magnitude across different rivers, despite variations in gold mining intensities along their courses. Generally, Hg concentrations were higher in compartments with a greater proportion of fine sediments (clay and silt), with average concentrations of 91.4 ± 13.0, 41.6 ± 11.0, and 22.2 ± 1.6 ng g−1 for SPM (n = 14), riverbank (n = 12), and riverbed (n = 4) sediments, respectively. Multivariate analysis shows Hg chemical associations related to clay minerals and organic matter (OM) for the riverbank and SPM compartments. However, in SPM, OM had a greater influence on Hg distribution. Conversely, one riverbed sample highlights with a high Hg concentration (547.78 ng g−1), large content of heavy minerals, and a distinct geochemical signature. This sample was collected in a river section upstream of Beni River's rapids where the river's hydrodynamics can induce the high concentration of heavy minerals in this riverbed sediment. This unexpectedly high Hg concentration encountered in sediment rich in heavy minerals is likely related to contamination by Hg-rich mine tailing discarded into the river. Overall, this study discusses the issue of Hg mobility in rivers suggesting its dispersion, i) associated with fine fraction rich in clay and OM, and ii) associated with heavy minerals.

Preparation of poly(5‐ferrocenyl‐dipyrromethane) as sensor for electrochemical removal of aluminum and barium ions in real water samples

In this work, 5‐ferrocenyl‐dipyrromethane (Fc‐DPM) synthesized from the pyrrole and ferrocenecarboxaldehyde condensation was electrochemically deposited on a gold (Au) electrode and used to remove metal ions found in rural waters. The structural analysis of Fc‐DPM was recorded by means of nuclear magnetic resonance (NMR) techniques. The Fc‐DPM was electrochemically coated on an indium tin oxide‐polyethylene terephthalate (ITO‐PET) surface, and the resulting Fc‐DPM/ITO‐PET was characterized using scanning electron microscopy (SEM)–energy dispersive X‐ray (EDX) analysis. The heavy metal and mineral content of four real water samples from the same rural area were determined by inductively coupled plasma mass spectrometry (ICP‐MS) before and after electrochemical removal. The proposed Fc‐DPM/Au electrode was successfully applied for aluminum ion (Al3+) and barium ion (Ba2+) removal for the first time, and the limit of detection (LOD) was calculated as 0.003 and 0.217 ppb for Ba2+ and Al3+, respectively.

Analysis of Sediment Characteristics and Depositional Environment of Beach Sediment along the Pulmoddai Mineral Sand Deposit in Eastern Coast of Sri Lanka

Abstract Pulmoddai mineral sand deposit which extends about 800,000m2 is located in the Northeast coastal zone of Sri Lanka. It is the largest and well known heavy mineral sand deposit in Sri Lanka. High-quality Zirconium-bearing minerals like Rutile, Zircon, and Ilmenite are concentrated in this deposit. This study focuses to analyse the spatial distribution of the heavy minerals abundance and sedimentlogical characteristics of the deposit. Five miles (8 km) long stretch along the coast of this deposit was selected as the study area. Ten traverses representing two traverses within each mile are demarcated across the coastline and are running from inshore to backshore. Forty sand samples representing inshore, swash zone, berm, and backshore region were collected. These samples were analysed using a dry sieve and heavy liquid separation methods. According to statistical analysis, sediments in the Pulmoddai mineral sand deposit are mostly fine-grained, moderately to moderately well sorted. Also, these are negatively skewed to nearly symmetrical and mesokurtic in nature. According to the linear discrimination function, these sediments are shallow marine agitated depositions controlled by aeolian, fluvial and marine depositional environments under the high impact of turbidity currents. The average heavy mineral concentration at the inshore, swash zone, berm region, and backshore (dune) region is 5.95%, 10.87%, 12.82%, and 23.5% respectively. The concentration of the heavy minerals increases towards the backshore and also increases towards the southern part of the study area.

Hydrogeological Investigations of Paghman Valleys in Kabul, Afghanistan

Paghman valleys are located at the foothills of the Hindu Kush Mountain range (Afghanistan) and consist of dissimilar kinds of valleys with different rocks and sediments. Valleys in this region consist of several types of streams which are clean, due to their filtration at the valley beds. Water resources, such as streams, springs, and rivers are used for drinking, irrigation, and other general-purpose usages. Due to years of regional conflict, the general water infrastructure needs to be upgraded, however since people need water for their day-to-day activities, it is necessary to characterize various sources of water to ensure their safety. Thus, this study aims to estimate the petrographic characteristics of the Paghman valleys and predict the resource suitability of the region through certain analyses: petrographic, gravel, and sieving analysis. The study is important since no such studies exist on this subject for this region, because of decades of war and much work remains to be done due to an ever-increasing population accompanied by air pollution which may affect the water resources of the region and thus causing health problems for people. The results provided through this investigation provide some preliminary quantification of heavy and light minerals, mechanical analysis, pH determination, electrical conductivity, and Cation and Anion concentrations of heavy and light minerals in water. Furthermore, as the regional population is steadily increasing, the authors highlight policy recommendations for a range of mitigation measures for the relevant authorities to keep water and soil quality within a safe range.

Benthic fauna along sandy beaches enriched by metals after mining disaster

In 2015, 60 million tons of ore tailings from the Fundão dam failure entered the Doce River basin, Brazil, and reached surrounding sandy beaches. This study evaluated the influence of sedimentology and morphology of beaches that received mining tailings on chemical element concentrations and consequent benthic community responses. We collected sediments for physical (granulometry, heavy mineral, and calcium carbonate content) and geochemical (chemical elements) analyses and biological diversity parameters (benthic macro- and meiofauna density, richness, and composition) on 8 beaches with different morphodynamic types. Beaches with more dissipative characteristics retained the highest contents of mud, As, Fe, Mn, V, and heavy minerals, present in the tailings. We also recorded the lowest density and richness of macrofauna on these beaches, compared to more reflective beaches. These results contradict the global trend, suggesting that anthropic disturbances outweigh the effects of morphodynamics in structuring the benthic fauna community, mainly in dissipative sandy beaches.

Delineation of the general framework and quantification of heavy minerals distribution at Durgarajupatnam coast, Nellore, East Coast of India

The present study involves quantifying the presence, concentration, and distribution patterns of heavy minerals in 24 beach samples from the Govindampalli-Durgarajupatnam (GP-DP) coast, Nellore, East coast of India. It explores fraction-wise distribution (+60, +120, +230) in four micro-environments (dune, backshore, berm, and foreshore). Notably, this study is the first of its kind in the investigation area. Using optical properties, minerals such as opaques, sillimanite, garnet, zircon, amphiboles, pyroxenes, tourmaline, etc., were identified. Total Heavy Minerals (THM) percentage in the area was determined as 19.03 %. Analysis reveals higher ratios of heavy minerals in the +230 fraction and foreshore environment, indicating the dominance of littoral currents and waves. Economically, a modest amount of heavy minerals (average 19.03 %) is present along the coast. The main objective is to highlight the availability and concentration of heavy minerals in different micro-environments. This objective aligns with the broader context of coastal sediment investigations and contributes valuable information for the development and utilization of placer mineral deposits along the Indian coastline. The study's implications extend to scientific understanding, resource assessment, environmental considerations, industrial applications, economic feasibility, strategic planning, policymaking, and contributes to global discussions on coastal sediment investigations and placer mineral deposits utilization.

Mineralogy of the Vovchansk Zircon-Rutile-Ilmenite Deposit (Ukrainian Shield)

The article provides generalized data on the geological structure, the results of laboratory analyzes of the heavy fraction of the main placer-forming minerals of the Vovchansk zircon-rutile-ilmenite deposit, which was being developed by Demurinsky Mining and Processing Plant LLC in 2002. The geological structure of the Vovchansk deposit includes a complex of Precambrian rocks of the crystalline basement, the Paleozoic-Cenozoic weathered crust, the Paleozoic-Cenozoic sediments, and Quaternary deposits. The industrial concentration of heavy minerals is confined to the middle and upper parts of the Middle Sarmatian subsuite of the Neogene, composed of fine-grained, essentially quartz sands, with a total thickness of 0.4 to 63 m. The content of heavy minerals in the ore-bearing horizon of the deposit ranges from 93.8 to 485 kg/m3 (ilmenite from 37.6 to 242.6 kg/m3, rutile from 15.9 to 64.6 kg/m3, zircon from 2.9 to 9.4 kg/m3, sillimanite and disthene from 20.4 to 117.5 kg/m3). The content of major and minor elements-impurities in individual minerals of the ore-bearing horizon (178 grains) was determined: ilmenite (18 samples), rutile (40 samples), zircon (35 samples), sillimanite (30 samples), staurolite (25 samples), tourmaline (12 samples), ganite (8 samples), monazite (10 samples). The conducted research clarified the typomorphic features of minerals from the sands of the Vovchansk deposit, established their absolute age and probable original sources.

Analyzing the role of coastal geomorphology on heavy mineral distribution along a coastal tract of Kerala, southwest India

A multitemporal morphological and heavy mineral study was conducted on the coastal area of the southwest coast of Kerala, India between two major rivers namely Chandragiri River and Karingotte River. The study revealed an interesting distribution pattern of heavy minerals in the area. An offshore fault and a minor river, Chithari River on land, divided the area into two sectors, namely sector-1 and sector-2. Sector-1, located north of the river, is characterized as a submerging coast and exhibits erosion, while sector-2, located south of the river, is characterized as an emerging coast and exhibits accretion. The study found that the total heavy mineral concentration in the area ranged from 2.9 wt.% to 37 wt.%, with an average of 13.65 wt.% in sector-2 and 7.38 wt.% in sector-1. This difference in heavy mineral concentration is reflected in the iso-concentration map, which shows that sediment in sector 2 is more enriched with heavy minerals. Furthermore, the mineralogy of the heavy mineral suite also differs between the two sectors, with sector-1 dominated by ilmenite-garnet-sillimanite suite and sector-2 dominated by garnet-ilmenite-sillimanite suite. Though the unique distribution of heavy mineral placers in the two sectors is influenced by factors such as geology, geomorphology, and surface and subsurface structural features in the area, the distribution and concentration of heavy minerals in the area were found to be influenced more by coastal geomorphology. Hence this study highlights the importance of considering coastal geomorphology in understanding the distribution and concentration of heavy mineral placers.

Physicochemical concentration of heavy minerals - a treatise on wet process media: gravity, centrifugal and flotation techniques

Physicochemical concentration of heavy minerals - a treatise on wet process media: gravity, centrifugal and flotation techniques

Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

Tsunami deposits around the North Sea basin are needed to assess the long‐term hazard of tsunamis. Here, we present sedimentary evidence of the youngest tsunami on the Shetland Islands from Loch Flugarth, a coastal lake on northern Mainland. Three gravity cores show organic‐rich background sedimentation with many sub‐centimetre‐scale sand layers, reflecting recurring storm overwash and a sediment source limited to the active beach and uppermost subtidal zone. A basal 13‐cm‐thick sand layer, dated to 426–787 cal. a CE based on 14C, 137Cs and Bayesian age–depth modelling, was found in all cores. High‐resolution grain‐size analysis identified four normally graded or massive sublayers with inversely graded traction carpets at the base of two sublayers. A thin organic‐rich ‘mud’ drape and a ‘mud’ cap cover the two uppermost sublayers, which also contain small rip‐up clasts. Grain‐size distributions show a difference between the basal sand layer and the coarser and better sorted storm layers above. Multivariate statistical analysis of X‐ray fluorescence core scanning data also distinguishes both sand units: Zr, Fe and Ti dominate the thick basal sand, while the thin storm layers are high in K and Si. Enriched Zr and Ti in the basal sand layer, in combination with increased magnetic susceptibility, may be related to higher heavy mineral content reflecting an additional marine sediment source below the storm‐wave base that is activated by a tsunami. Based on reinterpretation of chronological data from two different published sites and the chronostratigraphy of the present study, the tsunami seems to date to c. 1400 cal. a BP. Although the source of the tsunami remains unclear, the lack of evidence for this event outside of the Shetland Islands suggests that it had a local source and was smaller than the older Storegga tsunami (8.15 cal. ka BP), which affected most of the North Sea basin.

A study on seasonal dynamics of heavy mineral distribution and surface micro-textures of Beach sediment from Govindampalli – Durgarajupatnam Coast, East Coast of India

The main objective of this research is to investigate the distribution, concentration, and surface micro-textures of heavy minerals in beach sediments from four micro-environments: dune, backshore, berm, and foreshore. A total of forty-eight samples (twenty-four samples in each season) were collected along the Govindampalli (GP) to Durgarajupatnam (DP) Coast on the east coast of India, covering the pre-monsoon and post-monsoon periods from June 2016 to December 2016. The study revealed significant heterogeneity in beach sediment properties, heavy mineral distribution, and concentrations. Heavy mineral analysis was conducted on the coarse (+60), medium (+120), and fine (+230) fractions of the beach sediment. The analysis of weight percentage (wt%) demonstrated that a higher proportion of heavy minerals was associated with the fine fraction (+230) compared to the coarse and medium fractions at all stations. Opaque minerals, garnets, zircons, and monazites were found in promising quantities along the coast. The total concentrations of heavy minerals were higher during the pre-monsoon season compared to the post-monsoon season. The surface micro-textures of heavy mineral grains from various stations in the study area were primarily influenced by mechanical and chemical processes occurring on the grain surfaces. These micro-textures indicated significant mechanical influences at the estuary point and moderate to high wave energy in the beach deposits.

Thermal state of the Siberian craton marginal zone at the time of Mesozoic kimberlitic magmatism within the Kuoika field (Yakutian diamondiferous province)

Research subject. Clinopyroxene xenocrysts from the heavy-mineral concentrates of 14 kimberlite bodies (western part of the field: Obnazhennaya, Rubin, Seraya, Vodorazdelnaya, Vtorogodnitsa, Antoshka; central part of the field: Sliudyanka, Skiff II; western part of the field: Irina, Noyabrskaya, Vechernyaya, Lyusya, Dianga and Zhila 79) of the Kuoika field (Yakutian diamondiferous province, Siberian craton). Aim. To reconstruct the mantle paleogeotherms Under the six kimberlite pipes (Vodorazdelnaya, Obnazhennaya, Vtorogodnitsa, Sliudyanka, Dianga, and Zhila 79) using two independent approaches. Materials and methods. The chemical composition of clinopyroxene xenocrysts was investigated and last equilibrium temperatures and pressures were estimated using single-crystal thermobarometry. The geothermal line fitting to the P-T data set was performed using two methods. The first method is based on the D. Hasterok and D.S. Champan model, and the second - on the D. McKenzie model. Results. The value of lithosphere thickness falls within the margin of error for the two methods, being also comparable with earlier reconstructions for the Vtorogodnitsa, Dyanga, and Obnazhennaya pipes. The obtained results indicate that, during the Mesozoic kimberlitic magmatism, the lithosphere thickness beneath the Kuoika field was about 200 km. Conclusion. The determined peculiarities of the chemical composition of clinopyroxene xenocrysts indicate heterogeneity of the lithospheric mantle composition. Different depths of transported mantle material for kimberlite pipes of the Kuoika field, which are coeval and are located a few km apart, may be related to peculiarities of kimberlite magma ascent to the surface and the presence of intermediate magma chambers. The eastern part of the Kuoika field contains more garnet and garnet-spinel peridotites compared to the central and western parts, which may indirectly indicate a greater diamondiferous potential of the eastern block, where the diamondiferous Dianga pipe is located. The absence of diamonds in other discovered pipes of the Kuoika field may be connected with the metasomatic enrichment of the lithospheric mantle in the area of the “diamond window”, which is confirmed by a large number of high-temperature clinopyroxenes at these depths.

Sedimentological and Mineralogical Fingerprint of the Beach Sediments, Western Mediterranean Coast, Egypt

The composition and texture of beach sediments along continental coastlines vary considerably. Beach sands made completely of carbonate sediments are prevalent along Egypt's Western Mediterranean Coast. Forty-five sediment samples were collected from various locations (El-Dekhela, Kilo-21, Abu Talat, and Sidi Krir) along the Western Mediterranean Coast of Egypt. The sedimentological and mineralogical attributes of the collected sediments were investigated using collaborative techniques. The beach sediments in the coastal region between El-Dekhela and Sidi Krir consist mainly of carbonate sands that are mineralogically composed of dolomite, calcite, and aragonite with smaller amounts of quartz, sylvite, anhydrite, gypsum, and trace amounts of microcline. They contain ooids with bioclasts and very few heavy minerals, except for notable amounts of these minerals in the El-Dekhela region. These heavy minerals primarily consist of opaque minerals, amphiboles, and pyroxenes, with smaller amounts of epidote, zircon, tourmaline, rutile, garnet, kyanite, monazite, sphene, staurolite, and biotite. The combination of heavy minerals in these deposits indicates a wide variety of igneous, metamorphic, and sedimentary rock types as potential source rocks. Heavy mineral concentrations decrease westward from the Nile River's mouth near Rosetta to Egypt's Western Mediterranean Coast. Most of the studied ooids are white colored and usually have a pearly luster; these characteristics indicate that these sediments were formed in agitated water. The current study reveals that the ooids in the study area originated from a variety of sources, including autochthonous and allochthonous ooids that eroded and broke, implying that they may have originated from coastal plain carbonate ridges.

Neoichnology of vertebrate traces along the western barrier coast of Ukraine: preservation potential and subsurface visualization

A diverse quite of vertebrate traces covers beach, aeolian, and bay-side (deflation flats) surfaces along the NW Black Sea coast of Ukraine. These include avian, ungulate, and canid footprints, as well as mammal burrows (length >5 cm; depth ~2 cm). The preservation of biogenic structures is enhanced by rapid burial (low-energy sedimentation or event deposition), algal mat formation, and salt encrustation. Continuous high-frequency (800 MHz) ground-penetrating radar (GPR) imaging aided in visualizing subsurface sections of an active burrow complex within a beach-dune ridge. Images near an active fox burrow captured distinct subsurface anomalies (point-source hyperbolic diffractions) in the upper aeolian section above the water table. Unfilled tunnel sections are easily distinguished from buried roots and other targets based on signal velocity and polarity reversals relative to air-to-sediment response at the ground surface. The diffraction geometry (angle) is related to signal velocity, providing valuable information about relative saturation of the overlying substrate. Decimeter-scale deformation of shallow reflections may be attributed to tracking surfaces, with similar examples found immediately below modern surfaces affected by anthropogenic trampling. It is likely that muddy lagoonal tracking surfaces may be preserved under layers of sand (overwash or aeolian deposition) and, following saltwater expulsion, may be recognized in geophysical images as clear deformed paleo-surfaces. Heavy-mineral concentrations (e.g. magnetite-rich sand) are common for beach and dune horizons that have undergone reworking and such anomalies often accentuate physical and biogenic deformation structures. Due to moderate-to-high fraction of ferri- and paramagnetic minerals, these anomalies are also well-expressed in GPR images due to its electromagnetic signal response. A conceptual framework of trace preservation potential (taphonomy) and geophysical recognition (GPR) suitability is proposed for this coastal region, with implications to paleo-environmental reconstruction.

The Modern Nile Delta Continental Shelf, with an Evolving Record of Relict Deposits Displaced and Altered by Sediment Dynamics

The most extensive coverage of surficial sediment samples collected to date on Egypt’s Nile Delta coast and shelf is needed to better define sediment dispersal patterns across this setting’s rapidly eroding margin. Changes in time are now induced by River Nile sediment cutoff by dams, sea level rise, marked shelf subsidence, and regional climate changes, which have altered the amounts and components of sediments; these require replacement, along with the implementation of more effective coastal protection measures. Multiple computer-generated offshore maps depict the distributions and proportions of sand, silt, and mud; the mean grain size and standard deviation (sorting); heavy mineral concentrations; and carbonate content. Heavy mineral lobes at the coast and offshore identify former Nile branch sites. Channel lobes extending seaward resulted from their progradational phase and from the delta’s altered sedimentation from the early to late Holocene. The progressive deposition and erosion of these fossil fluvial lobes, and of two active Nile channels, selectively removed their quartz and less dense minerals, thus concentrating heavy minerals on the coast and inner shelf. The prolonged dispersal of original sediment effluence from relict and recent Nile tributaries induced variable depositional patterns on the present shelf. These coastal depocenters, along with extensive sand, silt, and mud from shelf sediments, were reworked further seaward and dispersed by bottom currents, thus masking most previous onshore-to-offshore transport patterns. The major surficial features document long-term responses to the diverse dispersal that influenced the shoreline to the outer shelf deposits from the Pleistocene to the present.