Beach Placer Research Articles

Seasonal assessment of biomarkers in Channa punctata from Tampara Lake, Odisha, India and toxicity of thorium nitrate on fish

Tampara Lake, a freshwater lake in the Chatrapur beach placer deposits of Ganjam, Odisha, India is a well-known tourist attraction. Multiple factors seem to disturb the aquatic life of Tampara Lake, especially fish. Chatrapur beach placers are rich in various heavy minerals including monazite, an ore of thorium, that emits high background radiations and can affect the biota. Run-offs from the monazite mining sites on the beach placers are also presumed to be carried to the lake. Thus, tourism, local transportation, fishing activities, presence of heavy minerals and mining run-offs appear to disrupt the lake's ecosystem. The present work assessed the protein and lipid concentrations in the liver and muscle, nuclear abnormalities in the peripheral blood erythrocytes and histopathology of gills, liver, kidney, intestine and stomach of Channa punctata from Tampara Lake in summer, winter and rainy seasons. The study also documented the effects of thorium nitrate, a byproduct of monazite ore processing, on Channa punctata of non-monazite areas. Channa punctata from the Tampara lake had significantly lower protein and lipid content in the liver and muscle, nuclear deformities and micronuclei in the erythrocytes and deformities in the gill, kidney, liver, stomach and intestine relative to the fish from the non-monazite areas. Seasonal alterations were observed in the protein and lipid content of muscle and liver, gill and kidney structure. Fish from the non-monazite areas treated with sub-lethal concentrations of thorium nitrate showed a dose-dependent response in the protein and lipid content of liver and muscle, erythrocyte nuclear abnormalities and histopathological aberrations. The present study provides evidence that Channa punctata from Tampara Lake have relatively low nutritional value compared to fish from undisturbed non-monazite areas and are probably distressed by the water contamination due to the presence of heavy minerals and anthropogenic interventions.

Judicious combinations of gravity, magnetic, electrostatic separators and microwave heat energy on recovery of ilmenite from Humma lean grade beach placer deposit

Microwave heating is an eco-friendly and novel technique for sintering and heating minerals and materials as it has several advantages in terms of phase transformation, energy efficiency, enhancing speed, process simplicity, improved properties. Such heating provides the composite materials to absorb electromagnetic energy volumetrically and transform into heat and produces larger densities as compared to conventional heating. This study focuses on two main objectives: the recovery of ilmenite through a strategic combination of mineral processing equipment, including a spiral concentrator, followed by magnetic and electrostatic separation, and the enhancement of ilmenite concentrate using microwave heat energy on a cleaner magnetic product, followed by electrostatic separation. Continuous magnetic separation results indicate that among the dry high-intensity belt magnetic separator, box mag wet high-intensity magnetic separator and dry rare earth drum magnetic separators, the rare earth magnetic separator yielded the highest quality product. The application of microwave heat energy before the rare earth drum magnetic separator at 1.4 T, followed by high-tension separation, produced the best grade of ilmenite. The magnetic product obtained after microwave treatment contained 98.6% ilmenite, which was further upgraded to a 99.6% ilmenite concentrate through high-tension separation. Therefore, it is recommended that an effective combination of gravity separation, microwave heat energy, rare earth drum dry magnetic separation and high-tension separation be employed to achieve the highest grade of ilmenite concentrate.

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.

Human and environmental risk assessment and plausible sources of toxic heavy metals at beach placers in southeast Sri Lanka

Beach placers are typically rich in heavy minerals, which are crucial for a wide range of industrial applications. This study investigates the human and environmental risks posed by toxic heavy metals (As, Pb, Zn, Cu, Cr, Fe, V and Mn) in beach placers of southeastern Sri Lanka using 42 X-ray fluorescence data. Risk indicators (EF, Igeo, CF and PLI) indicate the polluted nature of the placers. Correlation analysis (correlation matrix and HCA) identified pollution sources as heavy mineral-rich rocks, agricultural fertilizers, pesticides and municipal wastes. The environmental impact caused by toxic metals is less in placers. The highest non-carcinogenic risks (HI) resulted by Cr (1.69E+00), V (4.29E+00) and Fe (2.06E+00) to children. The total cancer risk of As and Cr in placers is unacceptable (children: 2.60E-04, 2.48E-03, and adults: 3.14E-05, 2.87E-04, respectively). Different strategies are introduced to mitigate the identified risks in source areas and the coastal environment.

Contrasting evolution of beach gold on two sides of an active orogen, Southern Alps, New Zealand

ABSTRACT Placer gold on beaches on either side of a major active mountain belt has strongly contrasting compositions and morphologies. Pleistocene-Holocene beach gold placers have formed along the West Coast where silver (Ag)-bearing gold has been eroded from mountains via steep rivers and glaciers, followed by rapid burial in the abundant associated coastal sediments. Deformation along transport pathways has produced flattened gold flakes, but some primary crystalline shapes are preserved. Internal deformation of particles has caused recrystallisation to fine-grained (µm scale) grain structures including mylonitic banding. However, only minor localised (µm scale) Ag leaching has occurred on some particle margins. In contrast, Pleistocene beach placers formed on the southern side of the mountains contain flattened gold particles with a complex transport history involving long-distance (hundreds of km) fluvial transport since Cretaceous. Most primary Ag has been leached from this gold during transport-related recrystallisation to fine (5–20 µm) internal grains. Sand-blasting on the southern beaches with low sediment supply has resulted in further deformation and leaching of Ag to form toroidal shapes with Ag-free delicate extremities. Placer gold which has undergone rapid transport and deposition is useful as a prospecting tool for bedrock deposits in glaciated terranes around the world.

U-Pb ages of detrital zircon and monazite from beach placers in Sri Lanka: Implications for configuration of the Columbia supercontinent

U-Pb ages of detrital zircon and monazite from beach placers in Sri Lanka: Implications for configuration of the Columbia supercontinent

Rare Earth Elements Geochemistry and 234U/238U, 235U/238U Isotope Ratios of the Kanyakumari Beach Placer Deposits: Occurrence and Provenance

Geochemical studies of rare earth elements (REEs) as well as major and trace elements were conducted on the beach placer sands from the Kanyakumari coastal region, a well-known high background natural radiation area (HBNRA). For the first time, uranium isotope ratios (234U/238U and 235U/238U) were determined in the study area to investigate the provenance and leaching of U from the beach sands. Inductively coupled plasma mass spectrometry was used for the measurement of REEs and trace elements whereas thermal ionization mass spectrometry (TIMS) was used for the measurement of U isotope ratios. ∑REEs were found to be in the range of 778.93 to 15,007. 54 µg/g, whereas ∑Light REEs were in the range of 770.58 to 14,860.80 µg/g and ∑Heavy REEs varied from 8.35 to 146.74 µg/g. The enrichment factor showed the LREEs Th and U were extremely enriched in the Kanyakumari beach placer sands. The 235U/238U isotope ratios were similar to the natural terrestrial ratio value. The 234U/238U activity ratio varied from 0.995 to 1.071, and showed the prevailing secular equilibrium among them. The δ238U results could, to some extent, explain the U fractionation and source.

Textural and Chemical Characters of Lean Grade Placer Monazite of Bramhagiri Coast, Odisha, India

The present study aims to investigate the textural, mineralogical and geochemical characteristics of lean grade placer monazite from the Bramhagiri beach sand deposit to assess the possibility for its use in industrial applications. The bulk back dune sand deposit with 18 samples showed the elements uranium and thorium in traces, phosphorus and calcium in minor amounts, and alumina, silica and titanium in major amounts. Since apatite was absent in this placer deposit, P and Ca were attributed to monazite only. Based on the chemical analysis, it was established that the monazite mineral exists in this deposit. The monazite is generally below the −150- to +90-micron size range, and the concentration of the monazite mineral in the bulk back dune sand is around 0.01% by weight. The structural data and complete chemical analysis established that the monazite is Ce-monazite. The monazites with other heavy mineral sands of the Bramhagiri beach placer deposits were derived from the Eastern Ghats, which closely resembles the mineralogical composition of khondalite, charnockite, leptynite and pegmatite groups of rocks. The Eastern Ghats’ provenance appears to be the primary source for the heavy mineral assemblages of the Bramhagiri placer deposit. Thus, these monazite sands are derived from the granulite facies of metamorphic rocks such as khondalites and charnockites from the Eastern Ghats group of rocks. Garnet is the major mineral, following ilmenite and sillimanite. Zircon, rutile and monazite are minor minerals in the deposit. All these minerals are well liberated and have uniform shapes with variable densities and size ranges, with different magnetic, electrical and surface properties. Hence, the occurrences of these heavy minerals are of economic importance. Further, these minerals can be recovered individually for industrial applications.

Distribution of 226Ra, 232Th and 40K in Kanyakumari beach placer deposits along Tamil Nadu coast, India

Distribution of 226Ra, 232Th and 40K in Kanyakumari beach placer deposits along Tamil Nadu coast, India

Geochemical and Radionuclide studies of sediments as tracers for enrichment of beach and alluvial placers along the eastern coast of India

The deltaic environment of the river basin and the beach associated with the meandering nature of river are considered for the exploration of REEs and Radionuclides. A multi-element based geochemical survey of stream and beach placers was carried out along the eastern coast of India to emphasizes the role of stream and river tributaries in the transportation and deposition of heavy mineral placers. The lithology of the river basin, the nature and number of channels, the meandering nature, delta and slope of the river influences the distribution of heavy minerals as placer deposits. The morphology of river basin along with the elevation profile plays a significant role towards the enrichment of heavy minerals. It was observed that the total Rare Earth Element (REE) content was ∼5.2 and ∼23.83 times higher than the UCC values for the Rushikulya River and Mahanadi River sediments, respectively. The total REEs were ∼90 times higher in the Podampata beach sediments and ∼20 times higher in the Paradeep beach sediments compared to UCC respectively, and exhibit a negative Eu anomaly. Th/U ratio is higher in beach sediments than the river sediments as compared to the UCC, which indicates the presence of radioactive heavy minerals in the former. The concentration of radionuclides as well as REE’s, exhibit specific enrichment for the beach sediments, at particular locations.

Effects of Borax and Grinding Alkalinity on the Reduction–Magnetic Separation of Beach Placer

The effect of borax on the reduction characteristics of Indonesia beach placers was investigated. The effect of grinding alkalinity on the magnetic separation of the reduced sample was also studied in this paper. The mineral phase transformation, microstructures of reduction, and magnetic separation products were analyzed to reveal the enhanced separation mechanism of titanium and iron in beach placer. The borax could effectively improve the metallization rate and the growth of iron grains in a reduced sample. When 3% borax was added to the reduction process, the metallization rate of the reduced beach placer reached 95.64%, and the metal iron grains grew to about 50 μm. Adjusting the grinding alkalinity could prevent the metallic iron from being oxidized and promote the monomer dissociation between mineral particles. The iron powder concentrates with 94.07% total Fe and vanadium-rich titanium slag with 36.32% Ti were obtained by grinding magnetic separation as the grinding alkalinity pH was 13.

Variation of natural radioactivity in sediments of beach placers along the eastern coast of India

Variation of natural radioactivity in sediments of beach placers along the eastern coast of India

One size does not fit all: Refining zircon provenance interpretations via integrated grain shape, geochronology, and Hf isotope analysis

Sediment provenance studies commonly utilize isotopic signatures to resolve detrital mineral sources and routing. However, non-unique ages and geochemical characteristics across geographically distinct crystalline source regions can lead to significant ambiguities in mineral provenance interpretations. Such ambiguity is apparent in southern Australia’s Cenozoic Eucla Basin, which hosts world-class heavy mineral sand resources. Here, new Hf isotope data are provided from four heavy mineral prospects (N = 8, n = 844 [N = samples, n = grains]). Zircon grain shape data are also presented for a suite of detrital Eucla Basin samples (N = 22, n = 35,604) and the basin’s underlying basement, the Coompana Province (N = 13, n = 824). The data are integrated with published detrital and non-detrital primary zircon data to investigate the efficacy of grain shape analysis to better resolve the basin’s mineral provenance. Zircon Hf isotope compositions indicate a primary Mesoproterozoic juvenile source for zircon melts (∼1250–1000 Ma, −2.5 <ɛHf > ∼+5) with additional contributions from a range of juvenile to evolved late Archean to Phanerozoic-aged zircon bearing magmas (−28.0 <ɛHf > +11). U–Pb geochronology and Hf isotopes are incapable of differentiating Mesoproterozoic-aged source rocks bounding the region for the majority of heavy mineral deposits analyzed as potential sources express overlapping crystallization ages and similarities in Hf-isotope characteristics. However, distinct zircon grain shapes (i.e., perimeter, major axis and circularity) facilitate improved differentiation across these Mesoproterozoic sources. Filtering of U–Pb age, Hf isotope and shape data implicate the underlying Madura and Coompana provinces as dominant sediment sources for Eucla Basin detritus aged ∼1400–1000 Ma. The lack of direct sediment pathways between the underlying basement provinces and placer sediments analyzed demonstrates the significance of zircon reworking from intermediate sedimentary basins in the formation of the economically significant Eucla Basin beach placers. Zircon grain shape represents a cheaply acquired and readily incorporated grain characteristic that can enhance provenance investigations.

Geochemical Studies of Detrital Zircon Grains from the River Banks and Beach Placers of Coastal Odisha, India

Zircon grains are reasonably ubiquitous in river banks and beach placers as detrital minerals, including along the ~1700 km long Indian east coast, from Odisha state to the state of Kerala. Zircons from beach placers and river banks located along the eastern part of Odisha, India, were studied using LA-ICP-MS in order to delineate their geochemical characteristics. Hf (mean = 11270 ppm) and Y (mean = 1064 ppm) were the two most abundant trace elements found within zircon grains as compared to other trace elements. The abundance of uranium was observed to be 2–4 times larger than that of thorium. Zircon overgrowths formed in equilibrium with a partial melt and were similar to magmatic zircon in terms of the high Y, Hf and P content, steep heavy-enriched REE pattern, positive Ce anomaly and negative Eu anomaly. The average low Th/U ratio of the studied zircon grains distinguished them from the magmatic ones. The REE present in zircon grains was restricted to high-grade metamorphic events. The result of the present study would be useful for delineating the source region and the efficacy of resource potential and indigenous export.

Coastal-marine and legacy placers of the southern Primorye (Russia): ecology and commercial exploitation

The article is devoted to the development of technology for reenrichment of waste from the exploitation of old gold-bearing placers that pose a significant threat to the environment. Technogenic and coastalmarine placers of the south of Primorye (Far East, Russia) were chosen as the object of research. At the same time, methods of powder metallurgy, as well as leaching of precious metals and metallic mercury with thiocarbamide-thiocinate solutions with their simultaneous demercurization were used. The application of this scheme for the extraction of useful and toxic components from placer material will allow to involve in industrial circulation numerous man-made and beach placers of the south of the Russian Far East in compliance with resource-saving principles and environmental aspects.

Geochemical, mineralogical and textural nature of beach placers, north-east Sri Lanka: Implications for provenance and potential resource

The Pulmoddai placer sands in Sri Lanka (9°3′23.65″–8°51′38.83″N and 80°55′22.91″–81°3′32.65″E) is considered to be one of the major rare earth element (REE) prospects world-wide. This deposit has a global significance in terms of strategic economic resources and can provide valuable insight for resource estimation and for its economic use. A detailed study of the geochemical, mineralogical, and textural properties of the heavy minerals of this region is undertaken applying the scanning electron microscopy–electron dispersive X-ray spectroscopy (SEM–EDS), inductively coupled plasma–optical emission spectroscopy (ICP–OES), X-Ray diffraction (XRD), and X-Ray fluorescence (XRF) techniques. The results from these analyses are modeled to delineate the source(s) which contribute to the formation of the mineral deposits and their subsequent enrichment. The beach sediment from this region, exhibited elevated concentrations of major elements like silicon (Si) and manganese (Mn) and high abundance of minor and trace elements like yttrium (Y), strontium (Sr), lanthanum (La), barium (Ba), which indicates that the provenance is similar to calcium-silicate rocks. The highest (total) concentration of Y, La, scandium (Sc) and cerium (Ce) are mainly associated to fine grained sediment, signifying that their occurrences are governed by the grain size distribution and ambient hydrodynamic conditions primarily from lagoonal input. Monazite, zircon, ilmenite, rutile, and xenotime are more abundant than garnet in the study area, as is evident from the higher abundance of thorium (Th) and uranium (U) and the enrichment of zirconium (Zr), Ce, vanadium (V), chromium (Cr), and Y. Textural analysis of sediment shows sediment particles are poorly sorted and have more angular grain boundaries, indicating their lower textural maturity. This suggests that the sediment is fluvially derived from a close source rock of charnockite specific to the hinterland lithology. The sediment transported by perennial rivers and the hydrodynamic conditions of the Kokkilai Lagoon estuary, are the two primary sources of heavy mineral enrichment in the study area, which is quite unique in terms of the placer formation. Subsequently, these sediment particles formed the beach placer deposits enriched in REE–Th rich heavy minerals, which are of immense strategic importance.

Tracing remnants of Ediacaran S-type granitoids from beach placers in SE Madagascar

Southeast Madagascar hosts several major deposits of beach placers, the provenance of which is little understood. To redress this imbalance, we present new laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS) U-Pb ages, and trace elements of zircons and monazites, as well as Hf isotopes of zircons from heavy mineral beach sands at Taolagnaro (Fort Dauphin) in SE Madagascar. The ages of detrital zircon grains range from 650 Ma to 450 Ma and from 1900 Ma to 1700 Ma (one grain has an age of 2633 Ma), and detrital monazite ages range from 574 Ma to 484 Ma. The Ediacaran−Cambrian zircons (650−450 Ma) and monazites (574−484 Ma) record a major Pan-African orogenic event in SE Madagascar. Geologically, the 650−450 Ma ages correlate well with coeval granitic gneisses in southern Madagascar, and a few 1900−1700 Ma ages can be linked to putative Paleoproterozoic protoliths of metasedimentary rocks from the Anosyen Domain and from the Itremo Group of central Madagascar. The zircon mineral chemistry indicates that some of the grains (P&amp;gt;25 μmol g−1) were sourced from S-type granitic rocks. The monazite chemistry points toward a metamorphic provenance from garnet-bearing amphibolite facies rocks, such as migmatitic gneisses in southern Madagascar. The Hf isotopic compositions of detrital zircons indicate reworking of their probable Paleoproterozoic−Archean source rocks. We conclude that the beach sand zircons and monazites were largely sourced from the uplifted and eroded Anosyen and Androyan Domains in SE Madagascar, and with minor contributions from central Madagascar, which were all transported by rivers to the ambient ocean to the southeast.

Implications of Magnetic Properties in the Concentration and Distribution of REEs in Beach Placer Monazites: A Case Study from Chhatrapur Coast, Odisha

Abstract The concentration of monazite, a rare earth and thorium phosphate, in the heavy mineral-bearing sands of Chhatrapur coast varies from 0.09 to 0.16%. Under the microscope, monazite displays color variation from colorless to various shades of yellow, green and brown. The color variation is further reflected in the chemistry of individual grains. Such monazites of distinct colors and different chemistry also show variation in their paramagnetic properties. Representative detrital monazites separated under varied magnetic field strength were analysed for their rare earth elements, Th and U content. The electron probe micro analysis (EPMA) data indicate that monazites separated under low magnetic field strength (separated at 0.80 amps) are characterized by their higher Nd, Sm, HREE, Y and U as well as low Th content, whereas those separated at 1.10 amps contain low Nd, Sm, HREE with negligible Y and U content as well as higher Th content. The wider variation in the concentration of different rare earths in varied magnetic field strength is a function of varied magnetic susceptibility of individual elements. Hence, the physical method for separation of monazite using magnetic properties may facilitate to segregate the monazites of a particular chemical composition with respect to their constituent elements like U, Th and rare earths based on their magnetic properties.

The Tertiary sequence of Varkala coastal cliffs, southwestern India: An ideal site for Global Geopark

Varkala, along the southwestern coast of Peninsular India, has a unique place in Indian geology and geomorphology due to the presence of coastal lateritic cliffs, which exposes the entire Mio-Pliocene sequence of Warkalli Formation, and is declared as the type area. Stratigraphically, this formation exposes carbonaceous clay with lenses of lignite and sticks of marcasite, followed by variegated clays and sandstone. The presence of variegated lithounits endows beauty to these cliffs. Varkala cliffs, edging the Arabian Sea, run for a length of 7.5 km. These cliffs, together with confined beaches, made Varkala a popular tourist destination. Several geodiversity spots within the Varkala Cliff geoheritage site make Varkala geologically unique, just like the vestiges of the last separation of Indian subcontinent from the Mascarene Plateau; showcasing lateritization and distribution of beach placers, and jarosite, formed as a diagenetic replacement mineral from marcasite and considered as a Martian analog, are distinctiveness of the cliff. Additionally, Varkala is an internationally acclaimed beach tourist destination. Furthermore, there are several geoheritage sites as well as socio-cultural-historical sites in the hinterland of Varkala Cliff geoheritage site, which are within the proposed Varkala Global Geopark jurisdiction. Thus, this area fulfills all the criteria to be a Global Geopark. The socio-economic-environmental analysis showcases the changes that have occurred in these 3-end members. When the economic sphere was unaffected, the social scenario was slightly affected (25%) whereas the environmental aspect then drastically deteriorated by 75%. But, the SWOT analysis still elects Varkala as a potential Global Geopark. The concept of geopark contributes to at least one of the 17 goals in Agenda 2030 Sustainable Development Goals (SDG) of the United Nations (UN). Consequently, this work also aims at propagating, not only the need for converting the geologically prominent areas to a geopark, but also attaining SDG, whatever is possible through geoparks.

Exploring beach placer minerals in the east coast of Tamil Nadu, India, using EO-1 Hyperion data

Recent advancements in remote sensing facilitate the mapping of mineral occurrences but lack quantitative estimation of mineral abundances. In the present study, EO-1 Hyperion data are used for mapping and estimating beach placer minerals in the Cuddalore coastal stretch of Tamil Nadu, India, using spectral angle mapper (SAM) algorithm, continuum removed band depth analysis, and random forest (RF) regression. Strategic beach placer minerals are exposed in the image due to their specific spectral reflection/absorption characteristics; these unique settings are used to explore their spatial distribution from associated features. EO-1 Hyperion images are analyzed for (i) atmospheric correction; (ii) selection and transformation of optimum bands; (iii) fixing the input pixels from selected bands; (iv) generating n-D angle—for the preparation of end-members with unique spectra of mineral classes; (v) comparative analysis between true end-member and reference spectra of minerals using SAM, spectral feature fitting, and binary encoding algorithms; and (vi) image classification using SAM. The result of SAM shows the occurrence of placer mineral deposits such as zircon with an overall accuracy of 81.06% and Kappa coefficient of 0.71. The zircon shows strong absorption in spectral geometric parameters of EO-1 Hyperion data, such as band depth and band area at the spectral range of 1075 to 1150 nm. The positive correlation between geometric parameters of mineral spectra in its absorption characteristics and the mineral concentration of in situ samplings is used for developing an RF prediction model for estimating the placer minerals from beach sand deposits. Significantly, the lower RMSE values estimated at 0.082 and 0.156 for reference spectra (in situ) and image spectra respectively proved the ability of EO-1 Hyperion data for quantifying mineral resources.