Distribution Of Heavy Minerals Research Articles

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.

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).

Heavy Minerals Distribution and Provenance in Modern Beach and Fluvial Sands of the Betic Cordillera, Southern Spain

This study uses heavy detrital minerals to determine actualistic fluvial and beach sand provenance across the Betic Cordillera (Spain), along the coast from Almeria to Marbella. The Betic Cordillera, primarily composed of metamorphic rocks to the east, supply an assemblage dominated by almandine and graphite, with a longshore dispersal from Almeria to Malaga. Buergerite and hypersthene indicate the provenance of calcalkaline lavas east of Cabo de Gata. The western part of the Betic Cordillera, which comprises the Ronda Peridotite Complex, supplies a chromite and diopside assemblage, with a dispersal from Marbella to Algeciras. Considering these mineralogical suites, the effects of source rock compositions and weathering are evaluated. The heavy mineral species mirror the mineralogy of the source rocks of local outcrops and wider source terranes. The fluvial heavy mineral suites do not differ significantly from those in the beaches except for some unstable species. Unstable species such as olivine, pyroxene, and amphibole do not show evidence of loss because of elevated topography and semiarid climate, which do not affect heavy minerals. This contribution also evaluates the potential of some heavy detrital species as ideal pathfinders in searching for diamonds.

Unveiling coastal dynamics: Investigating beach sediment distribution patterns along the Lithuanian Baltic Sea coast through heavy mineral analysis

Effective coastal management requires an understanding of sediment dynamics. This study examines the distribution of heavy minerals (HMs) in two distinct coastal regions: the mainland and spit, each with unique sediment deposition patterns. The spit accumulates sediment through alongshore sediment transport (AST), while the mainland experiences erosive processes and significant human impacts. The hydrodynamic behaviour and weathering resistance of HMs enables source identification. This has helped to reveal differences between the two regions, with apatite being characteristic of spit sediments and garnet of mainland beaches. Coastal processes, such as erosion, sediment transport, and accumulation, significantly shape the distribution of the HMs, with garnets dominating erosive shores and amphiboles dominating accumulative shores. Furthermore, the study found that human-made coastal infrastructure also affects the composition of HMs and the sediment distribution through AST. This research has implications beyond the local level, providing global insights into the complexities of coastal dynamics. The study emphasises the importance of using HM analysis in conjunction with grain size analysis to understand the distribution of beach sediment composition. It also highlights the significant role of coastal processes, including anthropogenic impacts such as jetty construction or deepening port entrance canals on AST.

Inherited Grain‐Size Distributions: Effect on Heavy‐Mineral Assemblages in Modern and Ancient Sediments

AbstractHeavy‐mineral suites are used widely in sandstone provenance and are key when connecting source and sink. When characterizing provenance related signatures, it is essential to understand the different factors that may influence a particular heavy‐mineral assemblage for example, chemical weathering or diagenetic processes. Hydrodynamics, causing size‐density sorting, exert major control on the distribution of heavy minerals. Here, we highlight the effect of grain‐size inheritance, essentially the absence of certain grain sizes within a specific heavy‐mineral species, on two distinct types of sediments. Modern deposits from a high‐energy beach in NW Denmark give an analog for heavily reworked sediment, primarily controlled by hydrodynamic processes. In contrast, three Palaeogene turbidite successions in the Eastern Alps were sampled, presenting a more complex history that includes diagenesis. All samples were processed for their heavy‐mineral compositions using Raman spectroscopy, and several techniques applied to determine the effect of grain‐size inheritance. Results show that (a) even within the hydrodynamically well‐sorted beach and placer deposits, evidence of grain‐size inheritance is apparent, and (b) turbidites of variable heavy‐mineral composition show strong effects of grain‐size inheritance for several mineral species. Moreover, considerable intersample contrasts within single turbidite beds are observed. We enforce the importance of understanding grain‐size inheritance, as well as other processes effecting size‐density relations in clastic sediment that go well beyond purely hydrodynamic control of intrasample heavy‐mineral variability.

Size Distribution And Heavy Mineral Pattern In Some E Gbe Streams, Southwestern Nigeria

The Egbe-Isanlu schist belt has received scholarly attention from several researchers but there is no documented report on types and the distribution of heavy minerals in streams of the area. This study is intended to reveal the types of heavy minerals, the distribution and possible source rocks to guide prospectors in gems. The study area lies within latitude 08o 03' and 08o 16 ' and longitude 05o 31' and 05o 43’ of the Southwestern Basement Complex terrain in Nigeria. Fifteen stream sediment samples were collected at appropriate points along river channels, air dried at room temperature, sieved and subjected to heavy mineral separation process using bromoform. Graphic mean, sorting, skewness and kurtosis were determined and heavy minerals identified under microscope. The graphic mean ranges between 0.67 (coarse sand) to 2.49 (fine sand), skewness between 0.75 and -0.10 and Kurtosis between 0.87 and 1.88. The calculated ZTR index ranges between 6.86% and 3.35.0%. The identified heavy minerals in the study area included tourmaline, epidote, rutile, zircon, kyanite, staurolite, garnet and zeolite. These minerals are modernly distributed across the sampled area and in some locations, they are relatively high in abundance. Some of the heavy minerals are angular to sub-angular in shape suggesting a short distance of travel from source. The graphic mean gives values that suggests a moderately to poorly sorted sediment and skewness indicated a platykurtic and leptokurtic nature for the sediments. Calculated ZTR index classified the sediments as immature to sub-mature indicating a short distance of travel suggesting that the sediments could have been derived within the catchment area. The presence of zircon, tourmaline and rutile suggests that the sediments might probably have its source from acid intrusive rocks and pegmatites.
 
 

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.

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.

Mineralogical Distribution and Characteristics of Fe-, Ti-, and V-Bearing Beach Ironsand Deposit in Adikarto Bay Kulonprogo, Yogyakarta, Indonesia

Identification of beach sand deposits was carried out in the south coastal area of Adikarto Bay, Kulonprogo, Yogyakarta in Indonesia. A total of 25 points were observed to identify the characteristics and mineralogy of beach sand related to the iron (Fe), titanium (Ti), and vanadium (Fe) bearing minerals that have an important role in the transition of fossil energy into clean energy as an energy storage technology known as Vanadium Redox flow batteries (VRBs) and lithium-vanadium-phosphate batteries [1]. Laboratory analysis was performed by mineral grain analysis, ore microscopy, and micro-XRF. Based on the mineralogical analysis, the beach sand deposit is composed of heavy minerals (magnetite, titanomagnetite, and hematite) and light minerals (quartz, clinopyroxene: hedenbergite and augite), biotite, hornblende, and ilvaite. The results of the analysis show that the distribution of heavy minerals is dominantly in the fraction size <0.106 mm (70-80%,) while light minerals are distributed in the fraction size 0.212-2 mm (80-90%). Mico-XRF for elemental analysis identification shows that magnetite is the mineral bearing of Fe, Ti, and V elements with a percentage of (79.02 - 92.43 wt%), Ti (6.08-7.89 wt%), and V (0.56-1.15 wt%). Therefore, it is important to characterize the mineralogy and distribution of magnetite, since it can be used as a “mineral pathfinder” for advanced exploration of Fe, Ti, and V elements. So, the ironsand is for the cement indsutry and has advanced utilization.

Study of the Variations in the Vertical and Horizontal Distribution of Heavy Sand Minerals in the Hilla River Sediments

Study of the Variations in the Vertical and Horizontal Distribution of Heavy Sand Minerals in the Hilla River Sediments

Mineral Associations of Concentrates from Gold-Bearing Placers of the Miass Placer Zone (South Urals) and Possible Primary Sources of Gold

Abstract —The placer deposits of the Miass valley in the Southern Urals have been known since the beginning of the 19th century. Over two centuries of mining more than 120 tons of gold have been extracted from alluvial and alluvial–deluvial placers. Despite the industrial significance of this territory, native gold of alluvial deposits is practically unstudied and there is no data on the mineral composition of concentrates. Native gold and heavy fraction minerals from seven placers of the Miass placer zone of deluvial–alluvial and alluvial types were researched. The study of the typomorphic features of native gold and distribution of heavy fraction minerals in loose deposits makes it possible to determine the genetic types of primary sources of placer formation. Chrome-spinel and ilmenite prevail in the concentrates, magnetite, epidote, rutile, titanite, clinopyroxene, hematite, zircon, garnets, and monazite are less common. Chromespinelides of various placers are represented by chromite and subferrichromite, they are characterized by a high average content of Cr2O3 (50.9 wt.%). Chromespinelide chemical composition features show evidence of its penetration into placer sediments from rocks of the ophiolitic association. The composition and morphological features of phosphates of rare earth elements (monazite and xenotime) indicate their metamorphogenic nature and penetration into placers from the Riphean strata. Native gold is characterized by a low degree of roundness. Mineral inclusions in native gold are represented by sulfides, arsenides, bismuthides, cuprous gold, platinoids. Composition of native gold from the Miass River valley placers varies over a wide range. The main admixtures are silver (4.5–23.4 wt.%) and mercury (up to 5.14 wt.%), copper (up to 2.03 wt.%) was noted in several grains. The EBSD study of native gold internal structure showed predominance of primary crystallization structures, a low degree of deformation and growth of gold-rich rims with a fine-grained mosaic structure. Formation of gold-rich rims in gold grains in placers is explained by recrystallization of the most deformed parts of gold during transportation. Placers occurred due to the destruction of primary sources located in the upper reaches of streams or near them, which is confirmed by a low degree of grains’ roundness. The composition of native gold in combination with a set of micro-inclusions indicate the gold–sulfide-quartz type of mineralization of most primary sources.

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.

Heavy Mineral Distribution and Clay Mineralogy of Injana Formation at Zawita and Daigala Northern Iraq

This study deals with the minerology of Injana Formation (Late Miocene- Pliocene) at Zawita and Daigala sections, north of Iraq. A total of 13 samples are collected from Injana Formation. The heavy minerals assemblages include opaque minerals, orthopyroxenes, clinopyroxenes, zircon, rutile, epidotes, garnet, amphiboles, tourmaline, chlorite, biotite, kyanite, muscovite and staurolite. The source rocks of these assemblages of heavy minerals are mafic igneous and metamorphic rocks principally as well as acidic igneous and old sedimentary rocks. The ZTR indices indicate the Injana sandstone is mineralogically immature .The tectonic origins of Injana Formation is characterized as lithic recycled of recycled orogeny .The mudstone consists of mixture of clay and silt percentage variable. The major clay minerals are chlorite, kaolinite, illite and smectite. The non-clay minerals are calcite, quartz and subordinate feldspars. The mineralogy of the clay fraction of Injana mudstone leads to be climate arid to semi-arid

Provenance discrimination and geodynamics analysis of open and island coasts, South East coast of India: Inference on heavy minerals and hydrodynamics

AbstractThe coastal sediments contain heavy minerals originating from the offshore and hinterland. We investigated the heavy minerals on different sediment layers of three trenches such as the Dhanushkodi open coast and Manoli island beach in India to identify the pervasiveness and depositional environment of the sediments. The primary objectives of this study are to identify the source rock and to establish the impact of hydrodynamics on the vertical textural trends of heavy mineral distribution. This is in conjunction with sediment deposits. The mineral array consists mainly of ilmenite, sillimanite, garnet, and pyroxene. Both surface and sub‐surface sediments indicate their origin, primarily from metamorphic and igneous rocks. To achieve the goal of the present study, during the low tide time, three shallow‐depth trenches, such as Trench‐1 (Palk Bay Side) and Trench‐2 (Gulf of Mannar side) were dug at Dhanushkodi beach and Trench‐3 excavated at Manoli island beach. The tip of the Dhanushkodi is called Arichalmunai and it is a continuously growing dynamic sandspit whereas Manoli Island has massive reefs with both live and dead corals on its Southern and Northern borders and it includes lagoonal lakes and extensive mudflats. The fine and very fine sand fractions of Trenches 1 and 2 contain a high concentration of ilmenite and sillimanite. Due to high energy sorting by the wave action, Trench 3 contains relatively high concentrations of mineral assemblages with very fine sand particles. Provenance relationships are established based on the mineralogical contents of trench sediments, and the observation of down‐core variation of heavy mineral assemblages implies that they were sourced from various igneous and metamorphic rocks of nearby land areas, such as the East and West coasts of India, as well as the Sri Lankan coast.

Sediment Properties and Provenance Study of Heavy Minerals Along Chinnavilai and Erayumanthurai Beach, South West Coast of India

The Chinnavilai and Erayumanthurai beach sediments of the Kanyakumari District consist of medium-grained, moderately well-sorted, unimodal, occasionally bimodal, mesokurtic, leptokurtic and platykurtic. The fine skewed and symmetrical nature of sediments implies the prevalence of high and low energy, entailing a mixed distribution of coarse and fine sediments. The washing and backwashing of waves cause the coarser sediments to retainment and entrapped amidst finer sediments. The heavy minerals distribution reflects that the less content in Erayumanthurai samples, whereas the Manavalakurichi, Enayam, Kurumpanai sediments comprise &gt;60%. The oval shape zircon is devoid of inclusions, whereas, the euhedral zircons comprise subhedral inclusions. Distinct fractures in zircons are caused due to transportation by waves and currents. The garnet and zircon grains are well-rounded, implying the source for these sediments are an admixture of medium to high-grade metamorphic rocks, reworked sediments, charnockite, and granite gneisses. Keywords : Sediment Texture, Provenance, Heavy Minerals, Kanyakumari,South West Coast of India

Heavy Mineral Distribution of Gercus Formation in Shaqlawa and Dokan Area in Northern Iraq

Heavy Mineral Distribution of Gercus Formation in Shaqlawa and Dokan Area in Northern Iraq

Global distribution, genesis, exploitation, applications, production, and demand of industrial heavy minerals

Heavy minerals (HMs) are used in many high-tech applications (e.g. nuclear reactors, photovoltaic cells, electronics, green, and nano- and space technology), and thus global demand is increasing day by day. This review article is focused on the global distribution, genesis, economic geology, exploration and exploitation, demand (i.e. past, present, and future status of annual global production, consumption, and price), applications (geological and industrial uses), and major environmental issues mostly related to the HM sand industry. Heavy mineral deposits are distributed in more than 45 countries. Major HM deposits are located in Australia, Asia, and Africa, as secondary coastal placers bordering the Indian Ocean. Onshore and offshore deposits in the Americas, Europe, and other countries also contribute to the global HM market. Heavy mineral deposits are categorised as primary (magmatic, hydrothermal, metamorphic) or secondary (weathered, eroded, and transported sediments) deposits. Titanium, zirconium, and rare earth element (REEs) bearing minerals are key industrial commodities in the current global market. The heavy mineral industry has experienced healthy growth in unit price and global production due to increased demand generated by rapidly expanding economies such as those of China and India. Global production of zircon, ilmenite, and rutile has gradually increased over the last few decades. Global apparent consumption of ilmenite declined slightly from 1970 to 1995, in part due to introduction of stringent regulatory measures and government environmental policies in Europe and North America, as the main consumers of HMs at present. Mining and utilisation planning following the United Nations Sustainable Development Goals are highly appropriate for the sustainability of the HM industry, and to overcome ecological challenges, health issues, and social resistance towards HM exploitation. Finally, we forecast changes in production and price of three HMs (ilmenite, rutile, and zircon) for the decade from 2020 to 2030, assuming there are no disturbances in production due to external factors such as the Covid-19 global pandemic or unfavourable geopolitical interventions.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12517-022-10874-0.

Source areas of the Eastern Ebro Valley loess (NE Iberian Peninsula): Heavy mineral composition as a provenance indicator

AbstractLoess deposits of the Eastern Ebro Valley (NE Iberian Peninsula) occupy an area of ~2000 km2 mostly on the east of the Ebro depression and locally in the Móra Basin. We studied 38 samples of loess and 47 samples of their possible source areas, in order to determine the location of the origin of the loess materials, based on their particle size distribution and composition of heavy minerals. Our results clearly differentiate two depositional loess basins disconnected by the reliefs of the Pre‐Coastal Range with different mineralogical signatures: the Ebro Basin and the Móra Basin. The most relevant variables to discern source areas were the percentage of heavy minerals, the concentrations of zircon, staurolite, rutile and inosilicates, and the presence of gypsum. In the Ebro Basin, the largest set of loess deposits is located around a depocenter in the Batea region and along several lateral areas, with materials that come from the central alluvial plain of the Middle Ebro River (25 to &gt;100 km travel distance), in addition to deflated materials from Miocene interfluvial substrates. On the other hand, loess deposits of the Móra Basin come from more proximal source areas (&lt;15 km), originating from the alluvial materials of the Lower Ebro River that contain the contributions of its tributaries, the Cinca and Segre rivers. Taking into account the homogeneity in the mineralogical composition of complex loess sequences, we deduced a general WNW–ESE wind direction, which would have remained constant over the last two cold periods (MIS‐2 and MIS‐6). Along this axis, the Pàndols–Cavalls Range, with a height difference of 200–350 m, acted as a wind barrier separating the loess of Ebro Basin from the loess of Móra Basin.

Nature and Provenance of Heavy Mineral Distribution at Krishna River Delta, East Coast of India

The present study deals with four sedimentary cores viz. Turumella (120m), Inturu (160m), Ponnapalli (110m) and Nizampatnam (150m) which were recovered from the Krishna delta. Total heavy minerals wt% varies from 0.32 to 7.00 (av. 2.44%) in the study area. The major heavy minerals were noticed in four studied cores i.e. opaques (Ilmenite + magnetite), pyriboles (pyroxenes + amphiboles), garnet, zircon, monazite, rutile and other heavy minerals (epidote, kyanite, tourmaline, etc.). Heavy mineral substance in Krishna river sediments forced by basement rocks, drainage basin and weathering conditions of the river environment. The occurrence of different lithological units in the drainage basins is contributing sediments, mainly opaques (Ilmenite + magnetite) and pyriboles (Amphibole + pyroxenes) from Deccan traps as well as Archean provenance which covered more than 55% of drainage basin. The red garnets (almandine), prismatic sillimanites and rounded zircons are derived from khondalites (metapeletic rocks) and pink garnets, elongated zircons and ortho- pyroxenes are derived from charnockites of Eastern Ghat Granulite Belt (EGGB). The fresh appearance of heavy minerals indicates short residence time in depositional environment without any chemical dissolution effect. The rounded and sub rounded grains of magnetite and ilmenite indicate long distance of transportation and/or reworked nature. The sub angular grains of magnetite and ilmenite indicate that they might have been derived from nearby sources, i.e. mainly an Eastern Ghat Group of rocks. The prismatic characteristic of the sillimanite mineral grains also suggests that their derivation is from khondalitic rocks. Opaques are from Deccan traps as well as Archean provenance. Garnets, sillimanites and zircons are derived from khondalites (metapeletic rocks) and charnockites of Eastern Ghat Granulite Belt.

Distribution and provenance of heavy minerals from recent sediments of Green Lake, North Brazil, revisited

Geostatistical and multivariate statistical analyses were applied to heavy mineral data from an Amazonian fluvial-lake system near the Tapajós River mouth to investigate the spatial distribution and source-area of sediments. Twenty-one points were investigated, and the physical characteristics of the Green Lake deepest point were determined. Sand accumulates in the lake margins and mud quantity increases towards the lake center. Heavy mineral assemblage is composed of zircon, tourmaline, kyanite, rutile, staurolite, anatase, sillimanite, garnet, and spinel. Tourmaline, staurolite, and spinel are more abundant in the southeast area of the lake, while kyanite is dominant in the north area and zircon is in the whole lake except in its southeast area. Zircon - tourmaline and zircon - staurolite pairs are negatively correlated (r= -0.947 and -0.775, respectively), while tourmaline - staurolite and sillimanite - anatase pairs have a positive correlation (r= 0.628 and 0.675, respectively) which indicate different source rock types. Geostatistical analysis grouped the heavy minerals in three grups: Group 1 (tourmaline – staurolite – spinel - kyanite) and Group 2 (garnet – rutile – sillimanite - anatase) related to metamorphic source rocks ranging from medium to high grade, and Group 3 (zircon) related to acid igneous source rocks. The heavy mineral assemblage of Green Lake is analogous to the assemblage of the Alter do Chão Formation, indicating that this formation is the source of sediments of Green Lake.