Provenance of Bengal Shelf Sediments: 1. Mineralogy and Geochemistry of Silt

This article illustrates a multi-technique frontier approach for the provenance study of silt-size sediments. The mineralogical composition of low-density and heavy-mineral fractions of four samples of fine to very coarse silt deposited on the Bengal shelf was analyzed separately for six different grain-size classes by combining grain counting under an optical microscope, Raman spectroscopy, and X-ray diffraction. The geochemical composition was determined on both bulk-sediment samples and on their <5-μm classes. Such a “multiple-window” approach allowed capturing the full mineralogical information contained in each sample, as well as the size-dependent intra-sample variability of all compositional parameters. The comparison between grain-size distributions obtained by different methods highlighted a notable fallacy of laser granulometry, which markedly overestimated the size of the finest mode represented by fine silt and clay. As a test case, we chose to investigate sediments of the Bengal shelf, where detritus is fed from the Meghna estuary, formed by the joint Ganga and Brahmaputra Rivers and representing the largest single entry point of sediment in the world’s oceans. The studied samples show the typical fingerprint of orogenic detritus produced by focused erosion of collision orogens. Bengal shelf silt is characterized by a feldspatho-quartzose (F-Q) composition with a Q/F ratio decreasing from 3.0 to 1.7 with increasing grain size, plagioclase prevailing over K-feldspar, and rich transparent-heavy-mineral assemblages including mainly amphibole with epidote, and minor garnet and pyroxene. Such a detrital signature compares very closely with Brahmaputra suspended load, but mineralogical and geochemical parameters, including the anomalous decrease of the Q/F ratio with increasing grain size, consistently indicate more significant Ganga contribution for cohesive fine silt. The accurate quantitative characterization of different size fractions of Bengal shelf sediments represents an essential step to allow comparison of compositional signatures characterizing different segments of this huge source-to-sink system, from fluvial and deltaic sediments of the Himalayan foreland basin and Bengal shelf to the Bengal Fan.

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Distribution of Mercury in Lake St. Clair and the St. Clair River Sediments

Water Quality Research Journal ◽

10.2166/wqrj.1989.002 ◽

1989 ◽

Vol 24 (1) ◽

pp. 1-22 ◽

Cited By ~ 3

Author(s):

Alena Mudroch ◽

K. Hill

Keyword(s):

Organic Matter ◽

Sediment Cores ◽

River Sediments ◽

Size Fraction ◽

Mineralogical Composition ◽

Recent Sediment ◽

Geochemical Composition ◽

Visual Appearance ◽

Decaying Wood ◽

Relationship Of

Abstract Sediment cores were collected in Lake St. Clair in 1985 and in the St. Clair River in 1986 to investigate the horizontal and vertical distribution and association of Hg in the sediments. A layer of recent sediment up to about 35 cm thick was differentiated by the geochemical composition and visual appearance from the underlying glacial-lacustrine deposits. The concentration of Hg in the surficial sediments in Lake St. Clair was lower in 1985 (<0.025 to 1.200 µg/g) than that found in 1974 (<0.20 to 3.00 µg/g). Up to 8.30 µg/g of Hg were found in the sediments collected from the nearshore area at Sarnia, Ontario, in the St. Clair River in 1986. The concentrations of Hg ranged from 5.05 to 16.00 µg/g in different sand-sized fractions (0.063 to 0.350 mm) of the sediment. The concentration of Hg was 17.80 µg/g in the silt-clay size fraction (<0.063 mm). No relationship was found between the concentration of organic matter and Hg, and the concentration of silica and Hg in the St. Clair River sediments. The results indicated a relationship of Hg with particles of different mineralogical composition. Up to 3.72 µg/g Hg was found in the surface sediment in Chenal Ecarte. The greatest concentration of Hg (13.15 µg/g) existed in the 0.350 mm particle size fraction, which consisted mainly of small pieces of decaying wood. A good relationship was found between the concentration of Hg and organic matter in the sediment at this area.

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The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.551-552.387 ◽

2007 ◽

Vol 551-552 ◽

pp. 387-392 ◽

Cited By ~ 4

Author(s):

Wen Juan Zhao ◽

Hua Ding ◽

D. Song ◽

F.R. Cao ◽

Hong Liang Hou

Keyword(s):

Grain Size ◽

Grain Growth ◽

Superplastic Deformation ◽

Initial Strain Rate ◽

Deformation Mode ◽

Tensile Tests ◽

Optical Microscope ◽

Coarse Grained ◽

Transmission Electron ◽

Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

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The Effect on Cement Mortar and Concrete by Admixture of Spray Drying Absorption Products

MRS Proceedings ◽

10.1557/proc-178-267 ◽

1989 ◽

Vol 178 ◽

Author(s):

Kirsten G. Jeppesen

Keyword(s):

Grain Size ◽

Fly Ash ◽

Cement Mortar ◽

Setting Time ◽

Mineralogical Composition ◽

Cement Clinker ◽

Strength Development ◽

Fall Meeting ◽

Freeze Thaw ◽

Spray Dried

AbstractSpray dried absorption products (SDA) having special characteristics are used as substitutes for cement in the preparation of mortars; the qualities of the resulting mixed mortars are described. Conditions are described for mortar mixes, data for which were presented at the MRS Fall Meeting 1987.The influence of the composition of the SDA on water requirement and setting time has been studied. A full scale project involving 3 precast, reinforced concrete front-elements containing 20 and 30 wt.% SDA is described. Strength development, mineralogical composition and corrosion were monitored for two years.A non-standard freeze-thaw experiment was performed which compares mortars containing SDA and fly ash (FA) and also shows the effect of superplasticizer.The possibility of improving the SDA by grinding has been tested and a limited improvement has been found. The strength of the mixed mortars seems slightly influenced by the grain size of SDAGypsum (CaSO4·2H2O), synthetic calcium-sulphite (CaSO3·½H2O) and 2 SDAs have been used as retarders for cement clinker. Mortar test prisms have been cast and comparative strengths after curing for 3 years are reported

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The minerals in the clay fractions of a black cotton soil and a red earth from Hyderabad, Deccan State, India

The Journal of Agricultural Science ◽

10.1017/s0021859600048279 ◽

1940 ◽

Vol 30 (4) ◽

pp. 639-653 ◽

Cited By ~ 21

Author(s):

G. Nagelschmidt ◽

A. D. Desai ◽

Alex. Muir

Keyword(s):

Grain Size ◽

Mineralogical Composition ◽

Principal Factor ◽

Black Cotton Soil ◽

Red Clay ◽

Black Clay ◽

Close Proximity ◽

Parent Rocks ◽

Red Earth ◽

Mineral Compositions

The mineral compositions of the clays from a red earth and a black cotton soil from Hyderabad, Deccan State, India, occurring in close proximity in the field are determined. Both soils are derived from the same or from very similar parent rocks, a coarsely crystalline granite or gneiss.For both soils there is practically no variation in the mineralogical composition of the clay throughout the profile, but for any given clay there is some variation with grain size. The main contrast between the two is that the red clay contains predominantly kaolinite or halloysite, whereas the black clay contains mainly beidellite, a member of the montmorillonite group. The topography appears to be the principal factor associated with this difference in minerals, and the processes of weathering believed to have produced the contrasted clays are discussed with reference to experiments on the leaching of felspar in the laboratory and on hydrothermal synthesis.

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Rare earth elements in different size fractions of a marine quick clay from Ullensaker, and a till from Upper Numedal, Norway

Clay Minerals ◽

10.1180/claymin.1979.014.3.08 ◽

1979 ◽

Vol 14 (3) ◽

pp. 229-240 ◽

Cited By ~ 18

Author(s):

Elen Roaldset

Keyword(s):

Grain Size ◽

Rare Earth ◽

Rare Earth Elements ◽

Mineralogical Composition ◽

Marine Clay ◽

Size Fractions ◽

Quick Clay

AbstractThe distribution of rare earth elements (REE) in two different sediments, a marine clay and a till, was found to be dependent both on grain size and mineralogical composition. In the marine clay the REE content was highest in the coarsest fraction; in the till REE were markedly enriched in the finest fraction. Detrital and authigenic origins for different size fractions have been attributed on the basis of REE contents.

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Grain Structure and Surface Roughness of Four Commercial NiTi Orthodontic Archwires

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.266.257 ◽

2017 ◽

Vol 266 ◽

pp. 257-263

Author(s):

Wassana Wichai ◽

Rutchadakorn Isarapatanapong ◽

Niwat Anuwongnukroh ◽

Surachai Dechkunakorn

Keyword(s):

Surface Roughness ◽

Grain Size ◽

Optical Microscope ◽

Grain Structure ◽

Wire Surface ◽

Average Grain Size ◽

Electron Mode ◽

The Mean ◽

The Wire ◽

Orthodontic Archwires

This study investigated four commercially available NiTi orthodontic archwires from different manufactures for their grain structure and surface roughness.Four commercially available pre-formed NiTi orthodontic archwire (Ormco, Sentalloy, Highland and NIC) with diameter 0.016 x 0.022 inch2 were tested. The wire samples were polished and etched to evaluate the morphology and structure of wire surface. Each NiTi archwire was investigated under a reflected light microscope of an Optical Microscope to analyze its grain structure and size, in longitudinal surfaces. The surfaces of wire were qualitatively examined in the secondary electron mode at common magnification (500X). The surface roughness was also evaluated by a surface roughness tester. The descriptive statistic was evaluated the mean and standard deviation of surface roughness and Medcale T-Test was to test the mean difference of the surface roughness in each brands. This study showed an average grain size of 2-8 μm for each NiTi archwire. The wire surface of Ormco and Highland showed straiations along the longitudinal axes, however Sentalloy and NIC showed small pores on the wire surface. The surface roughness was 0.09 μm for Highland, 0.25 μm for Sentalloy, 0.28 μm for Ormco and 0.46 μm for NIC archwire. The Highland was smoothest and NIC was the roughest. There were in significant (p < 0.05) difference of surface roughness of each brands. The results showed that the four manufactures NiTi archwires were different in grain size, wire surface and surface roughness. During clinical application, these archwires may exhibit different mechanical properties, such as strength, hardness, ductity, and friction because of their microstructure.

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Multimineral Fingerprinting of Transhimalayan and Himalayan Sources of Indus-Derived Thal Desert Sand (Central Pakistan)

Minerals ◽

10.3390/min9080457 ◽

2019 ◽

Vol 9 (8) ◽

pp. 457 ◽

Cited By ~ 4

Author(s):

Wendong Liang ◽

Eduardo Garzanti ◽

Sergio Andò ◽

Paolo Gentile ◽

Alberto Resentini

Keyword(s):

Relative Proportion ◽

Foreland Basin ◽

Sediment Supply ◽

Heavy Mineral ◽

Mineral Species ◽

Provenance Analysis ◽

Indus River ◽

Mineral Concentration ◽

River Sand ◽

Desert Sand

As a Quaternary repository of wind-reworked Indus River sand at the entry point in the Himalayan foreland basin, the Thal Desert in northern Pakistan stores mineralogical information useful to trace erosion patterns across the western Himalayan syntaxis and the adjacent orogenic segments that fed detritus into the Indus delta and huge deep-sea fan throughout the Neogene. Provenance analysis of Thal Desert sand was carried out by applying optical and semi-automated Raman spectroscopy on heavy-mineral suites of four eolian and 11 fluvial sand samples collected in selected tributaries draining one specific tectonic domain each in the upper Indus catchment. In each sample, the different types of amphibole, garnet, epidote and pyroxene grains—the four dominant heavy-mineral species in orogenic sediment worldwide—were characterized by SEM-EDS spectroscopy. The chemical composition of 4249 grains was thus determined. Heavy-mineral concentration, the relative proportion of heavy-mineral species, and their minerochemical fingerprints indicate that the Kohistan arc has played the principal role as a source, especially of pyroxene and epidote. Within the western Himalayan syntaxis undergoing rapid exhumation, the Southern Karakorum belt drained by the Hispar River and the Nanga Parbat massif were revealed as important sources of garnet, amphibole, and possibly epidote. Sediment supply from the Greater Himalaya, Lesser Himalaya, and Subhimalaya is dominant only for Punjab tributaries that join the Indus River downstream and do not contribute sand to the Thal Desert. The detailed compositional fingerprint of Thal Desert sand, if contrasted with that of lower course tributaries exclusively draining the Himalaya, provides a semi-actualistic key to be used, in conjunction with complementary provenance datasets and geological information, to reconstruct changes in paleodrainage and unravel the relationship between climatic and tectonic forces that controlled the erosional evolution of the western Himalayan-Karakorum orogen in space and time.

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Mineralogy of agglutinated benthic foraminifera; implications for paleo-environmental reconstructions

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.179.6.583 ◽

2008 ◽

Vol 179 (6) ◽

pp. 583-592 ◽

Cited By ~ 15

Author(s):

Eric Armynot du Chatelet ◽

Philippe Recourt ◽

Vincent Chopin

Keyword(s):

Grain Size ◽

Benthic Foraminifera ◽

Tidal Marsh ◽

Environmental Parameters ◽

Mineralogical Composition ◽

Test Construction ◽

Taxonomic Composition ◽

Tidal Elevation ◽

Sediment Grain Size

Abstract Benthic foraminifera of recent salt marsh environments are often dominated by species with an agglutinated test. The grains used for test construction by these foraminifera are collected from their surrounding environment. In this study we investigate the role of sediment grain size and mineralogical composition for richness, population density and taxonomic composition of agglutinating foraminifera. Foraminifera from 15 stations of the tidal marsh of the Canche estuary (Pas-de-Calais, France) were studied. The species richness depends on the grain size of the sediment, whereas the density is not related to sediment grain size. The distribution of foraminifera species throughout the tidal marsh may depend on many environmental parameters such as OM as well as tidal elevation, already largely discussed in literature. The mineralogical composition of the agglutinated grains in Trochammina inflata and Arenoparrella mexicana is very different from that of sediment; the composition of Jadammina macrescens is generally different from that of the sediment with some exceptions, and in Miliammina fusca, Paratrochammina haynesi and Remaneica plicata the mineralogical compositions are similar to those of the sediment. The studied species may be able to select their preferred grains based upon composition even if a particular mineral is scarce in the sediment.

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Heavy Mineral Variability in the Yellow River Sediments as Determined by the Multiple-Window Strategy

Minerals ◽

10.3390/min9020085 ◽

2019 ◽

Vol 9 (2) ◽

pp. 85 ◽

Cited By ~ 3

Author(s):

Bingfu Jin ◽

Mengyao Wang ◽

Wei Yue ◽

Lina Zhang ◽

Yanjun Wang

Keyword(s):

Particle Size ◽

Grain Size ◽

Yellow River ◽

River Sediments ◽

Size Fraction ◽

Heavy Mineral ◽

The Yellow River ◽

Yellow River Sediment ◽

Yellow River Sediments ◽

End Members

In this study, heavy mineral analysis was carried out in different size fractions of the Yellow River sediment to extract its end-members. It shows that heavy mineral contents, species, and compositions vary in different grain sizes. Distribution curve of heavy mineral concentration (HMC) and particle size frequency curve are in normal distribution. In most samples, the size fraction of 4.5–5.0 Φ contains the maximum HMC (18% on average). Heavy mineral assemblages of the Yellow River are featured by amphibole + epidote + limonite + garnet. Amphibole content is high in coarse fraction of >3.0 Φ and reaches its peak value in 3.5–4.5 Φ. Epidote is rich in a size fraction of >3.5 Φ, and increase as the particle size becomes fine. Micas content is high in coarse subsamples of <3.0 Φ, but almost absent in fine grains of >4.0 Φ. Metallic minerals (magnetite, ilmenite, hematite, and limonite) increase as the sediment particle size become fine, and reach the peak in silt (>4.0 Φ). Other minerals such as zircon, rutile, tourmaline, garnet, and apatite account for about 15%, and mainly concentrate in fine sediment. Further analysis reveals that similarity value between the most abundant grain size group and wide window grain size group is high (0.978 on average). The grain size of 4.0–5.0 Φ ± 0.5 Φ is suitable to carry out detrital mineral analysis in the Yellow River sediments. Our study helps to eliminate cognitive bias due to narrow grain size strategy, and to provide heavy mineral end-members of the Yellow River sediment for provenance discrimination in the marginal seas of East China.

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Evaluation of Cryogenic Mechanical Properties of Resistance Seam-Welded Invar Alloy Sheet by Instrumented Indentation Test

Journal of Marine Science and Engineering ◽

10.3390/jmse8121009 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1009

Author(s):

Seunghun Choi ◽

Jongho Won ◽

Jung-Jun Lee ◽

Hee-Keun Lee ◽

Seong-Min Kim ◽

...

Keyword(s):

Grain Size ◽

Plastic Zone ◽

Base Material ◽

Indentation Test ◽

Welding Current ◽

Optical Microscope ◽

Alloy Sheet ◽

Invar Alloy ◽

Instrumented Indentation ◽

Average Grain Size

Invar alloy sheet was welded by resistance seam welding (RSW) with a constant electrode force and three different welding currents. Tensile properties were evaluated using instrumented indentation testing (IIT) with a spherical indenter and microstructure observations were obtained under an optical microscope. IIT performed on the base material at room temperature (RT) and −163 °C, a cryogenic temperature (CT), gave results in good agreement with those of tensile testing. The strength of each zone was higher in the order of heat-affected zone (HAZ) < weld nugget (WN) < base material (BM) because the amount of cold working was least in the BM, heavy metal elements and carbon vaporized during melting, and the WN was formed more tightly than the HAZ, effectively constraining the plastic zone generated by the indentation. As for the welding current, the nugget, which becomes larger and tighter as the current increases, more effectively constrained the plastic zone in the indentation, and this soon increased the strength. Generally, Invar is known to consist of single-phase austenite, and microstructure observations have confirmed that the average grain size is ordered as BM < HAZ < WN. Fan-like columnar grains developed in the direction of the temperature gradient, and equiaxed grains were observed near the BM. It was confirmed that the grain size in the WN also increases as the current is increased. Interestingly, the constraint effect with increasing nugget size was more important for strength than the grain size.

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