scholarly journals Archean Itabirites From Ovan, NE-Gabon: Petrography, Mineralogy And Elemental Mapping

2021 ◽  
Vol 17 (25) ◽  
pp. 380
Author(s):  
Stévy Retonda-Kondja ◽  
Simplice Marin Ndong-Ondo ◽  
Ambroise Edou-Minko ◽  
Tomohiko Sato ◽  
Benjamin Musavu-Moussavou ◽  
...  
Keyword(s):  
Sedimentary Rocks ◽  
Chemical Precipitation ◽  
Elemental Mapping ◽  
Sem Images ◽  
Secondary Minerals ◽  
Field Investigations ◽  
Mineral Assemblages ◽  
Archean Greenstone Belt ◽  
The One ◽  
Primary Minerals

The Archean greenstone belt called Bélinga Group was highlighted in NE-Gabon around 1960. It consists of many petrographic types such as itabirites (BIFs), ultrabasites, and amphibolites. Recent geophysical studies revealed the presence of BIFs and associated rocks at Ovan, which were linked to the Bélinga Group according to similar magnetic and some petrographic characteristics. Unfortunately, data on itabirites in respect with petrography, mineralogy and geochemistry are rare. This note aims at contributing to petrography, mineralogy and elemental mapping of Ovan itabirites on the one hand, and giving strong proofs that they belong to the Bélinga Group on the other. Field investigations bring samples from six sites around Ovan. Selected itabirites samples have been studied in petrography, mineralogy (XRD) and elemental mapping (SEM). Two (2) itabirites lithofacies are recognized: the well-banded and the massive itabirites. Mineral assemblages show principally quartz, magnetite, hematite and goethite. SEM images show euhedral to sub-euhedral grains of quartz and Fe-oxides of two types: the biggest (Fe1), seen as primary minerals within Fe-rich bands and the smallest (Fe2), as secondary minerals disseminated in the siliceous levels. Elemental mapping clearly reveals alternating Fe- and Si-rich bands with Fe-rich bands predominance. Finally, the itabirites around Ovan are sedimentary rocks essentially formed by chemical precipitation and belonging to the Bélinga Group.

scholarly journals Clean one-pot multicomponent synthesis of pyrans using a green and magnetically recyclable heterogeneous nanocatalyst

SynOpen ◽  
2021 ◽  
Author(s):  
Mina Ghassemi ◽  
Ali Maleki
Keyword(s):  
Room Temperature ◽  
Significant Loss ◽  
Copper Ferrite ◽  
Multicomponent Synthesis ◽  
Thermo Gravimetric ◽  
Sem Images ◽  
One Pot ◽  
Three Component Reaction ◽  
Ft Ir ◽  
The One

Copper ferrite (CuFe2O4) magnetic nanoparticles (MNPs) were synthesized via thermal decomposition method and applied as a reusable and green catalyst in the synthesis of functionalized 4H-pyran derivatives using malononitrile, an aromatic aldehyde and a β-ketoester in ethanol at room temperature. Then it was characterized by Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) analysis, scanning electron microscopy (SEM) images, thermo gravimetric and differential thermo gravimetric (TGA/DTG) analysis. The catalyst was recovered from the reaction mixture by applying an external magnet and decanting the mixture. Recycled catalyst was reused for several times without significant loss in its activity. Running the one-pot three-component reaction at room temperature, no use of eternal energy source and using a green solvent provide benign, mild, and environmentally friendly reaction conditions; as well, ease of catalyst recovering, catalyst recyclability, no use of column chromatography and good to excellent yields are extra advantages of this work.

Micronutrients

1999 ◽  
Author(s):  
Robert F. Keefer
Keyword(s):  
Plant Growth ◽  
Plant Tissue ◽  
Internal Drainage ◽  
Secondary Minerals ◽  
Soil Particles ◽  
Ring Compounds ◽  
Poorly Drained Soils ◽  
Iron Manganese ◽  
Primary Minerals ◽  
Growth And Reproduction

Micronutrients needed by plants are Cu, Fe, Mn, Zn, B, Mo, Cl, Ni, Co, V, Si, and Na. The required amounts of each of these elements is very small but still essential for desirable plant growth and reproduction. These elements must be applied to soils cautiously for the range between deficient and toxic is very small. It is unwise to use a fertilizer containing all of these micronutrients. Any one of them may already be high enough in soils to cause toxicity from that particular element. If a micronutrient is suspected of being deficient, it would be wise to get soil tests and plant tissue tests to corroborate your suspicions. If a micronutrient is deficient, one should apply only the amount recommended but no more. Sometimes a toxicity of an element is more difficult to correct than a deficiency. Copper, iron, manganese, cobalt, and zinc can be present in soils as (a) several types of precipitates, (b) adsorbed onto the surface of soil particles, (c) present in primary minerals (rocks) and secondary minerals (clays), and (d) present as complex ring compounds. These forms may or may not be available to plants. Precipitates of Cu, Fe, Mn, or Zn often form in soils at high pH (after liming Fig. 14.1). This may occur in soils near buildings from the lime used in the mortar. Soil acids dissolve the lime into Ca++ or Mg++ that migrate into the soil raising the pH and cause these micronutrients to precipitate. Often an Fe deficiency is evident, particularly on acid-loving plants, such as azaleas, rhododendrons, or hollies. If this is extensive, the soil near the buildings may need to be replaced. With limited areas, the soil can be acidified by adding elemental S near the plants affected. The elements Cu, Fe, Mn, and Zn can exist as soluble forms or precipitates, depending on the pH of the soil. The soluble forms as cations are present when soils have poor internal drainage (poorly drained soils), whereas the oxides of these elements are present where the soil is well aerated.

Effect of Glutinous Rice Paste on Compressive Strength of Lime-Stabilized Soil

2011 ◽  
Vol 280 ◽  
pp. 5-8
Author(s):  
Hong Tao Peng ◽  
Qi Zhang ◽  
Nai Sheng Li ◽  
De Fa Wang
Keyword(s):  
Compressive Strength ◽  
Soil Sample ◽  
Experimental Results ◽  
Box Dimension ◽  
Sem Images ◽  
Sem Image ◽  
Glutinous Rice ◽  
Stabilized Soil ◽  
The Difference ◽  
The One

The lime-stabilized soil was mixed with glutinous rice paste in proper proportion to determine the difference in compressive strength caused by introduction of glutinous rice paste. The experimental results show that the unconfined compressive strengths of lime-stabilized soil specimens treated with glutinous rice paste are all higher than those without treated at different curing times (7d, 28d, 40d, and 60d). The calculated fractal box dimension value of SEM image of lime stabilized soil sample is close to and slightly less than the one treated with glutinous rice paste. The SEM images show that the microstructure of lime-stabilized soil treated with glutinous rice paste is denser than that without treated. This kind of denser microstructure should be the basis of higher unconfined compressive strengths of the specimens treated with glutinous rice paste.

Nature of the Quetico–Wabigoon boundary in the de Courcey – Smiley Lakes area, northwestern Ontario

1976 ◽  
Vol 13 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Manfred M. Kehlenbeck
Keyword(s):  
Regional Metamorphism ◽  
Sedimentary Rocks ◽  
Metamorphic Grade ◽  
Boundary Zone ◽  
Present Level ◽  
Metasedimentary Rocks ◽  
The North ◽  
Northwestern Ontario ◽  
Multiple Phase ◽  
Mineral Assemblages

In the de Courcey – Smiley Lakes Area, the boundary between the Quetico and Wabigoon Belts is expressed by a sequence of pelitic to semi-pelitic schists and gneisses. At the present level of erosion, these metasedimentary rocks are in contact with granodioritic gneisses, granites, and pegmatites, which are exposed to the south.To the north of this area, regional metamorphism of volcanic and sedimentary rocks has resulted in greenschist facies assemblages, which characterize the Wabigoon Belt in general. In the boundary zone, the metamorphic grade increases southward toward de Courcey and Smiley Lakes.Formation of three distinct foliation surfaces was accompanied by syn-tectonic as well as post-tectonic recrystallization, producing polymetamorphic schists.In the boundary zone, mineral assemblages comprising andalusile, sillimanite, cordierite, garnet. biotite, and muscovite form a facies series of the Abukuma type.The boundary between the Quetico and Wabigoon Belts in this area is a complex zone in which rocks of both belts have been reconstituted by multiple-phase metamorphism and partial melting.

Electrochemically Deposited Aluminum in Template of Porous Silicon Film

2010 ◽  
Vol 663-665 ◽  
pp. 1032-1035
Author(s):  
Bao Gai Zhai ◽  
Qing Lan Ma ◽  
Ming Meng ◽  
Yuan Ming Huang
Keyword(s):  
Porous Silicon ◽  
Electrochemical Deposition ◽  
High Surface ◽  
Silicon Film ◽  
Volume Ratio ◽  
Deposition Condition ◽  
Sem Images ◽  
Interesting Phenomenon ◽  
Electrochemically Deposited ◽  
The One

In this article, we report on the observations that in the aqueous electrolyte of aluminum nitrate, the thin metallic conducting films on both internal and external surface of porous silicon (PS) thin films that emit visible photoluminescence at room temperature prior to electrochemical deposition have been obtained under electrochemical deposition condition. Add to this high surface-to-volume ratio and these make it a good candidate for the catalyst supporter. We have investigated the surface morphology of PS after the interval of about 30 hours of electrochemically deposited aluminum by means of scanning electron microscopy (SEM). It has been shown from SEM images that not only micrometer-sized pores are smoothed by deposition of aluminum microcrystal, but also the presences of semi-sphere aluminum microcrystal which rooted in the tip of micrometer-sized pores are observed. On the one hand, this extremely interesting phenomenon which the micrometer-sized pores are smoothed may be explained in terms of principle of electrochemical deposition; on the other hand, we have laid the formation mechanism of semi-spherical aluminum microcrystal at the door of Gibbs free energy.

Synthesis of RePO4 (Re=La, Nd, Pr, or Y) Nanowires by Chemical Precipitation in Nanochannels

2011 ◽  
Vol 181-182 ◽  
pp. 495-500 ◽  
Author(s):  
Cheng Mu ◽  
Jun Hui He
Keyword(s):  
Rare Earth ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Aao Template ◽  
Sem Images ◽  
Transmission Electron ◽  
Rare Earth Phosphate ◽  
Xrd Patterns ◽  
Uniform Diameter

Monodisperse nanowires of rare earth phosphates were synthesized by chemical precipitation method using anodic aluminum oxide (AAO) template. Scanning electron microscope (SEM) images indicated that rare earth phosphate nanowires are parallelly arranged in AAO template, all of which are in uniform diameter of about 50 nm. X-ray diffraction (XRD) patterns and high magnification transmission electron microscopy (HRTEM) images showed that the nanowires were polycrystal structure.

scholarly journals Synthesis and characterization of nanocrystalline copper sulfide powders

2018 ◽  
Vol 16 (38) ◽  
pp. 124-131
Author(s):  
Ulla M. Sleman
Keyword(s):  
Copper Sulfide ◽  
Average Crystallite Size ◽  
Chemical Precipitation ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Nanocrystalline Copper ◽  
Intermediate Phases ◽  
Complex Agent ◽  
Scherrer Formula

Nanocrystalline copper sulphide (Cu2-xS) powders were synthesized by chemical precipitation from their aqueous solutions composed of different molar ratio of copper sulfate dehydrate (CuSO4.5H2O) and thiorea (NH2)2CS as source of Cu+2, S-2 ions respectively, and sodium ethylene diamine tetra acetic acid dehydrate (EDTA) as a complex agent. The compositions, morphological and structural properties of the nanopowders were characterized by energy dispersive spectroscopy (EDS), scanning electron microscope (SEM), and X-ray diffraction (XRD), respectively. The compositional results showed that the copper content was high and the Sulfur content was low for both CuS and Cu2S nanopowders. SEM images shows that all products consist of aggregate of fine nanospheres with uniform distribution and the size of the particles formed are in nanometer range. XRD results revealed that the obtained powders contains a mixture of copper sulfide phases specially the intermediate phases and the rough estimate of the average crystallite size using the Scherrer formula gives a range of values (4.1-36.9) nm.

Prehnitization in the Yahgan Formation of Navarino Island, southernmost Chile

1965 ◽  
Vol 34 (268) ◽  
pp. 517-527 ◽  
Author(s):  
W. A. Watters
Keyword(s):  
Sedimentary Rocks ◽  
Low Grade ◽  
Wide Spread ◽  
Modes Of Occurrence ◽  
Secondary Minerals ◽  
Grade Metamorphism ◽  
South Georgia ◽  
Hand Specimen ◽  
Upper Mesozoic

SummaryUpper Mesozoic geosynclinal sedimentary rocks, mainly of volcanic (andesitic) derivation, show widespread prehnitization caused by very low grade metamorphism (burial metamorphism). The sediments, which include greywackes, argillites, cherty rocks, and occasional limestone concretions and thin beds, appear little altered in hand specimen and in the field despite the wide extent of recrystalli-zation. Besides prehnite, secondary minerals include quartz, albite, chlorite, sericite, calcite, and sphene. The different modes of occurrence of the prehnite are described and briefly discussed. The alteration of the rocks is compared with similar wide-spread prehnitization recorded in probably correlative rocks on South Georgia.

THE GULF OF CARPENTARIA—A NEW BASIN AND NEW EXPLORATION TARGETS

1993 ◽  
Vol 33 (1) ◽  
pp. 297
Author(s):  
V. L. Passmore ◽  
P. E. Williamson ◽  
T. U Mating ◽  
A.R.G. Gray
Keyword(s):  
Shallow Water ◽  
Sedimentary Rocks ◽  
High Amplitude ◽  
Source Rocks ◽  
Petroleum Potential ◽  
Basin Floor ◽  
International Boundary ◽  
Fault Structures ◽  
The One ◽  
Sag Basin

The sparsely explored Gulf of Carpentaria is a shallow water frontier area of stacked basins. The petroleum potential was not tested by the one offshore well drilled in the Gulf in 1984.Recent re-interpretation of offshore seismic in Queensland waters delineated the Bamaga Basin, a new infrabasin below the Carpentaria Basin. This new basin is a northerly trending asymmetrical sag basin that continues north of the international boundary. The Bamaga Basin, containing up to 1.8 seconds of gently folded and faulted sediments, is untested and offers a new exploration objective. Apparent high velocities make the age of the basin uncertain, but Paleozoic reservoir and source rocks, similar to sedimentary rocks in nearby basins, are inferred, although analogue basins are not readily identifiable.Bamaga Basin source rock burial is sufficient to generate hydrocarbons and could source reservoirs in the Bamaga and Carpentaria Basins via migration along faults. Possible direct hydrocarbon indicators increase support for the presence of hydrocarbons in the Gulf.Structural and stratigraphic plays in the Carpentaria Basin that provide new exploration targets include: basal sandstones onlapping areas of higher relief or filling basin floor depressions, sandstone layers within the Wallumbilla Formation draping highs and possible carbonate zones appearing as high amplitude chaotic reflectors. Within the Bamaga Basin, horst, fault structures and anticlinal features are potential structural plays, and termination of units against the main unconformity are possible stratigraphic play targets.

Mineralogy

2003 ◽  
Author(s):  
Anthony S. R. Juo ◽  
Kathrin Franzluebbers
Keyword(s):  
Land Surface ◽  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Volcanic Glass ◽  
Igneous Rocks ◽  
Coarse Grained ◽  
Metamorphic Rocks ◽  
Great Pressure ◽  
Rock Texture ◽  
Primary Minerals

Soils are weathering products of rocks and minerals. The rocks in Earth’s outer surface can be classified as igneous, sedimentary, or metamorphic rocks. Igneous rocks are formed from molten magma. They are composed of primary minerals, which are minerals that have not been altered chemically since they formed as molten lava solidified. Examples of primary minerals are the light-colored minerals quartz, muscovite, feldspars, and orthoclase, and the dark-colored minerals biotite, augite, and hornblende. In general, dark-colored minerals contain iron (Fe) and magnesium (Mg) and are more easily weathered than light-colored minerals. Coarse-grained igneous rocks, such as granite and diorite, contain mainly lightcolored minerals, while medium-grained igneous rocks such as gabbro, peridotite, and hornblendite are composed of dark-colored primary minerals. Rhyolite and andesite are medium-grained igneous rocks containing light-colored primary minerals. Basalt is dark-colored with an intermediate to fine rock texture, and basaltic volcanic glass has a fine texture. Examples of light-colored igneous rocks with a fine texture are felsite and obsidian. Sedimentary rocks are the most common type of rock, covering about 75% of Earth’s land surface. They are mainly composed of secondary minerals, which are minerals that are recrystallized products of the chemical breakdown and/or alteration of primary minerals. Sedimentary rocks form when weathering products from rocks are cemented or compacted. For example, quartz (SiO2) sand, a weathering product of granite, may become cemented into sandstone. Another common sedimentary rock is limestone. There are two types of limestone, namely, calcite (CaCO3), and dolomite (CaCO3.MgCO3). Clays may become cemented into a sedimentary rock, which is known as shale. A sedimentary rock with several dominant minerals is called a conglomerate, in which small stones with different mineralogy are cemented together. Metamorphic rocks are formed by the metamorphism of igneous or sedimentary rocks. Great pressure and high temperatures, caused by the shifting of continental plates, can compress, distort, and/or partially re-melt the original rocks. Igneous rocks are commonly modified to form schist and gneiss, in which light and dark minerals have been reoriented into bands. Sedimentary rocks, such as limestone and shale, may be metamorphosed to form marble and slate, respectively.

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