Mineralogy of a hydrothermal sequence in a core from the Atlantis II Deep, Red Sea

AbstractThe clay fractions from a 1191-cm long sediment core in the SW Basin of the Atlantis II Deep, Red Sea, were investigated by XRD, electron microscopy and chemical analysis. Talc dominates in the botton portion of the core, near the brine discharge vent. At 1183 cm depth, the clay consists of vermiculite/chlorite and chrysotile. These minerals are of hydrothermal origin and two possible formation pathways are proposed: (i) vermiculite/chlorite and chrysotile formed by the submarine alteration of previously deposited talc; (ii) vermiculite/chlorite and chrysotile authigenically precipitated as a result of changes in the chemical composition of the brine. At 1170 cm depth, a new depositional sequence results from the progressive alteration of swelling 2:1 minerals into vermiculite. At 1025 cm, Mg-rich clay minerals such as chlorite, chrysotile and talc again become prominent. The upper part of the core is characterized by a transition from non-expanding Mg-rich clay minerals to Fe-rich expanding clays, principally nontronite. Periodically, the content of well-crystallized oxides such as hematite in the layers increases. At 1025 cm, some of the Fe-oxides have a morphology similar to that of akaganéite. In the uppermost part of the core, iron oxides appear to consist of a poorly crystalline hydrothermal hematite. An attempt has been made to correlate the various mineralogical assemblages geochemically.

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The multi-layered protective cuticle of Collembola: a chemical analysis

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.0619 ◽

2014 ◽

Vol 11 (99) ◽

pp. 20140619 ◽

Cited By ~ 42

Author(s):

Julia Nickerl ◽

Mikhail Tsurkan ◽

René Hensel ◽

Christoph Neinhuis ◽

Carsten Werner

Keyword(s):

Electron Microscopy ◽

Chemical Composition ◽

Chemical Analysis ◽

Decisive Role ◽

Arthropod Cuticle ◽

Characteristic Layers ◽

Protein Rich ◽

Base Structure ◽

Soil Habitat

Collembola, also known as springtails, are soil-dwelling arthropods that typically respire through the cuticle. To avoid suffocating in wet conditions, Collembola have evolved a complex, hierarchically nanostructured, cuticle surface that repels water with remarkable efficiency. In order to gain a more profound understanding of the cuticle characteristics, the chemical composition and architecture of the cuticle of Tetrodontophora bielanensis was studied. A stepwise removal of the different cuticle layers enabled controlled access to each layer that could be analysed separately by chemical spectrometry methods and electron microscopy. We found a cuticle composition that consisted of three characteristic layers, namely, a chitin-rich lamellar base structure overlaid by protein-rich nanostructures, and a lipid-rich envelope. The specific functions, composition and biological characteristics of each cuticle layer are discussed with respect to adaptations of Collembola to their soil habitat. It was found that the non-wetting characteristics base on a rather typical arthropod cuticle surface chemistry which confirms the decisive role of the cuticle topography.

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Evolution with depth from detrital to authigenic smectites in sediments from AND-2A drill core (McMurdo Sound, Antarctica)

Clay Minerals ◽

10.1180/claymin.2012.047.4.07 ◽

2012 ◽

Vol 47 (4) ◽

pp. 481-498 ◽

Cited By ~ 12

Author(s):

F. Iacoviello ◽

G. Giorgetti ◽

F. Nieto ◽

I. T. Memmi

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Clay Minerals ◽

Clay Fraction ◽

Drill Core ◽

Mcmurdo Sound ◽

Volcanic Material ◽

The Core ◽

Diagenetic Processes ◽

Scanning Electron

AbstractWe have examined the nature and origin of smectites in glaciomarine sediments of the AND-2A drill core (McMurdo Sound, Antarctica) by means of X-ray diffraction (XRD) analyses on the clay fraction, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. Relying on the smectite variation throughout the drill core it was possible to split the sequence into three units. Smectites throughout the core are either detrital or authigenic. Detrital smectites are close to montmorillonite-beidellite in composition while newly-formed smectites frequently have higher Fe-Mg contents and intermediate compositions between the saponite and nontronite field, with lower amounts in the montmorillonite-beidellite field. In the upper sedimentary sections (Unit I, and Unit II, 36-440 mbsf, 0.7-16.5 Ma) smectites are interpreted to be predominantly detrital, whereas in the lower portion of the core (Unit III, 440-1123.20 mbsf, 16.5-20.2 Ma) authigenic smectites are the most common feature. The predominance of mica, the abundance of chlorite, and the nature of smectites in the upper units indicate physical weathering under cold and dry climate, and a dominant provenance for the clay minerals from the Transantarctic Mountains. Smectites in the lower unit are considered mostly authigenic and they are most likely to be the result of early diagenetic processes, being formed from the alteration of volcanic material (glass, pyroxenes and feldspars) and/or through precipitation from fluids of a possible hydrothermal origin. Our survey attests to the importance of discriminating between a detrital and authigenic nature of smectites as the occurrence of authigenic clay minerals in ancient sedimentary successions might lead to incorrect palaeoclimatic interpretations, since they can be affected by diagenetic processes, thus obliterating the climatic signal.

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Interaction of Al-Si Alloys with SiC/C Ceramic Particles and their Influence on Microstructure of Composites

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.176.55 ◽

2011 ◽

Vol 176 ◽

pp. 55-62 ◽

Cited By ~ 8

Author(s):

Anna J. Dolata

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Chemical Composition ◽

Chemical Analysis ◽

Chemical Elements ◽

Chemical Compositions ◽

Structural Studies ◽

Liquid Aluminium ◽

Ceramic Particles ◽

Scanning Electron

Interaction of Al-Si alloys with SiC/C ceramic particles and their influence on microstructure of composites was discussed. This article presents a significant effect of modifying additives introduced into liquid aluminium. As it was shown in the research, Mg and Sr modifiers improve wetting conditions in Al/SiCp+Cp systems, as well as influence the composite’s structure and the structure of the interface between the components. The microstructure observations were performed using light microscopy (OLYMPUS GX 71) and scanning electron microscopy (PHILIPS XL30). Moreover, local analyses of chemical compositions as well as chemical elements mapping were performed using an EDX module for microarea chemical analysis. Based on structural studies, it was found that chemical composition of the aluminium alloy and its modification are equally important parameters.

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High-Resolution Transmission Electron Microscopy Study of Newly Formed Sediments in the Atlantis II Deep, Red Sea

Clays and Clay Minerals ◽

10.1346/ccmn.2001.0490207 ◽

2001 ◽

Vol 49 (2) ◽

pp. 174-182 ◽

Cited By ~ 9

Author(s):

Nurit Taitel-Goldman

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Red Sea ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Transmission Electron Microscopy Study ◽

Transmission Electron ◽

Atlantis Ii Deep

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The degradation of organic compounds impacts the crystallization of clay minerals and vice versa

Scientific Reports ◽

10.1038/s41598-019-56756-6 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Pierre Jacquemot ◽

Jean-Christophe Viennet ◽

Sylvain Bernard ◽

Corentin Le Guillou ◽

Baptiste Rigaud ◽

...

Keyword(s):

Electron Microscopy ◽

Chemical Composition ◽

Clay Minerals ◽

Organic Compounds ◽

Amorphous Silica ◽

Mineral Assemblage ◽

Laboratory Experiments ◽

Fine Scale ◽

Organic Fraction ◽

Hydrothermal Conditions

AbstractExpanding our capabilities to unambiguously identify ancient traces of life in ancient rocks requires laboratory experiments to better constrain the evolution of biomolecules during advanced fossilization processes. Here, we submitted RNA to hydrothermal conditions in the presence of a gel of Al-smectite stoichiometry at 200 °C for 20 days. NMR and STXM-XANES investigations revealed that the organic fraction of the residues is no longer RNA, nor the quite homogeneous aromatic-rich residue obtained in the absence of clays, but rather consists of particles of various chemical composition including amide-rich compounds. Rather than the pure clays obtained in the absence of RNA, electron microscopy (SEM and TEM) and diffraction (XRD) data showed that the mineralogy of the experimental residues includes amorphous silica and aluminosilicates mixed together with nanoscales phosphates and clay minerals. In addition to the influence of clay minerals on the degradation of organic compounds, these results evidence the influence of the presence of organic compounds on the nature of the mineral assemblage, highlighting the importance of fine-scale mineralogical investigations when discussing the nature/origin of organo-mineral microstructures found in ancient rocks.

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THE STRUCTURE OF EOSINOPHIL LEUKOCYTE GRANULES IN RODENTS AND IN MAN

The Journal of Cell Biology ◽

10.1083/jcb.31.2.349 ◽

1966 ◽

Vol 31 (2) ◽

pp. 349-362 ◽

Cited By ~ 89

Author(s):

Fritz Miller ◽

Etienne de Harven ◽

George E. Palade

Keyword(s):

Electron Microscopy ◽

Chemical Composition ◽

Guinea Pigs ◽

Cell Fractionation ◽

Cubic Lattice ◽

The Core ◽

Specific Granules ◽

Peritoneal Washings ◽

Eosinophil Leukocyte

The structure of the specific granules of eosinophil leukocytes has been studied by electron microscopy in sections of tissues, buffy coats, and sediments of peritoneal washings of rats, mice, guinea pigs, and men. The core of eosinophil granules is a crystal which has a cubic lattice with a repeat of ∼30 A in rodents and ∼40 A in man. The chemical composition of the core is discussed in connection with recent cell fractionation studies, and the hypothesis that the core is a crystal of peroxidase is considered.

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Mechanisms of Sampler Bias

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/50.2.407 ◽

1967 ◽

Vol 50 (2) ◽

pp. 407-413

Author(s):

W L Baker ◽

C W Gehrke ◽

G F Krause

Keyword(s):

Chemical Composition ◽

Chemical Analysis ◽

Particle Shape ◽

Latin Square ◽

Sieve Analysis ◽

Small Particles ◽

The Core ◽

Physical And Chemical ◽

Representative Samples ◽

Sampling Pattern

Abstract Possible mechanisms of sampler bias on dry mixed fertilizers were evaluated in an effort to develop better official sampling instruments and procedures. Three lots of dry mixed fertilizer (about 1 ton each) with known physical and chemical composition were prepared in the laboratory. Twelve vertical and 12 horizontal cores, arranged in a latin square sampling pattern, were secured from each lot with 3 triers: the AOAC double tube trier, a double tube compartmented trier, and an experimental double half-tube trier wherein the core was encompassed in place rather than being required to flow into a compartment as with conventional triers. Individual cores were analyzed physically and chemically. Only marginally significant differences were found between cores on the basis of tube opening size. The experimental double half-tube trier was less selective to particle shape than either the compartmented or AOAC triers, but differences were not statistically significant. All triers produced more representative samples from vertical cores than from horizontal cores. Cores drawn at a 60—75° angle from horizontal were not consistently different from vertical cores. Results of chemical analysis confirmed the sieve analysis findings quite closely. Horizontal cores secured with the experimental double half-tube trier confirmed that the bias observed in horizontal cores was due to downward drifting of small particles when the core area was disturbed by sampler insertion. Cores secured with the sample-retaining face upward contained an excess of fines, while cores secured with the sample-retaining face to the side or downward more nearly resembled vertical cores in composition.

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Mica weathering in acidic soils by analytical electron microscopy

Clay Minerals ◽

10.1180/claymin.1996.031.3.03 ◽

1996 ◽

Vol 31 (3) ◽

pp. 319-332 ◽

Cited By ~ 27

Author(s):

H. Aoudjit ◽

F. Elsass ◽

D. Righi ◽

M. Robert

Keyword(s):

Electron Microscopy ◽

Clay Minerals ◽

Analytical Electron Microscopy ◽

Soil Profiles ◽

Surface Layers ◽

Acidic Soils ◽

The Core ◽

Transmission Electron ◽

Large Particles ◽

Analytical Electron

AbstractThe mineralogy, crystallochemistry and microfabric of clay minerals from acidic soils were studied using transmission electron microscopy (TEM) and analytical electron microscopy (AEM). Soil profiles, developed on saprolites, sampled in the main crystalline massifs of France represent different pedological environments. The study focused on the microsystem of mica weathering, which appeared to be the main source of secondary clay minerals, and involves microdivision, transformation and dissolution. Microdivision begins with the splitting of large particles along layer planes and their shearing normal to the layers. This induces the breakdown of particles of one hundred layers into particles having only a few layers. The transformation of micas follows two steps: they first transform into 1–1.4 nm mixed-layer minerals and then into hydroxy-Al interlayered vermiculite. The formation of hydroxy-Al interlayered vermiculite derived from micas is dominant in acidic soils; particles are generally small, consisting of only three to seven layers, and always have a dioctahedral composition, whatever the type of the original mica (trioctahedral or dioctahedral). Dissolution affects the surface layers or large domains of the core of the particles and leads to the formation of multi-elementary gels rich in Fe and Al.

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Metastable Si-Fe phases in hydrothermal sediments of Atlantis II Deep, Red Sea

Clay Minerals ◽

10.1180/0009855023720030 ◽

2002 ◽

Vol 37 (2) ◽

pp. 235-248 ◽

Cited By ~ 10

Author(s):

N. Taitel-Goldman ◽

A. Singer

Keyword(s):

Clay Minerals ◽

Red Sea ◽

Inner Core ◽

Hydrothermal Conditions ◽

Cell Parameters ◽

Formative Stage ◽

Atlantis Ii Deep ◽

Amorphous Silicate ◽

Amorphous Si ◽

Rhombohedral Symmetry

AbstractAmorphous silicate sediments comprise most of the upper part of the sedimentary column of the Atlantis II Deep, whereas more crystalline phases are found in the lower part. The objective of this study was to focus on the newly-formed, metastable, hydrothermal phases, that eventually transform into clays or Fe oxides.Short-range ordered Si-Fe phases (Si/Fe = 0.2 0.6) rounded to elliptical in shape, and amorphous Si-Fe platy phases (Si/Fe = 0.09 pure Si) comprise some of the amorphous sediments in Atlantis II Deep. The rounded particles have distinct electron-dense (thicker, relatively ordered) margins and a less crystalline inner core. They have rhombohedral symmetry with unit-cell parameters of a= 0.504 nm and c= 1.08 nm. They presumably transform into crystalline clay minerals in statunascendi(at the formative stage) in the sediments. Synthesis in NaCl brines designed to simulate crystallization of the rounded particles, was performed successfully. Similar rounded phases (Si/Fe = 0.26) were synthesized under saline, neutral, hydrothermal conditions (40°C, pH 7, 2 M NaCl) with initial Si/Fe = 1.5. We suggest that the metastable rounded particles precipitate from the hot brine created by the encounter between Red Sea Deep Water and the hydrothermal brine underneath. Within a few thousands years they disintegrate and transform into clay minerals, probably nontronite.

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