Eolian origin of the Miocene loess-soil sequence at Qin’an, China: Evidence of quartz morphology and quartz grain-size

In the central part of the Volyn Upland, the Pryluky palaeosol unit have been studied in nine loess-soil sites (Boremel 1 - 3, Novyi Tik, Smykiv, Shybyn, Kolodezhi, Kovban, Novostav). Several sections were excavated along a slope in each studied site in order to reveal the palaeocatena and to study the most complete palaosol successions. The last were found in palaeorelief depressions, which were acting as sediment traps. The genetic interpretation of palaeosols was carried out on the basis on field macromorphological and analytical (micromorphology, grain-size analysis, content of humus and CaCO3) studies. In order to reconstruct the main features of palaeovegetation as an important factor of pedogenesis, pollen analysis of the palaeosols was carried out. It proved a good correspondence between a character of palaeovegetation and a palaeosol type. It has been shown that grain-size composition of the lower Prylyky soils strongly depends on that of parent rocks (Tyasmyn unit of hillwash sandy loam and Kaydaky unit of pedosediment).. The Chernozem-like polygenic soil is the most common within studied area. The lower part of soil has signs of podsolization (powder of SiO2, light color, low content of clay). The upper Pryluky soils are distorted by erosional and cryogenic processes (mainly by solifluction textures) that hampers the interpretation of diagenetic and original pedogenicprocesses. The abundant bioturbations in the subsoil (the largest number among the Late Plestocene soils), high content of humus, complex microaggregates, but leach in the СaCO3 have been established to Pryluky soil unit. The presence of relic pedogenic signs in the polygenetic soil, an assumption is made about the existence of several stages of its formation. The investigation of pedocomplexes confirm it. The study of well-developed pedocomplexes in sedimentation traps allows the allocation of those pedogenic phases during Pryluky times: pl1b1 – Podzolic, Cryptopodzolic, Albeluvisol, Albic Luvisol; pl1b2 – Luvic Chernozem, Chernic Chernozem and Cryptopodzolic,; pl1с – Umbrisol and Cambic Luvisol; pl3a – Luvic Cambisol; pl3b1 – Luvisol and Luvic Cambisol; pl3b2 – Mollic and Luvic Cambisol.

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Ice-Volume Forcing of East Asian Winter Monsoon Variations in the Past 800,000 Years

Quaternary Research ◽

10.1006/qres.1995.1059 ◽

1995 ◽

Vol 44 (2) ◽

pp. 149-159 ◽

Cited By ~ 322

Author(s):

Zhongli Ding ◽

Tungsheng Liu ◽

Nat W. Rutter ◽

Zhiwei Yu ◽

Zhengtang Guo ◽

...

Keyword(s):

Grain Size ◽

East Asian Winter Monsoon ◽

East Asian ◽

Continuous Process ◽

Loess Soil ◽

Winter Monsoon ◽

Monsoon Circulation ◽

Asian Winter Monsoon ◽

Ice Volume ◽

The Past

AbstractParticle-size measurements of some typical loess-soil samples taken in different localities of the Chinese Loess Plateau demonstrate that the grain size ratio of <2 μm/>10 μm (%) can be used as an indicator of variations in intensity of the East Asian winter monsoon winds. Grain-size curves of the Baoji and Weinan sections show that this proxy indicator is very sensitive to loess-soil alterations. Analytical results also suggest that during soil-forming periods, eolian dust accumulation was still substantial and, hence, loess deposition can be regarded as a nearly continuous process during the Quaternary period. In this study we compared the Baoji grain-size time series with the SPECMAP marine isotope record with the objective of elucidating the dynamic linkage between changes in global ice volume and the winter monsoon circulation. Both records show good agreement at both time and frequency domains. In particular, the winter monsoon variations are also dominated by a 100,000 yr period over the past 800,000 yr. It is thus inferred that direct local insolation forcing could be less important in driving the East Asian winter monsoon variability, and, alternatively, variations in glacial-age boundary conditions may have played a key role in modulating and pacing its strength and timing.

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Lithological indicators of loess sedimentation of SW Poland

Contemporary Trends in Geoscience ◽

10.1515/ctg-2017-0008 ◽

2017 ◽

Vol 6 (2) ◽

pp. 94-111 ◽

Cited By ~ 4

Author(s):

Marcin Krawczyk ◽

Kamila Ryzner ◽

Jacek Skurzyński ◽

Zdzisław Jary

Keyword(s):

Grain Size ◽

Size Distribution ◽

Loess Soil ◽

Climate Conditions ◽

The North ◽

Basic Parameters ◽

Climatic System ◽

The Difference ◽

Strong Winds ◽

Index Ratio

Abstract High-resolution grain-size investigations were carried out in two SW Polish loess sections: Biały Kościół (Niemcza-Strzelin Hills) and Zaprężyn (Trzebnica Hills). Each sequence was sampled by using the same methodology and samples were taken at 5 centimeters intervals. The particle size distribution was obtained with a Mastersizer 2000 laser, used for diffraction methods. From the obtained results the basic parameters and grain size indicators were calculated: Mz, Grain Size Index ratio, U-ratio and the percentage content of clay (< 4μm) and sand (> 63 μm). Both loess-soil sequences are composed of interfluve and slope loess facies and consist of five litho-pedostratigraphic units developed during the Late Pleistocene and Holocene: two loess units L1LL1, L1LL2 and three polygenetic fossil soils sets S0, S1 and L1SS1. The distance between these two profiles is about 60 km. Zaprężyn, as a section located more to the north, has almost no lower younger loess and higher level of weathering which could be related to proximity of this site to the Ice Sheet margin. The climate here was more extreme and harsh. What is more, the difference in development of soil L1SS1 can be observed: while in Biały Kościół pedogenesis process was slower and less disturbed than in Zaprężyn. The upper part of L1SS1 in Biały Kościół was deformed by gelifluction, frost heave and other periglacial processes. Mz indicator by the grain-size distribution in these sediments reflects subtle variations in the climatic system. Moreover, in Zaprężyn the content of sand fraction is higher than in Biały Kościół what can be the evidence of short episodes of strong winds during cold period of sedimentation. The aim of this paper is to compare two loess profiles by their stratigraphical and lithological similarities which are result of climate conditions and features of surrounding environment.

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New approach of clustering of late Pleni-Weichselian loess deposits (L1LL1) in Poland

Open Geosciences ◽

10.1515/geo-2020-0044 ◽

2020 ◽

Vol 12 (1) ◽

pp. 866-875

Author(s):

Marcin Krawczyk ◽

Małgorzata Wieczorek

Keyword(s):

Grain Size ◽

Clay Fraction ◽

Loess Soil ◽

Grain Structure ◽

Clustering Methods ◽

Data Set ◽

New Approach ◽

Sediment Research ◽

Loess Deposits ◽

Past Climate Change

AbstractThe results of grain size distribution of loess units are suitable for the study of past climate change. There are many methods for the analysis of the grain size, but clustering methods have not been used before. In this article, a new approach in the sediment research, the k-median method was used. This method separates the grain size classes of the youngest loess units of three loess-soil profiles in Poland: Biały Kościół, Złota and Tyszowce. In the analysis, only the content for the loess silt fraction (range from 4 to 63 µm) was used. This allowed eliminating the admixtures of sandy and clay fraction, considered as secondary material. For the purposes of this analysis, silt fractions were divided into smaller units using a 1/4 phi interval, resulting in 16 new subfractions. The grain size data from three profiles were combined into one data set. As a result, four classes with a similar internal of grain structure were obtained. The separated classes showed the sedimentological variability of the sediment well. It has been shown that the k-median method can be used to classify loess in a fast and objective way.

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Effect of Shock Loading on the Microstructure of Uniloy 326

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052535 ◽

1974 ◽

Vol 32 ◽

pp. 504-505

Author(s):

K. P. Staudhammer ◽

L. E. Murr

Keyword(s):

Grain Size ◽

Shock Loading ◽

Current Investigation ◽

Two Phase ◽

05 C ◽

Shock Deformation ◽

Heat Treated

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.

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Aspects of microanalysis in a transmission electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109690 ◽

1978 ◽

Vol 36 (1) ◽

pp. 510-511

Author(s):

R. Sinclair ◽

B.E. Jacobson

Keyword(s):

Grain Size ◽

Electron Beam ◽

Electron Microscope ◽

Chemical Analysis ◽

Transmission Electron Microscope ◽

Vapor Deposition ◽

Critical Currents ◽

X Ray ◽

Fine Grain ◽

Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

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Novel magneto-optical recording materials: Bi-substituted garnet films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088191 ◽

1991 ◽

Vol 49 ◽

pp. 776-777

Author(s):

Takao Suzuki ◽

Hossein Nuri

Keyword(s):

Grain Size ◽

Amorphous Film ◽

Nitrogen Atmosphere ◽

Optical Recording ◽

Garnet Film ◽

Media Noise ◽

Garnet Films ◽

Order Of Magnitude ◽

A New Technique ◽

A Current

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.

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Structure of second phases in TiAl alloys containing Cr and B

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087197 ◽

1991 ◽

Vol 49 ◽

pp. 576-577

Author(s):

Ernest L. Hall ◽

Shyh-Chin Huang

Keyword(s):

Grain Size ◽

Second Phase ◽

Structure And Properties ◽

Tial Alloys ◽

Second Phases ◽

Interstitial Elements

Addition of interstitial elements to γ-TiAl alloys is currently being explored as a method for improving the properties of these alloys. Previous work in which a number of interstitial elements were studied showed that boron was particularly effective in refining the grain size in castings, and led to enhanced strength while maintaining reasonable ductility. Other investigators have shown that B in γ-TiAl alloys tends to promote the formation of TiB2 as a second phase. In this study, the microstructure of Bcontaining TiAl alloys was examined in detail in order to describe the mechanism by which B alters the structure and properties of these alloys.

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Interfacial studies in Nb3Sn superconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087264 ◽

1991 ◽

Vol 49 ◽

pp. 590-591

Author(s):

Ernest L. Hall ◽

Lee E. Rumaner ◽

Mark G. Benz

Keyword(s):

Grain Size ◽

Grain Boundaries ◽

Flux Pinning ◽

Size Control ◽

High Magnetic Fields ◽

Type Ii ◽

Reaction Interface ◽

Liquid Diffusion ◽

Type Ii Superconductor ◽

Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

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