scholarly journals Environments of upper miocene sediments in the Hanoi depression interpreted from grain-size parameters

2019 ◽  
Vol 41 (2) ◽  
pp. 182-199
Author(s):  
Mai Thanh Tan ◽  
Dinh Van Thuan ◽  
Nguyen Dich Dy ◽  
Nguyen Van Tao ◽  
Le Duc Luong ◽  
...  
Keyword(s):  
Grain Size ◽  
River Mouth ◽  
Depositional Environments ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Discriminant Functions ◽  
Linear Discriminant ◽  
Upper Miocene ◽  
Grain Size Distributions ◽  
Sand Sheet

The grain-size analysis is carried out for 49 samples of Upper Miocene sediments taken from three boreholes in the Hanoi depression. The statistic parameters of the grain size distributions such as percentiles, median, graphic mean, sorting or inclusive graphic standard deviation, inclusive graphic skewness, and graphic kurtosis are used to decipher the depositional environments and transportation mechanisms of sediments. Bivariate plotting of these parameters, the discriminant functions with four basic parameters of graphics mean, sorting, inclusive graphic skewness and graphic kurtosis, and the CM pattern with the one percentile (C) and median (M) diameters are applied for this determination. The plots of graphics mean versus sorting suggest 14% of samples being the sand sheet, 46% related to rivers and 40% of the estuarine environment. The sorting - inclusive graphic skewness plot shows a river-related environment for all samples. Linear discriminant functions show the sandstone of upper Miocene in Hanoi depression are deltaic sediments formed in unstably transporting and depositional environment, impacted by turbidity current in the coastal river-mouth. The CM pattern shows sediment transportation for most of the samples in three modes: rolling, suspension and rolling, and uniform suspension. The environmental dynamics are relatively complex and change over time.

scholarly journals A Comparison of Grain Size Measurements in Al-Cu Thin Films: Imaging Vs. Diffraction Techniques

2002 ◽  
Vol 10 (6) ◽  
pp. 5-9 ◽  
Author(s):  
L.M. Gignac ◽  
C.E. Murray ◽  
K.P. Rodbell ◽  
M. Gribelyuk
Keyword(s):  
Grain Size ◽  
Measurement Techniques ◽  
Measurement Range ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Analysis Methodology ◽  
Grain Structures ◽  
Grain Size Distributions ◽  
Major Factors ◽  
Microscopy Techniques

Numerous microscopy techniques, based on both imaging and diffraction, exist for the measurement of grain size distributions in polycrystalline thin-film samples. The accuracy of each technique is affected by three major factors: the effective resolution of the instrument relative to the characteristic grain size, the detection of the grain size through the thickness of the film, and the recognition of boundaries between adjacent grains during post-processing. When the instrument resolution is primarily considered, the measurement technique has a practical grain size measurement range, see Fig. 1 for a comparison of ranges for several measurement techniques. In bulk metallurgy grain size analysis, methodology has been developed to represent 3-dimensionai grain structures from measurements taken on 2-dimensional images.

scholarly journals Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Christopher Baiyegunhi ◽  
Kuiwu Liu ◽  
Oswald Gwavava
Keyword(s):  
South Africa ◽  
Grain Size ◽  
Depositional Environments ◽  
Energy Conditions ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Equal Proportion ◽  
Eastern Cape Province ◽  
Eastern Cape ◽  
Fine Grained

AbstractGrain size analysis is a vital sedimentological tool used to unravel the hydrodynamic conditions, mode of transportation and deposition of detrital sediments. In this study, detailed grain-size analysis was carried out on thirty-five sandstone samples from the Ecca Group in the Eastern Cape Province of South Africa. Grain-size statistical parameters, bivariate analysis, linear discriminate functions, Passega diagrams and log-probability curves were used to reveal the depositional processes, sedimentation mechanisms, hydrodynamic energy conditions and to discriminate different depositional environments. The grain-size parameters show that most of the sandstones are very fine to fine grained, moderately well sorted, mostly near-symmetrical and mesokurtic in nature. The abundance of very fine to fine grained sandstones indicate the dominance of low energy environment. The bivariate plots show that the samples are mostly grouped, except for the Prince Albert samples that show scattered trend, which is due to the either mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under shallow marine environments for samples from the Prince Albert, Collingham and Ripon Formations, while those samples from the Fort Brown Formation are lacustrine or deltaic deposits. The C-M plots indicated that the sediments were deposited mainly by suspension and saltation, and graded suspension. Visher diagrams show that saltation is the major process of transportation, followed by suspension.

scholarly journals GRAINet: mapping grain size distributions in river beds from UAV images with convolutional neural networks

2021 ◽  
Vol 25 (5) ◽  
pp. 2567-2597
Author(s):  
Nico Lang ◽  
Andrea Irniger ◽  
Agnieszka Rozniak ◽  
Roni Hunziker ◽  
Jan Dirk Wegner ◽  
...  
Keyword(s):  
Grain Size ◽  
Training Data ◽  
Grain Size Analysis ◽  
Training Dataset ◽  
Size Analysis ◽  
Size Distributions ◽  
Mean Diameter ◽  
Grain Size Distributions ◽  
Gravel Bars ◽  
Uav Images

Abstract. Grain size analysis is the key to understand the sediment dynamics of river systems. We propose GRAINet, a data-driven approach to analyze grain size distributions of entire gravel bars based on georeferenced UAV images. A convolutional neural network is trained to regress grain size distributions as well as the characteristic mean diameter from raw images. GRAINet allows for the holistic analysis of entire gravel bars, resulting in (i) high-resolution estimates and maps of the spatial grain size distribution at large scale and (ii) robust grading curves for entire gravel bars. To collect an extensive training dataset of 1491 samples, we introduce digital line sampling as a new annotation strategy. Our evaluation on 25 gravel bars along six different rivers in Switzerland yields high accuracy: the resulting maps of mean diameters have a mean absolute error (MAE) of 1.1 cm, with no bias. Robust grading curves for entire gravel bars can be extracted if representative training data are available. At the gravel bar level the MAE of the predicted mean diameter is even reduced to 0.3 cm, for bars with mean diameters ranging from 1.3 to 29.3 cm. Extensive experiments were carried out to study the quality of the digital line samples, the generalization capability of GRAINet to new locations, the model performance with respect to human labeling noise, the limitations of the current model, and the potential of GRAINet to analyze images with low resolutions.

scholarly journals Granulometric and facies analysis of Middle–Upper Jurassic rocks of Ler Dome, Kachchh, western India: an attempt to reconstruct the depositional environment

Geologos ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 51-73 ◽  
Author(s):  
Asma A. Ghaznavi ◽  
M.A. Quasim ◽  
A.H.M. Ahmad ◽  
Sumit K. Ghosh
Keyword(s):  
Grain Size ◽  
Facies Analysis ◽  
Upper Jurassic ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Energy Conditions ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Western India ◽  
Jurassic Rocks

Abstract Grain size analysis is an important sedimentological tool used to unravel hydrodynamic conditions, mode of transportation and deposition of detrital sediments. For the present study, detailed grain size analysis was carried out in order to decipher the palaeodepositional environment of Middle–Upper Jurassic rocks of the Ler Dome (Kachchh, western India), which is further reinforced by facies analysis. Microtextures were identified as grooves, straight steps and V-shaped pits, curved steps and solution pits suggesting the predominance of chemical solution activity. Grain size statistical parameters (Graphic and Moment parameters) were used to document depositional processes, sedimentation mechanisms and conditions of hydrodynamic energy, as well as to discriminate between various depositional environments. The grain size parameters show that most of the sandstones are medium- to coarse-grained, moderately to well sorted, strongly fine skewed to fine skewed and mesokurtic to platykurtic in nature. The abundance of medium- to coarse-grained sandstones indicates fluctuating energy levels of the deposition medium and sediment type of the source area. The bivariate plots show that the samples are mostly grouped, except for some samples that show a scattered trend, which is either due to a mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is predominantly indicative of turbidity current deposits under shallow-marine conditions. The C-M plots indicate that the sediments formed mainly by rolling to bottom suspension and rolling condition in a beach subenvironment. Log probability curves show that the mixing between the suspension and saltation populations is related to variable energy conditions.

High-resolution records of grain-size and depositional environment correlated to the Homo erectus Nariokotome Boy site, West Turkana, Kenya

2021 ◽  
Author(s):  
Conner O'Reilly ◽  
Catherine C. Beck ◽  
Jeroen H. van der Lubbe ◽  
Craig S. Feibel ◽  
Bruce Wegter ◽  
...  
Keyword(s):  
Grain Size ◽  
High Resolution ◽  
Homo Erectus ◽  
Eastern Africa ◽  
Coarse Grained ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Sedimentary Sequences ◽  
Grain Size Distributions ◽  
Material Grain Size

<p>The Turkana Basin in northern Kenya contains a robust record of hominin fossils, including Nariokotome Boy (discovered from the NK3 site), the most complete H. erectus specimen found to date. Understanding the paleoenvironmental context in which hominins such as H. erectus evolved has been an objective of decades of research in eastern Africa. Here, we present a study using grain size analyses to infer the paleoenvironmental conditions responsible for the deposition of the sedimentary sequences directly associated with NK3. We resampled a ~14 m interval at from the West Turkana Kaitio (WTK13) core, collected as part of the Hominin Sites and Paleolakes Drilling Project. This interval ties directly to the outcrop where Nariokotome Boy was recovered. By sampling continuously at 0.5 cm intervals (~7 yrs/sample), we document the paleoenvironment in ultra high-resolution (i.e. a scale relevant to a hominin life) that directly correlates to the NK3 site. Over 350 sediment samples were pre-treated to remove carbonate, biogenic silica, and other organic material from detrital material. Grain size distributions were measured on a Malvern Mastersizer 3000 using wet suspension. Based on these analyses, the interval was dominated by silt, which was further investigated using end-member modeling. A four end-member solution explained on average 99% of the population variability. The bottom of the interval was more coarse-grained, with an abrupt fining transition at 38.83 meter below surface (mbsf), which corresponds with the transition out of a tuffaceous interval (Natoo tuff) and into a pedogenically modified interval. This correlation is significant as the top of this tuff is the surface upon which Nariokotome Boy was recovered. Previous facies and grain size analyses revealed and quantified Turkana’s dynamic lake level history. However, our grain size analysis provides unprecedented resolution for the paleoenvironment during which Nariokotome Boy lived. Our 0.5 cm sampling resolution enables us to quantify depositional changes on a scale comparable with previous descriptive facies analyses and to refine transitions between paleosols, fluvial deposits, and lacustrine deposition at the interface of these three paleoenvironments enabling us to reconstruct a dynamic lakeshore environment during the lifetime of the Nariokotome Boy.</p>

scholarly journals SEDIMENTOLOGY AND PALAEOENVIRONMENTAL RECONSTRUCTION OF AG-1 CORE OF AYVALIK REGION, NW TURKEY

2017 ◽  
Vol 50 (1) ◽  
pp. 354
Author(s):  
K. Nikolaou ◽  
A. Alysandratou ◽  
K. Karanika ◽  
Y. Kaya ◽  
H. Inaner ◽  
...  
Keyword(s):  
Grain Size ◽  
Late Holocene ◽  
Depositional Environments ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Sediment Samples ◽  
Nw Turkey ◽  
Moment Measures ◽  
Definition Of ◽  
Skewness And Kurtosis

This study presents sedimentological and palaeontological data retrieved from a coastal lagoon near Ayvalik in NW Turkey. The objective of this study is to interpret the depositional environments and reconstruct the evolution of the study area during the late Holocene. 42 sediment samples have been retrieved from a 13m core. Sedimentological analyses such as grain size analysis, moment measures of mean, sorting, skewness and kurtosis, definition of total organic carbon (T.O.C.), total nitrogen (T.N.), colour and CaCO3 (%) were employed. Moreover, macro and microfossils were collected to reconstruct the depositional environments. The palaeoenvironmental - palaeoecological analyses indicated a closed shallow shelf environment (around 4000 to 2400 yr BP) that gradually turned into a leaky lagoon (around 2400 yr BP to present).

scholarly journals PROSES SEDIMENTASI SUNGAI KALIJAGA, DAN SUNGAI SUKALILA PERAIRAN CIREBON

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Deny Setiady ◽  
Asep Permana
Keyword(s):  
Grain Size ◽  
Size Range ◽  
River Mouth ◽  
Fine Sand ◽  
Silty Sand ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Medium Size ◽  
Sandy Silt ◽  
Bathymetric Map

Berdasarkan hasil analisis besar butir sebanyak 36 percontoh sedimen permukaan dasar laut di Perairan Cirebon, didapatkan 4 jenis sedimen: lanau, lanau pasiran, pasir lanauan dan pasir. Sedimen lanau, lanau pasiran, dan pasir, tersebar di lepas pantai Cirebon dan muara Sungai Kalijaga, sedangkan pasir lanauan di muara sungai Sukalila. Dari Peta Batimetri terlihat daerah dangkal di sekitar muara Sungai Kalijaga. Sedimen paling tebal terdapat di sekitar muara Sungai Kalijaga dan Sungai Sukalila. Sedimen tersebut tersebar ke arah lepas pantai dan ke daerah rencana lokasi pelabuhan. Di muara Sungai Kalijaga sedimennya berupa pasir. Berdasarkan plot pada grafik antara ukuran besar butir terhadap persen frekuensi, didapatkan hasil sedimen dengan persen frekuensi yang tinggi antara 2.25 phi - 2.75 phi atau pasir sedang sampai pasir halus. Berdasarkan grafik frekuensi kumulatif terhadap besar butir terdapat 2 cara transpor yaitu traksi untuk butiran pasir sedang dan saltasi untuk kisaran butiran lanau sampai pasir halus. Kata Kunci : S. Kalijaga, S. Sukalila, Cirebon, besar butir, sedimen Based on grain size analysis of 36 seafloor surficial sediment samples from Cirebon Water; there are 4 types of sediments silt, sandy silt, silty sand and sand. Silt, sandy silt and sand are distributed offshore of Cirebon and in the river mouth of Kalijaga, while silty sand is in the river mouth of Sukalila. From the bathymetric map the shallow water can be observed in Kalijaga river mouth. The thicker sediments are found in Kalijaga mouth and Sukalila river. These sediments have been transported to the offshore and to the proposed Harbour location. Sediment in Kalijaga river mouth is sand. Based on graphic presentation between grain size and percent frequencies, it indicates that the percentage of higher frequencies ranges between 2.25 TO 2.75 phi. Based on the cumulative frequency to grain size graphic, there are two transport modes: traction for medium size sand and saltation for grain size range silt to fine sand. Keywords : Kalijaga River, Sukalila River, Cirebon, grain size, sediment

scholarly journals Grain-Size Distribution and Structural Characteristics of Varved Sediments from Lake Żabińskie (Northeastern Poland)

Quaternary ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 8 ◽  
Author(s):  
Maurycy Żarczyński ◽  
Jacek Szmańda ◽  
Wojciech Tylmann
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Layer Thickness ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Grain Size Distributions ◽  
Northeastern Poland ◽  
Size Data

Typically, the description of varve microfacies is based on microscopic sedimentary structures, while standard grain-size analysis is commonly applied with lower resolution. Studies involving a direct comparison of varve microfacies and particle-size distributions, common for clastic environments, are scarce for biogenic varves. In this study, we analyzed nine-year resolution grain-size data from Lake Żabińskie (northeastern Poland) to detect differences between varve microfacies. Six varve microfacies were differentiated using grain-size distributions and sedimentological attributes (calcite layer thickness, dark layer thickness, mass accumulation rate). However, changes in particle-size distributions between different varve types are relatively small and indicate a similar source for the material deposited. Decomposition of grain-size distributions with the end-member approach allows recognition of relative changes for the deposition of allochthonous (mineral) and autochthonous (carbonates, (hydr)oxides) components. Grain-size data suggest that sources of allochthonous material remained constant, while varve formation was controlled mostly by in-lake processes.

scholarly journals Tephra fallout from the long-lasting Tungurahua eruptive cycle (1999-2014): Variations through eruptive style transition and deposition processes

2017 ◽  
Vol 45 (1) ◽  
pp. 47 ◽  
Author(s):  
Jorge Eduardo Bustillos A. ◽  
Jorge Eduardo Romero ◽  
Alicia Guevara C. ◽  
Juan Díaz-Alvarado
Keyword(s):  
Grain Size ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Density Currents ◽  
Tephra Fall ◽  
X Ray ◽  
Eruptive Cycle ◽  
Grain Size Distributions ◽  
Deposition Processes ◽  
Glass Shards

The Tungurahua volcano (Northern Andean Volcanic Zone) has been erupting since 1999, with at least four eruptive phases up to present. Although a dozen of research focuses in tephra fall deposits during this period, none of them cover the full eruptive cycle. We investigated the eruptive mechanisms and tephra fall deposition processes at Tungurahua between 1999 and 2014, through systematic analyses of tephra samples collected westward of the volcano using mechanical sieving grain size analysis, lithology, scanning electron microscopy, X-Ray fluorescence and X-Ray diffraction. Tephra is compounded by varying amounts of scoria (black and brown), lithics, hydrothermally altered fragments, pumice, glass shards and free crystals. Textural analyses of juvenile grains (scoria, pumice and glass shards) revealed a diversity of features concerning to their vesicularity, shape and surface/perimeter. Initially, tephra was characterized by hydrothermally altered fragments related to a phreatic phase which then evolved to a pure magmatic activity with Strombolian eruptions. A homogeneous andesitic composition was observed between 1999 and 2003; however silicarich compositions occurred later in 2006. Similarly, the mineral assemblage contained plagioclase, pyroxene and olivine, but magnetite and akermanite were then included during 2006, thus indicating the eruption of a new, probably mixed magma. As consequence, Plinian activity occurred in August 2006. Further activity in 2007 ejected notable amounts (40-65%) of recycled material during Vulcanian eruptions. New eruptions occurred between 2008 and 2010, and juvenile ash revealed the interplay between brittle and ductile fragmentation through ash explosions, jetting events and Strombolian activity. The activity between 2010 and 2012 incorporated hydrothermally altered material at time that eruptive silences became longer and frequent, thus suggesting the development of a sporadic hydrothermal system. Finally, between 2013 and 2014 a series of Vulcanian events occurred. Observed grain size distributions allow us to propose three different processes occurring during tephra deposition: 1) deposition of multiple ash plumes, 2) contributions from elutriated pyroclastic density currents or grain size mixing due to major eruptions, and 3) the aggregation of particles due to rain and/or lighting. From mineralogy and grain size we infer that exposition to ash may produce acute human health effects.

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