scholarly journals Grain Size and Chemical Composition of Sediments to Determine the Governing Geochemical Processes in Fluvial Environments

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
S.M. Young
Keyword(s):  
Grain Size ◽  
Tidal Flat ◽  
Size Variation ◽  
River System ◽  
Mass Transfer Process ◽  
Climatic Conditions ◽  
Fluvial Processes ◽  
Tidal Area ◽  
Fluvial Environments ◽  
Mineral Concentrations

The environmental impact on the river system and the bay or a tidal flat area is of significance since these environments act as sinks of pollutants. The river system gradually gathers the material that flows along the river and settles it at the downstream area. The geochemistry of sediments of the rivers and the Bay or tidal area are signatures of the mass transfer process that occur in fluvial environments. Thus, the processes such as provenance, maturity of sediments, weathering, climatic implications, sedimentary processes, heavy mineral concentrations, sorting and mixing effect, grain size variation, transport and downstream accumulation and effect of tributaries can be determined using geochemistry. The major oxides and trace element concentration of the sediments of the river and the Bay or Tidal area is thus very important to determine the fluvial processes. Comparison of two different fluvial environments with different climatic conditions and geology where one consists of the river with a Bay in Sri Lanka and the other consisting of a river with a tidal flat in Japan is thus conceded. The environmental assessment using elements of sediments in such environments have been effective due to the possibility of being able to identify the fluvial processes that are affected by the river and Bay or tidal sediments in two different systems.

Sedimentological and Geochemical Charectesization of Manaveli and Cuddalore Formations, Puducherry Basin, India

2020 ◽  
Vol 37 (2) ◽  
pp. 115-130
Author(s):  
Shyam Narayan Mude ◽  
Shyam Yawale ◽  
Vishal Choudhari
Keyword(s):  
Grain Size ◽  
Discriminant Function ◽  
Function Analysis ◽  
Size Variation ◽  
Source Area ◽  
Climatic Conditions ◽  
Sieve Analysis ◽  
Element Geochemistry ◽  
Statistical Parameters ◽  
Chemical Index

Sedimentological and Geochemical Charectesization  of Manaveli and Cuddalore Formations, Puducherry Basin, India   Shyam N. Mude, Shyam Yawale and Vishal Choudhari   Department of Geology, Fergusson College (Autonomous), Pune- 411004, India Email: [email protected]; [email protected]   Abstract: The lithostratigraphically rocks of Puducherry basin (Sub-basin of Cauvery Basin) have been classified as Valudavur, Mettuveli, Karasur, Manaveli, Cuddalore formations in ascending order of deposition. The sedimentological and geochemical studies of sediments from Manavali (Paleocene) and Cuddalore (Mio-Pliocene) formations were carried out to understand grain size variation and distribution of major oxides and trace elements.  The sieve analysis was used to study grain size variation and on the basis of grain sizes various geo-statistical parameters were calculated to understand depositional environment. The discriminant function analysis of the sediments from the Cuddalore Formation infers that mostly the sedimentation was occurred in fluvio-deltaic environment with incursions of shallow marine environment whereas bivariate plots suggests that the deposition was occurred in riverine to deltaic environment. The major element geochemistry of the Manaveli and Cuddalore formations have been carried out to understand the provenance, paleoclimate and source area weathering conditions. The values of CIA (Chemical Index of Alteration), CIW (Chemical Index of Weathering), ICV (Index of Compositional Variability) and PIA (Plagioclase Index of Alteration) of the sediments infer high weathering was occurred in source area of sediments for Manaveli and Cuddalore formations.  The ratio (Al2O3+K2O+Na2O)/SiO2 indicate semi-humid climatic conditions during deposition of Cuddalore Formation whereas Manaveli Formation was deposited in semi-arid climatic conditions. The discriminant function diagram (A-CN-K Plot), suggest Quartzose sedimentary provenance for Cuddalore and Mafic igneous provenance for Manaveli Formation.     Keywords:  Grain Size, Geochemistry, Manaveli, Cuddalore, Puducherry Basin

scholarly journals Finite element modelling of microstructural changes during equal channel angular drawing of pure aluminium

2021 ◽  
Author(s):  
Serafino Caruso ◽  
Stano Imbrogno
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Size Variation ◽  
Fe Model ◽  
Pure Aluminium ◽  
Continuous Dynamic Recrystallization ◽  
Research Activities ◽  
Hardness Change ◽  
Continuous Dynamic

AbstractGrain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,…) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation…) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterized by large plastic deformation.

scholarly journals The Variation of Riverbed Material due to Tropical Storms in Shi-Wen River, Taiwan

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Chin-Ping Lin ◽  
Yu-Min Wang ◽  
Samkele S. Tfwala ◽  
Ching-Nuo Chen
Keyword(s):  
Grain Size ◽  
Geometric Mean ◽  
Size Variation ◽  
Annual Rainfall ◽  
Geometric Standard Deviation ◽  
Roughness Coefficient ◽  
Bed Form ◽  
Subsurface Material ◽  
Typhoon Season ◽  
Bed Material

Taiwan, because of its location, is a flood prone region and is characterised by typhoons which brings about two-thirds to three quarters of the annual rainfall amount. Consequently, enormous flows result in rivers and entrain some fractions of the grains that constitute the riverbed. Hence, the purpose of the study is to quantify the impacts of these enormous flows on the distribution of grain size in riverbeds. The characteristics of riverbed material prior to and after the typhoon season are compared in Shi-Wen River located at southern Taiwan. These include grain size variation, bimodality, and roughness coefficient. A decrease (65%) and increase (50%) in geometric mean size of grains were observed for subsurface and surface bed material, respectively. Geometric standard deviation decreased in all sites after typhoon. Subsurface material was bimodal prior to typhoons and polymodal after. For surface material, modal class is in the gravel class, while after typhoons it shifts towards cobble class. The reduction in geometric mean resulted to a decrease in roughness coefficient by up to 30%. Finally, the relationship of Shields and Froude numbers are studied and a change in the bed form to antidunes and transition form is observed, respectively.

scholarly journals Vorschlag zur bodenartlichen Kennzeichnung von Wattsedimenten

1960 ◽  
Vol 11 (1) ◽  
pp. 190-195
Author(s):  
J. L. Ruyter
Keyword(s):  
Grain Size ◽  
Physical Properties ◽  
Tidal Flat ◽  
Soil Analysis ◽  
Boundary Values ◽  
Special Mapping ◽  
Tidal Flat Sediments

Abstract. During a special mapping in the tidal flat of Eastern Frisia the question arose as to how the soils in this area could most suitably be classified and represented on maps (grain size mixtµres). The grouping suggested in this paper is done according to chemical and physical properties of these recent tidal flat sediments. Simultaneously conformity with the soil definitions of the marsh mapping by the „Niedersächsisches Landesamt für Bodenforschung" was tried to be reached. Based on the soil analysis, the most outstanding qualities of tidal flat sediments found here and their relations are being discussed. Furthermore the boundary values for the classification are investigated.

scholarly journals Facies Evaluation and Depositional Environments of Carbonates of the Bagh Group, Dhar District, Madhya Pradesh, India

2021 ◽  
Vol 38 (1) ◽  
pp. 33-40
Author(s):  
Sreejita Chatterjee ◽  
Dhiren Kumar Ruidas
Keyword(s):  
Grain Size ◽  
Large Scale ◽  
Energy Condition ◽  
Size Variation ◽  
High Energy ◽  
Depositional Environments ◽  
Small Scale ◽  
Peninsular India ◽  
Sedimentary Structures ◽  
Nodular Limestone

A significant event of marine transgression took place in Central India during Late Turonian-Coniacian. Fossiliferous marine succession of Bagh Group is one of the few carbonate successions exposed in peninsular India which was in focus of the current study for understanding this event. The signatures of this event were identified in the carbonate succession. The carbonates of Bagh Group are composed of two formations: the lower part is represented by Nodular limestone Formation which is overlain by Bryozoan limestone Formation at the top. On the basis of grain size variation and sedimentary structures, the Nodular limestone is divisible into three facies: facies ‘A’, facies ‘B’ and facies ‘C’. A hardground exists between facies B and facies C. Lack of sedimentary structures and high mud content indicates low energy depositional setting for the Nodular limestone Formation. Similarly, Bryozoan limestone Formation is divisible into five facies: facies ‘D’, facies ‘E’, facies ‘F’, facies ‘G’ and facies ‘H’ based on grain size variation and sedimentary structures. All of these five facies are fossiliferous. Glauconites are present within facies ‘G’ and have two modes of occurrence - as infilling within Bryozoan limestone and as altered feldspar. Presence of both small- and large-scale cross-stratification in Bryozoan limestone with lesser mud content are indicative of high energy shallow marine conditions. Large-scale cross-stratifications are possibly representing tidal bars while the small scale cross stratifications are formed in inter bar setting. Presence of reactivation surfaces within facies ‘E’ also supports their tidal origin. Increase in depositional energy condition is also evident from dominated by packstone facies.

scholarly journals Resolving conflicts over trans-boundary rivers using bankruptcy methods

2013 ◽  
Vol 10 (11) ◽  
pp. 13855-13887 ◽  
Author(s):  
M. Zarezadeh ◽  
K. Madani ◽  
S. Morid
Keyword(s):  
Temporal Distribution ◽  
Stability Index ◽  
River System ◽  
Planning Horizon ◽  
Climatic Conditions ◽  
Index Method ◽  
Allocation Rules ◽  
Available Water ◽  
Time Sensitivity ◽  
Solution Methods

Abstract. A bankruptcy approach is proposed for resolving trans-boundary rivers conflicts in which the total water demand or claim of the riparian parties is more than the available water. Bankruptcy solution methods can allocate the available water to the conflicting parties with respect to their claims. Four bankruptcy rules are used here to allocate the available water to the riparian parties. Given the non-uniform spatial and temporal distribution of water across river basins, bankruptcy optimization models are proposed to allocate water based on these rules with respect to time sensitivity of water deliveries during the planning horizon. Once allocation solutions are developed, their acceptability and stability must be evaluated. Thus, a new stability index method is developed for evaluating the acceptability of bankruptcy solutions. To show how the bankruptcy framework can be helpful in practice, the suggested methods are applied to a real-world tarns-boundary river system with eight riparians under various hydrologic regimes. Stability analysis based on the proposed stability index method suggests that the acceptability of allocation rules is sensitive to hydrologic conditions and demand values. This finding has an important policy implication suggesting that fixed allocation rules and trans-boundary treaties may not be reliable for securing cooperation over trans-boundary water resources as they are vulnerable to changing socio-economic and climatic conditions as well as hydrologic non-stationarity.

Paleoenvironmental context of the evolution of the Baodun Culture at Chengdu Plain, Sichuan Province, China

The Holocene ◽  
2019 ◽  
Vol 29 (11) ◽  
pp. 1731-1742 ◽  
Author(s):  
Ming Huang ◽  
Cheng Zhu ◽  
Chunmei Ma ◽  
Kunyu He ◽  
Jiajia Xu
Keyword(s):  
Grain Size ◽  
Climatic Conditions ◽  
Alluvial Fan ◽  
Human Migration ◽  
Cultural Groups ◽  
Hydrothermal Conditions ◽  
Chengdu Plain ◽  
Minjiang River ◽  
Archeological Evidence ◽  
Better Than

The Baodun Culture (4600–3700 a BP) is currently the earliest archeological culture found at the Chengdu Plain in southwestern China. Archeological evidence has shown that the Baodun Culture likely originated from the upper reaches of the Minjiang River, with two possible routes for human migration into the lower Chengdu Plain proposed: (1) At about 5000 a BP, favorable climatic conditions in the upper reaches of the Minjiang stimulated the growth of populations and the development of agriculture in the region. Due to this shift, some groups expanded from the upper Minjiang River to sites in the northern area of the Chengdu Plain, such as the Guiyuanqiao site; (2) during 4800–4300 a BP, a drying event occurred in the upper regions of the river valley causing a reduction in agricultural harvests and the migration of populations into sites – including the Baodun site – from this area of the Minjiang to the southwest piedmont of the Chengdu Plain. A multi-facetted study of the T3321 profile at Baodun site, including pollens, grain size, and geochemistry, demonstrates that after 6000 a BP, the climate of the Chengdu Plain shifted from cool, toward warmer and dryer conditions. However, as the Chengdu Plain is located in an alluvial fan, hydrothermal conditions here are still generally better than those in the upper reaches of Minjiang River. A change in the proportion of Concentricystes seen in the profile T3321 also indicates that after 4700 a BP, the lake and marsh areas associated with the Baodun site further decreased. However, as a result of this reduction, more terrestrial surfaces were exposed, providing favored space for Baodun Cultural groups in the area of the site. Due to such conditions, by about 4600 cal. a BP, people in the upper reaches of the Minjiang River had primarily moved to the southwest piedmont regions of the Chengdu Plain.

Crystallization of basaltic magma as recorded by variation of crystal-size in dikes

1949 ◽  
Vol 28 (205) ◽  
pp. 557-574 ◽  
Author(s):  
Helmut G. F. Winkler
Keyword(s):  
Grain Size ◽  
Quantitative Data ◽  
Crystal Size ◽  
Basaltic Magma ◽  
Size Variation ◽  
Progressive Increase ◽  
Lava Flows ◽  
The Individual

It is a familiar fact that in dikes, lava-flows, and sills the grain-size of the individual minerals normally varies according to the distance from the contacts. At or near the margins of the igneous body the grainsize is usually very much less than in the centre, and this phenomenon has been attributed to differences in the cooling-velocities at these spots. On the basis of measurements carried out by Queneau (8) the opinion seems to have been formed that the crystal-size always shows a progressive increase from the contacts towards the centre. This is not so, however, for as Lane (6) has shown, the crystal-size may increase to a maximum at a certain distance from the margin, and thereafter decrease again towards the centre of the intrusion. Apart from these investigations, carried out by Queneau and Lane, the only additioual quantitative data oil crystal-size variation known to the writer concerns a series of measurements made on an olivine-diabase by B. H. Dollen, under the direction of H. L. Alling.

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