scholarly journals A record of deglaciation-related shifting of the proximal zone of a sandur — a case study from the Gwda sandur, NW Poland (MIS 2)

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mateusz Mleczak ◽  
Małgorzata Pisarska-Jamroży
Keyword(s):  
Structural Features ◽  
Complex Problem ◽  
Coarse Grained ◽  
Fine Grained ◽  
Depositional Processes ◽  
Long Time ◽  
Sedimentary Succession ◽  
Late Weichselian ◽  
Proximal Zone ◽  
Nw Poland

AbstractThe study analyses a 7.5-m-thick sedimentary succession deposited in the largest sandur (the Gwda sandur, a glacial outwash plain) in NW Poland, during the late Weichselian (MIS 2). Although the study site is located in the distal zone of the sandur, its sedimentological features and palaeohydrological parameters reflect the presence of an energetic, powerful environment typical of the proximal zone. Three sedimentary units were recognized in the studied sedimentary succession: (1) lower unit — fine-grained sands with ripple cross-lamination and horizontal lamination; (2) middle unit — gravelly coarse-grained sands and sandy gravels with planar cross-stratification; and, (3) upper unit — sands and gravelly sands with trough cross-stratification. Although the age of deposition of the sandur is accepted to be convergent with that of end-moraines of the same phase, the sediments in the distal zone of the Gwda sandur correlate with an earlier glaciation phase/subphase. Our findings hint at a complex problem: large sandurs such as the Gwda sandur were probably deposited over a long time, and their successions might record the textural and structural features of the proximal subenvironment, even in their distal parts due to deglaciation-related shifting of the proximal zone of a sandur. This paper presents a new approach to analysing the depositional processes in large sandurs, shows a new light on glaciofluvial water supply dynamics of distal parts of sandurs, and may solve several fundamental problems related to the sandur deposition.

Origins and engineering hazards of Swedish glaciomarine and marine clays

1991 ◽  
Vol 7 (1) ◽  
pp. 257-264 ◽  
Author(s):  
R. L. Stevens ◽  
M. S. Rosenbaum ◽  
L. G. Hellgren
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Three Dimensional ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Land Uplift ◽  
Fine Grained ◽  
Depositional Settings ◽  
Late Weichselian ◽  
Three Dimensional Models

AbstractThis paper relates the Engineering features of fine-grained clays in the Göteborg area to their glacial sources, depositional settings and postdepositional changes. These deposits occupy valley and coastal areas where urban expansion has been concentrated, despite the considerable problems with settlement and quick-clay behaviour. Both mineralogical and permeability trends are largely determined by the textural characteristics of the deposits. The depositional environments, which have largely controlled the textural trends, are known to have evolved during late Weichselian times due to glacial retreat, isostatic land uplift and climatic changes. A generalized lithostratigraphical model has been produced and this is used here to help understand and predict the variability of the geotechnical properties. The stratigraphical trends in texture, mineralogy and structure are considered within four broad genetic categories: 1) coarse-grained glacial deposits, 2) glaciomarine deposits, 3) very distal glaciomarine deposits, and 4) shallow-marine deposits. These divisions can often be recognized within the logs of geotechnical reports, which suggested that they could provide the basis for development of three-dimensional models which have both geological and geotechnical predictive power within the vicinity of Göteborg. They could also act as a guide for the development of similar models in urban areas elsewhere.

scholarly journals The Failure of Structural Metals Subjected to Strain-Cycling Conditions

1959 ◽  
Vol 81 (2) ◽  
pp. 203-208 ◽  
Author(s):  
R. W. Swindeman ◽  
D. A. Douglas
Keyword(s):  
Grain Size ◽  
Rupture Life ◽  
Thermal Strain ◽  
Coarse Grained ◽  
Fine Grained ◽  
Long Time ◽  
Structural Metals ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Strain Cycling

Data showing the isothermal strain-cycling capacity of three metals, Inconel, Hastelloy B, and beryllium are presented. It is noted that at frequencies of 0.5 cycle per min the data satisfied an equation of the form Nαϵp = K, where N is the number of cycles to failure, ϵp is the plastic strain per cycle, and α and K are constants whose values depend on the material and test conditions. Data on Inconel are given to establish the effect of grain size, specimen geometry, temperature, and frequency. It is found that, at temperatures above 1300 F, grain size and frequency exert a pronounced effect on the rupture life. Fine-grained metal survives more cycles before failure than coarse-grained material. Long time cycles shorten the number of cycles to failure when the strain per cycle is low. Thermal-strain-cycling data for Inconel are compared to strain-cycling data at the same mean temperature. Good correlation is found to exist between the two types of tests.

scholarly journals Siliciclastic sedimentation in the interlude between two Neoproterozoic glaciations, Mirbat area, southern Oman: A missing link in the Huqf Supergroup?

GeoArabia ◽  
2008 ◽  
Vol 13 (4) ◽  
pp. 45-72
Author(s):  
Ruben Rieu ◽  
Philip A. Allen
Keyword(s):  
Arabian Peninsula ◽  
Sedimentary Rocks ◽  
Crystalline Basement ◽  
Coarse Grained ◽  
Shallow Marine ◽  
Fluvial Deposits ◽  
Fine Grained ◽  
Marine Deposits ◽  
Sedimentary Succession ◽  
Late Neoproterozoic

ABSTRACT The Huqf Supergroup in Oman contains an exceptionally well-preserved and complete sedimentary record of the Late Neoproterozoic era, including the oldest components in some of Oman’s hydrocarbon plays. Outcrops of the Huqf Supergroup in northern and central Oman are now well-documented. However, a key succession in the Mirbat area of southern Oman, the Mirbat Group, which includes a stratigraphic interval missing elsewhere in the Arabian Peninsula, remains poorly understood. The <1.5 km-thick Cryogenian (850–635 Ma) Mirbat Group comprises an essentially continuous succession of little-deformed sedimentary rocks containing two glacial intervals separated by c. 1 km of non-glacial marine deposits. The lowermost glacial interval (Ayn Formation) occupies deep paleovalleys incised into crystalline basement. The overlying Arkahawl Formation records at its base a major post-glacial transgression over the previous basin margin and a 300 to 400 m-thick turbidite complex consisting of 1 to 5 km-wide, coarse-grained depositional lobes embedded vertically and laterally in fine-grained distal turbidite fan deposits. Ayn Formation paleovalleys continued to serve as sediment transport routes for the coarse-grained turbidite complexes of Arkahawl times. The turbidite complex deposits gradationally pass up into a c. 500 m-thick unit of distal-marine mudstone and siltstone. The overlying c. 100 m-thick Marsham Formation records highstand deposition and the pulsed progradation of shallow-marine and fluvial deposits over offshore mudstone and siltstone in the approach to a second glaciation, represented by the Shareef Formation. The sedimentary succession described in this paper is believed to largely fill the stratigraphic gap present between the Ghubrah and Fiq formations in the Al Jabal al-Akhdar in northern Oman represented by an unconformity.

scholarly journals Spatial Distribution of Cementite Particles in Fe-0.67% C Steel

2013 ◽  
Vol 58 (2) ◽  
pp. 631-634
Author(s):  
P. Matusiewicz ◽  
A. Czarski
Keyword(s):  
Pair Correlation ◽  
Reference Points ◽  
Coarse Grained ◽  
Distance Information ◽  
Fine Grained ◽  
Planar Section ◽  
Point Field ◽  
Long Time ◽  
Material Space ◽  
The One

The particles arrangement in material space is represented by point field determined by the particle reference points, i.e., particle centers which can be described by the pair-correlation function (PCF) g3(r); r - correlation distance. Information about g3(r) can be obtained by stereological method based on the PCF g2(r), which describes the point field on the planar section determined by the centers of particle planar sections. In this paper the arrangement of cementite (Fe3C) particles during coarsening in Fe - 0,67%C steel at 715ºC in a form of two materials (A, B) of different microstructure of the coarse spheroidite (with different matrix grain size and particles position) was investigated. In material A, the particles are mainly at grain (subgrain) boundaries of fine-grained matrix. In material B, particles are mainly inside grains of coarse-grained ferrite. For material A, the empirical PCF g2(r) for a long time of coarsening (600 hours) is shifted towards larger r and is more flat near the g2(r) =1 than the one of coarsening for 50 hours. For material B, the g2(r) for both annealing times are not significantly different. This is consistent with the results of the probability density function f2(d) analysis for diameter (d) of the particle sections. Obtained PCF g2(r) are similar to the PCF g2(r) for planar section of the Stienen model. This means that for both type of microstructures the PCF - g3(r) =1, i.e., particles are distributed randomly in space and the sizes of the neighboring particles are correlated with each other.

Multi-Objective Optimization of Fine-Pitch Gear Based on Variable-Grain Strategy

2010 ◽  
Vol 44-47 ◽  
pp. 4191-4195
Author(s):  
Fu Qiang Zhao ◽  
Tie Wang
Keyword(s):  
Optimization Design ◽  
Optimal Solution ◽  
Complex Problem ◽  
Friction Torque ◽  
Coarse Grained ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Fine Grained ◽  
Fine Pitch ◽  
Tooth Flank

A variable-grain strategy is proposed to tackle the complex problem of optimization design of fine-pitch gear with multiple objectives and restrictions involved. Multi-objective optimization mathematical models of various grains are established, in order to ensure the tooth profile optimal and reduce the noise generated by the slide of tooth flank meshing and the mutation of friction torque as criteria to evaluate different schemes. The coarse-grained model is utilized in the early design to efficiently determine the direction to the globally optimal solution. Then more accurate model can be utilized and finally the optimal scheme can be acquired on the basis of the fine-grained model. Based on the theory of meshing noise and the superiority criteria, the algorithm is put forward for the fine-pitch gear design problem, and the Pareto optimal sets are obtained.

scholarly journals Source and depositional processes of coarse-grained limestone event beds in Frasnian slope deposits (Kostomłoty-Mogiłki quarry, Holy Cross Mountains, Poland)

Geologos ◽  
2010 ◽  
Vol 16 (3) ◽  
pp. 153-168 ◽  
Author(s):  
Aleksandra Vierek
Keyword(s):  
Carbonate Platform ◽  
Transitional Zone ◽  
High Energy ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Fine Grained ◽  
Holy Cross Mountains ◽  
Depositional Processes ◽  
Platform Margin ◽  
Slope Deposits

Source and depositional processes of coarse-grained limestone event beds in Frasnian slope deposits (Kostomłoty-Mogiłki quarry, Holy Cross Mountains, Poland)The Kostomłoty-Mogiłki succession is situated in the Kostomłoty transitional zone between the shallow-water Kielce stromatoporoid-coral platform and the deeper Łysogóry basin. In the Kostomłoty-Mogiłki quarry, the upper part of the Szydłówek Beds and Kostomłoty Beds are exposed. The Middle-Upper Frasnian Kostomłoty Beds are composed of shales, micritic and nodular limestones with abundant intercalations of detrital limestones. The dark shales and the micritic and nodular limestones record background sedimentation. The interbedded laminated and detrital limestones reflect high-energy deposition (= event beds). These event beds comprise laminated calcisiltites, fine-grained calcarenites, coarse-grained grain-supported calcirudites fabrics, and matrix-supported calcirudites. The material of these event beds was supplied by both erosion of the carbonate-platform margin and cannibalistic erosion of penecontemporaneous detrital limestones building the slope of this platform. Storms and the tectonic activity were likely the main causes of erosion. Combined and gravity flows were the transporting mechanisms involved in the reworking and redeposition.

scholarly journals Sole marks reveal deep-marine depositional process and environment: Implications for flow transformation and hybrid-event-bed models

2021 ◽  
Vol 91 (9) ◽  
pp. 986-1009
Author(s):  
Jaco H. Baas ◽  
Niall D. Tracey ◽  
Jeff Peakall
Keyword(s):  
Debris Flow ◽  
Transition Zone ◽  
Process Model ◽  
High Density ◽  
The Body ◽  
Coarse Grained ◽  
Turbidity Currents ◽  
Fine Grained ◽  
Depositional Processes ◽  
Hybrid Event

ABSTRACT Deposits of sediment gravity flows in the Aberystwyth Grits Group (Silurian, west Wales, United Kingdom) display evidence that sole marks are suitable for reconstructing depositional processes and environments in deep-marine sedimentary successions. Based on drone imagery, 3D laser scanning, high-resolution sedimentary logging, and detailed descriptions of sole marks, an outcrop 1600 m long between the villages of Aberarth and Llannon was subdivided into seven lithological units, representing: a) mudstone-poor, coarse-grained and thick-bedded submarine channel fills, dominated by the deposits of erosive high-density turbidity currents with flute marks; b) mudstone-rich levee deposits with thin-bedded, fine-grained sandstones formed by low-density turbidity currents that scoured the bed to form flute marks; c) channel–lobe transition-zone deposits, dominated by thick beds, formed by weakly erosive, coarse-grained hybrid events, with pronounced mudstone-rich or sandstone-dominated debritic divisions and groove marks below basal turbiditic divisions, and with subordinate amounts of turbidites and debris-flow deposits; d) tabular, medium- to thick-bedded turbiditic sandstones with flute marks and mixed sandstone–mudstone hybrid event beds mainly with groove marks, interpreted as submarine lobe-axis (or off-axis) deposits; and e) tabular, thin- to medium-bedded, fine-grained, mainly turbiditic sandstones mostly with flute marks, formed in a lobe-fringe environment. Both lobe environments also comprised turbidites with low-amplitude bed waves and large ripples, which are interpreted to represent transient-turbulent flows. The strong relationship between flute marks and turbidites agrees with earlier predictions that turbulent shear flows are essential for the formation of flute marks. Moreover, the observation as part of this study that debris-flow deposits are exclusively associated with groove marks signifies that clay-charged, laminar flows are carriers for tools that are in continuous contact with the bed. A new process model for hybrid event beds, informed by the dominance of tool marks, in particular grooves, below the basal sand division (H1 division of Haughton et al. 2009) and by the rapid change from turbidites in the channel to hybrid event beds in the channel–lobe transition zone, is proposed. This model incorporates profound erosion of clay in the channel by the head of a high-density turbidity current and subsequent transformation of the head into a debris flow following rapid lateral flow expansion at the mouth of the channel. This debris flow forms the groove marks below the H1 division in hybrid event beds. A temporal increase in cohesivity in the body of the hybrid event is used to explain the generation of the H1, H2, and H3 divisions (sensuHaughton et al. 2009) on top of the groove surfaces, involving a combination of longitudinal segregation of bedload and vertical segregation of suspension load. This study thus demonstrates that sole marks can be an integral part of sedimentological studies at different scales, well beyond their traditional use as indicators of paleoflow direction or orientation.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

Sign in / Sign up

Export Citation Format

Share Document