Upper Devonian (Frasnian) stromatactis-bearing mud mounds, western Alberta, Canada: reef framework dominated by peloidal microcrystalline calcite

2019 ◽  
Vol 89 (9) ◽  
pp. 833-848
Author(s):  
Kai Zhou ◽  
Brian R. Pratt
Keyword(s):  
Dynamic Balance ◽  
Upper Devonian ◽  
Time Interval ◽  
Fair Weather ◽  
Cyanobacterial Mats ◽  
Mud Mounds ◽  
Storm Wave ◽  
Reef Type ◽  
Metabolic Activities ◽  
Destructive Processes

ABSTRACT Two well-preserved mud mounds, approximately 50 m thick, in the Mount Hawk Formation (Upper Devonian, Frasnian) in western Alberta provide an unparalleled opportunity to study the microstructure of this reef type in detail for this time interval. This reveals that they are composed dominantly of peloidal sediments—more than a quarter of mud mound volume—along with dense micrite, particulate micrite, bioclasts, and stromatactis cavities. Five types of peloids are differentiated: bacterial, cyanobacterial, bioclastic, intraclastic, and pseudo-peloids. Bacterial peloids were generated by bacterial metabolic activities with possibly some contribution from organomineralization in areas within spicular networks. Three subtypes of cyanobacterial peloids are distinguished based on whether they are physically reworked calcified filaments, aggregates of calcified coccoids, or precipitated within stromatolite-forming cyanobacterial mats or biofilms. Bioclastic peloids are fully micritized fragments of skeletons and shells. Intraclastic peloids are eroded fragments of early-lithified matrix. Pseudo-peloids represent artifacts of poorly preserved sponge spicular networks reflecting the interplay between dissolution of spicules and organomineralization. The distribution of the various peloid types shows specificity in different microfacies. They prove to be valuable paleoecological indicators, and taken together suggest that the mud mounds accreted within the photic zone above storm wave base but below the fair-weather wave base, during deposition of a transgressive and perhaps highstand systems tracts. They are the products reflecting a dynamic balance between constructional versus destructive processes. Bacterial peloids combined with dense micrite constitute the framework, which in turn makes up close to 40% of the mud mounds. This indicates that microbial activities are responsible for the early-indurated framework. The onset of bacterial peloid formation in the bedded sediment immediately underlying the mud mounds further demonstrates that it may have been a necessary precursor to mud-mound initiation. Bacterial peloids appear to characterize most Paleozoic and Mesozoic reefal mud mounds as an essential framework element.

scholarly journals A CARBONATE RAMP EVOLUTION IN THE TRANSITION FROM THE APULIA PLATFORM TO THE IONIAN BASIN DURING EARLY TO LATE CRETACEOUS (NW GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 53
Author(s):  
K. Getsos ◽  
F. Pomoni-Papaioannou ◽  
A. Zelilidis
Keyword(s):  
Sea Level ◽  
Late Cretaceous ◽  
Facies Analysis ◽  
Carbonate Ramp ◽  
Time Interval ◽  
Storm Wave ◽  
Lowermost Part ◽  
Storm Deposits ◽  
Homoclinal Ramp ◽  
Apulia Platform

Facies analysis of Cretaceous carbonate sequences from the external and central Ionian zone revealed a homoclinal ramp model of evolution. During Berriasian to Valanginian, the carbonate ramp was differentiated to an inner-mid and outer ramp environment, which corresponded to the external and central Ionian zone, respectively, while the main inner ramp environment is assumed that was located in the Pre-Apulian zone. The external Ionian zone (inner-mid ramp) is characterized by muds tones-wackes tones with fragmented echinoderms, bivalves, radiolarians and rare aptychus considered to be deposited below the fairweather wave base (FWWB). Locally, thin graded storm deposits intervene, indicating deposition above the storm weather wave base (SWB). Minor occurrences of packs tonesgrainstones, with fragmented echinoderms, calcareous algae, tubiphytes, lagenid foraminifera and rare ooids occur, as well, considered to be deposited at the lowermost part of the inner ramp, near the constantly agitated fairweather wave base (FWWB). The central Ionian zone (outer ramp) is mainly characterized by mudstones-wackestones with abundant radiolarians and rare calpionellids and calcispheres, considered to be deposited below the storm wave base (SWB). No talus or breccias deposits were observed, during the mentioned time interval, in any part of the studied area. From Hauterivian to Turonian, continual sea-level rise, led to establishment of outer ramp environment in the external Ionian zone, over the previous inner-mid ramp, and outer ramp-basin environment, over the previous outer ramp, in the central Ionian zone. The transition from shallower to deeper conditions is characterized by an overall deposition of mudstones-wackestones with abundant radiolarians rooted in pure micrite. 

A study of multi-objective dynamic water resources allocation modeling of Huai River

2015 ◽  
Vol 15 (4) ◽  
pp. 817-824 ◽  
Author(s):  
Jing Peng ◽  
Ximin Yuan ◽  
Lan Qi ◽  
Qiliang Li
Keyword(s):  
Water Resources ◽  
Dynamic Balance ◽  
Supply And Demand ◽  
Low Flow ◽  
Resources Allocation ◽  
Time Interval ◽  
Water Resources Allocation ◽  
Allocation Model ◽  
Multi Objective ◽  
Huai River

Water resources supply and demand has become a serious problem. Water resources allocation is usually a multi-objective problem, and has been of concern for many researchers. In the north of China, the lack of water resources in the Huai River Basin has handicapped the development of the economy, especially badly in the low-flow period. So it is necessary to study water resources allocation in this area. In this paper, a multi-objective dynamic water resources allocation model has been developed. The developed model took the overall satisfaction of water users in a time interval as the objective function, applied an improved simplex method to solve the calculation, considered the overall users' satisfaction variation with time, and followed the principle that the variation of the system satisfaction within adjacent periods of time must be minimal. The established model was then applied to the Huai River, for the present situation (2010), short-term (2020) and long-term (2030) planning timeframes. From the calculation results, the overall satisfaction in late May and mid September in 2030 was 0.65 and 0.70. After using the model allocation optimization, the overall satisfaction was improved, increasing to 0.78 and 0.79, respectively, thus achieving the dynamic balance optimization of water resources allocation in time and space. This model can provide useful decision support in water resources allocation, when it is used to alleviate water shortages occurring in the low-flow period.

A reappraisal of the conditions of deposition of the Maentwrog Beds (Upper Cambrian) at Porth Ceiriad, North Wales

1983 ◽  
Vol 120 (1) ◽  
pp. 73-80 ◽  
Author(s):  
P. K. Bose
Keyword(s):  
Shallow Water ◽  
Depositional Environment ◽  
Fair Weather ◽  
Upper Cambrian ◽  
North Wales ◽  
Storm Wave

SummaryThe marine Maentwrog Beds comprise a repetition of sand and mud facies and follow a non-sequence. A shallow water depositional environment is inferred from the nature of the basal unit (with stromatolites and intraformational conglomerate), and hummocky cross-stratification and mud-draped erosion surfaces. The bulk of the formation was deposited between fair weather and storm wave base, the sand facies representing storm depositional events.

scholarly journals Bioerosion traces and borings in the Upper Devonian vertebrate remains from the Holy Cross Mountains, Poland Bioerosion in fish remains

2021 ◽  
Author(s):  
Piotr Szrek ◽  
Patrycja G. Dworczak ◽  
Olga Wilk
Keyword(s):  
Shallow Water ◽  
Cross Section ◽  
Water Environment ◽  
Trace Fossils ◽  
Upper Devonian ◽  
Holy Cross Mountains ◽  
Shallow Tunnels ◽  
Shallow Water Environment ◽  
Storm Wave ◽  
Fish Remains

Among the hundreds of collected Devonian vertebrate macrofossils in the Holy Cross Mountains, placoderms dominate and provide data on their morphology, distribution and taphonomy. So far 17 out of more than 500 studied specimens have revealed bones with surfaces covered by sediment-filled trace fossils. The traces have been made on the vertebrate remains before their final burial. The borings, oval in cross-section, include dendroidal networks of shallow tunnels or short, straight or curved individual scratches and grooves, which frequently create groups on the both sides of the bones. ?Karethraichnus isp. from Kowala and ?Osteocallis isp. from Wietrznia are the oldest record of these ichnogenera. Sedimentological clues indicate a shallow water environment, probably from the slope below the storm wave base.

scholarly journals Analysis of the Influence of Carried Out Repairs Efficiency on Transport Means Operational Reliability

2010 ◽  
Vol 14-15 (1) ◽  
pp. 359-376
Author(s):  
Andrzej Wdzięczny ◽  
Łukasz Muślewski
Keyword(s):  
Operational Reliability ◽  
Poor Quality ◽  
Transport Systems ◽  
Time Interval ◽  
Technical Object ◽  
Operation Analysis ◽  
Short Period ◽  
Functional Features ◽  
Destructive Processes ◽  
Interval Lengths

Analysis of the Influence of Carried Out Repairs Efficiency on Transport Means Operational Reliability The Maintenance factors and destructive processes which affect systems and elements of technical objects result in undesirable changes of values of their functional features, which causes damages. A damage to a technical object has been defined as exceeding permitted boundary values by significant features characterizing their elements. On the basis of analysis results of the author's own research concerning damages to means of transport, used in real transport systems, it has been found that these damages are the effect of different forcing factors. A certain number of damages is caused by natural wear of machine elements, whereas other damages can occur in result of ineffective repair of a previous damage. Thus, the so called recurrent (secondary) damages occur in a short period of time. On the basis of literature and maintenance and operation analysis results it was found that the most frequent cause of recurrent damage occurrence is improper quality of repairs of the analyzed means of transport. Primary damages are not dependent on each other and they appear randomly, whereas recurrent damages do depend on each other and their occurrence is the conditioned by earlier occurrence of a repair, and above all, by its poor quality. In the paper, a method for evaluation the influence of carried out repairs on transport means operational reliability, has been presented On the basis of the analysis of the moments in which damages to the means of transport and of the time interval lengths between them a simulation model representing a real stream of the damages was built, which enables to evaluate influence of the efficiency of the performed repairs of the means of transport in the real transport system

scholarly journals RELIABILITY AND STABILITY OF THE Y BALANCE TEST IN HEALTHY EARLY ADOLESCENT FEMALE ATHLETES

2019 ◽  
Vol 7 (3_suppl) ◽  
pp. 2325967119S0005
Author(s):  
Eric T. Greenberg ◽  
Matthew Barle ◽  
Erica Glassman ◽  
Liya Jacob ◽  
Hussein Jaafar ◽  
...  
Keyword(s):  
Female Athletes ◽  
Dynamic Balance ◽  
Adolescent Females ◽  
Early Adolescent ◽  
Time Interval ◽  
Adolescent Female ◽  
Balance Test ◽  
Left Limb ◽  
Balance Deficits ◽  
The Right

BACKGROUND/PURPOSE: Adolescent females are at an increased risk of lower extremity injuries and may be partially explained by the interaction of peak rates of skeletal growth, an immature neuromuscular system, and deficits in muscle strength and recruitment patterns. Reliable tests of dynamic stability can help identify athletes with balance deficits and assess changes in limb function after injury. Sophisticated measures of dynamic postural control, such as stabilometry, are able to detect subtle deficits in young athletes, but are expensive and may not be readily available in a clinical setting. The Y Balance Test (YBT) is a low-cost, clinical measure of dynamic postural control that mimics the demands of sports requiring unilateral balance. It requires the athlete to dynamically balance on each leg while performing a maximal reach with the other limb in three different directions: anterior (ANT), posteromedial (PM), and posterolateral (PL). The athlete is required to maintain unilateral balance during the test as maximal reach distance is measured to the nearest 0.5 cm. Though the YBT has been predicative of injury in the adult population, studies are lacking regarding the utility in adolescents. The purpose of this study was to estimate the inter- and intra- rater reliability and stability of the YBT in early adolescent females over a one-month period. METHODS: Twenty-five female athletes (mean age 12.7 ± 0.6 years) participated. Subjects were tested at their respective practice facilities and participated in various sporting activities (Figure 1). Two novice raters with minimal training in YBT administration were randomly selected from a pool of five. The raters simultaneously assessed each subject’s YBT performance and were blinded to each other’s results. A second testing session was performed approximately one month later (n=21, mean 32.3± 9.6 days) by the same two raters, blinded to previous measurements (Figure 2). The time interval was chosen to mimic a typical duration between reassessments in standard clinical care. Maximum reach distances and composite (COMP) scores were collected on both limbs and normalized to leg length (Figure 3). Intraclass correlation coefficients (ICC) were calculated for between rater (ICC 2,1) and between session (ICC 3,1) agreement. Measurement error and minimal detectable change (MDC) values were calculated for clinical interpretation. RESULTS: There was a significant increase in height (p=0.016) and weight (p=0.003) from day 1 to day 2 of testing. Interrater reliability was excellent for all corrected reach directions and COMP scores of the right limb (ICC 0.973- 0.998) and left limb (ICC 0.960-0.999) except for the day 1 left ANT reach which was good (ICC 0.811) (Figure 4). Intrarater (test-retest) reliability were moderate to excellent for the right limb (ICC 0.681- 0.908) and moderate to good for left limb (ICC 0.714 - 0.811). Standard error of measurement (SEM) percentages were all less than 2% of all respective mean reach distances. MDC values for the right and left limbs ranged between 2.02-3.62% and 2.77-3.63%, respectively (Figure 5). CONCLUSIONS/SIGNIFICANCE: The early adolescent female is a unique population, where dynamic balance deficits are escalated by the interaction of an immature neuromuscular system, peak maturational growth rates, and emergence of sex specific differences. The incidence of ACL injuries is greatest during the high school years and recommendations support the implementation of targeted neuromuscular interventions prior to the time of this peak injury risk. The YBT is a reliable and stable tool to assess dynamic balance in early adolescent females and may be utilized by clinicians, physical education teachers, and coaches to help identify high risk individuals, mitigate the risk of injury, and determine functional improvements. The time span between testing sessions in the current study was longer than previous work in attempt to improve external validity by mimicking a typical time interval between outcome measure reassessments performed in a clinical setting. Between session reliability measures were lower than previous studies in adults and highlights the unique performance variation with dynamic balance tasks in the female preadolescent population. This is exemplified by the anthropometric changes that occurred over just a one month interval. This study supports the reliability and stability of the YBT in healthy early adolescent females and can be administered by those with minimal YBT training. Though the YBT has been shown to be predicative of injury in adults and is often included in return to sport functional test batteries after injury, future studies are needed to further understand its utility in this high-risk early adolescent female population. [Figure: see text]

Late Ordovician (Hirnantian) depositional pattern and sea-level change in shallow marine to shoreface cycles in central Sweden

2004 ◽  
Vol 141 (5) ◽  
pp. 605-616 ◽  
Author(s):  
PETER DAHLQVIST
Keyword(s):  
Foreland Basin ◽  
Late Ordovician ◽  
Fair Weather ◽  
Upper Ordovician ◽  
Sedimentary Structures ◽  
Accommodation Space ◽  
Facies Associations ◽  
Storm Wave ◽  
Marine Facies ◽  
Abundant Supply

The Upper Ordovician Kyrkås Quartzite Formation at the Nifsåsen Quarry (Jämtland, Sweden) exhibits c. 90 m of siliciclastic sedimentary rocks deposited on a shallow shelf at the craton-attached part of the Caledonian foreland basin. Five lithologies are distinguished, including claystone, mudstone, siltstone, subarkose and sublitharenite. Based on these five lithologies, sedimentary structures and biota, three marine facies associations are defined: the Mudstone association (FA1) deposited close to storm wave base, the Sandstone/mudstone association (FA2) formed between storm and fair-weather wave bases, and the Sandstone association (FA3) accumulated above fair-weather wave base. The facies associations are arranged in two sequences, c. 50 and 40 m thick, separated by a transgressive surface, indicating repeated shoreline progradation. Both sequences commence with marine heterolithic shales and siltstones, with upwardly increasing frequency of tempestites. Continued shoaling is indicated by a dominance of hummocky and trough (locally tabular) cross-stratified sandstone beds in the upper part of each sequence. Sand beds are increasingly amalgamated up-sequence, reflecting progressively diminishing accommodation space. The depositional style and sedimentary structures indicate that the study area was storm-dominated with an abundant supply of siliciclastic material. Biostratigraphic data tie the depositional changes to the globally recognized Late Ordovician (Hirnantian) glacial interval. These data suggest that the first sequence was formed during the initial phase of regression in the earliest Hirnantian. The lowermost part of the overlying sequence contains elements of a typical Hirnantia fauna followed by beds yielding Normalograptus persculptus, suggesting a second regressive cycle in the Jämtland basin during the early N. persculptus Biozone.

Ostracods and lithofacies of the Middle/Upper Devonian boundary stratotype (Puech de la Suque, Montagne Noire, France)

2007 ◽  
Vol 178 (4) ◽  
pp. 293-304 ◽  
Author(s):  
Jean-Georges Casier ◽  
Alain Préat
Keyword(s):  
Upper Devonian ◽  
Environmental Setting ◽  
Storm Wave ◽  
Montagne Noire ◽  
Stratotype Section ◽  
Storm Deposits

Abstract This paper discusses ostracods and their environmental setting close to the Givetian/Frasnian boundary in the Puech de la Suque Global Stratotype Section and Point. The ostracod fauna belongs exclusively to the Eifelian mega-assemblage and is largely dominated by Podocopina instars. Consequently, the majority of the 33 species recognised and illustrated is described in open nomenclature. The abundance of instars also indicates that most of beds are related to storm deposition. The composition of the fauna suggests a regression in the late Givetian followed by a transgression at the beginning of the Frasnian. Only one ostracod assemblage collected in the upper part of the section indicates a deeper setting below the storm wave base. Eight taxa disappeared in two steps near the Givetian / Frasnian boundary, probably in relation to the Frasnes Event. The sedimentological analysis confirms that the section is constituted principally of storm deposits and reveals in addition the presence of numerous reddish hardgrounds highlighting an important condensation of the sequence.

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