Reappraisal of the Beekmantown Group sedimentology and stratigraphy, Montréal area, southwestern Quebec: implications for understanding the depositional evolution of the Lower-Middle Ordovician Laurentian passive margin of eastern Canada

2003 ◽  
Vol 40 (2) ◽  
pp. 149-176 ◽  
Author(s):  
O Salad Hersi ◽  
D Lavoie ◽  
G S Nowlan
Keyword(s):  
Temporal Evolution ◽  
High Energy ◽  
Field Application ◽  
Passive Margin ◽  
Coarse Grained ◽  
Energy Conditions ◽  
Eastern Canada ◽  
Middle Ordovician ◽  
Platform Margin ◽  
Depositional Evolution

Detailed lithostratigraphic mapping of the Beekmantown Group of southwestern Quebec has refined the field application of the previously proposed tripartite division of the group (i.e., Theresa, Beauharnois, and Carillon formations). The group is a peritidal-dominated succession that accumulated on the epicontinental Laurentian passive margin. Biostratigraphic data based on conodonts from this group indicate an Early to early Middle Ordovician age and are partially time-correlative with the Wallace Creek to Naylor Ledge strata of the Philipsburg Group, southern Quebec. This conodont biostratigraphy sheds new light on the temporal evolution and depositional framework of the Beekmantown platform. The platform evolved as a distally steepened ramp during deposition of the Theresa Formation and the Ogdensburg Member of the Beauharnois Formation (early to middle Ibexian). Correlative strata of the Philipsburg Group include the Wallace Creek and Morgan Corner formations, which represent outer platform sediments. The coarse-grained sandstone of the Theresa Formation accumulated in the innermost platform, whereas coarse-grained carbonates of the Ogdensburg Member indicate open-marine, subtidal to intertidal carbonate sand shoals. By late Ibexian, the platform developed a pronounced margin where thrombolites flourished under high-energy conditions. These are represented by the thrombolite-rich Hasting Creek and Naylor Ledge formations of the Philipsburg Group. Consequently, a broad lagoon formed on the lee side of the platform margin, where low-energy conditions prevailed and accumulation of burrow-mottled dolostones of the Huntingdon Member of the upper Beauharnois Formation took place. The lagoon became more restricted during the latest stages of the basin fill (Whiterockian), and high intertidal to supratidal sediments of the Carillon Formation were deposited.

scholarly journals Distribution of smaller benthic foraminifera in the Chagos Archipelago, Indian Ocean

1994 ◽  
Vol 13 (1) ◽  
pp. 47-53 ◽  
Author(s):  
John W. Murray ◽  
Christopher W. Smart
Keyword(s):  
Indian Ocean ◽  
Distribution Patterns ◽  
High Energy ◽  
Coarse Grained ◽  
Energy Conditions ◽  
Shallow Waters ◽  
High Species Diversity ◽  
The Indian Ocean ◽  
Strong Winds ◽  
Chagos Archipelago

Abstract. The Chagos Archipelago is a series of atolls situated in the centre of the Indian Ocean close to the equator. The area experiences small tides and periods of strong winds. The combined effects of these is to cause relatively high energy conditions to exist in the shallow waters around the reefs, therefore the bottom sediments are coarse grained and mobile. Although the coral faunas are diverse, seagrasses are rare. The total benthic foraminiferal assemblages have low to high species diversity and are dominated by hyaline taxa. On the oceanic side of the atoll reefs, the dominant foraminiferan is Amphistegina lessonii, with subsidiary miliolids. Planklonic tests form up to 20% of the combined benthic and planktonic component. In the lagoon, the assemblages are dominated by Calcarina calcar, with subsidiary miliolids. Planktonic tests are relatively uncommon. Some post-mortem transport and damage to tests has taken place but the distribution patterns are believed to be representative of the original living ones.

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 Current Knowledge and Future Directions for Improving Subsoiling Quality and Reducing Energy Consumption in Conservation Fields

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 575
Author(s):  
Shangyi Lou ◽  
Jin He ◽  
Hongwen Li ◽  
Qingjie Wang ◽  
Caiyun Lu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Cover Crops ◽  
Current Knowledge ◽  
High Energy ◽  
Field Application ◽  
Research Progress ◽  
Monitoring And Control ◽  
Future Directions ◽  
Tillage Depth ◽  
And Control

Subsoiling has been acknowledged worldwide to break compacted hardpan, improve soil permeability and water storage capacity, and promote topsoil deepening and root growth. However, there exist certain factors which limit the wide in-field application of subsoiling machines. Of these factors, the main two are poor subsoiling quality and high energy consumption, especially the undesired tillage depth obtained in the field with cover crops. Based on the analysis of global adoption and benefits of subsoiling technology, and application status of subsoiling machines, this article reviewed the research methods, technical characteristics, and developing trends in five key aspects, including subsoiling shovel design, anti-drag technologies, technologies of tillage depth detection and control, and research on soil mechanical interaction. Combined with the research progress and application requirements of subsoiling machines across the globe, current problems and technical difficulties were analyzed and summarized. Aiming to solve these problems, improve subsoiling quality, and reduce energy consumption, this article proposed future directions for the development of subsoiling machines, including optimizing the soil model in computer simulation, strengthening research on the subsoiling mechanism and comprehensive effect, developing new tillage depth monitoring and control systems, and improving wear-resisting properties of subsoiling shovels.

scholarly journals Diverse floodplain deposits of reworked loess in a monsoon climate (Hanzhong Basin, central China)

2021 ◽  
pp. 1-17
Author(s):  
Jef Vandenberghe ◽  
Xun Yang ◽  
Xianyan Wang ◽  
Shejiang Wang ◽  
Huayu Lu
Keyword(s):  
Soil Formation ◽  
High Energy ◽  
Central China ◽  
Energy Conditions ◽  
Middle Pleistocene ◽  
Sedimentary Sequences ◽  
Varied Intensity ◽  
Floodplain Deposits ◽  
Flooding Events ◽  
Floodplain Sediments

Abstract This paper describes an assemblage of diverse floodplain facies of reworked loess (facies b, c) in a Middle Pleistocene monsoonal setting of the Hanzhong Basin, central China. The vertical and lateral sedimentary sequences show changing energy conditions. Apart from the highest energy in the channel facies (facies a), a relatively high energy floodplain environment (facies b) prevailed in waterlogged conditions, with small, laterally migrating (sub)channels. Facies b generally interfingers with aggrading horizontal sheets of overbank deposits in alluvial pools and swamps in a floodplain with much lower energy (facies c), in which phases of stability (soil formation) occasionally interrupted overbank deposition. Reworked loess forms the main part of the floodplain deposits. The paleosols are considered to have been formed under low hydrodynamic conditions in an interglacial environment. These interglacial conditions follow the commonly assumed glacial conditions of channel facies a. The sedimentary successions in the floodplain show a recurrent composition and cyclicity between wet and dry floodplain sedimentation terminated by stability with soil formation. The cyclic rhythm of stacked high- and low-energy floodplain sediments is attributed to varied intensity of different hydrodynamic flooding events that may have been due to changing monsoonal rainfall or simple intrinsic fluvial behavior.

Nucularcidae: a new family of palaeotaxodont Ordovician pelecypods (Mollusca) from North America and Australia

2007 ◽  
Vol 44 (10) ◽  
pp. 1479-1501 ◽  
Author(s):  
John Pojeta Jr. ◽  
Christopher A Stott
Keyword(s):  
New Species ◽  
Type Species ◽  
New Genus ◽  
Late Ordovician ◽  
Eastern Canada ◽  
Middle Ordovician ◽  
New Family ◽  
Central Australia ◽  
Northeastern Usa ◽  
Subjective Synonym

The new Ordovician palaeotaxodont family Nucularcidae and the new genus Nucularca are described. Included in Nucularca are four previously described species that have taxodont dentition: N. cingulata (Ulrich) (the type species), N. pectunculoides (Hall), N. lorrainensis (Foerste), and N. gorensis (Foerste). All four species are of Late Ordovician (Cincinnatian Katian) age and occur in eastern Canada and the northeastern USA. Ctenodonta borealis Foerste is regarded as a subjective synonym of Nucularca lorrainensis. No new species names are proposed. The Nucularcidae includes the genera Nucularca and Sthenodonta Pojeta and Gilbert-Tomlinson (1977). Sthenodonta occurs in central Australia in rocks of Middle Ordovician (Darriwilian) age. The 12 family group names previously proposed for Ordovician palaeotaxodonts having taxodont dentition are reviewed and evaluated in the Appendix.

Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England

1988 ◽  
Vol 322 (1210) ◽  
pp. 221-272 ◽  
Keyword(s):  
Amino Acid ◽  
High Energy ◽  
Coarse Grained ◽  
Core Material ◽  
Stage System ◽  
Pollen And Spores ◽  
Shallow Marine Sediments ◽  
Amino Acid Chronology ◽  
Tectonic Origin ◽  
Borehole Core

This study uses a variety of criteria to examine short-range correlation within the Crag deposits in order to assess the validity of longer-range correlations within the British Pleistocene stage system. To this end, six rotary cored boreholes spaced at 0.5-1.0 km intervals were drilled along a north-south-aligned traverse between Aldeburgh and Sizewell, Suffolk. These show that the thick Red/Norwich Crag sequence is confined to a deep, sharply bounded basin, which is of probable erosional rather than tectonic origin. The undisturbed borehole core material enabled an assessment of the limits of stratigraphic resolution within these dominantly high-energy, shallow marine sediments to be made. Subdivision of the sequence was done on the basis of lithostratigraphical and biostratigraphical (foraminifera, pollen and spores, dinoflagellate cysts, and molluscs) criteria; chronostratigraphical methods (palaeomagnetism and amino acid chronology) were also applied. The various subdivisions indicated by each of these disciplines were in large part consistent, demonstrating that valid stratigraphic units had been identified. Only amino acid chronology did not indicate any obvious subdivision of the sequence. Three lithostratigraphical units were recognized within the thick Crag sequence. The lowest unit (AS-Lith 1) consists of coarse shelly sands interbedded with thinly laminated muds and fine sands. The middle unit (AS-Lith 2) consists of fine- to coarse-grained shelly sands arranged in two coarsening-upwards cycles. Units AS-Lith 1 and AS-Lith 2 are correlated on a lithostratigraphical basis with the Red Crag Formation of the adjacent Aldeburgh-Orford area to the south and are named the Sizewell Member and the Thorpeness Member respectively. The uppermost unit (AS-Lith 3) comprises fine- to medium-grained, well-sorted sands; it correlates with the Chillesford Sand Member of the Norwich Crag Formation of the adjacent Aldeburgh-Orford area. The Sizewell Member of the Red Crag Formation is normally magnetized and palaeontologically distinctive. The pollen, foraminifera and dinoflagellate assemblages firmly establish it as Pre-Ludhamian in age, and probably equivalent to an interval within the Reuverian C to Praetiglian Stages of the Netherlands. The Thorpeness Member of the Red Crag Formation is less easy to place within the British Pleistocene stage system. It is reverse magnetized, at least in part, and foraminifera assemblages suggest possible correlation with the Ludhamian Stage. No identifiable pollen or dinoflagellate assemblages were obtained. The Chillesford Sand Member of the Norwich Crag Formation is largely unfossiliferous but the borehole material has yielded a single pollen spectrum that suggests correlation with the Bramertonian Stage.

scholarly journals Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

2017 ◽  
Vol 154 (3) ◽  
pp. 121 ◽  
Author(s):  
V. Bourrier ◽  
J. de Wit ◽  
E. Bolmont ◽  
V. Stamenković ◽  
P. J. Wheatley ◽  
...  
Keyword(s):  
Water Content ◽  
Temporal Evolution ◽  
High Energy ◽  
Energy Irradiation ◽  
High Energy Irradiation

scholarly journals Involvement of Progranulin in Hypothalamic Glucose Sensing and Feeding Regulation

Endocrinology ◽  
2011 ◽  
Vol 152 (12) ◽  
pp. 4672-4682 ◽  
Author(s):  
Hyun-Kyong Kim ◽  
Mi-Seon Shin ◽  
Byung-Soo Youn ◽  
Churl Namkoong ◽  
So Young Gil ◽  
...  
Keyword(s):  
Neuropeptide Y ◽  
Energy Condition ◽  
Physiological Role ◽  
High Energy ◽  
Glucose Sensing ◽  
Energy Conditions ◽  
Related Peptide ◽  
Feeding Regulation ◽  
Nocturnal Feeding ◽  
Hypothalamic Regulation

Progranulin (PGRN) is a secreted glycoprotein with multiple biological functions, including modulation of wound healing and inflammation. Hypothalamic PGRN has been implicated in the development of sexual dimorphism. In the present study, a potential role for PGRN in the hypothalamic regulation of appetite and body weight was investigated. In adult rodents, PGRN was highly expressed in periventricular tanycytes and in hypothalamic neurons, which are known to contain glucose-sensing machinery. Hypothalamic PGRN expression levels were decreased under low-energy conditions (starvation and 2-deoxy-D-glucose administration) but increased under high-energy condition (postprandially). Intracerebrovetricular administration of PGRN significantly suppressed nocturnal feeding as well as hyperphagia induced by 2-deoxyglucose, neuropeptide Y, and Agouti-related peptide. Moreover, the inhibition of hypothalamic PGRN expression or action increased food intake and promoted weight gain, suggesting that endogenous PGRN functions as an appetite suppressor in the hypothalamus. Investigation of the mechanism of action revealed that PGRN diminished orexigenic neuropeptide Y and Agouti-related peptide production but stimulated anorexigenic proopiomelanocortin production, at least in part through the regulation of hypothalamic AMP-activated protein kinase. Notably, PGRN was also expressed in hypothalamic microglia. In diet-induced obese mice, microglial PGRN expression was increased, and the anorectic response to PGRN was blunted. These findings highlight a physiological role for PGRN in hypothalamic glucose-sensing and appetite regulation. Alterations in hypothalamic PGRN production or action may be linked to appetite dysregulation in obesity.

scholarly journals A Review of the Morphology, Physical Processes and Deposits of Modern Straits

2021 ◽  
pp. SP523-2021-76
Author(s):  
Robert W. Dalrymple
Keyword(s):  
High Energy ◽  
Energy Conditions ◽  
Physical Processes ◽  
Content Type ◽  
Fluvial Deposits ◽  
Sediment Waves ◽  
Contourite Drifts ◽  
Supplementary Material ◽  
Maximum Flooding Surface ◽  
Oceanic Currents

AbstractThis study reviews the morphology, hydrodynamics and sedimentology of 33 modern straits, including examples from diverse tectonic and climatic settings. Strait morphology ranges from short, simple straits to long, tortuous passages many 100s of kilometers long; depths range from 10 m to >1 km. The morphological building block of strait sedimentation is a constriction flanked by open basins; a single strait can contain one or several of these. Currents accelerate through the constrictions and decelerate in the basins, leading to a spatial alternation of high- and low-energy conditions. Currents in a strait can be classified as either ‘persistent’ (oceanic currents or density-driven circulation) or ‘intermittent’ (tidally or meteorologically generated currents). Constrictions tend to be bedload partings, with the development of transport paths that diverge outward. Deposition occurs where the flow decelerates, generating paired subaqueous ‘constriction-related deltas’ that can be of unequal size. Cross-bedding predominates in high-energy settings; muddy sediment waves and contourite drifts are present in some straits. In shallow straits that were exposed during the sea-level lowstand, strait deposits typically occur near or at the maximum flooding surface, and can overlie estuarine and fluvial deposits. The most energetic deposits need not occur at the time of maximum inundation.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5746061

scholarly journals The correlative behavior of sandbars and shoreline along Sulina – Sf. Gheorghe beaches (Danube Delta Coast)

2016 ◽  
Vol 18 (1) ◽  
pp. 19-31
Author(s):  
Florin TĂTUI
Keyword(s):  
High Energy ◽  
Sandy Beaches ◽  
Energy Conditions ◽  
Danube Delta ◽  
Dune System ◽  
Migration Rates ◽  
System Protection ◽  
Main Driver ◽  
Southern Central

Longshore sandbars along wave-dominated sandy beaches are important for beach-dune system protection during storms. Our analysis is based on 6 years of seasonal and annual bathymetric surveys along 16 km of erosive, stable and accumulative low-lying non-tidal beaches northward of Sf. Gheorghe arm mouth (Danube Delta – Romanian Black Sea coast). Our results show significant correlations established between longshore sandbar crest positions and morphology with more intense coupling between the inner and outer sandbar sub-systems during high-energy conditions and more frequent along the northern erosive sector in comparison with the southern/central accumulative/stable ones. There is a good connection between the long-term shoreline mobility and sandbars offshore migration rates along different sectors of the study area, with faster sandbars movement and shorter cycle return periods along the northern erosive sector in comparison with the central (stable) and southern (accretionary) sectors. The longshore variations of the nearshore slope are the main driver of the relationship between long-term sandbars dynamics and shoreline variability along the study site.

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