scholarly journals Foraminiferal stratigraphy and palaeoecological implications in turbidite-like deposits from the Early Tortonian (Late Miocene) of Greece

2007 ◽  
Vol 26 (2) ◽  
pp. 145-158 ◽  
Author(s):  
H. Drinia ◽  
A. Antonarakou ◽  
N. Tsaparas ◽  
M. D. Dermitzakis
Keyword(s):  
Habitat Preferences ◽  
High Energy ◽  
Environmental Stability ◽  
Ecological Niches ◽  
Feeding Strategies ◽  
Sedimentary Environments ◽  
Bottom Waters ◽  
Broad Variety ◽  
Consistent Picture ◽  
Of Greece

Abstract. The Lower Tortonian Ag. Giannis section, in Gavdos Island, Greece, consists of an outer neritic to upper bathyal, marly hemipelagic sequence which is interrupted by thick turbidite-like sandy deposits. During deposition of the marly intervals, reworking was considerably reduced.This paper contributes to knowledge concerning benthic foraminiferal response to dynamic sedimentary environments. Important palaeoecological information for benthic foraminiferal assemblages was gathered and analyzed in order to create a regionally consistent picture of the palaeoenvironment. Samples were analyzed statistically in order to identify the different palaeoenvironmental settings during turbiditic sedimentation. Undisturbed basal marls of the section are characterized by the predominance of a diversified Uvigerina striatissima assemblage typified by a broad variety of morphotypes with different inferred habitat preferences and feeding strategies, indicating rather well-oxygenated bottom waters. This environmental stability was subsequently disrupted by recurrent deposition of turbidite-like sands. A low-diversity Valvulineria complanata-Globobulimina sp. assemblage is dominant in this part of the succession, as these specialized endobenthic species could keep pace with high-energy sedimentary settings. Just above the turbidites, a “recolonization” fauna (Bolivina alata assemblage), composed entirely of infaunal elements is observed, indicating a nutrient-rich substrate. This oligotypic fauna is later replaced by a more diversified microfauna capable of occupying a wider range of ecological niches.

Faunal dynamics of foraminiferal assemblages in the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland

2012 ◽  
Vol 62 (3) ◽  
pp. 403-419 ◽  
Author(s):  
Jolanta Smoleń
Keyword(s):  
Sedimentation Rate ◽  
Middle Jurassic ◽  
Taxonomic Diversity ◽  
Feeding Strategies ◽  
Type I ◽  
Type Ii ◽  
Low Oxygen ◽  
Sedimentary Environments ◽  
South Central ◽  
Bottom Waters

ABSTRACT Smoleń, J. 2012. Faunal dynamics of foraminiferal assemblages in the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland. Acta Geologica Polonica, 62(3), 403-419. Warszawa. The faunal dynamics of benthic foraminifera in the Middle Jurassic ore-bearing clays of Gnaszyn (Kraków- Częstochowa Upland, south-central Poland) are used to reconstruct sedimentary environments. Two types of foraminiferal assemblages, distinct in their quantitative and qualitative composition, were distinguished; type I assemblages, characterizing intervals between horizons with sideritic concretions; and type II assemblages, characterising horizons with sideritic concretions. Benthic foraminifers were further subdivided into eight ecological morphogroups, based on their morphological features and micro-habitats. Type I assemblages consist mostly of plano/concavo-convex, small-sized epifaunal morphotypes, with a restricted occurrence of shallow infaunal forms and a scarcity of deep infaunal taxa, which suggests low-oxygen conditions in both sediment and bottom waters, and a high sedimentation rate in an outer shelf environment. Type II assemblages are characterized by high taxonomic diversity, high specimen abundance and variability of epifaunal and infaunal morphotypes representing a mixed group of specialized feeding strategies. This suggests optimum living conditions controlled by a lower sedimentation rate, relatively well-oxygenated bottom waters and sufficient or high food supply.

Patterns of Evolution of the Ediacaran Soft-Bodied Biota

2014 ◽  
Vol 88 (2) ◽  
pp. 269-283 ◽  
Author(s):  
Dmitriy Grazhdankin
Keyword(s):  
High Energy ◽  
Ecosystem Engineering ◽  
Low Energy ◽  
Geological Time ◽  
Time Intervals ◽  
Inner Shelf ◽  
Sedimentary Environments ◽  
Burrowing Activity ◽  
Ecological Associations ◽  
Channel Systems

When each of the Avalon-, Ediacara-, and Nama-type fossil assemblages are tracked through geological time, there appear to be changes in species composition and diversity, almost synchronized between different sedimentary environments, allowing a subdivision of the late Ediacaran into the Redkinian, Belomorian and Kotlinian geological time intervals. The Redkinian (580–559 Ma) is characterized by first appearance of both eumetazoan traces and macroscopic organisms (frondomorphs and vendobionts) in a form of Avalon-type communities in the inner shelf environment, whereas coeval Ediacara-type communities remained depauperate. The Belomorian (559–550 Ma) is marked by the advent of eumetazoan burrowing activity in the inner shelf, diversification of frondomorphs, migration of vendobionts from the inner shelf into higher energy environments, and appearance of tribrachiomorphs and bilateralomorphs. Ediacaran organisms formed distinctive ecological associations that coexisted in the low-energy inner shelf (Avalon-type communities), in the wave- and current-agitated shoreface (Ediacara-type communities), and in the high-energy distributary systems (Nama-type communities). The Kotlinian (550–540 Ma) witnessed an expansion of the burrowing activity into wave- and current-agitated shoreface, disappearance of vendobionts, tribrachiomorphs and bilateralomorphs in wave- and current-agitated shoreface, together with a drop in frondomorph diversity. High-energy distributary channel systems of prodeltas served as refugia for Nama-type communities that survived until the end of the Ediacaran and disappeared when the burrowing activity reached high-energy environments. This pattern is interpreted as an expression of ecosystem engineering by eumetazoans, with the Ediacaran organisms being progressively outcompeted by bilaterians.

3D model-based estimations of volume and mass of high-energy dislocated boulders in coastal areas of Greece by terrestrial laser scanning

2014 ◽  
Vol 58 (3) ◽  
pp. 115-135 ◽  
Author(s):  
Dirk Hoffmeister ◽  
Konstantin Ntageretzis ◽  
Helge Aasen ◽  
Constanze Curdt ◽  
Hanna Hadler ◽  
...  
Keyword(s):  
Laser Scanning ◽  
3D Model ◽  
Terrestrial Laser Scanning ◽  
High Energy ◽  
Coastal Areas ◽  
Model Based ◽  
Of Greece

scholarly journals Phylogenomics, Biogeography, and Morphometrics Reveal Rapid Phenotypic Evolution in Pythons After Crossing Wallace’s Line

2020 ◽  
Vol 69 (6) ◽  
pp. 1039-1051 ◽  
Author(s):  
Damien Esquerré ◽  
Stephen Donnellan ◽  
Ian G Brennan ◽  
Alan R Lemmon ◽  
Emily Moriarty Lemmon ◽  
...  
Keyword(s):  
Body Shape ◽  
Habitat Preferences ◽  
Ecological Niches ◽  
Mitochondrial Genomes ◽  
Phenotypic Evolution ◽  
Conservative Group ◽  
Anchored Hybrid Enrichment ◽  
Nuclear Loci ◽  
Wallace’S Line ◽  
Diverse Groups

Abstract Ecological opportunities can be provided to organisms that cross stringent biogeographic barriers towards environments with new ecological niches. Wallace’s and Lyddeker’s lines are arguably the most famous biogeographic barriers, separating the Asian and Australo-Papuan biotas. One of the most ecomorphologically diverse groups of reptiles, the pythons, is distributed across these lines, and are remarkably more diverse in phenotype and ecology east of Lydekker’s line in Australo-Papua. We used an anchored hybrid enrichment approach, with near complete taxon sampling, to extract mitochondrial genomes and 376 nuclear loci to resolve and date their phylogenetic history. Biogeographic reconstruction demonstrates that they originated in Asia around 38-45 Ma and then invaded Australo-Papua around 23 Ma. Australo-Papuan pythons display a sizeable expansion in morphological space, with shifts towards numerous new adaptive optima in head and body shape, coupled with the evolution of new micro-habitat preferences. We provide an updated taxonomy of pythons and our study also demonstrates how ecological opportunity following colonization of novel environments can promote morphological diversification in a formerly ecomorphologically conservative group. [Adaptive radiation; anchored hybrid enrichment; biogeography; morphometrics; snakes.]

scholarly journals Can mandible morphology help predict feeding habits in Antarctic amphipods?

2020 ◽  
Vol 32 (6) ◽  
pp. 496-507
Author(s):  
Loïc N. Michel ◽  
Fabienne L. Nyssen ◽  
Patrick Dauby ◽  
Marie Verheye
Keyword(s):  
Functional Groups ◽  
Trophic Ecology ◽  
Feeding Habits ◽  
Gut Contents ◽  
Ecological Niches ◽  
Feeding Strategies ◽  
Generalist Predators ◽  
Dietary Specialization ◽  
Important Place ◽  
Antarctic Amphipod

AbstractIn Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do so, we compared mandible morphology in nine species spanning seven families and five functional groups (grazers, suspension feeders, generalist predators, specialist predators and scavengers). Mandible morphology adequately depicted some aspects of amphipod trophic ecology, such as the trophic level at which animals feed or their degree of dietary specialization. On the other hand, links between mandible morphology and amphipod diet were seldom unambiguous or straightforward. Similar adaptations were found in distinct functional groups. Conversely, mandible morphology could vary within a single functional group, and phylogenetic effects sometimes complicated the interpretation of form-function relationships. Overall, mandible morphology on its own was generally not sufficient to precisely predict amphipod feeding strategies. However, when combined with other methods (e.g. gut contents, trophic markers), it constitutes a valuable source of information for integrative studies of amphipod ecological diversity in the Southern Ocean.

scholarly journals Late Quaternary Paleoceanography and Sedimentary Environments in Hudson Strait

2007 ◽  
Vol 43 (2) ◽  
pp. 161-178 ◽  
Author(s):  
G. Vilks ◽  
B. MacLean ◽  
B. Deonarine ◽  
C. G. Currie ◽  
K. Moran
Keyword(s):  
Late Quaternary ◽  
Tidal Mixing ◽  
Last Deglaciation ◽  
Eastern Basin ◽  
Sedimentary Environments ◽  
Minimum Age ◽  
Bottom Waters ◽  
Salinity Difference ◽  
Seismic Reflection Profiles ◽  
Glaciomarine Sediments

ABSTRACT Airgun and high resolution Huntec seismic reflection profiles are interpreted to show up to 130 m of glacial, glaciomarine and postglacial sediments overlying bedrock. In a basin at the eastern entrance to Hudson Strait most of the surficial sediment was deposited during the last déglaciation, but in western Hudson Strait multiple till sequences from previous glaciations are recognized. Five acoustic units were identified, at least three of which were penetrated with piston cores. Foraminifera of the stratigraphically deepest core in the eastern basin indicate a proximal glaciomarine environment and a likely presence of an ice shelf. A 14C date of 8060 ± 70 yBP (TO 750) on molluscan shells gives a minimum age for the top of the acoustically laminated distal glaciomarine sediments. The early postglacial foraminifera suggest a period of increased influence of offshore bottom waters restricted to the deep eastern basin. The surface sediments of all cores contain species indigenous of colder and fresher inshore waters of the present time. The ratio of 18CV16O in the benthic foraminifer Cibicides lobatulus is herein related to bottom salinity. Downcore measurements of 8'8O on C. lobatulus tests indicate bottom paleosalinities lower by about 0.5%o shortly before the dated horizon of 8000 yBP. By this time Hudson Strait was sufficiently clear of glacial ice for establishment of the present tidal regime. The lower bottom salinities indicate that tidal mixing took place between glacial meltwater leaving Hudson Bay and the offshore counterflow. This process is thought to have reduced the sharpness of the salinity difference between the offshore water and the surface plume of Laurentide meltwater as it entered the ocean.

scholarly journals Garnet-type solid electrolyte: Advances of ionic transport performance and its application in all-solid-state batteries

2021 ◽  
Author(s):  
P. M. Gonzalez Puente ◽  
Shangbin Song ◽  
Shiyu Cao ◽  
Leana Ziwen Rannalter ◽  
Ziwen Pan ◽  
...  
Keyword(s):  
Solid State ◽  
Solid Electrolyte ◽  
Solid Electrolytes ◽  
High Energy ◽  
Environmental Stability ◽  
Preparation Methods ◽  
Metal Anode ◽  
Safety Issues ◽  
Electrochemical Window ◽  
Increasing Demand

AbstractAll-solid-state lithium batteries (ASSLBs), which use solid electrolytes instead of liquid ones, have become a hot research topic due to their high energy and power density, ability to solve battery safety issues, and capabilities to fulfill the increasing demand for energy storage in electric vehicles and smart grid applications. Garnet-type solid electrolytes have attracted considerable interest as they meet all the properties of an ideal solid electrolyte for ASSLBs. The garnet-type Li7La3Zr2O12 (LLZO) has excellent environmental stability; experiments and computational analyses showed that this solid electrolyte has a high lithium (Li) ionic conductivity (10−4–10−3 S·cm−1), an electrochemical window as wide as 6 V, stability against Li metal anode, and compatibility with most of the cathode materials. In this review, we present the fundamentals of garnet-type solid electrolytes, preparation methods, air stability, some strategies for improving the conductivity based on experimental and computational results, interfacial issues, and finally applications and challenges for future developments of LLZO solid electrolytes for ASSLBs.

scholarly journals Recent Foraminifera from the North Sea (Forties and Ekofisk areas) and the continental shelf west of Scotland

1985 ◽  
Vol 4 (2) ◽  
pp. 117-125 ◽  
Author(s):  
John W. Murray
Keyword(s):  
Continental Shelf ◽  
North Sea ◽  
Standing Crop ◽  
High Energy ◽  
The West ◽  
The North ◽  
Energy Environment ◽  
Bottom Waters ◽  
The North Sea ◽  
Northern North Sea

Abstract. The regions studied are all of mid continental shelf depth (70–145 m) and have bottom waters of normal marine salinity. The North Sea has lower bottom water temperatures than those to the west of Scotland. However, the major difference between the two regions is one of tidal and/or wave energy: the northern North Sea is a low energy environment of muddy sand deposition whereas the sampled part of the continental shelf west and north of Scotland is a moderate to high energy environment of medium to coarse biogenic carbonate sedimentation.The physical differences between the two main areas are reflected in the living and dead foraminiferal assemblages. The northern North Sea is a region of free-living species whereas the continental shelf west of Scotland has immobile and mobile attached species living on firm substrates. The northern North Sea is very fertile and has high standing crop values.The dead assemblages are small in size and very abundant. To the west of Scotland the sea is less fertile, standing crop values are low, the dead assemblages are moderate to large in size and reasonably abundant due to the slow rate of dilution by sediment.

scholarly journals The population of TeV pulsar wind nebulae in the H.E.S.S. Galactic Plane Survey

2018 ◽  
Vol 612 ◽  
pp. A2 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Plane ◽  
High Energy ◽  
Pulsar Wind Nebulae ◽  
Upper Limits ◽  
Very High Energy ◽  
Consistent Picture ◽  
Pulsar Wind ◽  
Asymmetric Environment ◽  
First Time

The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of TeV pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spin-down power Ė. This seems to be caused both by an increase of extension with decreasing Ė, and hence with time, compatible with a power law RPWN(Ė) ~Ė−0.65±0.20, and by a mild decrease of TeV gamma-ray luminosity with decreasing Ė, compatible with L1−10 TeV ~Ė0.59±0.21. We also find that the offsets of pulsars with respect to the wind nebula centre with ages around 10  kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar offset is correlated with a high apparent TeV efficiency L1−10 TeV∕Ė. In addition to 14 HGPS sources considered firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that are likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.

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