The allochthonous origin of the reefal facies of the Stuart Bay Formation (Early Devonian), Bathurst Island, arctic Canada

1984 ◽  
Vol 21 (6) ◽  
pp. 657-668 ◽  
Author(s):  
Kevin P. Polan ◽  
Colin W. Stearn
Keyword(s):  
Deep Water ◽  
Lower Devonian ◽  
Linear Groups ◽  
Fold Belt ◽  
Arctic Canada ◽  
Catastrophic Events ◽  
Early Devonian ◽  
Bedding Planes ◽  
Reefal Facies ◽  
Reef Tract

Blocks of limestone and dolomite up to tens of metres across occur near the base of the Lower Devonian (Siegenian–Emsian) Stuart Bay Formation at six sites on eastern Bathurst Island. These blocks occur in groups of up to 30. At the two localities with the greatest number of blocks they are disposed in two or three roughly linear groups reflecting their occurrence on bedding planes. The blocks are mostly wackestones and floatstones and they contain abundant fossils of the reefal biofacies of which stromatoporoids and corals are most prominent.The blocks have weathered from a matrix of finely laminated deep-water siltstone. Most of the blocks are unbedded but where bedding attitudes can be measured they are discordant with that of the siltstone and those of neighbouring blocks. Although they have been described as bioherms that grew in place, the evidence indicates that they are allochthonous blocks derived when several catastrophic events such as earthquakes disturbed a Devonian reef tract developed on the western flank of the Cornwallis Fold Belt.

The role of contemporaneous faulting on Late Silurian sedimentation in the eastern M'Clintock Basin, Prince of Wales Island, Arctic Canada

1986 ◽  
Vol 23 (9) ◽  
pp. 1401-1411 ◽  
Author(s):  
Paul S. Mortensen ◽  
Brian Jones
Keyword(s):  
Carbonate Platform ◽  
Fold Belt ◽  
Arctic Canada ◽  
Early Devonian ◽  
Eastern Margin ◽  
Basement Faults ◽  
Somerset Island ◽  
East West

During the Late Silurian, the eastern margin of the M'Clintock Basin was the site of slow sedimentation on a relatively stable carbonate platform. It is apparent, however, that contemporaneous (syndepositional) faults segmented this basin into several quasi-independent subbasins during deposition of the Cape Storm, Douro, and Somerset Island formations. Differential subsidence of these subbasins played a major role in controlling sedimentation patterns and stratigraphie thickness. These subbasins may have been sustained into the Early Devonian, as is evident from the facies of the overlying Peel Sound Formation. The east–west orientated, reactivated basement faults bounding the subbasins served as zones of weakness during the development of the Cornwall is Fold Belt and are evident in the present-day outcrop.

The lower Devonian Kowmung volcaniclastics: A deep‐water succession of mass‐flow origin, northeastern Lachlan Fold Belt, N.S.W.

1981 ◽  
Vol 28 (3-4) ◽  
pp. 271-288 ◽  
Author(s):  
R. A. Cas ◽  
C. McA. Powell ◽  
C. L. Fergusson ◽  
J. G. Jones ◽  
W. D. Roots ◽  
...  
Keyword(s):  
Mass Flow ◽  
Deep Water ◽  
Lower Devonian ◽  
Fold Belt ◽  
Lachlan Fold Belt

scholarly journals Evaluating the impacts of major cyclonic catastrophes in coastal Bangladesh using geospatial techniques

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
Mashoukur Rahaman ◽  
Md. Esraz-Ul-Zannat
Keyword(s):  
Deep Water ◽  
Water Body ◽  
Crop Production ◽  
Vector Analysis ◽  
Agricultural Crop ◽  
Geospatial Technologies ◽  
Catastrophic Events ◽  
Change Vector Analysis ◽  
Change Vector ◽  
Post Disaster

AbstractCyclonic catastrophes frequently devastate coastal regions of Bangladesh that host around 35 million people which represents two-thirds of the total population. They have caused many problems like agricultural crop loss, forest degradation, damage to built-up areas, river and shoreline changes that are linked to people’s livelihood and ecological biodiversity. There is an absence of a comprehensive assessment of the major cyclonic disasters of Bangladesh that integrates geospatial technologies in a single study. This study aims to integrate geospatial technologies with major disasters and compares them, which has not been tried before. This paper tried to identify impacts that occurred in the coastal region by major catastrophic events at a vast level using different geospatial technologies. It focuses to identify the impacts of major catastrophic events on livelihood and food production as well as compare the impacts and intensity of different disasters. Furthermore, it compared the losses among several districts and for that previous and post-satellite images of disasters that occurred in 1988, 1991, 2007, 2009, 2019 were used. Classification technique like machine learning algorithm was done in pre- to post-disaster images. For quantifying change in the indication of different factors, indices including NDVI, NDWI, NDBI were developed. “Change vector analysis” equation was performed in bands of the images of pre- and post-disaster to identify the magnitude of change. Also, crop production variance was analyzed to detect impacts on crop production. Furthermore, the changes in shallow to deep water were analyzed. There is a notable change in shallow to deep water bodies after each disaster in Satkhira and Bhola district but subtle changes in Khulna and Bagerhat districts. Change vector analysis revealed greater intensity in Bhola in 1988 and Satkhira in 1991. Furthermore, over the years 2007 and 2009 it showed medium and deep intense areas all over the region. A sharp decrease in Aus rice production is witnessed in Barishal in 2007 when cyclone “Sidr” was stricken. The declination of potato production is seen in Khulna district after the 1988 cyclone. A huge change in the land-use classes from classified images like water body, Pasture land in 1988 and water body, forest in 1991 is marked out. Besides, a clear variation in the settlement was observed from the classified images. This study explores the necessity of using more geospatial technologies in disastrous impacts assessment around the world in the context of Bangladesh and, also, emphasizes taking effective, proper and sustainable disaster management and mitigation measures to counter future disastrous impacts.

scholarly journals First records of marine tardigrades of the genus Coronarctus (Tardigrada, Heterotardigrada, Arthrotardigrada) from Mexico

Check List ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1-7
Author(s):  
Wilbert Andrés Pérez-Pech ◽  
Jesper Guldberg Hansen ◽  
Erica DeMilio ◽  
Alberto de Jesús-Navarrete ◽  
Ivonne Martínez Mendoza ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Deep Water ◽  
Deep Sea ◽  
Water Sampling ◽  
Fold Belt ◽  
Taxonomic Analysis

Deep-water sampling in the Perdido Fold Belt, Gulf of Mexico, Mexican Economic Exclusive Zone yielded five specimens of tardigrades belonging to the genus Coronarctus Renaud-Mornant, 1974. The specimens represent the first records of the genus for Mexico. Two two-clawed larvae and two four-clawed larvae of Coronarctus mexicus Romano, Gallo, D’Addabbo, Accogli, Baguley & Montagna, 2011 and a single four-clawed larval specimen of an undescribed Coronarctus species were identified. Taxonomic analysis of the specimens contributed to the knowledge of deep-sea and Mexican marine tardigrades, two data-poor areas of study.

The first zosterophyll from the Lower Devonian Rhynie Chert, Aberdeenshire

1991 ◽  
Vol 82 (4) ◽  
pp. 324-332 ◽  
Author(s):  
A. G. Lyon ◽  
Dianne Edwards
Keyword(s):  
Lower Devonian ◽  
New Genus ◽  
New Genus And Species ◽  
Early Devonian ◽  
Precise Positioning ◽  
Cortical Zone ◽  
Lack Of Information ◽  
Rhynie Chert

ABSTRACTFragmentary remains of a vascular sporophyte from the Rhynie Chert are described as a new genus and species, Trichopherophyton teuchansii. The plant, which is characterised by the possession of unicellular spinous hairs, exarch xylem and laterally attached, marginally dehiscent sporangia, is assigned to the Zosterophyllophytina, but lack of information on the arrangement of sporangia prevents its more precise positioning within the subdivision. Unusual features include the combination of circinate tips to axes with almost terete xylem strands, and the lack of a thick-walled outer cortical zone. Associated axes, lacking spinous hairs, but having papillate or rhizoid-like epidermal emergences, are interpreted as likely rhizomes of Trichopherophyton. Features, such as unicellular spinous hairs, rhizoid-like emergences, circinate tipsand parenchymatous cortex are considered in relation to the functioning and growth of aplant inhabiting an early Devonian wetland.

scholarly journals Further evidence for fungivory in the Lower Devonian (Lochkovian) of the Welsh Borderland, UK

PalZ ◽  
2020 ◽  
Vol 94 (4) ◽  
pp. 603-618
Author(s):  
Dianne Edwards ◽  
Lindsey Axe ◽  
Jennifer L. Morris ◽  
Lynne Boddy ◽  
Paul Selden
Keyword(s):  
Carbon Cycling ◽  
Lower Devonian ◽  
Terrestrial Ecosystems ◽  
Lower Surface ◽  
Early Devonian ◽  
Faecal Pellets ◽  
Terrestrial Invertebrates ◽  
Terrestrial Animal ◽  
Complete Digestion ◽  
Terrestrial Fungi

Abstract The recent demonstrations that widespread mid-Palaeozoic Prototaxites and other nematophytes had fungal affinities indicate that terrestrial fungi were important elements in carbon cycling in the Early Devonian. Here, we provide evidence for their participation in the recycling of nutrients by early terrestrial invertebrates. Evidence is in the form of coprolites, both those associated with nematophytes or containing their fragmentary remains. Cylindrical coprolites consistently associated with fungal mats are placed in a new ichnospecies, Bacillafaex myceliorum. Their contents are granular to amorphous, suggestive of complete digestion of the ingested hyphae, with the inference of possession of chitinases in the digestive tracts of the consumers. A further single example comprises a cluster of cylindrical bodies attached to the lower surface of a Nematothallus fragment. Here, homogenisation was less complete, with traces of hyphae remaining. Terrestrial animal fossils have not been found at the locality, but scorpions, pseudoscorpions, Opiliones, mites, centipedes (carnivores) and millipedes, and Collembola (detritivores) have been recorded from the slightly younger Rhynie cherts. Studies of fungivory in extant arthropods have concentrated on Collembola and, to a lesser extent, mites, but their faecal pellets are much smaller than the fossil examples. Millipedes, based on body size and faeces of extant forms, are considered more realistic producers, but little is known about fungal feeding in these animals. Regardless of the affinities of the producers, the diversity in morphology, sizes, aggregations, and composition of nematophyte-containing examples suggests that fungivory was an important component of carbon cycling in early terrestrial ecosystems.

Kobayashiceras gifuense, a new actinocerid cephalopod from the Lower Devonian of Japan

1998 ◽  
Vol 72 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Shuji Niko
Keyword(s):  
New Species ◽  
Lower Devonian ◽  
Shell Morphology ◽  
Central Japan ◽  
Early Devonian

A new actinocerid genus, Kobayashiceras, is defined on the basis of Kobayashiceras gifuense new species from the Lochkovian (Early Devonian) of the Fukuji Formation, central Japan. This genus shares with known actinocerids in the apical shell morphology, but is diagnosed by its orthocerid like stenosiphonate form in the adoral shell. Its taxonomic and paleobiogeographic implications are discussed.

Early Devonian stylonurine eurypterids from Arctic Canada (project)

10.7934/p541 ◽  
2014 ◽  
Author(s):  
C Lamsdell ◽  
J Braddy ◽  
J Loeffler ◽  
L Dineley
Keyword(s):  
Arctic Canada ◽  
Early Devonian
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