A new fossil occurrence from the Vendom Fiord Formation (type area), Ellesmere Island

1978 ◽  
Vol 15 (10) ◽  
pp. 1675-1679 ◽  
Author(s):  
D. G. Perry
Keyword(s):  
Sea Level ◽  
North American ◽  
Ellesmere Island ◽  
The Arctic ◽  
Early Devonian ◽  
The North ◽  
Type Area ◽  
Formation Type ◽  
Devonian Age

Probable reworked Lochkovian (early Early Devonian) brachiopods and conodonts were recovered from the basal clastic beds of the Vendom Fiord Formation in the type area on central Ellesmere Island. Although most of the fossils are reworked from underlying strata, none appear to be younger than Lochkovian. Data obtained by other workers from more northerly exposures of the Vendom Fiord Formation show that the lower part of the formation is no older than late Pragian (middle Early Devonian). Elsewhere, the North American Early Devonian eustatic sea-level minimum occurs in the Pragian and is followed by transgressive deposits of late Early Devonian age of which the Vendom Fiord Formation possibly represents the basal transgressive unit in the Arctic Archipelago.

THE GEOMAGNETIC LATITUDE EFFECT ON THE NUCLEON AND MESON COMPONENT OF COSMIC RAYS AT SEA LEVEL

1956 ◽  
Vol 34 (1) ◽  
pp. 1-19 ◽  
Author(s):  
D. C. Rose ◽  
J. Katzman
Keyword(s):  
Cosmic Rays ◽  
Sea Level ◽  
North American ◽  
Geomagnetic Latitude ◽  
Vertical Direction ◽  
Temperature Correction ◽  
The Arctic ◽  
High Latitudes ◽  
Primary Spectrum ◽  
The North

Measurements have been taken on the changes in intensity of the nucleon and meson components of cosmic rays during a cruise of the Canadian Naval Icebreaker Labrador into the Arctic, through the North West Passage, and circumnavigating the North American Continent. The geomagnetic latitudes covered extend from 18°N. to 89°N. The latitude knee is clearly shown at a geomagnetic latitude of about 52° in the case of the nucleon component and less definitely between 40° and 50° in the case of the meson component. The rigidity of particles arriving in a vertical direction at 52° is 2.1 Bv. and at 45° is 3.7 Bv. Meyer and Simpson have shown that changes in the primary spectrum between 1948 and 1954 probably extend up to these rigidities and such changes should, therefore, be observable at sea level. The longitude effect at low latitudes is clearly shown by differences in intensity between the measurements on the east and west sides of North America. In the case of the meson component, the magnitude of the longitude effect at these longitudes was found to be greater than that shown by Millikan and Neher in 1936. The interpretation of the meson component results above the knee is complicated by difficulties in temperature correction. In the case of the nucleon component, an apparent longitude effect exists above the knee in that there was a small difference in the intensity at high latitudes in the eastern and western parts of the North American Arctic. No satisfactory explanation is offered for this. The diurnal variation of the nucleon component at high latitudes is shown but no unusual features were found. Appreciation is expressed to the Royal Canadian Navy for making these measurements possible.

Early Devonian age of the Detroit River Group, inferred from Arctic stromatoporoids

1993 ◽  
Vol 30 (12) ◽  
pp. 2465-2474 ◽  
Author(s):  
Eric C. Prosh ◽  
Colin W. Stearn
Keyword(s):  
United States ◽  
Close Relationships ◽  
Species Level ◽  
Ellesmere Island ◽  
The Arctic ◽  
Early Devonian ◽  
Detroit River ◽  
Devonian Age ◽  
First Time ◽  
Group Species

The Detroit River Group of southwestern Ontario and the adjacent United States has traditionally been considered mostly or entirely Middle Devonian in age. Detroit River Group faunas are, however, highly endemic and difficult to correlate to the chronostratigraphic standard; widely accepted conodont-based ages are similarly constrained by endemism and rely heavily upon inferential correlations. Recent evidence from the Blue Fiord Formation of southwestern Ellesmere Island suggests an Emsian (late Early Devonian) age for the full Detroit River Group, based upon shared stromatoporoid species. Four Detroit River Group species, Stromatoporella perannulata Galloway and St. Jean, Stictostroma mamilliferum Galloway and St. Jean, Habrostroma proxilaminata (Fagerstrom), and Parallelopora campbelli Galloway and St. Jean, are recognized for the first time in the Arctic. In addition, Blue Fiord Formation (and younger) species of Trupetostroma and Pseudoactinodictyon demonstrate close relationships to Detroit River Group species. Together, the stromatoporoid evidence and the available conodont data imply a serotinus age for the Amherstburg Formation and a serotinus to patulus age for the Lucas Formation. This is the first direct species-level correlation of a Detroit River Group "endemic" to a globally dateable level and the first regional application of stromatoporoid biostratigraphy in North America.

scholarly journals Ammonites from the Upper Cretaceous of West Greenland

1965 ◽  
Vol 56 ◽  
pp. 1-192
Author(s):  
T Birkelund
Keyword(s):  
North America ◽  
North American ◽  
Upper Cretaceous ◽  
The Arctic ◽  
Arctic Seas ◽  
West Greenland ◽  
The North ◽  
Type Area ◽  
The Pacific ◽  
Lower Campanian

Ammonites from Nûgssuaq and Svartenhuk, belonging to the genera Hypophylloceras, Saghalinites, Pseudophyllites, Baculites, Diplomoceras, Scaphites, Clioscaphites, Haresiceras and Borissjakoceras, are described. Baculites and Scaphites are richly represented, and the material provides a basis for evaluating the subgenera Hoploscaphites and Discoscaphites. The ontogeny and the phylogeny of most of the genera are discussed and juvenile stages of Saghalinites and Scaphites described. Eleven new species and three new subspecies are introduced. The stratigraphical, palaeogeographical and palaeoecological aspeets of the ammonite assemblages are considered, and a discussion of sexual dimorphism in Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian ?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian ?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.

scholarly journals Palynological indications for Silurian – earliest Devonian age strata in the Netherlands

2021 ◽  
Vol 100 ◽  
Author(s):  
Alexander J.P. Houben ◽  
Geert-Jan Vis
Keyword(s):  
The Netherlands ◽  
Core Material ◽  
Late Devonian ◽  
Time Interval ◽  
The South ◽  
Early Devonian ◽  
The North ◽  
Depositional Settings ◽  
Palynological Study ◽  
Devonian Age

Abstract Knowledge of the stratigraphic development of pre-Carboniferous strata in the subsurface of the Netherlands is very limited, leaving the lithostratigraphic nomenclature for this time interval informal. In two wells from the southwestern Netherlands, Silurian strata have repeatedly been reported, suggesting that these are the oldest ever recovered in the Netherlands. The hypothesised presence of Silurian-aged strata has not been tested by biostratigraphic analysis. A similar lack of biostratigraphic control applies to the overlying Devonian succession. We present the results of a palynological study of core material from wells KTG-01 and S05-01. Relatively low-diversity and poorly preserved miospore associations were recorded. These, nonetheless, provide new insights into the regional stratigraphic development of the pre-Carboniferous of the SW Netherlands. The lower two cores from well KTG-01 are of a late Silurian (Ludlow–Pridoli Epoch) to earliest Devonian (Lochkovian) age, confirming that these are the oldest sedimentary strata ever recovered in the Netherlands. The results from the upper cored section from the pre-Carboniferous succession in well KTG-01 and the cored sections from the pre-Carboniferous succession in well S05-01 are more ambiguous. This inferred Devonian succession is, in the current informal lithostratigraphy of the Netherlands, assigned to the Banjaard group and its subordinate Bollen Claystone formation, of presumed Frasnian (i.e. early Late Devonian) age. Age-indicative Middle to Late Devonian palynomorphs were, however, not recorded, and the overall character of the poorly preserved palynological associations in wells KTG-01 and S05-01 may also suggest an Early Devonian age. In terms of lithofacies, however, the cores in well S05-01 can be correlated to the upper Frasnian – lower Famennian Falisolle Formation in the Campine Basin in Belgium. Hence, it remains plausible that an unconformity separates Silurian to Lower Devonian strata from Upper Devonian (Frasnian–Famennian) strata in the SW Netherlands. In general, the abundance of miospore associations points to the presence of a vegetated hinterland and a relatively proximal yet relatively deep marine setting during late Silurian and Early Devonian times. This differs markedly from the open marine depositional settings reported from the Brabant Massif area to the south in present-day Belgium, suggesting a sediment source to the north. The episodic presence of reworked (marine) acritarchs of Ordovician age suggests the influx of sedimentary material from uplifted elements on the present-day Brabant Massif to the south, possibly in relation to the activation of a Brabant Arch system.

Paleomagnetism of the Clam Bank Formation and paleolatitude estimates for western Newfoundland

1993 ◽  
Vol 30 (4) ◽  
pp. 776-786
Author(s):  
G. Murthy ◽  
R. Pätzold
Keyword(s):  
North American ◽  
Early Paleozoic ◽  
The North ◽  
Northerly Direction ◽  
Deformation Event ◽  
Recent Origin ◽  
Component C ◽  
Acadian Orogeny ◽  
North American Craton ◽  
Devonian Age

The Pridolian Clam Bank Formation around Lourdes Cove on the Port au Port Peninsula, western Newfoundland, underwent deformation during the Acadian orogeny. As a result, some of the beds were overturned, but the stratification planes can be accurately determined everywhere. Paleomagnetic studies of the Clam Bank Formation have yielded three well-defined components of magnetization, all acquired subsequent to the deformation event: component A with D = 337.3°, I = −28.3°, (N = 16 sites, k = 25.3, α95 = 7.5°), with a corresponding paleopole at 23.2°N, 145.0°E (dp, dm = 4.5°, 8.2°); component B with D = 172.9°, I = 5.7° (N = 35 specimens, k = 10.2, α95 = 6.4°), with a corresponding paleopole at 38.2°N, 130.1°E (dp, dm = 3.2°, 6.4°); component C with D = 350.4°, I = 69.8° (N = 33 specimens, k = 8.9, α95 = 8.9°). A pre-Mesozoic origin of the A and B components is indicated by the presence of normal and reversed components in specific sites; by the lack of correspondence between the A and B paleopoles and the Mesozoic and later pole positions from the Appalachians and the North American craton; and by agreement with Paleozoic poles from the region. The A component was probably acquired immediately after deformation during the Acadian orogeny. The B component is probably a chemical remanence that was acquired during Permo-Carboniferous (Kiaman) time. The C component is of recent origin, probably acquired in the present Earth's field. Paleomagnetic data from western Newfoundland are used in a localized setting to construct a paleopole sequence and to estimate paleolatitudes for western Newfoundland during the Paleozoic. Keeping in mind the paucity of data for Siluro-Devonian age from this region, western Newfoundland seems to have been at its southernmost position at the end of the Ordovician and to have occupied equatorial latitudes during the Permo-Carboniferous. The paleolatitude trend suggests that this block, which is part of the North American craton, moved in a southerly direction during the early Paleozoic and in a northerly direction during the middle and late Paleozoic.

scholarly journals Carbon cycling in the North American coastal ocean: A synthesis

2018 ◽  
Author(s):  
Katja Fennel ◽  
Simone Alin ◽  
Leticia Barbero ◽  
Wiley Evans ◽  
Timotheé Bourgeois ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
North American ◽  
Inorganic Carbon ◽  
Co2 Flux ◽  
Carbon Fluxes ◽  
Coastal Ocean ◽  
Open Ocean ◽  
The Arctic ◽  
The North ◽  
Anthropogenic Carbon

Abstract. A quantification of carbon fluxes in the coastal ocean and across its boundaries, specifically the air-sea, land-to-coastal-ocean and coastal-to-open-ocean interfaces, is important for assessing the current state and projecting future trends in ocean carbon uptake and coastal ocean acidification, but is currently a missing component of global carbon budgeting. This synthesis reviews recent progress in characterizing these carbon fluxes with focus on the North American coastal ocean. Several observing networks and high-resolution regional models are now available. Recent efforts have focused primarily on quantifying net air-sea exchange of carbon dioxide (CO2). Some studies have estimated other key fluxes, such as the exchange of organic and inorganic carbon between shelves and the open ocean. Available estimates of air-sea CO2 flux, informed by more than a decade of observations, indicate that the North American margins act as a net sink for atmospheric CO2. This net uptake is driven primarily by the high-latitude regions. The estimated magnitude of the net flux is 160 ± 80 Tg C/y for the North American Exclusive Economic Zone, a number that is not well constrained. The increasing concentration of inorganic carbon in coastal and open-ocean waters leads to ocean acidification. As a result conditions favouring dissolution of calcium carbonate occur regularly in subsurface coastal waters in the Arctic, which are naturally prone to low pH, and the North Pacific, where upwelling of deep, carbon-rich waters has intensified and, in combination with the uptake of anthropogenic carbon, leads to low seawater pH and aragonite saturation states during the upwelling season. Expanded monitoring and extension of existing model capabilities are required to provide more reliable coastal carbon budgets, projections of future states of the coastal ocean, and quantification of anthropogenic carbon contributions.

scholarly journals Graptolite dynamics in Silurian and Devonian time

1987 ◽  
Vol 35 ◽  
pp. 149-159
Author(s):  
T. N. Koren'
Keyword(s):  
Environmental Factors ◽  
Sea Level ◽  
Comparative Studies ◽  
Climate Changes ◽  
Environmental Changes ◽  
Time Intervals ◽  
Early Devonian ◽  
Carbonate Sedimentation ◽  
Reference Sections ◽  
Devonian Age

On the basis of biostratigraphic data known at present some preliminary attempts are made to evaluate graptolite dynamics, that is changes in graptolite diversity in time and space within pelagic fades of Si­lurian and Early Devonian age. For the comparative studies of diversity fluctuations versus some major environmental changes a standard graptolite zonation is used. Several critical and more or less well stu­died stratigraphical intervals are chosen; among them the Ordovician/Silurian, Sheinwoodian/Gorstian and Gorstian/Ludfordian boundary beds. For each level the most complete reference sections are analy­zed. Special attention is given to the graptolite extinction, specification and radiation events within these time intervals. They might have been partly connected with or influenced by the environmental factors as a result of eustatic sea-level and climate changes, alteration of anoxic conditions, migration of carbonate sedimentation in pelagic direction, and other globally detectable events. The graptolite evolution during the time of monograptid existence can be subdivided into three phases using the comparison of the ampli­tude of the extinction-origination events and repeatability of the synphasic cycles.

Radiogenic Isotope Signatures of Holocene Sediments from Kane Basin: Linkage with the Re-opening and Evolution of Nares Strait

2021 ◽  
Author(s):  
Lina Madaj ◽  
Friedrich Lucassen ◽  
Claude Hillaire-Marcel ◽  
Simone A. Kasemann
Keyword(s):  
Ellesmere Island ◽  
The Arctic ◽  
Baffin Bay ◽  
Low Salinity ◽  
The Core ◽  
The Past ◽  
Nares Strait ◽  
The North ◽  
Sediment Input ◽  
Detrital Sediment

<p>The re-opening of the Arctic Ocean-Baffin Bay gateway through Nares Strait, following the Last Glacial Maximum, has been partly documented, discussed and revised in the past decades. The Nares Strait opening has led to the inception of the modern fast circulation pattern carrying low-salinity Arctic water towards Baffin Bay and further towards the Labrador Sea. This low-salinity water impacts thermohaline conditions in the North Atlantic, thus the Atlantic Meridional Overturning Circulation. Available land-based and marine records set the complete opening between 9 and 7.5 ka BP [1-2], although the precise timing and intensification of the southward flowing currents is still open to debate. A recent study of a marine deglacial sedimentary record from Kane Basin, central Nares Strait, adds information about subsequent paleoceanographic conditions in this widened sector of the strait and proposed the complete opening at ~8.3 ka BP [3].</p><p>We present complementary radiogenic strontium, neodymium and lead isotope data of the siliciclastic detrital sediment fraction of this very record [3] further documenting the timing and pattern of Nares Strait opening from a sediment provenance approach. The data permit to distinguish detrital material from northern Greenland and Ellesmere Island, transported to the core location from both sides of Nares Strait. Throughout the Holocene, the evolution of contributions of these two sources hint to the timing of the ice break-up in Kennedy Channel, north of Kane Basin, which led to the complete opening of Nares Strait [3]. The newly established gateway of material transported to the core location from the north via Kennedy Channel is recorded by increased contribution of northern Ellesmere Island detrital sediment input. This shift from a Greenland (Inglefield Land) dominated sediment input to a northern Ellesmere Island dominated sediment input supports the hypothesis of the newly proposed timing of the complete opening of Nares Strait at 8.3 ka BP [3] and highlights a progressive trend towards modern-like conditions, reached at about 4 ka BP.</p><p>References:</p><p>[1] England (1999) Quaternary Science Reviews, 18(3), 421–456. [2] Jennings et al. (2011) Oceanography, 24(3), 26-41. [3] Georgiadis et al. (2018) Climate of the Past, 14 (12), 1991-2010.</p>

Revision of Tenticospirifer Tien, 1938, and similar spiriferid brachiopod genera from the Late Devonian (Frasnian) of Eurasia, North America, and Australia

2000 ◽  
Vol 74 (3) ◽  
pp. 444-463 ◽  
Author(s):  
Xueping Ma ◽  
Jed Day
Keyword(s):  
North America ◽  
Sea Level ◽  
South China ◽  
North American ◽  
Type Species ◽  
Western Europe ◽  
Late Devonian ◽  
Carbonate Platforms ◽  
The North ◽  
New Family

The cyrtospiriferid brachiopod genus Tenticospirifer Tien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears that Tenticospirifer evolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations of Tenticospirifer from eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American species Spirifera cyrtinaformis Hall and Whitfield, 1872, and related species identified as Tenticospirifer by North American workers, are reassigned to Conispirifer Lyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed with Conispirifer Lyashenko, 1985, selected as the type genus. The new family also includes the new genus Pyramidaspirifer with Platyrachella alta Fenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species of Pyramidaspirifer are restricted to late Frasnian deposits of central and western North America.

scholarly journals Origin of the Late Ordovician Lepidocyclus brachiopod fauna in North America and its biogeographic significance

1992 ◽  
Vol 6 ◽  
pp. 149-149
Author(s):  
Jisuo Jin
Keyword(s):  
North America ◽  
Sea Level ◽  
North American ◽  
Plate Tectonics ◽  
Late Ordovician ◽  
Sea Level Changes ◽  
Stepping Stones ◽  
Shell Size ◽  
Larval Stages ◽  
The North

Three rhynchonellid brachiopod genera, Hiscobeccus, Lepidocyclus, and Hypsiptycha, are the most diagnostic elements of the Lepidocyclus fauna of North America in Late Ordovician time. These are characterized by relatively large, strongly biconvex to globular shells with coarse imbricating growth lamellae and, internally, with septiform cardinal processes in brachial valves. Among the three genera, Hiscobeccus appears the earliest, now known from rocks of late Trentonian-Edenian age in the Canadian Rocky Mountains and Mackenzie Mountains. Morphologically, Hiscobeccus is distinguished from the other two genera by its open delthyrium in the pedicle valve. Early forms of Hiscobeccus show close morphological similarity to Rhynchotrema in their non-globular biconvex shells covered by strong growth lamellae only in the anterior portions. It has been suggested that Hiscobeccus evolved from the Rhynchotrema wisconsinense stock through increase in shell size, globosity, and strength of growth lamellae. Earliest species of Rhynchotrema has been documented convincingly from rocks of early Trentonian age, and the derivation of Hiscobeccus most likely took place during the mid-Trentonian. Lepidocyclus and Hypsiptycha evolved from either Rhynchotrema or Hiscobeccus by developing a pair of deltidial plates covering the delthyrium.Rhynchotrema and other rhynchonellids that evolved before mid-Trentonian time are common to the North American (Laurentian) and the Siberia-Kazakhstan paleocontinents. In contrast, Hiscobeccus, Lepidocyclus, and Hypsiptycha that evolved after the mid-Trentonian are virtually restricted to Laurentia. Therefore, Rhynchotrema marked the last successful intercontinental migration of rhynchonellids during their Llandeilian-Caradocian cosmopolitanism. The pronounced provincialism of the North American Lepidocyclus fauna may have been caused by a number of factors. Facies control is not likely the explanation because these rhynchonellids occur in nearly all the inland and marginal platform seas of Laurentia and commonly are found together in the same types of rocks. Plate tectonics and sea-level changes are considered major causes. The Ordovician rhynchonellids lived in shallow marine (intertidal-subtidal) environments and were incapable of crossing vast, deep oceanic barriers because of their sedentary mode of life and short-lived motile larval stages. The widening of the ocean between North America and Siberia, coupled with high sea-level stand, may have created a sufficiently wide oceanic barrier to interrupt faunal mixing between the two paleocontinents by late Trentonian time. Moreover, the rise in sea level would have resulted in the disappearance of island faunas, which could have served as stepping stones for intercontinental migration of shallow-water benthic faunas during low sea-level stand.

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