A Devonian age for the Sarhlef Formation (Jebilet Massif, Morocco) – evidence from new biostratigraphic data based on metamorphosed conodonts

2021 ◽  
Vol 572 ◽  
pp. 110395
Author(s):  
Nezha Lazreq ◽  
Peter Königshof ◽  
Abderrahim Essaifi ◽  
Ali Bouari ◽  
Abdelhak Outigua
Keyword(s):  
Devonian Age

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 Crystalline Schists of Devonian Age

Nature ◽  
1894 ◽  
Vol 49 (1276) ◽  
pp. 554-554
Author(s):  
ARTHUR R. HUNT
Keyword(s):  
Devonian Age

XV.—On Rhamphodopsis, a Ptyctodont from the Middle Old Red Sandstone of Scotland

1938 ◽  
Vol 59 (2) ◽  
pp. 397-410 ◽  
Author(s):  
D. M. S. Watson
Keyword(s):  
Upper Devonian ◽  
Red Sandstone ◽  
Number Of Teeth ◽  
Devonian Age

In 1858 C. H. Pander described as Ptydodus a number of teeth from Upper Devonian limestones in Russia. His admirable figures of complete teeth and of sections through them established the very chimæroid structure of these bodies. Since that time similar teeth have been repeatedly described, and have served for the establishment of three genera and many species from rocks of Middle and Upper Devonian age.

Age and Composition of Zircons From the Devonian Petrivske Kimberlite Pipe of the Azov Domain, the Ukrainian Shield

2021 ◽  
Vol 43 (4) ◽  
pp. 50-55
Author(s):  
L.V. SHUMLYANSKYY ◽  
V. KAMENETSKY ◽  
B.V. BORODYNYA
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Continental Crust ◽  
Kimberlite Pipe ◽  
Zircon Crystal ◽  
Precambrian Rock ◽  
Weighted Mean ◽  
Terrigenous Rocks ◽  
Devonian Age ◽  
Isotope Systematics

Results of a study of U-Pb and Hf isotope systematics and trace element concentrations in five zircon crystals separated from the Devonian Petrivske kimberlite are reported in the paper. Four zircons have yielded Paleoproterozoic and Archean ages, while one zircon grain gave a Devonian age of 383.6±4.4 Ma (weighted mean 206Pb/238U age). The Precambrian zircons have been derived from terrigenous rocks of the Mykolaivka Suite that is cut by kimberlite, or directly from the Precambrian rock complexes that constitute continental crust in the East Azov. The Devonian zircon crystal has the U-Pb age that corresponds to the age of kimberlite emplacement. It is 14 m.y. younger than zircon megacrysts found in the Novolaspa kimberlite pipe in the same area. In addition, Petrivske zircon is richer in trace elements than its counterparts from the Novolaspa pipe. Petrivske and Novolaspa zircons crystallized from two different proto-kimberlite melts, whereas the process of kimberlite formation was very complex and possibly included several episodes of formation of proto-kimberlite melts, separated by extended (over 10 M.y.) periods of time.

Regional geochemical study of the Slave Point carbonates, Western Canada

1969 ◽  
Vol 6 (2) ◽  
pp. 247-268 ◽  
Author(s):  
E. M. Cameron
Keyword(s):  
Discriminant Function ◽  
Element Distribution ◽  
Western Canada ◽  
Prominent Feature ◽  
Reef Facies ◽  
Geochemical Study ◽  
Facies Change ◽  
Devonian Age ◽  
Multivariate Discriminant ◽  
Significant Chemical

A regional geochemical study of the Slave Point Formation within an area of 35 000 square miles (~90 000 km2) in the subsurface of western Canada was made to relate chemical variation to facies change. Core and cuttings samples were obtained from 90 wells drilled for petroleum. The Slave Point Formation is a relatively uniform and pure calcitic limestone of Middle Devonian age. A reef facies, dolomitized in places, is developed along the margin of the carbonate shelf with a shale basin. These dolomites produce natural gas from several fields.R-mode factor analysis methods have been used to help interpret the element distribution. There are slight, but significant, chemical differences between limestones occurring close to dolomites and gas discoveries and limestones distant from these features. The principal differences are a smaller content of magnesium and strontium held in solid solution in the calcites and less clay minerals and pyrite in limestones occurring close to gas discoveries. These differences, which are related to dissimilar conditions during deposition and diagenesis, are used to form a multivariate discriminant function separating the two groups of limestone. This discriminant function is used to classify the different limestone sections. Sphalerite (with galena and quartz), a prominent feature of the unit, occurs principally in the dolomites along the margin of the shale basin.

Algites enteromorphoides sp. nov. A Filamentous Alga of Devonian Age from Missouri

1970 ◽  
Vol 83 (1) ◽  
pp. 283 ◽  
Author(s):  
Philip W. Basson ◽  
Joseph M. Wood
Keyword(s):  
Filamentous Alga ◽  
Devonian Age

scholarly journals О геологическом и изотопном возрасте золоторудных месторождений на примере золото-серебряного месторождения Кубака (Северо-Восток России)

2021 ◽  
pp. 3-12
Author(s):  
V. A. Stepanov ◽  
Keyword(s):  
Gold Mineralization ◽  
Early Carboniferous ◽  
North East ◽  
The North ◽  
Ore Bodies ◽  
Geological Age ◽  
Gold Silver ◽  
Devonian Age ◽  
Isotope Dating ◽  
Silver Mineralization

Information on the geological and isotopic age of the Kubaka gold-silver deposit in the Omolon middle massif in the North-East of Russia is presented. It has been established that the Kubaka deposit geological age lies in between the Late Devonian age of the Kedon series volcanites, containing the gold-silver mineralization, and the Early Carboniferous age of the Korbinsky suite terrigenous rocks, overlapping the volcanites and the mineralization. The post-ore nature of the Omolon complex dykes, which produce no significant impact on the distribution of gold mineralization in ore bodies, is shown. According to isotope dating, the following stages of the Kubaka deposit formation are distinguished: the accumulation of the Kubaka suite tuffs (369 Ma); the introduction of subvolcanic intrusions (344 and 337 Ma); the formation of ore metasomatites (335±5 Ma); the formation of gold-silver mineralization (330 and 334 - 324 Ma); the introduction of post-ore dikes (179±8 - 176±10 Ma).

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