The geology of the western part of the Fintona Block, Northern Ireland: evolution of Carboniferous basins

1990 ◽  
Vol 127 (5) ◽  
pp. 407-426 ◽  
Author(s):  
W. I. Mitchell ◽  
B. Owens
Keyword(s):  
Northern Ireland ◽  
Early Carboniferous ◽  
Alluvial Fans ◽  
The South ◽  
Red Beds ◽  
Early Devonian ◽  
Bed Sediments ◽  
The North ◽  
Devonian Age ◽  
Marine Basin

AbstractThe western part of the Fintona Block is divided into four fault-bounded segments that contain red-bed sediments formerly assigned to the Lower Old Red Sandstone.Dating by miospores indicates the presence of deposits of early Devonian age in the Irvinestown Segment, late Viséan–early Silesian age in the Tempo–Lisbellaw Segment, and late Viséan–early Silesian and late Silesian ages in the Milltown Segment. Northward migration of the early Carboniferous marine transgression in the northern part of Ireland coincided with the sequential propagation of back-stepping faults and resulted in the development of diachronous facies belts between late Courceyan and Arundian times. Tectonic uplift, of a possible southwesterly extension of the Tyrone Igneous Complex, gave rise to the deposition of Asbian to Pendleian red-beds to the south of a massif. An interface between these red-beds and contemporaneous marine sediments farther to the south is recognized and dated. A new non-marine basin, containing Brigantian and Pendleian red-beds, also developed to the north of the massif A waterlogged floodplain that developed during Westphalian A times may be coeval with more widespread coal-bearing sequences elsewhere in Ireland. Alluvial fans prograded southwards over this plain during Westphalian B times when faults bordering a northern landmass were reactivated.

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.

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).

scholarly journals A Lower Devonian age for the Corvock Granite and its significance for the structural history of South Mayo and the Laurentian margin of western Ireland

2021 ◽  
Author(s):  
John Graham ◽  
Nancy Riggs
Keyword(s):  
Lower Devonian ◽  
Early Devonian ◽  
North East ◽  
The North ◽  
Granite Emplacement ◽  
History Of ◽  
Western Ireland ◽  
Laurentian Margin ◽  
Devonian Age ◽  
Restraining Bend

The Silurian Croagh Patrick succession, which crops out just south of a fundamental Caledonian structural zone near Clew Bay, western Ireland, is a series of psammites and pelites with a strong penetrative cleavage. These rocks are intruded by the Corvock granite. A suite of minor intrusions associated with the granite contains the regional cleavage whereas the Corvock granite is undeformed. New U-Pb dates are 413 + 7 / -4 Ma for a strongly cleaved sill and 410 ± 4 Ma for the main granite and closely constrain the age of crystallization of the granite and coeval cleavage formation as Lower Devonian (Lochkovian or Pragian), implying syn- to late-kinematic granite emplacement. These data are consistent with evidence for strong sinistral shear shown by the Ox Mountains granodiorite just to the north-east dated at 412.3 ± 0.8 Ma. This Devonian cleavage is superimposed on Ordovician rocks of the South Mayo Trough. The localisation of the strong deformation is interpreted as being due to its position at a restraining bend during regional sinistral motion on a segment of the Fair Head-Clew Bay Line to the north. Contemporaneous deformation in the syn-kinematic Donegal batholith suggests a transfer of sinistral motion to this intra-Grampian structure rather than simple along-strike linkage to the Highland Boundary Fault in Scotland. Our new data indicate diachronous deformation during the late Silurian and early Devonian history of the Irish and Scottish Caledonides and also support previous interpretations of diachronous deformation between these areas and the Appalachian orogens.

Stratigraphy and geochemistry of the Early Carboniferous Clyde Plateau Lavas in south Bute, Midland Valley of Scotland

2010 ◽  
Vol 148 (4) ◽  
pp. 597-618 ◽  
Author(s):  
G. M. YOUNG ◽  
W. G. E. CALDWELL
Keyword(s):  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Hydrothermal Activity ◽  
The South ◽  
Basaltic Rocks ◽  
Weathering Processes ◽  
The North ◽  
Lower Division ◽  
Sandstone Formation ◽  
Mafic Lavas

AbstractA succession of Viséan (mid- to late Holkerian) volcanic rocks up to 340 m thick is preserved in three fault-blocks at the south end of the Isle of Bute in the Firth of Clyde, Scotland. These rocks form part of the Clyde Plateau Volcanic Formation, which, in this area, disconformably overlies sandstones of the lower Millport Member of the Clyde Sandstone Formation. The lower part of the volcanic succession in south Bute,c. 140 m thick, corresponds to the lower Strathgryfe lavas of the Renfrewshire Hills. This part of the succession is composed dominantly of feldspar-macrophyric and feldspar-microphyric basaltic rocks and mugearites. It is present in all three fault-blocks, whereas the succeeding volcanic rocks (middle and upper divisions) are only preserved in the median St Blane's block where they have a combined thickness of about 200 m. The two younger subdivisions are respectively correlative to the Misty Law Trachytic Centre, which forms a lens between the lower and upper Strathgryfe Members, and the upper Strathgryfe Member of the North Ayrshire section. Lavas of the lower division are feldspar-macrophyric and feldspar-microphyric basaltic rocks and mugearites, but those of the middle and upper divisions display a wider compositional spectrum, including feldspar-macro- and microphyric rocks but ranging from olivine-augite-macrophyric and olivine-augite-feldspar-macrophyric basalts to trachytes. The mafic lavas of south Bute have chondrite-normalized multi-element plots similar to those of ocean island basalts, with enrichment in incompatible elements. The trachytic lavas have similar patterns but are strongly depleted in Sr, P and Ti, reflecting fractionation of such minerals as plagioclase, apatite and magnetite/ilmenite during evolution of the parent magmas. Distribution of high field strength elements favours a within-plate origin for the south Bute lavas and supports derivation from a relatively deep (>50 km) mantle source (garnet lherzolite). Chondrite-normalized REE plots for basaltic lavas of the lower division show enrichment in LREEs and lack strong Eu anomalies. Strong positive Eu anomalies in both felsic and mafic lavas of the middle and upper divisions may be attributable to high oxygen fugacities, but hydrothermal activity or feldspar fractionation may also have played a role. Fe-rich weathering profiles attest to intermittent extrusion and intense weathering processes.

scholarly journals Late Silurian and early Devonian graptolites from North Greenland

1974 ◽  
Vol 65 ◽  
pp. 11-13
Author(s):  
W.B.N Berry ◽  
A.J Boucot ◽  
P.R Dawes ◽  
J.S Peel
Keyword(s):  
Field Work ◽  
Fold Belt ◽  
The South ◽  
Early Devonian ◽  
The North ◽  
The Subject ◽  
North Greenland

The precise age of the youngest part of the geosynclinal fill of the North Greenland fold belt has been the subject of important discussion, particularly with regard to the problem of dating the Palaeozoic diastrophism (Kerr, 1967; Dawes, 1971). Since Lauge Koch's field work between 1916 and 1923 it has been known that strata bearing Monograptus priodon were involved in the folding (Koch, 1920), indicating the presence of Silurian of Llandovery-Wenlock age. In addition, Poulsen (1934) identified Cyrtograptus cf. C. multiramus and Monograptus bohemicus in collections made by Koch from unfolded shales on the platform, to the south of the fold belt, which demonstrated that the section included Wenlock and early Ludlow strata.

scholarly journals Hydrocarbon source rock sampling in Peary Land 1980

1981 ◽  
Vol 106 ◽  
pp. 99-103
Author(s):  
F Rolle
Keyword(s):  
Sedimentary Basin ◽  
Carbonate Platform ◽  
Early Carboniferous ◽  
Early Cambrian ◽  
The South ◽  
Hydrocarbon Source Rock ◽  
The North ◽  
Lower Palaeozoic ◽  
North Greenland ◽  
Land Region

The Peary Land region in North Greenland (fig. 31) contains a sequence of Lower Palaeozoic sediments which is probably more than 4 km thick (Dawes, 1976; Christie & Peel, 1977; Hurst, 1979; Christie & Ineson, 1979; Hurst & Surlyk, 1980; Ineson & Peel, 1980; Surlyk, Hurst & Bjerreskov, 1980). From Early Cambrian to Wenlock the area was divided into a northern turbidite trough and a southern, mainly carbonate platform (fig. 32). The platform seems to have undergone several phases of backstepping to the south, accompanied by expansion of the turbidite basin (fig. 32) (Surlyk et al., 1980). The region was affected by an orogeny of assumed Devonian - early Carboniferous age (Dawes, 1976). Deformation is most intense in northern Johannes V. Jensen Land (fig. 31), where an amphibolite facies is attained along the north eoast (Dawes & Soper, 1973) and decreases southwards, leaving the platform earbonates virtually undeformed. A separate, strongly block-faulted sedimentary basin, the Wandel Sea Basin is present in eastern Peary Land and farther to the south-east (Dawes & Soper, 1973; Håkansson, 1979). It eontains a sequenee of Upper Palaeozoie carbonates and Upper Palaeozoic - Mesozoic mainly coarse clastics more than 3 km thick.

scholarly journals Permian

1982 ◽  
Vol 8 ◽  
pp. 28-32
Author(s):  
Fritz Lyngsie Jacobsen ◽  
Jørgen Gutzon Larsen
Keyword(s):  
North Sea ◽  
Initial Phase ◽  
Late Carboniferous ◽  
Early Permian ◽  
The South ◽  
Permian Basin ◽  
Red Beds ◽  
North West ◽  
The North

In North-West Europe two mega-basins began their development during Late Carboniferous to Early Permian: The South Permian Basin stretching from eastern England into Poland , and the North Permian Basin reaching from Scotland into Denmark. These two basins were separated by the Mid North Sea High and the Ringkøbing-Fyn High which came into existence early in Permian. The initial phase of subsidence was accompanied by extensive subaerial volcanism. This was followed by a period of oxidation and erosion under desert conditions and deposition of red beds and sabkha sediments in the two Permian basins (fig. 19). These rocks are included in the Rotliegendes Group as originally established by Werner (1786). Continuous subsidence and transgression of the sea, but with a restricted connection to the ocean, lead to the formation of the evaporites of the Zechstein Group.

The Craig-Collins pacts of 1922: two attempted reforms of the Northern Ireland government

1990 ◽  
Vol 27 (106) ◽  
pp. 145-158 ◽  
Author(s):  
Michael Hopkinson
Keyword(s):  
Northern Ireland ◽  
Equal Weight ◽  
British Government ◽  
The South ◽  
North East ◽  
The North ◽  
Treaty Negotiations ◽  
Before And After ◽  
The Stability ◽  
Shipyard Workers

The six months following the Anglo-Irish treaty of 1921 saw an appalling level of violence in Belfast and on the border, which threatened the stability of the newly formed Northern Ireland government. Official figures for the period between 6 December 1921 and 31 May 1922 listed seventy-three protestants and 147 catholics killed in Belfast and eight protestants and twenty-two catholics killed in the six counties outside Belfast. In that period two wide-ranging agreements aimed to reform the northern government and security system: they became known, somewhat inaccurately, as the Craig-Collins pacts, of 21 January and 30 March 1922. This article discusses the motivation behind the pacts and the reasons for their failure in a wide context, by giving equal weight to the attitudes of the British government and to opinion on both sides of the Irish border.The Northern Ireland government was established in 1920–21. It was unrecognised by the dáil government in the south and by much of the northern catholic minority. The province developed against a background of violence and upheaval, including the expulsion of catholic shipyard workers from their work in the summer of 1920; the dáil retaliated by boycotting Belfast goods. The period also saw increasing I.R.A. activity in the north during the latter stages of the Anglo-Irish war, and the five-month truce that followed it. Though the northern government was not a party to the treaty negotiations, only reluctantly accepting the granting of dominion status to the south, the months before and after the settlement greatly increased tensions in the north-east.

Paleomagnetism of Carboniferous diabase dykes from Gaspé, Quebec

1987 ◽  
Vol 24 (8) ◽  
pp. 1705-1714 ◽  
Author(s):  
Maurice K. Seguin
Keyword(s):  
Early Carboniferous ◽  
Pole Position ◽  
Common Component ◽  
The North ◽  
Paleomagnetic Study ◽  
Short Period ◽  
Middle Carboniferous ◽  
North American Craton ◽  
Devonian Age ◽  
Geological Units

The reported paleomagnetic study was carried out on 53 oriented samples (156 specimens) at 10 sites in the eastern Gaspé Peninsula. All sampled geological units are composed of sub vertical diabase dykes that cut the sedimentary formations of late Early Devonian – early Middle Devonian age. The radiogenic (whole-rock K/Ar) age of these and similar dykes ranges from Late Devonian to early Middle Carboniferous (mean whole rock K/Ar age = 310 Ma). Two components were isolated. The most common component, A (D = 152°, I = +41°), is normal, whereas the second component, B (D = 315°, I = −44°), is reverse. Both components may be considered as a single one; alternatively, component A may be considered slightly older than component B. Unblocking temperatures, median destructive fields, relative frequency of occurrence of the components, and various degrees of alteration are arguments favouring the first or the second situation. The case of a single component is more probable, representing an Early Carboniferous time of acquisition of remanence (thermoremanent magnetization (TRM) probably corresponding to the time of intrusion and resetting of surrounding sedimentary rocks). The corresponding paleopole position in 148°E, 11°N. This pole position is located some 25 °to the southeast of the cluster of Carboniferous poles (mainly Middle to Late Carboniferous) for the North American craton. The significance of this discrepancy is not well understood, but it is worth noting that very recent paleomagnetic results from western Newfoundland and central New Brunswick are located closer to the paleomagnetic results of this study. The age and direction of the dyke system suggest a short period of extension following the compressive pulse of the Acadian orogeny and preceding the Alleghenian orogeny. For these reasons, the dyke system is unrelated to the initial opening of the present Atlantic Ocean.

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.

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