scholarly journals Intrusion history of the Portrush Sill, County Antrim, Northern Ireland: evidence for rapid emplacement and high-temperature contact metamorphism

2011 ◽  
Vol 149 (1) ◽  
pp. 67-79 ◽  
Author(s):  
MORGANE LEDEVIN ◽  
NICHOLAS ARNDT ◽  
MARK R. COOPER ◽  
GARTH EARLS ◽  
PAUL LYLE ◽  
...  
Keyword(s):  
Northern Ireland ◽  
Sedimentary Rocks ◽  
Lower Jurassic ◽  
Contact Metamorphism ◽  
Geochemical Data ◽  
Contact Aureole ◽  
The North ◽  
Geochemical Analyses ◽  
Element Enrichment ◽  
County Antrim

AbstractThe gabbroic Portrush Sill in Northern Ireland, part of the North Atlantic Igneous Province, intruded Lower Jurassic mudstones and siltstones about 55 Ma ago. We used petrologic observations and geochemical analyses to study how the sill interacted with the sedimentary rocks. Field relationships show that an Upper Sill and numerous associated Minor Intrusions were emplaced in the sedimentary host rocks before intrusion of the Main Sill, some 10 m above its upper contact. Geochemical analyses reveal two magma contamination processes: Nb and Ta anomalies, coupled with incompatible element enrichment, record contamination by deep crustal rocks, whereas Li, Pb and Ba anomalies reveal a superficial contamination through fluid circulation at the contact between magmatic and sedimentary rocks. Analysis of mineral assemblages and geochemical data from the contact aureole demonstrate uniform metamorphic conditions between the two main intrusions and an absence of a thermal gradient. The identification of pyrrhotite by magnetization analyses and of orthopyroxene by microprobe analyses indicates very high temperatures, up to 660°C. Thermal modelling explains these temperatures as the coupled effects of the Main Sill and the earlier intruded Upper Sill and Minor Intrusions. Even though the chemical composition of the Main Sill suggests another type of parental liquid, all three units were emplaced in a very short time, certainly less than five years.

Some aspects of Tertiary acid magmatism in NE Ireland

1984 ◽  
Vol 48 (348) ◽  
pp. 351-363 ◽  
Author(s):  
I. G. Meighan ◽  
D. Gibson ◽  
D. N. Hood
Keyword(s):  
Northern Ireland ◽  
Central Complex ◽  
Geochemical Data ◽  
Igneous Province ◽  
Granitic Intrusions ◽  
Isotope Evidence ◽  
County Antrim ◽  
Geochemical Studies ◽  
Basic Rocks ◽  
Highly Evolved

Abstract Geochemical data (including REE determinations) are presented for all five Mourne Mountains granites and three Northern Ireland rhyolites. These confirm (1) the extremely fractionated nature of some of the rocks (Sr and Ba < 10 ppm, Rb > 400 ppm, Eu/Eu* < 0.1, and K/Rb < 100), and (2) a major revision to the outcrops of the E. Mourne granites G1 and G2 in which much of the former is reclassified as G2. Combined petrographic and geochemical studies have also indicated that magmatic pulses were involved in the emplacement of Mourne intrusions G2 (Revised)-G5 inclusive. The N. Ireland Tertiary acid rocks exhibit general geochemical similarities to their analogues elsewhere in the British Tertiary Igneous Province (in which Sr is generally < 100 ppm and CeN/YbN generally < 8 with Eu/Eu* often < 0.6), but as a suite the Mourne granites are enriched in Rb and some other LIL elements relative to their N. Arran counterparts. The more fractionated acid magmas of NE Ireland are believed to have evolved from primitive granitic parent liquids by crystal fractionation at depth which involved major and accessory phases (including zircon and allanite). In the Mourne (and County Antrim) areas the primitive acid compositions lie at the ends of basaltic (tholeiitic) differentiation series, and in the Mourne central complex there is a complete geochemical sequence from basic rocks through intermediate members to primitive and ultimately highly evolved, subalkaline, granitic intrusions. It is concluded that the data are consistent with the Mourne granites and Northern Ireland rhyolites being essentially basaltic differentiates, although Sr isotope evidence indicates some (probably minor) crustal involvement.

The western margin of the Coast Plutonic Complex on Hardwicke and West Thurlow Islands, British Columbia

1979 ◽  
Vol 16 (6) ◽  
pp. 1166-1175 ◽  
Author(s):  
Jo Anne Nelson
Keyword(s):  
Quartz Diorite ◽  
Contact Metamorphism ◽  
Contact Aureole ◽  
Western Margin ◽  
Late Mesozoic ◽  
The North ◽  
Early Mesozoic ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Maximum Contact

The western margin of the Coast Plutonic Complex, one of the major tectonic boundaries of the Canadian Cordillera, has been variously interpreted as an intrusive contact, a shear zone, and a suture zone joining the Early Mesozoic Insular Belt to the North American continent. A representative section of this boundary, exposed on islands in Johnstone Strait, is an intrusive contact along which a quartz diorite with peripheral mafic phases truncates Early Mesozoic sediments and volcanics of the Insular Belt. Concordant hornblende–biotite pairs and two whole rock biotite isochrons date the intrusion as Late Jurassic (151 Ma). Prior to intrusion the stratified units underwent prehnite–pumpellyite facies metamorphism and west-northwest block faulting.The contact aureole of the quartz diorite and its associated mafic phases involves greenschist and hornblende–hornfels facies assemblages. Total pressure in the upper Karmutsen Formation during contact metamorphism was less than 2.5 × 105 kPa. The maximum contact temperature was between 670 and 700 °C. Forcible emplacement of the intrusion caused penetrative deformation of wall rocks in the inner aureole. The maximum contact temperatures indicate that the plutonic bodies were at near-liquidus temperatures when emplaced.The contact on Hardwicke and West Thurlow Islands appears representative of most of the tectonic boundary between the southern Coast Plutonic Complex and the Insular Belt. The western margin of the Coast Plutonic Complex is thus a Late Mesozoic magmatic front, the western limit of the intense magmatism that generated the Coast Plutonic Complex. The formation of Georgia Depression over the province boundary was a later event, coeval with major uplift of the Coast Plutonic Complex.

scholarly journals A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland

Geosciences ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 266 ◽  
Author(s):  
Kristoffer Szilas
Keyword(s):  
Magma Mixing ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Present Contribution ◽  
Data Set ◽  
Basaltic Rocks ◽  
The North ◽  
Metavolcanic Rocks ◽  
Geochemical Analyses ◽  
Southwest Greenland

The present contribution reviews bulk-rock geochemical data for mid-Archaean (ca. 3075–2840 Ma) metavolcanic rocks from the North Atlantic Craton of southwest Greenland. The data set includes the most recent high quality major and trace element geochemical analyses for ten different supracrustal/greenstone belts in the region. When distilling the data set to only include the least altered metavolcanic rocks, by filtering out obviously altered samples, mafic/ultramafic cumulate rocks, late-stage intrusive sheets (dolerites) and migmatites, the remaining data (N = 427) reveal two fundamentally distinct geochemical suites. The contrasting trends that emerge from the filtered geochemical data set, which best represents the melt compositions for these mid-Archaean metavolcanic rocks are: (1) tholeiitic (mainly basaltic) versus (2) calc-alkaline (mainly andesitic). These two rock suites are effectively separated by their La/Sm ratios (below or above three, respectively). It is demonstrated by geochemical modelling that the two contrasting suites cannot be related by either fractional crystallization or crustal assimilation processes, despite occurring within the same metavolcanic sequences. The tholeiitic basaltic rocks were directly mantle-derived, whereas the petrogenesis of the calc-alkaline andesitic rocks involve a significant (>50%) felsic component. The felsic contribution in the calc-alkaline suite could either represent slab-melt metasomatism of their mantle source, mafic-felsic magma mixing, or very large degrees of partial melting of mafic lower crust. At face value, the occurrence of andesites, and the negative Nb-Ta-Ti-anomalies of both suites, is consistent with a subduction zone setting for the origin of these metavolcanic rocks. However, the latter geochemical feature is inherent to processes involving crustal partial melts, and therefore independent lines of evidence are needed to substantiate the hypothesis that plate tectonic processes were already operating by the mid-Archaean.

Liberalism in north Antrim, 1900–14

1982 ◽  
Vol 23 (89) ◽  
pp. 17-29 ◽  
Author(s):  
J.R.B. McMinn
Keyword(s):  
Nineteenth Century ◽  
Northern Ireland ◽  
General Election ◽  
House Of Commons ◽  
Interesting Phenomenon ◽  
Town Hall ◽  
The North ◽  
Liberal Government ◽  
County Antrim ◽  
Orange Order

In the general election of January 1906, R. G. Glendinning, a taciturn baptist linen manufacturer of Belfast, won the North Antrim parliamentary seat. The significance of this event was his success in an overwhelmingly protestant constituency at the expense of the highly articulate and intelligent unionist sitting member, William Moore, the principal architect of the Ulster Unionist Council and the leader of the unionist campaign to expose the devolutionary dangers of ‘Macdonnellism’. Furthermore Glendinning had campaigned as a ‘liberal unionist’, but had been condemned as a home ruler by his opponent and indeed upon arrival in the house of commons took his seat on the liberal government benches. Some years later, in 1913, despite the heightened political temperature, it was still possible for a meeting on 24 October in Ballymoney town hall attended by some four or five hundred protestants to denounce ‘the lawless policy of Carsonism’, and for this same meeting to be addressed by such noted nationalists as Captain Jack White, Sir Roger Casement and Mrs Alice Stopford Green. Their audience was invited to sign an anti-covenant devised by White and closely modelled on, though directly opposed to, the Ulster Solemn League and Covenant. As late as 1925 an independent protestant candidate, George Henderson, representing the Unbought Tenants Association, secured one of the seven County Antrim seats in the Northern Ireland parliament, thus preventing the election of an official unionist, R. D. Megaw. Then there is the interesting phenomenon of the Independent Orange Order which in the years before 1914 had established itself more firmly in north Antrim than anywhere else. The area also threw up in this period a number of prominent individuals who became active in non-unionist politics, of whom the Reverend J. B. Armour, the Reverend D. D. Boyle, John Pinkerton and Samuel Craig McElroy are perhaps the best known. Finally Bally money and the Route was the epicentre of the Ulster tenant-right movement in the last three decades of the nineteenth century.

scholarly journals Geochemical features of the organic matter from Jurassic sediments of the Nadym‑Taz interfluve

Georesursy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 21-27
Author(s):  
Lyubov S. Borisova ◽  
Alexander N. Fomin ◽  
Ekaterina S. Yaroslavtseva
Keyword(s):  
Organic Matter ◽  
Sedimentary Cover ◽  
Lower Jurassic ◽  
Geochemical Data ◽  
The North ◽  
Deep Wells ◽  
Geochemical Parameters ◽  
Insoluble Organic Matter ◽  
Bazhenov Horizon ◽  
Rock Eval

This paper deals with the evaluation of oil-generation potential derived from the geochemical data on deep-buried Jurassic sedimentary rocks of the Nadym-Taz interfluve being part of the West Siberian petroleum basin (PB). The study provides analysis of samples from ultra-deep and deep wells that penetrated the Mesozoic-Cenozoic sedimentary cover in the north of the central part of PB (En-Yakhinsky, Evo-Yakhinsky, Yarudeysky, Tyumensky areas, etc.). The research focuses on the insoluble organic matter (OM) from Upper, Middle and Lower Jurassic sediments (54 samples). A comprehensive study of the kerogen by elemental, isotope analyses and pyrolysis Rock-Eval allowed obtaining the data critical for determining the genetic type of OM, its thermal maturity and residual petroleum generating potential. Using the Surfer and Corel Draw software, schematic maps and diagrams of variations in the most informative (i.e. area-specific and depth-dependent) geochemical parameters of the kerogen on the studied area and also down the section (from the Upper to the Lower Jurassic) were constructed and analyzed. The obtained geochemical data indicate that in the Jurassic sediments of the Nadym-Tazovsky interfluve, the highest OM generation potential is found in the Bazhenov horizon, as well as in individual members of the Malyshevsky, Leontievsky, Sharapovsky and Kiterbyutsky horizons. Based upon the level of OM maturity in the Upper and Middle Jurassic sediments, deposits of mainly oil and fat gases could be preserved, and in the Lower Jurassic – deposits of fat and dry gases.

Geochronology, geochemistry, and tectonic implications of upper Silurian – Lower Devonian meta-sedimentary rocks from the Jiangyu Group in eastern Jilin Province, Northeast China

2018 ◽  
Vol 55 (5) ◽  
pp. 490-504 ◽  
Author(s):  
Zuo-Zhen Han ◽  
Hui Liu ◽  
Zhi-Gang Song ◽  
Wen-Jian Zhong ◽  
Chao Han ◽  
...  
Keyword(s):  
Northeast China ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Jilin Province ◽  
Geochemical Data ◽  
Isotopic Data ◽  
Early Devonian ◽  
Northern Margin ◽  
The North ◽  
Two Samples

In this study, we present detrital zircon U–Pb ages and Hf isotopic data and whole-rock geochemical data from meta-sedimentary rocks of the Jiangyu Group in eastern Jilin Province (Northeast China) to constrain the late Silurian – Early Devonian tectonic evolution of the southeastern Xing’an–Mongolia Orogenic Belt. Two samples of the meta-sedimentary rocks from the Jiangyu Group yielded concordant ages ranging from 2926 to 415 Ma, and the youngest zircon populations of the two samples yielded weighted mean ages of 427 ± 3 and 426 ± 3 Ma, respectively. Combined with reliable published muscovite 40Ar-39Ar ages of 408 Ma from the overlying metamorphic ophiolitic mélange, these data indicate that the protoliths of the Jiangyu Group were deposited during the late Silurian – Early Devonian Era. A comparison of the U–Pb ages and Hf isotopic data for detrital zircons from northeastern Gondwana and the Jiangyu Group indicates a probable tectonic affinity. The whole-rock geochemical data indicate that the protoliths of the meta-sedimentary rocks from the Jiangyu Group were graywackes deposited in a continental arc setting. Based on the recognition of the early to middle Paleozoic subduction–accretion events along the eastern segment of the northern margin of the North China Craton (NCC), we infer that the subduction–accretion events may have occurred in the Yanbian area followed by one or more arc–continent collisions after the Early Devonian.

Biogenic native Sulfur linked to the Neogene deposits from the Riffian Corridors (Northern Morocco): preliminary study and characterization

2021 ◽  
Author(s):  
Laila Boubkari ◽  
Otmane Raji ◽  
Mohammed Achalhi ◽  
Muhammed Ouabid ◽  
Jean Louis Bodinier
Keyword(s):  
Elemental Sulfur ◽  
Sedimentary Rocks ◽  
Mediterranean Area ◽  
Geochemical Data ◽  
Bacterial Sulfate Reduction ◽  
Total Sulfur Content ◽  
Authigenic Carbonates ◽  
Native Sulfur ◽  
Preliminary Study ◽  
Geochemical Analyses

<p>Elemental sulfur in sedimentary rocks is commonly associated with evaporites and authigenic carbonates. The genesis of this evaporite hosted native sulfur has been traditionally considered as a result of bacterial sulfate reduction under specific geological and paleogeographic conditions. Some biogenic sulfur occurrences are found in the Mediterranean area associated with the Neogene formations (e.g. Hellin, Lorca, Teruel, Sicily). They are described as interbedded layers in large evaporitic sequences or as sulfur nodules enclosed in secondary gypsum or carbonate deposits. Quite similar geological settings are present in Northern Morocco where several sediment-hosted sulfur showings were noted. However, these potential sulfur occurrences in the Pre-Rif and post-nappe Neogene basins have not been studied and still basically unknown. This work aims to explore these occurrences and assess their potentials using preliminary field, mineralogical and geochemical data. Several potential areas were identified at the Tortono-Messinian formations of Oued Amlil, Arbaa Taourirt, Taghzout Tassa, and Boudinar basins. They show favorable settings composed mainly of gypsiferous marls, carbonate, and organic matter-rich black sediments. In terms of sulfur contents, preliminary XRD data confirmed the presence of elemental sulfur and geochemical analyses show total sulfur content reaching 18.5 wt.%. However, further fieldwork combined with advanced mineralogical and isotopic geochemistry is still necessary for this area to try understanding their paragenesis in comparison with other similar Mediterranean occurrences.</p>

Redistributing the Population: GIS Adds Value to Historical Demography

1996 ◽  
Vol 8 (2) ◽  
pp. 90-104 ◽  
Author(s):  
Janette Lee
Keyword(s):  
Northern Ireland ◽  
Settlement Pattern ◽  
Historical Demography ◽  
Water Bodies ◽  
Choropleth Mapping ◽  
County Antrim ◽  
Gis Software

A model for more accurately representing the distribution of population is currently under development using some of the functionality of the Arc/Info GIS software. Included are factors for settlement pattern, topography and the presence of water bodies. The model is tested on County Antrim in Northern Ireland and the value of traditional choropleth mapping assessed in comparison with the output from the model.

scholarly journals Statherian (ca. 1714–1680 Ma) Extension-Related Magmatism and Deformation in the Southwestern Korean Peninsula and Its Geological Significance: Constraints from the Petrological, Structural, Geochemical and Geochronological Studies of Newly Identified Granitoids

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 557
Author(s):  
Byung-Choon Lee ◽  
Weon-Seo Kee ◽  
Uk-Hwan Byun ◽  
Sung-Won Kim
Keyword(s):  
Korean Peninsula ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Ductile Deformation ◽  
Southwestern Part ◽  
The North ◽  
Deformation Event ◽  
Geochemical Analyses ◽  
A Minor ◽  
T Values

In this study, petrological, structural, geochemical, and geochronological analyses of the Statherian alkali feldspar granite and porphyritic alkali feldspar granite in the southwestern part of the Korean Peninsula were conducted to examine petrogenesis of the granitoids and their tectonic setting. Zircon U-Pb dating revealed that the two granites formed around 1.71 Ga and 1.70–1.68 Ga, respectively. The results of the geochemical analyses showed that both of the granites have a high content of K2O, Nb, Ta, and Y, as well as high FeOt/MgO and Ga/Al ratios. Both granites have alkali-calcic characteristics with a ferroan composition, indicating an A-type affinity. Zircon Lu-Hf isotopic compositions yielded negative εHf(t) values (−3.5 to −10.6), indicating a derivation from ancient crustal materials. Both granite types underwent ductile deformation and exhibited a dextral sense of shear with a minor extension component. Based on field relationships and zircon U-Pb dating, it was considered that the deformation event postdated the emplacement of the alkali feldspar granite and terminated soon after the emplacement of the porphyritic alkali feldspar granite in an extensional setting. These data indicated that there were extension-related magmatic activities accompanying ductile deformation in the southwestern part of the Korean Peninsula during 1.71–1.68 Ga. The Statherian extension-related events are well correlated with those in the midwestern part of the Korean and eastern parts of the North China Craton.

U–Pb ages and tectonic significance of late Archean alkalic magmatism and nonmarine sedimentation: Timiskaming Group, southern Abitibi belt, Ontario

1991 ◽  
Vol 28 (4) ◽  
pp. 489-503 ◽  
Author(s):  
F. Corfu ◽  
S. L. Jackson ◽  
R. H. Sutcliffe
Keyword(s):  
Greenstone Belt ◽  
Early Stage ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Geochemical Data ◽  
Lake Area ◽  
Quartz Porphyry ◽  
Bear Lake ◽  
Lake Formation ◽  
Dominant Period

The paper presents U–Pb ages for zircons of the calc-alkalic to alkalic igneous suite and associated alluvial–fluvial sedimentary rocks of the Timiskaming Group in the late Archean Abitibi greenstone belt, Superior Province. The Timiskaming Group rests unconformably on pre-2700 Ma komatiitic to calc-alkalic volcanic sequences and is the expression of the latest stages of magmatism and tectonism that shaped the greenstone belt. An age of 2685 ± 3 Ma for the Bidgood quartz porphyry, an age of about 2685–2682 Ma for a quartz–feldspar porphyry clast in a conglomerate, and ages ranging from 2686 to 2680 Ma for detrital zircons in sandstones appear to reflect an early stage in the development of the Timiskaming Group. The youngest detrital zircons in each of three sandstones at Timmins, Kirkland Lake, and south of Larder Lake define maximum ages of sedimentation at about 2679 Ma; the latter sandstone is cut by a porphyry dyke dated by titanite at [Formula: see text], identical to the 2677 ± 2 Ma age for a volcanic agglomerate of the Bear Lake Formation north of Larder Lake. Similar ages have previously been reported for syenitic to granitic plutons of the region. The dominant period of Timiskaming sedimentation and magmatism was thus 2680–2677 Ma. Xenocrystic zircons found in a porphyry and a lamprophyre dyke have ages of 2750–2720 Ma, which correspond to the ages of the oldest units in the belt, predating the volumetrically dominant ca. 2700 Ma greenstone sequences. The presence of these xenocrysts and the onlapping of the Timiskaming Group on all earlier lithotectonic units of the southern Abitibi belt support the concept that the 2700 Ma ensimatic sequences were thrust onto older assemblages during a phase of compression that culminated with the generation of tonalite and granodiorite at about 2695–2688 Ma. Published geochemical data for the Timiskaming igneous suite, notably the enrichments in large-ion lithophile elements and light rare-earth elements and the relative depletion of Nb, Ta, and Ti compare with the characteristics of suites at modern convergent settings such as the Eolian and the Banda arcs and are consistent with generation of the melts from deep metasomatized mantle in the final stages of, or after cessation of, subduction. Late- and post-Timiskaming compression caused north-directed thrusting and folding. Turbiditic sedimentary units of the Larder Lake area which locally structurally overly the alluvial–fluvial sequence and were earlier thought to be part of the Timiskaming Group, appear to be older "flyschoid" sequences, possibly correlative with sedimentary rocks deposited in the Porcupine syncline at Timmins between 2700 and 2690 Ma.

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