scholarly journals Late Permian volcanic dykes in the crystalline basement of the Považský Inovec Mts. (Western Carpathians): U–Th–Pb zircon SHRIMP and monazite chemical dating

2017 ◽  
Vol 68 (6) ◽  
pp. 530-542 ◽  
Author(s):  
Ondrej Pelech ◽  
Anna Vozárová ◽  
Pavel Uher ◽  
Igor Petrík ◽  
Dušan Plašienka ◽  
...  
Keyword(s):  
Sedimentary Basin ◽  
Early Carboniferous ◽  
Metamorphic Rocks ◽  
Late Permian ◽  
Geochronological Data ◽  
Shrimp Dating ◽  
Alkali Basalts ◽  
The Past ◽  
Chime Age ◽  
Chemical Dating

AbstractThis paper presents geochronological data for the volcanic dykes located in the northern Považský Inovec Mts. The dykes are up to 5 m thick and tens to hundreds of metres long. They comprise variously inclined and oriented lenses, composed of strongly altered grey-green alkali basalts. Their age was variously interpreted and discussed in the past. Dykes were emplaced into the Tatricum metamorphic rocks, mostly consisting of mica schists and gneisses of the Variscan (early Carboniferous) age. Two different methods, zircon SHRIMP and monazite chemical dating, were applied to determine the age of these dykes. U-Pb SHRIMP dating of magmatic zircons yielded the concordia age of 260.2 ± 1.4 Ma. The Th-U-Pb monazite dating of the same dyke gave the CHIME age of 259 ± 3Ma. Both ages confirm the magmatic crystallization at the boundary of the latest Middle Permian to the Late Permian. Dyke emplacement was coeval with development of the Late Paleozoic sedimentary basin known in the northern Považský Inovec Mts. and could be correlated with other pre-Mesozoic Tethyan regions especially in the Southern Alps.

scholarly journals Stratigraphy and depositional history of the Upper Palaeozoic and Triassic sediments in the Wandel Sea Basin, central and eastern North Greenland

1989 ◽  
Vol 143 ◽  
pp. 21-45
Author(s):  
L Stemmerik ◽  
E Håkansson
Keyword(s):  
Early Carboniferous ◽  
Upper Permian ◽  
Lower Permian ◽  
Late Permian ◽  
The West ◽  
Depositional History ◽  
Lower Carboniferous ◽  
Upper Carboniferous ◽  
Lithostratigraphic Units ◽  
History Of

A lithostratigraphic scheme is erected for the Lower Carboniferous to Triassic sediments of the Wandel Sea Basin, from Lockwood Ø in the west to Holm Land in the east. The scheme is based on the subdivision into the Upper Carboniferous - Lower Permian Mallemuk Mountain Group and the Upper Permian - Triassic Trolle Land Group. In addition the Upper Carboniferous Sortebakker Formation and the Upper Permian Kap Kraka Formation are defined. Three formations and four members are included in the Mallemuk Mountain Group. Lithostratigraphic units include: Kap Jungersen Formation (new) composed of interbedded limestones, sandstones and shales with minor gypsum - early Moscovian; Foldedal Formation composed of interbedded limestones and sandstones -late Moseovian to late Gzhelian; Kim Fjelde Formation composed of well bedded Iimestones - late Gzhelian to Kungurian. The Trolle Land Group includes three formations: Midnatfjeld Formation composed of dark shales, sandstones and limestones - Late Permian; Parish Bjerg Formation composed of a basal conglomeratic sandstone overlain by shales and sandstones - ?Early Triassic (Scythian); Dunken Formation composed of dark shales and sandstones - Triassic (Scythian-Anisian). The Sortebakker Formation (new) is composed of interbedded sandstones, shales and minor coal of floodplain origin. The age is Early Carboniferous. The Kap Kraka Formation (new) includes poorly known hematitic sandstones, conglomerates and shales of Late Permian age.

Monazite U-Th/Pb chemical dating of the Early Carboniferous syn-kinematic MP/MT metamorphism in the Variscan French Massif Central

2009 ◽  
Vol 180 (3) ◽  
pp. 283-292 ◽  
Author(s):  
Jérémie Melleton ◽  
Michel Faure ◽  
Alain Cocherie
Keyword(s):  
Electron Probe ◽  
Early Carboniferous ◽  
Variscan Belt ◽  
French Massif Central ◽  
Massif Central ◽  
Close Range ◽  
Chemical Dating

AbstractIn situ U-Th-Pb geochronology on monazite using Electron Probe Micro Analyser, constrained by structural and textural observations, has been performed on four samples from the Limousin area (northwest part of the French Massif Central) in order to date the syn-kinematic MP/MT metamorphism related to the top-to-the-NW shearing that deformed the stack of nappes in this zone of the Variscan belt. All the analyzed samples lead to a mean age at 360 ± 4 Ma. The close range of ages obtained during this study (360 Ma) and with the previous 40Ar-39Ar ones (360–350 Ma) suggests fast processes of cooling and exhumation during the Early Carboniferous in internal zones of the Variscan belt. The geodynamic significance of this Early Carboniferous event is discussed at the scale of the Ibero-Armorican orocline.

Evidence of Acidification of Some Nova Scotian Rivers and Its Impact on Atlantic Salmon, Salmo solar

1983 ◽  
Vol 40 (4) ◽  
pp. 462-473 ◽  
Author(s):  
W. D. Watt ◽  
C. D. Scott ◽  
W. J. White
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
River Discharge ◽  
Average Rate ◽  
Metamorphic Rocks ◽  
Ph Variation ◽  
The Past ◽  
Discharge Rates ◽  
Ph Range ◽  
Nova Scotian

River pH's in Nova Scotia are closely related to geology, and seasonal pH variation is well correlated with river discharge rates. In the geologically sensitive areas (granite and metamorphic rocks), river pH's have fallen significantly over the past 27 yr at an apparent average rate of 0.017 pH units/year. Concomitant with this decrease are a decline in [Formula: see text] concentrations and increases in Al+++ and [Formula: see text]. On average, 73% of the increase in acid is attributable to increased [Formula: see text]. Changes in Na+, K+, Ca++, and Mg++ concentrations were not significant. In rivers presently at mean annual pH's < 4.7, the Atlantic salmon (Salmo salar) runs have disappeared and are presumed extinct. Rivers in the pH range 4.7–5.0 show a decline in salmon angling returns of 2.8%/yr, beginning about 1954, and low densities of juvenile salmon. Rivers presently of pH > 5.0 generally have normal juvenile densities and show no significant trend in angling returns.

Visean overprint of the Devonian-Early Carboniferous granites: result of Variscan collisional stage revealed by zircon SHRIMP dating (Tribeč Mts., Western Carpathians)

2020 ◽  
Author(s):  
Igor Broska ◽  
Keewook Yi ◽  
Milan Kohút ◽  
Igor Petrík
Keyword(s):  
Early Stage ◽  
Early Carboniferous ◽  
White Mica ◽  
Granitic Rocks ◽  
Western Carpathians ◽  
Variscan Orogeny ◽  
Shrimp Dating ◽  
The West ◽  
Volcanic Arc ◽  
Type Granite

&lt;p&gt;The granites with I- and S-type affinity in the Variscan segments of the Alpine West-Carpathian edifice belong to the oldest intrusions within the European Variscides. Granites and granodiorites of the West-Carpathian crystalline basement are mostly classified as S-type, whereas tonalities and granodiorites belong to the I-type suite. Both suites probably originated in the volcanic arc setting as product of subduction-related regime in the Galatian superterrane (Broska et al. 2013). The I-&amp;#160;and S-type granite bodies were firstly identified in the West-Carpathian Tribe&amp;#269; Core Mountains and the new SHRIMP and CHIME datings recognised their Visean geotectonic overprint. The subduction-related I-type granites show the age span 364-358 Ma followed by the intrusion of the S-type granites dated by SHRIMP on 358 Ma. The bimodal SHRIMP data of a dyke placed within S-type granites show ages 351 Ma and 330 Ma, or primary vs. alteration age. The CHIME age from monazite dating shows 347 Ma because monazite indicate probably early stage of massive granite alteration perhaps during collisional process, younger zircons represents later phase of the event. &amp;#160;CHIME dating of newly formed monazite in greisenised S-type granite gives the age 344 Ma. The granite showing strong greisenization (total degradation of feldspars and formation of quartz - white mica assemblages) is dated by SHRIMP on 355 Ma. The greisenised granite contains abundant tourmaline with high dravitic molecule, Sr-rich apatite and common monazite. Abundant tiny stoichiometrically pure apatite grains in this granite indicate their exsolution from feldspars enriched in phosphorus. The S-type granite dyke from the ridge of the Tribe&amp;#269; Mts gives zircon SHRIMP age 355 Ma and CHIME monazite age 342 Ma. The dating results of the Tribe&amp;#269; granites identified: (&lt;strong&gt;1&lt;/strong&gt;) older Upper Devonian/Lower Mississippian subduction-related I-type tonalites (ca. 364-351 Ma), and (&lt;strong&gt;2&lt;/strong&gt;) S-type granites Middle/Upper Mississippian (Visean) intruding in time span 342-330 Ma reflecting probably of the collisional event in the Variscan orogeny. Dual evolution of the Tribe&amp;#269; Mts. Variscan granitic rocks is partly corroborated by Hf isotopes from the dated zircons with &amp;#949;Hf&lt;sub&gt;(t)&lt;/sub&gt; = +3.5 ~ &amp;#8211;2.4 for the older granites, and &amp;#949;Hf&lt;sub&gt;(t)&lt;/sub&gt; = &amp;#8211;0.3 ~ &amp;#8211;4.9 for the younger ones. The evolution of the I- and S-type granites seems to be rather different from the granite evolution known in the Bohemian Massif and therefore the origin of Variscan hybrid granites from the Western Carpathians we placed on the SW side of Galatian volcanic arc as result of Paleo-Tethys subduction (see Stampfli and Borel, 2002, Stampfli et al. 2013).&lt;/p&gt;&lt;p&gt;Acknowledgments: Support from Slovak Research and Development Agency: APVV SK-KR-18-0008, APVV-14-0278/, APVV-18-0107, and VEGA 2/0075/20 are greatly appreciated.&lt;/p&gt;

scholarly journals Mesostructures and deformational history of the Central Crystallines: an example from Garhwal Himalaya, India

1998 ◽  
Vol 17 ◽  
Author(s):  
V. K. Singh ◽  
S. P. Singh ◽  
P. S. Saklani ◽  
C. S. Dubey
Keyword(s):  
Large Scale ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Geochronological Data ◽  
Deformational History ◽  
Crenulation Cleavage ◽  
Ductile Shearing ◽  
History Of ◽  
Transcurrent Faults ◽  
East West

Structural analysis reveals that the Central Crystallines in the Garhwal region were subjected to four phases of deformations (D1 to D4). The D1 deformational phase is highly obliterated and usually found as F1 intrafolial (rootless) tight isoclinal folds in migmatites and gneisses. The D2 deformational phase produced strong pervasive S2 schistosity and asymmetric and open fold (F2) plunging 20-30° towards ENE-WSW. The L2 lineation plunge 5-10° towards east-west is well developed in medium grade metamorphic rocks. The D1 deformations were responsible for F3 folds reflected in large scale anticlinal and synclinal, overturned and recumbent folds, which have 10-40° plunges towards NW. The late D3 deformational stresses were responsible for shearing along the middle limbs of F1 folds and they ultimately initiated thrusting. The NNE­ SSW plunging mineral or stretching lineation (L3), S3 crenulation cleavage and S-C fabrics were developed during the dominant ductile shearing related to the late D3 deformation. The D4 phase characterised by brittle-ductile deformation (minor kinks, puckers, transverse/transcurrent faults, and S-C' fabrics) and extensive cataclasis along thrust- and fault-zones reflects the last episode of deformation. The structural and geochronological data indicate that D1 and D2 deformation episodes may be related to the Precambrian time while D3 and D4 are exclusively of the Tertiary age.

scholarly journals On The Supposed Onshore Extension Of The Penyu Basin, Peninsular Malaysia

Warta Geologi ◽  
2021 ◽  
Vol 47 (3) ◽  
pp. 204-210
Author(s):  
Mazlan Madon ◽  
Keyword(s):  
Coastal Plain ◽  
Sedimentary Rock ◽  
Sedimentary Basin ◽  
Peninsular Malaysia ◽  
River Delta ◽  
Metamorphic Rocks ◽  
Quaternary Sediments ◽  
The West

The Penyu Basin is a Tertiary sedimentary basin located offshore Peninsular Malaysia. The basin is assumed to continue westwards beneath the Pahang River delta where as much as 115 m of Quaternary sediments overlie a bedrock of pre-Tertiary granites and metamorphic rocks. No Pliocene or older sediments beneath the delta have been reported. If the Quaternary sediments are considered as part of the Cenozoic Penyu Basin, the basin’s western limit may be delineated at the foothills of the coastal plain where those sediments onlap onto pre-Tertiary rocks. Therefore, any sedimentary rock of Tertiary age that may occur to the west of that limit most probably represents a separate basin.

scholarly journals Chemical Analyses of Igneous and Metamorphic Rocks of Denmark, the Faeroes and Greenland. (To and including 1940)

1942 ◽  
Vol 68 ◽  
pp. 1-105
Author(s):  
Sole Munck ◽  
Arne Noe-Nygaard
Keyword(s):  
Comparative Study ◽  
Igneous Rocks ◽  
Geological Survey ◽  
Metamorphic Rocks ◽  
Chemical Analyses ◽  
The Past ◽  
De Quervain ◽  
Set Up ◽  
The Comparative Study

The past ten years or so have seen the publication of collections of chemical rock analyses which, as a result of their clear form of set-up, in many ways faciliate the comparative study of the chemistry of the rocks and their mutual relationships. Among these publications there are: P. Niggli, F. De Quervain & R. U. Wintherthalter: Chemismus schweizerischer Gesteine. Bern 1930, and the analyses publish ed by the Geological Survey of Great Brita in: Chemical Analyses of Igneous Rocks, Metamorphic Rocks and Minerals. London 1931. Similar publications are available from two neighbouring countries, i.e. from Sweden: W. Larsson: Chemical Analyses of Swedish Rocks (Bull. Geol. Inst., Uppsala 1932) and from Finland : L. Lokka: Neuere Chemische Analysen von Finnisch en Gesteinen (Bull. Comm. Geol. de Finlande No. 105. Helsingfors 1934).

The Duration and Geodynamics of Formation of the Angara–Vitim Batholith: Results of U–Pb Isotope (LA-ICP-MS) Dating of Magmatic and Detrital Zircons

2021 ◽  
Vol 62 (12) ◽  
pp. 1331-1349
Author(s):  
V.B. Khubanov ◽  
A.A. Tsygankov ◽  
G.N. Burmakina
Keyword(s):  
Drainage Basin ◽  
Detrital Zircons ◽  
Late Paleozoic ◽  
Metamorphic Rocks ◽  
Zircon Geochronology ◽  
Geochronological Data ◽  
Pb Isotope ◽  
Alluvial Deposits ◽  
Detrital Zircon Geochronology ◽  
Icp Ms

Abstract —We present results of U–Pb (LA-ICP-MS) dating of detrital zircons from the alluvial deposits of the Angarakan River (North Muya Ridge, northern Baikal region), whose drainage basin is composed mainly of granitoids of the Barguzin Complex, typomorphic for the late Paleozoic Angara–Vitim batholith (AVB). Three age clusters with peaks at 728, 423, and 314 Ma have been identified in the studied population of detrital zircons. It is shown that small outliers of igneous and metamorphic rocks, probably similar to the large AVB roof pendants mapped beyond the drainage basin, are the source of Neoproterozoic and early Paleozoic zircons. The late Paleozoic cluster comprises two close peaks at 314 and 28 Ma, which totally “overlap” with the time of the AVB formation and mark a granitoid source of the zircons. The results of detrital-zircon geochronology, together with the data on bedrocks, point to the prolonged (~40 Myr) formation of the AVB, but the intensity of magmatism during this period calls for additional study. Based on the analysis of published geological, geochemical, and geochronological data, we assume that the AVB resulted from the plume–lithosphere interaction that began in the compression setting and gave way to extension 305–300 Ma (the Carboniferous–Permian boundary), which caused replacement of “crustal” granitoids by granitoids formed from a mixed mantle–crustal source.

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