scholarly journals Permian single crystal U-Pb zircon age of the Rožňava Formation volcanites (Southern Gemeric Unit, Western Carpathians, Slovakia)

2009 ◽  
Vol 60 (6) ◽  
pp. 439-448 ◽  
Author(s):  
Anna Vozárová ◽  
Miloš Šmelko ◽  
Ilya Paderin
Keyword(s):  
Single Crystal ◽  
Volcanic Activity ◽  
Late Ordovician ◽  
Western Carpathians ◽  
Magmatic Zircon ◽  
Zircon Age ◽  
Zircon Population ◽  
Growth Zoning ◽  
Gemeric Unit ◽  
Rock Complex

Permian single crystal U-Pb zircon age of the Rožňava Formation volcanites (Southern Gemeric Unit, Western Carpathians, Slovakia)Zircon populations from the Rožňava Formation volcanic rock complex have been analysed. Euhedral zircons from the 1stvolcanogenic horizon with fine oscillatory growth zoning, typical of magmatic origin, gave the average concordia age of 273.3 ± 2.8 Ma, with Th/U ratios in the range of 0.44-0.73. The Permian ages ranging from 266 to 284 Ma were identified in the wider, zoned or unzoned, central zircon parts, as well as in their fine-zoned oscillatory rims. The average concordia age of 275.3 ± 2.9 was obtained from the euhedral zircon population of the 2ndvolcanogenic horizon of the Rožňava Formation. The analyses were performed on zoned magmatic zircons in the age interval from 267 to 287 Ma, with Th/U ratios in the range of 0.39-0.75. In the later zircon population two inherited zircon grains were dated giving the age of 842 ± 12 Ma (Neoproterozoic) and 456 ± 7 Ma (Late Ordovician). The magmatic zircon ages document the Kungurian age of Permian volcanic activity and contemporaneous establishment of the south-Gemeric basin. The time span of volcanic activity corresponds to the collapse of the Western Carpathian Variscan foreland which expanded southward.

496 ± 3 Ma zircon ion microprobe age for pre-Hercynian granite, Central Iberian Zone, NE Portugal (earlier claimed 618 ± 9 Ma)

2006 ◽  
Vol 144 (1) ◽  
pp. 21-31 ◽  
Author(s):  
H. P. ZECK ◽  
M. J. WHITEHOUSE ◽  
J. M. UGIDOS
Keyword(s):  
Secondary Electron ◽  
Weighted Average ◽  
Heterogeneous Population ◽  
Magmatic Zircon ◽  
Ion Microprobe ◽  
Zircon Age ◽  
Zircon Population ◽  
Central Iberian Zone ◽  
Zircon Crystallization ◽  
Microscopy Images

Ion microprobe (SIMS) dating of zircon from the Miranda do Douro orthogneiss, Central Iberian Zone, Hercynian Iberian belt, defines an Early Ordovician U–Pb age of 496.0 ± 2.6 Ma (95 % conf., MSWD = 1.14) for magmatic zircon crystallization in its granitic protolith. The age contrasts with an earlier, conventional (ID-TIMS) U–Pb zircon age of 618 ± 9(95 % conf.) Ma, now thought to be an artefact of the complex zircon population. Individual SIMS ages for zircon from the rock range from 2700 to 180 Ma and comprise inherited and magmatic zircon, both concordant and common Pb-enriched, and younger, reset ages. The ID-TIMS study seems to have misinterpreted this heterogeneous population as a cogenetic suite consisting of magmatic zircon and its age-reset equivalents produced by recent Pb loss. The 496 ± 3 Ma SIMS age represents the weighted average for 26 magmatic zircon domains located by careful inspection of cathodoluminescence, secondary electron and optical microscopy images of ∼ 700 individual zircon crystals. Inherited zircon is widespread, ranging in age from 2700 to 550 Ma, with age clusters, which are statistically indistinguishable from those known from pre-Hercynian granitic basement material elsewhere in the Central Iberian Zone. Including the present age information, 582 ± 4 Ma (95 % conf., MSWD = 1.02, n = 13) and 619 ± 9 Ma (95 % conf., MSWD = 0.93, n = 7) appear as prevailing inherited zircon age components in basement intrusions in the Central Iberian Zone.

scholarly journals Permian volcanics in the Northern Gemericum and Bôrka Nappe system: U-Pb zircon dating and the implications for geodynamic evolution (Western Carpathians, Slovakia)

2012 ◽  
Vol 63 (3) ◽  
pp. 191-200 ◽  
Author(s):  
Anna Vozárová ◽  
Miloš Šmelko ◽  
Ilya Paderin ◽  
Alexander Larionov
Keyword(s):  
Time Span ◽  
Middle Permian ◽  
Western Carpathians ◽  
Magmatic Zircon ◽  
Geodynamic Evolution ◽  
Zircon Age ◽  
Zircon Dating ◽  
The North ◽  
Sedimentary Cycle ◽  
Kungurian Stage

Permian volcanics in the Northern Gemericum and Bôrka Nappe system: U-Pb zircon dating and the implications for geodynamic evolution (Western Carpathians, Slovakia)U-Pb dating (SHRIMP) of magmatic zircon ages from the Northern Gemericum Permian volcanics (Petrová Hora Formation) yielded the Concordia age of 272.4 ± 7.3 Ma for basaltic andesite, as well as the Concordia age of 275.2 ± 4 Ma for rhyodacites. Both zircon ages correspond to the Cisuralian Epoch in the time span of the Kungurian Stage. Acquired206Pb/238U zircon age data support the nearly contemporaneous origin of the acid and basic volcanogenic members in the Northern Gemericum Permian strata. The bimodal volcanic suite proves the transtension/extension tectonic regime in the North Gemeric sedimentary basin during the Late Cisuralian. The magmatic zircon ages of rhyodacites, occurring in the lower thrust sheet of the Bôrka Nappe (Jasov Formation), gave a younger Concordia age of 266 ± 1.8 Ma proving the Guadalupian Epoch, in the time span of the Wordian/Capitanian. In comparison to the Northern Gemericum realm, this age refers to the relatively younger stage of rift-related extensional movements. In the wide Alpine-Dinarides realm the Middle Permian (Guadalupian) movements are related to the beginning of the Alpine sedimentary cycle. Thus, the Middle Permian rifting expresses the beginning of the formation of the future Meliata oceanic trough.

Detrital zircon populations of the eastern Laurentian margin in the Appalachians

Geology ◽  
2020 ◽  
Author(s):  
Yvette D. Kuiper ◽  
Christopher Hepburn
Keyword(s):  
United States ◽  
Detrital Zircon ◽  
Orogenic Belt ◽  
Grenville Province ◽  
Zircon Age ◽  
Zircon Population ◽  
Middle Ordovician ◽  
Archean Crust ◽  
Laurentian Margin

Newly compiled U-Pb detrital zircon data from eight geographic domains along the eastern Laurentian margin from Newfoundland (Canada) to Alabama (United States) show a highly consistent signature along strike, with only minor local variations. The Precambrian signature is characterized by a small ca. 2.7 Ga population and a major ca. 1.9–0.9 Ga population that peaks at ca. 1.2–1.0 Ga. Detrital zircon populations are from Laurentian Archean crust (ca. 2.7 Ga population), Paleoproterozoic orogens (ca. 1.9–1.6 Ga), the Granite-Rhyolite Province (ca. 1.5–1.4 Ga), and the Elzevir terrane and Grenville Province (ca. 1.3–0.9 Ga). The Mesoproterozoic populations vary in size depending on proximity to the ca. 1.5–1.4 Ga Granite-Rhyolite Province, the ca. 1245–1225 Ma Elzevir terrane, and the ca. 1.2–0.9 Ga Grenville Province. A middle Ordovician zircon population varies in size along strike depending on input from the Taconic orogenic belt, but it is strongest in the northern Appalachians. Because of the general along-strike consistency in detrital zircon age populations, the compilation of all 7534 concordant U-Pb detrital zircon data can be used in future U-Pb detrital zircon studies as an indicator for eastern Laurentian margin sources.

U–Pb ages of detrital zircons from Paleozoic metasandstones of the Gelnica Terrane (Southern Gemeric Unit, Western Carpathians, Slovakia): evidence for Avalonian–Amazonian provenance

2011 ◽  
Vol 101 (4) ◽  
pp. 919-936 ◽  
Author(s):  
Anna Vozárová ◽  
Katarína Šarinová ◽  
Nickolay Rodionov ◽  
Dušan Laurinc ◽  
Ilya Paderin ◽  
...  
Keyword(s):  
Detrital Zircons ◽  
Western Carpathians ◽  
Gemeric Unit

scholarly journals Re-Os and U-Th-Pb dating of the Rochovce granite and its mineralization (Western Carpathians, Slovakia)

2013 ◽  
Vol 64 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Milan Kohút ◽  
Holly Stein ◽  
Pavel Uher ◽  
Aaron Aimmerman ◽  
L’ubomír Hraško
Keyword(s):  
Oscillatory Zoning ◽  
Western Carpathians ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Collisional Orogen ◽  
Granite Intrusion ◽  
Metallogenic Belt ◽  
Central Western Carpathians ◽  
Lower Crustal ◽  
Gemeric Unit

Abstract The subsurface Rochovce granite intrusion was emplaced into the contact zone between two principal tectonic units (the Veporic Unit and the Gemeric Unit) of the Central Western Carpathians (CWC), Slovakia. The Cretaceous age of this granite and its Mo-W mineralization is shown using two independent methods: U-Pb on zircon and Re-Os on molybdenite. The studied zircons have a typical homogeneous character with oscillatory zoning and scarce restite cores. SHRIMP U-Pb data provide an age of 81.5 ± 0.7 Ma, whereas restite cores suggest a latest Neoproterozoic-Ediacaran age (~565 Ma) source. Zircon εHf(81) values -5.2 to + 0.2 suggest a lower crustal source, whereas one from the Neoproterozoic core εHf(565)= + 7.4 call for the mantle influenced old precursor. Two molybdenite- bearing samples of very different character affirm a genetic relation between W-Mo mineralization and the Rochovce granite. One sample, a quartz-molybdenite vein from the exocontact (altered quartz-sericite schist of the Ochtiná Formation), provides a Re-Os age of 81.4 ± 0.3 Ma. The second molybdenite occurs as 1-2 mm disseminations in finegrained granite, and provides an age of 81.6 ± 0.3 Ma. Both Re-Os ages are identical within their 2-sigma analytical uncertainty and suggest rapid exhumation as a consequence of post-collisional, orogen-parallel extension and unroofing. The Rochovce granite represents the northernmost occurrence of Cretaceous calc-alkaline magmatism with Mo-W mineralization associated with the Alpine-Balkan-Carpathian-Dinaride metallogenic belt.

Geochronology of the Twillingate Granite and Herring Neck Group, Notre Dame Bay, Newfoundland

1976 ◽  
Vol 13 (11) ◽  
pp. 1591-1601 ◽  
Author(s):  
Harold Williams ◽  
R. D. Dallmeyer ◽  
R. K. Wanless
Keyword(s):  
New World ◽  
Linear Array ◽  
Volcanic Rocks ◽  
Ocean Basin ◽  
Late Ordovician ◽  
Island Arc ◽  
Zircon Age ◽  
Mafic Dike ◽  
Plate Convergence ◽  
Late Cambrian

Zircons from the Twillingate Granite form a linear array with a concordia intercept of 510 + 17 – 16 m.y. Mafic dikes that cut deformed granite along the southern contact of the pluton at New World Island record 40Ar/39Ar hornblende ages of 440 ± 10 and 473 ± 9 m.y. These ages indicate that the mafic dikes are Ordovician, and confirm their correlation with mafic volcanic rocks of the nearby Herring Neck Group. The dates also suggest that Herring Neck volcanism and mafic dike intrusion extended from Early to Late Ordovician. Together with the zircon age, they define a narrow chronologic bracket for intrusion, deformation, and metamorphism of the Twillingate Granite (`~510–475 m.y.).Within the central portion of the Twillingate pluton. a metamorphosed mafic dike cutting massive granite and an amphibolite inclusion within Foliated granite yield similar,40Ar/39Ar hornblende ages of 443 ± 11 and 438 ± 9 m.y. These ages are anomalously young compared with the 473 m.y. age of a mafic dike cutting deformed granite at New World Island. They are interpreted to indicate prolonged metamorphism and/or slower post-meta mo rphic cooling for central portions of the pluton compared to its southern margin.The isotopic ages support the view that the Twillingate Granite and nearby mafic volcanic rocks are collectively part of a single island-arc complex. The granite may have been generated during a period of subduction as sociated with plate convergence and closing of the proto-Atlantic ocean. A 510 m.y. (Late Cambrian) age for the granite suggests that convergence began rather early in the evolution of the Northern Appalachians. In addition, where dated Newfoundland ophiolite suites appear to be younger than, or contemporaneous with some granitic plutons (such as Twillingate), it is likely that they formed in a marginal ocean basin environment behind an older island-arc terrane.Les zircons du granite de Twillingate forment un réseau linéaire avec intercept à 510 + 17 – 16 Ma. Les dykes mafiques qui recoupent le granite déformé le long de la bordure sud du pluton à New World Island donnent des âges 40Ar/39Ar pour la hornblende de 440 ± 10 et de 473 ± 9 Ma. Ces âges indiquent que les dykes mafiques sont Ordoviciens et confirment leurs liens avec des roches mafiques volcaniques du groupe de Herring Neck dans le voisinage. Les dates suggèrent aussi que le volcanisme de Herring Neck et l'intrusion de dykes mafiques se sont produits du début à la fin de l'Ordovicien. Avec les âges des zircons, ils définissent un intervalle de temps assez court pour l'intrusion, la déformation et le métamorphisme du granite de Twillingate (~510–475 Ma).A l'intérieur de la portion centrale du pluton de Twillingate, un dyke mafique métamorphisé recoupant un granite massif et une inclusion d'amphibolite dans un granite foliacé donnent des âges 40Ar/39Ar semblables pour les hornblendes de 443 ± 11 et 438 ± 9 Ma. Ces âges sont anormalement faibles si on les compare avec l'âge de 473 Ma du dyke mafique qui recoupe le granite déformé de New World Island. On les interprète comme indiquant un métamorphisme prolongé et/ou un refroidissement post-métamorphique plus lent pour les portions centrales du pluton par comparaison à sa bordure sud.

scholarly journals Central European Variscan Basement in the Outer Carpathians: A Case Study from the Magura Nappe, Outer Western Carpathians, Poland

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 256
Author(s):  
Aleksandra Gawęda ◽  
Krzysztof Szopa ◽  
Jan Golonka ◽  
David Chew ◽  
Anna Waśkowska
Keyword(s):  
Source Region ◽  
Western Carpathians ◽  
Zircon Age ◽  
Central European ◽  
Outer Western Carpathians ◽  
Granite Belt ◽  
Outer Carpathians ◽  
Siliciclastic Rocks ◽  
Mineral Analyses

Exotic crystalline blocks within the Outer Carpathian flysch have the potential to establish the nature of their eroded basement source(s) and thus to reconstruct the paleogeography of the Outer Carpathians. Petrological investigations (including mineral analyses) coupled with zircon and apatite U-Pb dating were performed on an exotic crystalline block within Eocene siliciclastic rocks in the Rača Zone of the Magura Nappe in the Outer Western Carpathians, Poland. This exotic block is a large (c. 1 m diameter) pink porphyritic granitoid block found in the Osielczyk Stream, southeast of Osielec village in the Makowski Beskid mountains. The timing of magmatic crystallization is constrained by a U-Pb zircon age of 315.9 ± 2.6 Ma (MSWD = 0.69), while inherited zircon cores yield Archean (c. 2780 Ma), Cadomian (541.8 ± 6.7 Ma; MSWD = 0.53), Devonian (417 ± 11 Ma; MSWD = 0.57) and Early Variscan (c. 374 Ma) ages. Apatites from the same sample yield a Tera Wasserburg lower intercept U-Pb age of 311.3 ± 7.5 (MSWD = 0.87). The granitoid exhibits geochemical characteristics typical of I-type granites and eNd(316 Ma) = 2.15 (with a TDM model age of 1.18 Ga) and 87Sr/86Sr(316 Ma) = 0.704710. These data suggest a likely source region in the Saxo-Danubian Granite Belt, which possibly formed the basement of the Fore-Magura Ridge.

scholarly journals Rapid endogenic rock recycling in magmatic arcs

2020 ◽  
Author(s):  
Junyong Li ◽  
Ming Tang ◽  
Cin-Ty Lee ◽  
Xiaolei Wang ◽  
Zhi-Dong Gu ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Pressure Ratio ◽  
Age Distribution ◽  
Magmatic Zircon ◽  
Arc Magmatism ◽  
Thrust Faults ◽  
Yangtze Block ◽  
Zircon Age ◽  
Deep Crust ◽  
O Isotopes

Abstract In subduction zones, materials on Earth’s surface can be transported to the deep crust or mantle, but the exact mechanisms and the nature of the recycled materials are not fully understood. Here, we report a set of migmatites from western Yangtze Block, China. These migmatites have similar bulk compositions as forearc sediments. Zircon age distribution and Hf–O isotopes indicate that the precursors of the sediments were predominantly derived from juvenile arc crust itself. Using phase equilibria modelling, we show that the sediments experienced high temperature-to-pressure ratio metamorphism and were most likely transported to deep arc crust by intracrustal thrust faults. By dating the magmatic zircon cores and overgrowth rims, we find that the entire rock cycle, from arc magmatism, to weathering at the surface, then to burial and remelting in the deep crust, took place within ~ 10 Ma. Our findings highlight thrust faults as an efficient recycling channel in compressional arcs and endogenic recycling as an important mechanism driving internal redistribution and differentiation of arc crust.

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