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Wyszukujesz frazę "SHRIMP zircon geochronology" wg kryterium: Wszystkie pola


Wyświetlanie 1-7 z 7
Tytuł:
Early Carboniferous (~337 Ma) granite intrusion in Devonian (~400 Ma) ophiolite of the Central-European Variscides
Autorzy:
Kryza, R.
Powiązania:
https://bibliotekanauki.pl/articles/2059145.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Variscides
ophiolites
SHRIMP zircon geochronology
Opis:
The Central-Sudetic ophiolites comprise mafic-ultramafic complexes around the E and S edges of the Góry Sowie Massif in SW Poland and are recognized as fragments of Devonian (~400 Ma old) oceanic crust. They contain small rodingite bodies and tectonized granite dykes that potentially can highlight the igneous, metamorphic and structural development of the ophiolitic suites. The granite dykes have been tentatively correlated with the Variscan granitoids of the Strzegom-Sobótka Massif to the north. However, new U-Pb SHRIMP zircon data for granites from the serpentinite quarry at Jordanów show a concordia age of 337 š4 Ma for the main zircon population, and of 386 š10 Ma for minor inheritance. Thus, the age of the granite is considerably older than the ages of the Strzegom-Sobótka granitoids, dated at ~310-294 Ma. The granite dyke has a similar age as some other granitoids found near the ophiolitic fragments, e.g., the Niemcza granitoids to the south, dated at 338 +2/-3 Ma; these older granitoids all represents a relatively early stage of granitoid magmatism recorded in that part of the Variscan Orogen. The age of the granitoid dyke within serpentinites confirms that the Paleozoic ophiolites were incorporated into the continental crust already in early Visean times.
Źródło:
Geological Quarterly; 2011, 55, 3; 213-222
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variscan granitoid plutonism in the Strzelin Massif (SW Poland) : petrology and age of the composite Strzelin granite intrusion
Autorzy:
Oberc-Dziedzic, T.
Kryza, R.
Pin, C.
Madej, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059728.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
zircon SHRIMP geochronology
composite granitoid plutons
Variscan granitoids
Strzelin Massif
Opis:
Petrological data and recently published U/Pb zircon SHRIMP ages reveal a protracted Variscan magmatic evolution in the Strzelin Massif (SW Poland), with three main stages of granitoid plutonism: 1 – tonalitic I, 2 – granodioritic and 3 – tonalitic II/granitic. The granitoids of the second and third stages form the Strzelin intrusion that is composed of three varieties: medium-grained biotite granite, fine-grained biotite granite and fine-grained biotite-muscovite granite. New SHRIMP data show that the medium-grained and fine-grained biotite granites comprise different zircon populations that reflect complex and prolonged plutonic processes. Two distinct magmatic events seem to be represented by well-defined zircon populations with apparent 206Pb/238U ages of 303 ± 2 Ma in the medium-grained biotite granite, and 283 ± 8 Ma in the fine-grained biotite granite. These dates, however, do not necessarily reflect the true magmatic ages, possibly being “rejuvenated” by radiogenic lead loss in zircons (impossible to resolve based on routine SHRIMP data). Based on field evidence, the third variety, the biotite-muscovite granite, postdates both types of biotite granites. The petrographic and geochemical features, including Nd isotope signature, along with various zircon inheritance patterns and ages, suggest that the parental magmas of the three granites originated from different crustal sources and were emplaced during three successive magmatic pulses.
Źródło:
Geological Quarterly; 2013, 57, 2; 269--288
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zircon U-Pb ages of granitoid apophyses in the western part of the Kłodzko–Złoty Stok Granite Pluton (SW Poland)
Autorzy:
Mikulski, S.Z.
Williams, I. S.
Powiązania:
https://bibliotekanauki.pl/articles/2059727.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Variscan granitoids
apophyses
zircon
SHRIMP geochronology
Sudetes
Opis:
Granitoids from the Graniec–Bardo and Myszak apophyses of the Kłodzko–Złoty Stok (KZS) Granite Pluton that intrude the Upper Paleozoic flysch of the Bardo Unit have zircon U-Pb ages, measured by SHRIMP, of 341.6 ± 2.8 Ma and 341.4 ± 2.2 Ma, respectively. These results augment our previous dating that recorded a short period of Middle Mississippian (Visean) hypabyssal magmatism that produced a variety of KZS igneous rocks of different compositions between ca. 341 and 331 Ma. The Graniec–Bardo and Myszak apophyses belong to the earliest stage of the pluton emplacement. Geochemical and petrographic studies of the dated samples indicate that they are biotite- and hornblende-rich tonalite and syenogabbro of diverse composition and typical of rocks originating from hybrid magmas formed in the geotectonic transition from an early stage collisional granitoid emplacement to its fast orogenic uplift. The polymetallic auriferous ore mineralisation of contact metasomatic type found in intimate contact with the Graniec–Bardo apophysis near Bardo Śląskie may also be of Visean age.
Źródło:
Geological Quarterly; 2014, 58, 2; 251--262
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zircon U-Pb dating of igneous rocks in the Radzimowice and Wielisław Złotoryjski auriferous polymetallic deposits, Sudetes, SW Poland
Autorzy:
Mikulski, S. Z.
Williams, I. S.
Powiązania:
https://bibliotekanauki.pl/articles/191720.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
zircon
SHRIMP geochronology
gold deposit
porphyries
Variscides
Sudetes
Opis:
A rhyolite porphyry in the Radzimowice deposit at Bukowinka Hill has a SHRIMP zircon U-Pb age of 314.9 ± 3.1 Ma. This is consistent with previous zircon dating of a monzogranite and a rhyodacite (ca. 315 Ma) in the Żeleźniak sub-volcanic intrusion (ZI), considered to be the igneous rocks, representing the oldest magmatic pulses in the region. First-stage mesothermal auriferous sulphide mineralization in the deposit was connected to hydrothermal processes, associated with the rhyodacite intrusions. This was followed by tectonic activity and younger alkaline magmatism in a post-collisional geotectonic setting. The first-stage Au-bearing sulphide mineralization was cataclased and overprinted by younger epithermal base-metal sulphides with microscopic Au, associated with Bi-Te-Ag minerals. The younger magmatic pulses are represented by porphyritic andesites and lamprophyric dykes, which cut the ZI. Zircon from these dykes yielded ages of 312.8 ± 2.8 Ma for an andesite porphyry and 312.4 ± 4 Ma for a lamprophyre. All these magmatic pulses, evidenced in the Radzimowice deposit, are considered to be the oldest post-orogenic sub-volcanic magmatism cutting the basement of the intramontane basins in the Sudetes, on the NE margin of the Bohemian Massif. A rhyolite porphyry in the famous 'Organy' exposure at Wielisław Złotoryjski (WZ) on the SE margin of the North-Sudetic Basin is younger, 297.5 ± 2.8 Ma. Vein-type auriferous ore mineralization, hosted by Early Palaeozoic graphitic schists in intimate contact with rhyolite porphyry in WZ, is also correlated with this magmatism. The auriferous ore mineralization at Radzimowice and Wielisław Złotoryjski formed at different times, during different magmatic pulses and successive hydrothermal stages, despite several similarities in geologic setting and country- and host-rock compositions. There was a transition from a post-collisional to a within-plate setting over about 20 Ma in Late Carboniferous-Early Permian times, with the older Żeleźniak and Bukowinka sub-volcanic intrusions in the uplifted part of the Kaczawa Metamorphic Complex (ZI) and the younger Wielisław Złotoryjski sub-volcanic intrusion in the metamorphic basement of an intramontane basin.
Źródło:
Annales Societatis Geologorum Poloniae; 2014, 84, 3; 213-233
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SHRIMP U-Pb zircon chronology of the Polish Western Outer Carpathians source areas
Autorzy:
Budzyń, B.
Dunkley, D. J.
Kusiak, M. A.
Poprawa, P.
Malata, T.
Skiba, M.
Paszkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/191475.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
zircon
U-Pb geochronology
ion microprobe
provenance
Carpathians
Opis:
The Western Outer Carpathians flysch of Poland comprises clasts of crystalline rocks representing source areas that supplied sedimentary basins with clastic material. Zircon from quartz syenite and granite cobbles representing the Silesian Ridge, the currently unexposed source area located at the southern margin of the Silesian Basin, yielded uniform U-Pb dates of 604š6 Ma and 599š6 Ma. These are interpreted as the age of igneous crystallization. Similarly, zircon from a gneiss cobble derived from the northern source terrain gave 610š6 Ma date, which is interpreted as the age of crystallization of the granitic protolith to the gneiss. The Neoproterozoic magmatism is interpreted to have occurred at the Gondwana active margin.
Źródło:
Annales Societatis Geologorum Poloniae; 2011, 81, No 2; 161-171
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wczesnokarboński wiek intruzji platformowych w podłożu krystalicznym NE Polski
Early Carboniferous age of the cratonic intrusions in the crystalline basement of NE Poland
Autorzy:
Krzemińska, E.
Wiszniewska, J.
Williams, I.S.
Powiązania:
https://bibliotekanauki.pl/articles/2074482.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
zircon
U-Pb SHRIMP geochronology
closure temperature
mafic-alkaline magmatism
Early Carboniferous
NE Poland
Opis:
Three mafic-alkaline intrusive bodies in NE Poland: Ełk, Pisz and Tajno, have been dated recently with U-Pb SHRIMP method. An earlier Rb-Sr whole rock isochron of Ełk syenites pointed to an age 355š4 Ma, while K-Ar age estimates suggested a Late Paleozoic age of Pisz and Tajno rocks, however, in a wide range between 349-291 Ma and 327-289 Ma, respectively. In the paper, we present new geochronological results and discuss the problem of the closure temperatures for different minerals and different isotopic systems used in previous age determinations. Much of the early dating works has been done using K-Ar method. Biotite and K-feldspar retain radiogenic Ar quantitatively below 280 -200şC. Only if magmatic bodies cooled quickly and remained unmetamorphosed, K-Ar and Rb-Sr ages estimate accurately the intrusion emplacement. Zircon used for U-Pb datings has a closure temperature over 800şC, that is comparable to the temperature of magma’s solidus. Therefore U-Pb magmatic zircons dates could be interpreted as an intrusion emplacement ages. The obtained U-Pb results of 347.7 š8 Ma (Ełk) and 345.5š5 Ma (Pisz) have shown very consistent Early Carboniferous age of platform mafic-alkaline magmatic activity. This new U-Pb SHRIMP dating indicates that Ełk and Pisz intrusions are coeval and together with the Tajno alkaline-carbonatite massif could be affined with the Late Devonian Kola Alkaline Carbonatite Province (KACP).
Źródło:
Przegląd Geologiczny; 2006, 54, 12; 1093-1098
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rewizja wieku "najstarszych" skał w podłożu krystalicznym północno-wschodniej Polski
Revision of the "oldest" rocks age in the crystalline basement of NE Poland
Autorzy:
Krzemińska, E.
Wiszniewska, J.
Williams, I.S.
Powiązania:
https://bibliotekanauki.pl/articles/2074437.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
pegmatyt
monacyt
ziarna cyrkonu
mikroskopia elektronowa
wysokopróżniowy mikroskop skaningowy
zircon
monazite
U-Pb SHRIMP geochronology
Late Paleoproterozoic
NE Poland
Opis:
The oldest geochronological results between 2.69–2.57 Ga was previously obtained by using K–Ar method on biotite from pegmatite from Jastrzębna IG–1 borehole. In consequence, in many published reports up to 1998, the Mazowsze (or Masovian) granitoid massif has been regarded as Archean age structure. Therewithal, other rocks in the area, e.g. Bargłów gneiss sequence traditionally were described as Archean in age. In the paper we present new U–Pb SHRIMP zircon and monazite results for above mentioned rocks which have been considered as Archean. Cathodoluminescence images and SHRIMP analysis were carried out for zircons and monazites from Jastrzebna IG–1 pegmatite of 514 m depth (a historical sample previously dated by K–Ar method) and for zircon magmatic cores from Bargłów IG–2 orthogneiss of the 708 m depth. The obtained U–Pb ages of 1826 š12 Ma (zircon) and 1789š34 Ma (monazite), and 1835š28 Ma (zircon) for two rock samples respectively have shown Paleoproterozoic origin. Only 4 of the 24 analysed zircons have clearly discordant results, which are all from the Jastrzebna pegmatite, where Pb–loss was possible (in partially metamict U–rich zircon grains). The new U–Pb SHRIMP dating indicates that Jastrzębna pegmatite and Bargłów magmatic protolith of the orthogneiss is only Late Paleoproterozoic in age and in general about 700 Ma younger than previously reported by K–Ar method. Therefore, there is no unequivocal evidence of the presence of Archean rocks in crystalline basement of NE Poland. This study has been undertaken as a part of a collaborative research agreement between the Polish Geological Institute and Geochronology and Isotope Geochemistry Research School of Earth Sciences of the Australian National University in Canberra.
Źródło:
Przegląd Geologiczny; 2006, 54, 11; 967-973
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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