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1

Detrital zircon populations in Ediacaran Period sediments distinguish active from passive continent margins even when metamorphosed and help resolve the Gondwana-Panotia supercontinent/megacontinent argument

Crow Michael, Zaw Khin, Thu Kyaw, Belousov Ivan, Goemann Karsten

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

16--17

EN

Great thicknesses of sand and greywacke were deposited on the margins of megacontinents during the Ediacaran Period (620–542 Ma). Zircon age populations in sediments with long deep-time flat profiles distinguish passive margin sedimentation from shorter humped zircon profiles characteristic of sediments derived from volcanic arcs and their feeder zones in active margins. An example of a single hump detrital profile is given by an Ediacaran Period volcano present in the Charnian Supergroup in the Anglo-Brabant Massif of the East Avalonia terrane. This Gondwana fragment was originally part of the West Africa craton and was subsequently accreted to Laurentia. A volcanic complex with sediments carrying an Ediacaran biota is overlain by Triassic sediments. The main phase of eruption at c. 561 Ma provides a single hump zircon age histogram with a few pre-eruption zircon xenocrysts up to 40 Ma older

2

Silesian Ridge in the light of petrological analyses and LA-ICP MS U-Pb analyses of the cohesive debrites from the Istebna Formation (Silesian Nappe, Outer Western Carpathians, Poland)

Szczuka Monika, Gawęda Aleksandra, Waśkowska Anna, Golonka Jan, Szopa Krzysztof, Chew David, Drakou Foteini

Geological Quarterly

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2022

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Vol. 66, No. 2

art. no. 20

EN

Exotic clasts present in flysch deposits of the Western Outer Carpathians enable investigation and reconstruction of the eroded crystalline basement of the Silesian Ridge. The flysch rocks of the Istebna Formation (Jasnowice Member: Paleocene) in the Silesian Nappe contain magmatic and metamorphic clasts derived from the Silesian Ridge basement. The crystalline rock fragments acquired from cohesive debrites were analyzed petrographically and geochemically, and zircon and rutile crystals were subject to LA-ICP-MS U-Pb dating. Granitoid clasts yielded Meso-Variscan U-Pb zircon ages (325.7 and 330.6 Ma), with older (Neoproterozoic to Paleoproterozoic) inherited cores and eNd330 = –12.0 (TDM age of 1.98 Ga). The orthogneiss clast yielded a protolith age of 1635 Ma and fingerprint of thermal reworking at ~288 Ma. Zircon crystals from the detrital clasts yielded similar U-Pb zircon ages to the granitoid clasts (311.5 to 391 and 331 Ma). The rutile crystals from sandstone yielded concordia age of 344.7 Ma. Zircon crystals from paragneiss, interpreted as a granitoid envelope, yielded 238U/206Pb ages between 557 and 686 Ma and include an inherited core of age ~1207.4 ±33.8 Ma. Age data from exotic clasts and the detrital zircon and rutile fraction suggest the core part of the Silesian Ridge was a Neoproterozoic to Mesoproterozoic envelope intruded by Meso-Variscan granitoid plutons.

3

Zirconium silicates in a peralkaline granite: a record of the interplay of magmatic and hydrothermal processes (Ilímaussaq complex, Greenland)

Cegiełka Małgorzata, Bagiński Bogusław, Macdonald Ray, Belkin Harvey E., Kotowski Jakub, Upton Brian G. J.

Acta Geologica Polonica

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2022

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Vol. 72, no. 2

235--245

EN

Compositional and textural data are presented for zircon, secondary Zr-silicates, catapleiite and elpidite in a peralkaline granite from the Ilímaussaq complex, south Greenland. The zircon is essentially stoichiometric, with (Zr + Hf + Si) = 1.96–1.98 a.p.f.u. The secondary Zr-silicates show a wide range of Zr/Si atomic ratios (0.13–0.79). The catapleiite varies from close to stoichiometric to a Na-depleted type showing cation deficiency (5.2–5.8 a.p.f.u.). Elpidite shows similar variations (7.2–9.0 a.p.f.u.). Textural relationships between the Zr phases are interpreted to show that magmatic zircon interacted with hydrous fluids exsolved from the magma to form the secondary Zr-silicates. Formation of catapleiite was late-magmatic, in equilibrium with a Na-Si-bearing fluid. This was followed by the crystallization of elpidite, the fluid having a different Na/Si ratio. Both catapleiite and elpidite experienced Na-loss during late-stage hydrothermal alteration.

4

Neoarchean to Paleoproterozoic fragments in the Brunovistulia terrane, S Poland : a component of the Columbia Supercontinent?

Żelaźniewicz Andrzej Ryszard, Fanning C. Mark

Geological Quarterly

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2020

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Vol. 64, No. 1

120--129

EN

The composite terrane of Brunovistulia includes basement of the Upper Silesia Block, southern Poland. In its NE part, the basement is elevated by the Rzeszotary Horst. In the Rzeszotary 2 borehole (Rz2) drilled in the horst, partly migmatized amphibolites, felsic gneisses and granites occur. An Na-plagioclase-phengite-K-feldspar neosome contained zircons that yielded U-Pb SHRIMP ages ~2.75-2.6 Ga (cores and single grains) and ~2.0 Ga (rims and single grains). The older ages are interpreted as the time of origin of the igneous protolith of the migmatized amphibolites. The younger ages recorded metamorphism and migmatization that affected both the magmatic precursor of the amphibolites and accompanying felsic rocks during a contractional tectonic/orogenic event. Migmatization was greatly enhanced by an influx of alkali-bearing fluids which heralded intrusion of late-orogenic unfoliated K-granite in an extensional regime, terminating the 2.0 Ga event. It is proposed that the entire orogenic edifice, of which the Brunovistulian rocks drilled in Rz 2 are a small part, represents fragments of the Columbia Supercontinent that was assembled in the Paleoproterozoic and broken up in the Mesoproterozoic. In Ediacaran times, these fragments became eventually incorporated into the Cadomian orogen in the form of its foreland and contributed to the formation of the composite terrane of Brunovistulia. Such a scenario explains why the U-Pb zircon age spectra in the Rzeszotary terrain differ dramatically from those in the remainder of Brunovistulia, which is thought to be the Cadomian hinterland.

5

A reappraisal of K-Ar and new U-Pb age data for felsic rocks in the vicinity of the Kraków-Lubliniec Fault Zone (southern Poland)

Jarmołowicz-Szulc Katarzyna

Geological Quarterly

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2020

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Vol. 64, No. 3

754--765

EN

New U-Pb zircon SHRIMP determinations from magmatic silicic rocks adjacent to the NE part of the Upper Silesia Coal Basin (USB) are provided and compared with earlier data obtained by K-Ar dating. The zircon samples studied came from the same boreholes and depth intervals previously sampled for K-Ar datings. Recalculations of the earlier K-Ar values for biotites yielded isochron ages in the range of 297-309 Ma. The zircon U-Pb SHRIMP values gave more precise ages between 300.1 ±1.2 Ma and 292.6 ±1.3 Ma (1б) consistent with U-Pb and Re-Os determinations. In two cases, the recalculated results of K-Ar dates were nearly identical with those obtained from the SHRIMP isotopic analyses. In this context, the granitoids and porphyries of the USB area, once assigned to the Carboniferous-Permian based on the older K-Ar studies, actually are of the same age as other felsic igneous rocks from the vicinity of the Kraków-Lubliniec Fault Zone, with a higher dating precision, however. The new data underline the importance of Late Carboniferous-Early Permian felsic magmatism at the SW margin of the Trans-European Suture Zone in southern Poland. In the zircon populations dated, besides the dominant Late Paleozoic ages, there are some inherited zircon cores, likely remnant detrital grains from a sediment component in the source rocks, that reveal much older ages which range from ~2051 to 569 Ma.

6

Magmatic episodes in the Holy Cross Mountains, Poland – a new contribution from multi-age zircon populations

Krzemińska Ewa, Krzemiński Leszek

Biuletyn Państwowego Instytutu Geologicznego

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2019

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nr 474

43--57

EN

This contribution reports on new U-Pb zircon age data from magmatic rocks from the Holy Cross Mountains (HCM) of Poland. The analyzed samples were taken from lamprophyre and diabase veins of Podkranów and Janowice-2 as well as from tuff horizon of Kielce Beds (Ludlow). Internal morphologies have been investigated by SEM-BSE and cathodoluminescence images and they have been used as a guide for the selection of genetically various type of grains, e.g. potential auto-, ante- and xenocrysts, that were analyzed by ion microprobe. The U-Pb age of the magmatic events at 414.2 ±6.6 Ma (Kielce tuff), 322 ±12 Ma (Podkranów, lamprophyre), and 300±10 Ma (Janowice-2, diabase) confirmed the time frame of known magmatic activity reported within the HCM, as determined by 40Ar/39Ar geochronology in previous studies. The zircon investigation revealed also multiple populations with record of an earlier pulse of magma system (antecrysts), as well as abundant xenocrysts.

PL

W artykule przedstawiono nowe oznaczenia wieku U-Pb cyrkonu w skałach magmowych z obszaru Gór Świętokrzyskich (HCM). Próbki pobrano z żył lamprofiru i diabazu z Podkranowa i Janowic-2 oraz z poziomu tufu w warstwach kieleckich (ludlow). Morfologię i wewnętrzne cechy budowy ziaren zbadano za pomocą obrazów SEM-BSE i katodoluminescencji SEM, stosując je jako przewodnik do selekcji genetycznie różnych typów ziaren, potencjalnych auto-, ante- i ksenokryształów, które były analizowane na mikrosondzie jonowej. Wiek U-Pb epizodów magmowych, 414,2 ±6,6 Ma (Kielce, tuf), 322 ±12 Ma (Podkranów, lamprofir) i 300 ±10 Ma (Janowice-2, diabaz), potwierdza znane z wcześniejszych publikacji ramy czasowe aktywności magmowej na obszarze HCM oznaczone metodą 40Ar/39Ar. Badania wieku U-Pb cyrkonu ujawniły także szereg populacji z zapisem wcześniejszych impulsów magmowych (antekryształy) i licznych ksenokryształów.

7

Cathodoluminescence of synthetic zircon implanted by He+ ion

Tsuchiya Y., Kayama M., Nishido H., Noumi Y.

Geochronometria

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2017

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Vol. 44, no. 1

129--135

EN

He+ ion implantation at 4.0 MeV, equivalent to energy of α particles from natural radioactive nuclei 238U and 232Th, has been conducted for undoped synthetic zircon. The cathodoluminescence (CL) of implanted samples was measured to clarify the radiation-induced effects. Unimplanted synthetic zircon shows pronounced and multiple blue emission bands between 310 nm and 380 nm, whereas the implanted samples have an intense yellow band at ~550 nm. The blue emission bands can be assigned to intrinsic defect centers formed during crystal growth. The yellow band should be derived from induced-defect centers by He+ ion implantation, which might be related to the metamicitization originated from a self-induced radiation in natural zircon. The yellow band may be separated into two emission components at 1.96 eV and 2.16 eV. The emission component at 2.16 eV is recognized in both unimplanted and implanted samples, and its intensity increases with an increase in the implantation dose. The CL of zircon can be used as the geodosimeter.

8

W poszukiwaniu fragmentów najstarszej skorupy kontynentalnej na Labradorze

Kusiak M. A., Sałacińska A.

Przegląd Geologiczny

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2016

|

Vol. 64, nr 11

896--901

EN

There are few unresolved questions in the Earth Sciences which generate as much debate as the nature of the Hadean Earth: i.e. the rock record between the Earth’s formation and about 3.8 billion years ago. Current knowledge of the nature and origin of the earliest crust comes largely from studies of the mineral zircon (ZrSiO4). The oldest zircon grains on Earth (4.46 Ga) are found in Jack Hills, Australia. They represent a time capsule of what the Earth was like from ca. 4.4-4.0 Ga during the Hadean. The other ancien rocks (>3.8 Ga) are preserved in Antarctica, Canada, China, Greenland, Labrador, Western Australia and Swaziland, with the oldest known rochi on Earth from the Acasta gneiss in Northern Canada, dated at 4.03 Ga. Most likely, the second oldest rock record in the world (>3.9 Ga) may be derivedfrom the Nanok gneiss in the Nain Complex of the Saglek-Hebron area in the northern part of the Labrador Peninsula. Extensive investigation of these rocks will allowfurther characterizing the nature of the earliest preserved crust.

9

Zircon U-Pb ages of granitoid apophyses in the western part of the Kłodzko–Złoty Stok Granite Pluton (SW Poland)

Mikulski S.Z., Williams I. S.

Geological Quarterly

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2014

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Vol. 58, No. 2

251--262

EN

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.

10

SHRIMP U-Pb zircon geochronology of the Jawornik granitoids (West Sudetes, Poland)

Białek D

Geologia Sudetica

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2014

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Vol. 42

4--4

11

Saxothuringian provenance of suspected terranes in the Central Sudetes, Bohemian Massif: zircon evidence of a recycled subducted slab

Mazur S., Szczepański J., Tumiak K., McNaughton N. J.

Geologia Sudetica

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2014

|

Vol. 42

56--58

12

High-Ti muscovite as a prograde relict in HP granulites with metamorphic Devonian zircon ages (Bestvina granulite body)

Nahodilova R, Stipska P, Powell R, Kosler J, Racek M

Geologia Sudetica

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2014

|

Vol. 42

64--64

13

Relacje metodyczne i wiekowe pomiędzy analizą trakową a potasowo-argonową na przykładzie masywu Karkonoszy i jego osłony

Jarmołowicz-Szulc K.

Biuletyn Państwowego Instytutu Geologicznego

|

2014

|

nr 458

31--37

PL

W kontekście coraz większego znaczenia metod izotopowych w Polsce i zrozumienia ich możliwości interpretacyjnych, przedstawiono porównanie metodyczne i wiekowe analizy trakowej i oznaczeń metodą potasowo-argonową (K-Ar) w odniesieniu do minerałów budujących skały masywu Karkonoszy oraz jego północnej osłony. Prezentowane wyniki stanowią kompilację wcześniejszych oznaczeń trakowych z obszaru karkonosko-izerskiego (Jarmołowicz-Szulc, 1984), oznaczeń K-Ar z tego samego obszaru (Jarmołowicz-Szulc i in., 2009) oraz nowszych metodycznie danych literaturowych z masywu Karkonoszy (Danišik i in., 2010). Wykazano zaletę metody trakowej, którą są przede wszystkim możliwości interpretacyjne związane z datowaniem wypiętrzenia i/lub pogrzebania w historii geologicznej skał. Pokazano również walory metody K-Ar, umożliwiającej m.in. uzyskanie wartości wieku oziębiania np. po wypiętrzeniu plutonu.

EN

Isotopic methods have been gaining their importance in Poland in last decades. The understanding on the interpretation potential of isotopic determinations of minerals has been growing up as well. In that context, age relations and methodology of the fission track and K-Ar methods have been presented based on the case of minerals forming rocks of the Karkonosze Massif and its northern metamorphic envelope. The presented results are the compilation of earlier fission track determinations from the Karkonosze-Izera Block (Jarmołowicz-Szulc, 1984), K-Ar data from the same area (Jarmołowicz-Szulc et al., 2009) and newer methodological data from the Karkonosze granitoid (Danišik et al., 2010). Advantages of the fission track method have been shown, i.e., interpretation possibilities of burial and exhumation in geological history of rocks. Importance of the K-Ar method has been presented, in that determination of a cooling age after the pluton uplift.

14

Synthesis and Characterization of New Refractory Coatings Based on Talc, Cordierite, Zircon and Mullite Fillers for Lost Foam Casting Process

Prstić A., Aćimović-Pavlović Z., Terzić A., Pavlović L.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 1

89--95

EN

Refractory coatings based on different refractory fillers (talc, cordierite, zircon and mullite) for application in Lost Foam casting process were investigated. Design and optimization of the coatings composition with controlled, rheological properties included, and consequently synthesis were achieved by application of different coating components, namely different suspension agents and fillers and by alteration of the coating production procedure. Morphologic and microstructural analysis of fillers was carried out by means of scanning electronic microscope. X-ray diffraction analysis by means of X-ray diffractometer was applied in determination and monitoring the phase composition changes of the refractory fillers. An analysis of the particle size and shape was carried out by means of the PC software application package OZARIA 2.5. To assess the effects of application of individual refractory coatings, a detailed investigation of structural and mechanical properties of the moldings obtained was performed. Highlight was placed on revealing and analyzing surface and volume defects present on moldings. Radiographic molding tests were carried out by means of the X-ray device SAIFORT type-S200. Attained results are essential for the synthesis of refractory coatings based on high-temperature fillers and their applications in Lost Foam casting process for manufacturing of moldings with in-advance-set properties.

PL

W pracy przedstawiono wyniki badań materiałów wysokotemperaturowych - powłok ogniotrwałych na bazie talku, kordierytu. cyrkonii i mulitu, które są stosowane w procesie odlewania metodą piany traconej. Projektowanie i optymalizację składu powłoki o kontrolowanych właściwościach teologicznych, a następnie syntezę osiągnięto poprzez zastosowanie różnych skład- ników powłok, tj. różnych stabilizatorów zawiesiny i wypełniaczy oraz poprzez zmiany w procesie produkcji powłok. Analizę morfologiczną i mikrostruktura!ną wypełniaczy przeprowadzono za pomocą elektronowego mikroskopu skaningowego. Analizę dyfrakcji promieni rentgenowskich zastosowano do określania i monitorowania zmian składu fazowego wypełniaczy ognio- trwałych. Analizę wielkości i kształtu cząstek przeprowadzono za pomocą pakietu oprogramowania użytkowego PC OZARIA 2.5. Żeby ocenić skutki stosowania poszczególnych powłok ogniotrwałych, przeprowadzono szczegółowe badania właściwości strukturalnych i mechanicznych otrzymanych form. Nacisk został położony na ujawnienie i analizę defektów powierzchni i objętości obecnych w formach. Radiograficzne testy formowania przeprowadzono za pomocą urządzenia SAJFORT typu S200. Uzyskane wyniki są niezbędne do syntezy powłok ogniotrwałych w oparciu o wysokotemperaturowe wypełniacze i ich zastosowań w procesie odlewania metodą piany traconej do produkcji form o z góry ustalonych właściwościach.

15

Zircon U-Pb dating of igneous rocks in the Radzimowice and Wielisław Złotoryjski auriferous polymetallic deposits, Sudetes, SW Poland

Mikulski S. Z., Williams I. S.

Annales Societatis Geologorum Poloniae

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2014

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Vol. 84, No. 3

213--233

EN

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.

16

Baddeleyite segregations in zircon of the Azov zirconium-rare-earth deposit (Ukrainian Shield)

Voznyak D. K., Chernysh D. D., Melnikov V. S., Ostapenko S. S.

Mineralogia

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2013

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Vol. 44, iss. 3/4

125--131

EN

Baddeleyite as inclusions in zircon crystals is described for the first time from the ore zone of the Azov zirconium-rare-earth deposit in the Volodarsky (Pivdennokalchytsky) syenite Massif in the Ukrainian Shield. The main admixture in the zircon containing baddeleyite is hafnium (0.68 wt%). The baddeleyite occurs in a substance that fills cracks and that probably corresponds to glass. The chemical compositions of four baddeleyite segregations, and of the hosting glass, are presented. The baddeleyite formed as a result of interaction between zircon and silicate melt with a low SiO2 content. The silicate melt formed under the influence of highthermobaric CO2-fluid flows on the rock.

17

Wpływ wapnia na zmianę składu fazowego tworzyw ogniotrwałych Al2SiO5-ZrSiO4

Szczerba J., Madej D.

Materiały Ceramiczne

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2013

|

T. 65, nr 1

116--120

PL

W artykule omówiono korozję materiałów ogniotrwałych Al2SiO5-ZrSiO4 w środowisku zewnętrznego wymiennika ciepła (ZWC) linii technologicznej pieca cementowego w temperaturze 1000 ± 100 °C. Szczególną uwagę poświęcono oddziaływaniu na materiał ogniotrwały składników występujących w ZWC, głównie Ca2+/CaO, a także K+/K2O, Cl-, SO2. Jak wykazały badania XRD oraz SEM/EDS w wyniku oddziaływania wapnia z andaluzytem z materiału ogniotrwałego przejściowo powstawał glinokrzemian wapnia – gehlenit Ca2Al2SiO7. Z kolei reakcje w układzie K2O-Al2SiO5 doprowadziły do syntezy glinokrzemianów potasu – leucytu KAlSi2O6 i kalsilitu KAlSiO4. Cyrkon ZrSiO4 z materiału ogniotrwałego uległ przeobrażeniu w CaZrO3 (Tmp = 2345°C). We wcześniejszych stadiach reakcji powstawały struktury nieuporządkowane typu CSZ (C = CaO, S = SiO2, Z = ZrO2).

EN

The study of corrosion of the Al2SiO5-ZrSiO4 refractories in corroding environment of an external heat exchanger of the cement kiln was carried out at the temperature of 1000 ± 100 °C. Main corrosive agents in the external heat exchanger were in the solid (CaO) and gaseous (K+/K2O, SO2, Cl-) form. The XRD and SEM/EDS analyses showed a reaction of calcium and potassium with the refractory matrix. As a consequence of these reactions, gehlenite Ca2Al2SiO7, leucite KAlSi2O6 and kalsilite KAlSiO4 were formed in the corroded refractory brick. Kalsilite was the main compound formed in the corroded sample. Moreover, zircon was decomposed, and high refractory calcium zirconate CaZrO3 (Tmp = 2345 °C) was formed. In the early stages of reactions, the CSZ (C = CaO, S = SiO2, Z = ZrO2) disordered structures were formed.

18

Heavy-mineral, mineral-chemical and zircon-age constraints on the provenance of Triassic sandstones from the Devon coast, southern Britain

Morton Andrew, Hounslow Mark W., Frei Dirk

Geologos

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2013

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Vol. 19, No. 1-2

67--85

EN

An integrated heavy-mineral, mineral-chemical and zircon-dating study of the Triassic succession exposed on the south Devon coast, in the western part of the Wessex Basin, indicates derivation from a combination of granitic and metasedimentary lithologies of ages of mostly over 550 Ma. These sources were probably located at a relatively proximal location near the southern margin of the basin. Derivation from more distal sources in the Armorican Massif or local Variscan sources to the west appears unlikely in view of the scarcity of Permo-Carboniferous (Variscan-age) zircons. The Budleigh Salterton Pebble Bed Formation was derived from a different combination of source lithologies than the Otter Sandstone Formation, the former including staurolite-grade metasediments that were absent in the catchment area of the Otter Sandstone. The Devon coast succession has provenance characteristics that differ from equivalent sandstones further east in the Wessex Basin, and from sandstones in the East Irish Sea Basin to the north. These differences indicate that sediment supply patterns to the linked Triassic basin systems in southern Britain are complex, involving multiple distinct sub-catchment areas, and that heavy-mineral studies have considerable potential for unravelling these sub-catchment area sources.

19

SHRIMP U-Pb zircon chronology of the Polish Western Outer Carpathians source areas

Budzyń B., Dunkley D. J., Kusiak M. A., Poprawa P., Malata T., Skiba M., Paszkowski M.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 2

161-171

EN

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.

20

Dissolved-recrystallized zircon from mariupolite in the Mariupol Massif, Priazovje (SE Ukraine)

Dumańska-Słowik M., Sikorska M., Heflik W.

Acta Geologica Polonica

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2011

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Vol. 61, no. 3

277-288

EN

Zircon in mariupolite from the alkaline Mariupol Massif has a relatively simple, monotonous composition with only some variation in its REE2O3 and ThO2 content, i.e., 0.00-1.55 and 0.00-0.34 wt. %, respectively. It contains numerous inclusions such as albite, lepidomelane, aegirine, K-feldspars, pyrochlore, paristite and bastnńsite-(Ce). The crystallization of the inclusions (except for REE-bearing carbonates) was contemporaneous with the formation of the zircon crystals. These inclusions were enclosed by faster growing zircons. The SEM-CL images of the zircon are typical of crystals with signs of local thermal recrystallization, i.e., primary oscillatory zoning along the grain margins and secondary irregular patchy zoning in the interior. Its complex internal texture most probably formed as a result of a coupled dissolution-recrystallization process during the late magmatic or post-magmatic stage of the cooling of the host rocks. The abundant micropores could have originated as a result of leaching of the zircon. The recrystallization process definitely disturbed the concentric oscillatory zoning pattern characteristic of magmatic zircon.