scholarly journals Two stages of Late Carboniferous to Triassic magmatism in the Strandja Zone of Bulgaria and Turkey

2021 ◽  
pp. 1-14
Author(s):  
Anna Sałacińska ◽  
Ianko Gerdjikov ◽  
Ashley Gumsley ◽  
Krzysztof Szopa ◽  
David Chew ◽  
...  

Abstract Although Variscan terranes have been documented from the Balkans to the Caucasus, the southeastern portion of the Variscan Belt is not well understood. The Strandja Zone along the border between Bulgaria and Turkey encompasses one such terrane linking the Balkanides and the Pontides. However, the evolution of this terrane, and the Late Carboniferous to Triassic granitoids within it, is poorly resolved. Here we present laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) U–Pb zircon ages, coupled with petrography and geochemistry from the Izvorovo Pluton within the Sakar Unit (Strandja Zone). This pluton is composed of variably metamorphosed and deformed granites which yield crystallization ages of c. 251–256 Ma. These ages are older than the previously assumed age of the Izvorovo Pluton based on a postulated genetic relationship between the Izvorovo Pluton and Late Jurassic to Early Cretaceous metamorphism. A better understanding of units across the Strandja Zone can now be achieved, revealing two age groups of plutons within it. An extensive magmatic episode occurred c. 312–295 Ma, and a longer-lived episode between c. 275 and 230 Ma. Intrusions associated with both magmatic events were emplaced into pre-Late Carboniferous basement, and were overprinted by Early Alpine metamorphism and deformation. These two stages of magmatism can likely be attributed to changes in tectonic setting in the Strandja Zone. Such a change in tectonic setting is likely related to the collision between Gondwana-derived terranes and Laurussia, followed by either subduction of the Palaeo-Tethys Ocean beneath Laurussia or rifting in the southern margin of Laurussia, with granitoids forming in different tectonic environments.

2013 ◽  
Vol 151 (5) ◽  
pp. 816-829 ◽  
Author(s):  
MAGNUS KRISTOFFERSEN ◽  
TOM ANDERSEN ◽  
ARILD ANDRESEN

AbstractU–Pb and Lu–Hf isotope analyses of detrital zircon from the latest Ordovician (Hirnantian) Langøyene Formation, the Late Silurian Ringerike Group and the Late Carboniferous Asker Group in the Oslo Rift were obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Overall the U–Pb dating yielded ages within the range 2861–313 Ma. The U–Pb age and Lu–Hf isotopic signatures correspond to virtually all known events of crustal evolution in Fennoscandia, as well as synorogenic intrusions from the Norwegian Caledonides. Such temporally and geographically diverse source areas likely reflect multiple episodes of sediment recycling in Fennoscandia, and highlights the intrinsic problem of using zircon as a tracer-mineral in ‘source to sink’ sedimentary provenance studies. In addition to its mostly Fennoscandia-derived detritus, the Asker Group also have zircon grains of Late Devonian – Late Carboniferous age. Since no rocks of these ages are known in Fennoscandia, these zircons are inferred to be derived from the Variscan Orogen of central Europe.


2013 ◽  
Vol 40 (2) ◽  
pp. 134-144 ◽  
Author(s):  
Jolanta Burda ◽  
Aleksandra Gawęda ◽  
Urs Klötzli

Abstract Detailed cathodoluminescence (CL) imaging of zircon crystals, coupled with Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) U-Pb zircon dating was used to develop new insights into the evolution of granitoids from the High Tatra Mountains. The zircon U-Pb results show two distinct age groups (350±5 Ma and 337±6 Ma) recorded from cores and rims domains, respectively. Obtained results point that the last magmatic activity in the Tatra granitoid intrusion occurred at ca. 330 Ma. The previously suggested age of 314 Ma reflects rather the hydrothermal activity and Pb-loss, coupled with post-magmatic shearing.


2021 ◽  
Author(s):  
Shiqiang Huang ◽  
Yucai Song ◽  
Limin Zhou ◽  
David L. Leach ◽  
Zhaoshan Chang ◽  
...  

Abstract This study evaluates the effect of organic matter impurities on pyrite Re-Os dating, using the giant Jinding sediment-hosted Zn-Pb deposit in China as an example. The Jinding deposit is hosted in a Paleocene evaporite dome that was a hydrocarbon reservoir before mineralization. Pyrite in Jinding formed in two stages: pre-ore (py1) and syn-ore (py2). Two types of py1 are recognized, organic matter-free and organic matter-bearing. The organic matter-free py1 contains homogeneously distributed low concentrations of Re (<2.5 ppb) that yields an isochron age of 51 ± 1 Ma (mean square of weighted deviates [MSWD] = 3.2). This date is interpreted to be the age of py1 formation. The organic matter-bearing py1 contains organic matter inclusions trapped during py1 growth and synchronous with bacterial reduction of sulfate. Elemental mapping with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) shows that the organic matter inclusions have Re signals 1 to 4 orders of magnitude higher than those of pyrite, revealing that organic matter is the major host for Re. Such pyrite separates contain 37 to 1,145 ppb Re. The Re-Os data of organic matter-bearing py1 yield an isochron age of 72.9 ± 0.5 Ma (MSWD = 0.2). This age is older than the actual py1 formation age of 51 ± 1 Ma but overlaps with previously dated bitumen Re-Os isochron age of 68 ± 5 Ma at Jinding, indicating that organic matter inclusions can significantly influence the Re-Os dates of pyrite and likely other sulfides. This study demonstrates that in order to date sulfides formed in organic-rich environments using the Re-Os method, it is necessary to determine the distribution of Re in samples using detailed petrography and LA-ICP-MS trace element mapping plus spot analysis.


Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1071
Author(s):  
Sumit Mishra ◽  
Alexander Slabunov ◽  
Sergei Svetov ◽  
Anna Kervinen ◽  
Natalia Nesterova

In the present work, we studied zircons from the less foliated granites of the Chail Group, which form a thrust sheet of the Lesser Himalayan Sequences, Garhwal region. Compositionally, these granites are S–type, formed in a collisional tectonic setting. Zircons possess an internal structure, mineral inclusions, and geochemical characteristics typical of magmatic origin. The U–Th–Pb geochronology and geochemistry were assessed using the laser ablation multi–collector inductively coupled plasma spectrometry (LA–ICP–MS) technique. U–Th–Pb isotope dating of zircons from two different samples revealed their age, estimated from the upper intersection of the discordia, to be 1845 ± 19 Ma. Zircons from one sample contained inherited cores belonging to three age groups: Paleoarchean (3.52 Ga), Neoarchean (2.78 Ga and 2.62 Ga), and Paleoproterozoic (2.1 Ga). Zircons with ages of 3.52, 2.62, and 2.1 Ga were interpreted as magmatic based on their geochemical characteristics. The 2.78 Ga core was interpreted as metamorphic. The observed inheritance is consistent with the melting of sedimentary rocks. The inherited zircons could have originated from Aravalli and Bundelkhand Craton and Paleoproterozoic Aravalli Fold Belt rocks. This confirms that the studied granites are S–type and could have been formed in a collisional environment at 1.85 Ga on the western flank of the Columbia Supercontinent.


2021 ◽  
Author(s):  
Fang Luan ◽  
Bin Liu ◽  
Shuzhen Sun ◽  
Yuan Chen ◽  
Yanqiu Xu ◽  
...  

Abstract Background Several researches have been conducted on the associations between elements and diseases. Few studies have examined trace elements in young people’s hair. The objective of this study is to investigate the influence of age, gender and season on the contents of magnesium (Mg), calcium (Ca), Iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), selenium (Se) and strontium (Sr) as well as to establish the reference intervals (RIs). Methods We conducted a retrospective study of 589 apparently healthy children and adolescents under 19 years old. Quantitative analysis has been carried out using inductively coupled plasma-mass spectrometry (ICP-MS). Eight nutrient elements in peripheral blood of children and adolescents in eastern China were grouped according to age, sex or season, and analyzed using and Mann-Whitney U test and spearman statistical analyses. RIs were defined by using 95% confidence interval. Results Precisions of ICP-MS detecting for Mg, Ca, Fe, Cu, Zn, Mn, Se and Sr are 2.8%~12.2%. The linearity were all > 0.999 and the bias were all within 10%. Differences between contents of particularly Mg, Fe, Cu and Zn in girls’ and boys’ whole blood were found, and higher contents of Mg, Cu for boys were measured in some age groups. Positive correlations for Fe, Zn, Se and Sr, while negative for Ca and Cu were found with age. And substantial differences between age groups were stated. In general, an increasing trend was found for bioelements (Fe, Zn,Se) both for girls and boys in all age groups, while for Ca and Cu changes were even decreasing for children and teenagers. The most frequently correlating element pairs were Fe-Zn, Mg-Se, and Fe-Se in five successive age groups. Lower contents of essential elements (Mg, Ca, Fe, Zn, Se) were found in summer comparing with other seasons. Finally, the reference interval of each element was initially established according to age and gender grouping. Conclusions The contents of elements in whole blood varies depending mainly on the gender and age of children and adolescents. Besides, season is also a factor that affects the contents of elements in the body. The reference intervals of elements in whole blood grouped by age and gender provide a reference basis for clinical diagnosis and treatment of element-related diseases.


2019 ◽  
Author(s):  
Ingo Strenge ◽  
Carsten Engelhard

<p>The article demonstrates the importance of using a suitable approach to compensate for dead time relate count losses (a certain measurement artefact) whenever short, but potentially strong transient signals are to be analysed using inductively coupled plasma mass spectrometry (ICP-MS). Findings strongly support the theory that inadequate time resolution, and therefore insufficient compensation for these count losses, is one of the main reasons for size underestimation observed when analysing inorganic nanoparticles using ICP-MS, a topic still controversially discussed.</p>


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