scholarly journals U-Pb zircon age of a sheeted dike complex in ophiolites in the structure of the Revdinsky massif, Ural Рlatinum Belt

LITOSFERA ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 849-866
Author(s):  
S. V. Berzin ◽  
V. S. Chervyakovsky

Research subject. A tectonic block of ophiolites, corresponding to the root zone of a sheeted dike complex, in the eastern part of the Revdinsky massif of the Platinum-bearing belt of the Urals (UPB).Materials and methods. Zircons for dating were collected in the first-generation dolerite dikes of the sheeted dike complex under study, which had been previously considered as Ordovician. U-Pb dating of zircons was performed by LA-ICP-MS on a NexION 300S quadrupole mass spectrometer with a laser ablation attachment NWR 213.Results. Zircons with an age of 425.6 ± 2.9 Ma are characterized by primary magmatic zoning and apparently correspond to the time of intrusion of the sheeted dike complex. In zircons with an age of 404.0 ± 2.9 Ma, inclusions of metamorphogenic minerals (amphibole, chamosite, quartz, clinozoisite) were discovered. This age reflects rock recrystallization or metamorphism, for example, during the intrusion of later vein rocks of the diorite-tonalite series or dolerite dikes of the second generation. Three points of determination showed a younger age of 362 ± 5.6 Ma, probably reflecting the time of metamorphism at the beginning of collisional processes. Conclusions. For the first time, the Silurian U-Pb age of zircons (LA-ICP-MS) was obtained for the ophiolite block (root zone of the sheeted dike complex) in the structure of the Revdinsky massif UPB. The obtained age of intrusion of the sheeted dike complex (425.6 ± 2.9 Ma) coincides with the age of zircons (428.5 ± 3.7 Ma) from gabbro screens in sheeted dikes of the East Ural zone determined earlier (Smirnov, Ivanov, 2010) and corresponds to the time of spreading over the subduction zone in the Middle Urals.

2008 ◽  
Vol 9 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Adolphe Nicolas ◽  
Françoise Boudier ◽  
Jurgen Koepke ◽  
Lydéric France ◽  
Benoît Ildefonse ◽  
...  

VASA ◽  
2009 ◽  
Vol 38 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Schubert

We describe a case of aortic coarctation at the level of the infrarenal abdominal aorta which is encountered in less than six individuals in one million. In contrast to aortic narrowing above or including the renal arteries, this seems to be a relatively benign anomaly without systemic hypertension or impaired renal function. For the first time in this type of anomaly, contrast-enhanced MR angiography (ce-MRA) on a multi-receiver channel MR system, with an 8-channel phased array coil and parallel imaging was used. Ce-MRA displayed a tortuous, narrowed aortic segment that was found to be associated with mesenteric artery stenosis and compression of the orthotopic left renal vein, also known as the nutcracker phenomenon. All major aortic branches could be depicted using 3D surface-shaded displays and subvolume maximum intensity projections (MIPs). Collateral vessels of the abdominal wall were identified using whole-volume MIPs. Since the majority of aortic malformations are diagnosed at a younger age, and many suffer from renal insufficiency, we conclude that ce-MRA will eventually place conventional DSA as the modality of choice in malformations of the abdominal aorta.


Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 934
Author(s):  
Evangelos Tzamos ◽  
Micol Bussolesi ◽  
Giovanni Grieco ◽  
Pietro Marescotti ◽  
Laura Crispini ◽  
...  

The importance of magnesite for the EU economy and industry is very high, making the understanding of their genesis for the exploration for new deposits a priority for the raw materials scientific community. In this direction, the study of the magnesite-hosting ultramafic rocks can be proved very useful. For the present study, ultramafic rock samples were collected from the magnesite ore-hosting ophiolite of the Gerakini mining area (Chalkidiki, Greece) to investigate the consecutive alteration events of the rocks which led to the metallogenesis of the significant magnesite ores of the area. All samples were subjected to a series of analytical methods for the determination of their mineralogical and geochemical characteristics: optical microscopy, XRD, SEM, EMPA, ICP–MS/OES and CIPW normalization. The results of these analyses revealed that the ultramafic rocks of the area have not only all been subjected to serpentinization, but these rocks have also undergone carbonation, silification and clay alteration. The latter events are attributed to the circulation of CO2-rich fluids responsible for the formation of the magnesite ores and locally, the further alteration of the serpentinites into listvenites. The current mineralogy of these rocks was found to be linked to one or more alteration event that took place, thus a significant contribution to the metallo- and petrogenetic history of the Gerakini ophiolite has been made. Furthermore, for the first time in literature, Fe inclusions in olivines from Greece were reported.


Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 783-794 ◽  
Author(s):  
Natalia E Zaretskaya ◽  
Sönke Hartz ◽  
Thomas Terberger ◽  
Svetlana N Savchenko ◽  
Mikhail G Zhilin

Two well-known archaeological sites, the peat bogs of Shigir and Gorbunovo (Middle Urals, Russia), have been radiocarbon dated (61 conventional and accelerator mass spectrometry [AMS] dates from various natural and artifact samples). For the first time, a detailed chronology of Early to Late Mesolithic and Early Neolithic occupation for this region has been obtained, and a paleoenvironmental history reconstructed. Based on these results, we propose that the Mesolithic settlement of the Middle Urals region started in the early Holocene, at the same time as in central and eastern Europe.


Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1236
Author(s):  
Sylwia Svorová Pawełkowicz ◽  
Barbara Wagner ◽  
Jakub Kotowski ◽  
Grażyna Zofia Żukowska ◽  
Bożena Gołębiowska ◽  
...  

Impurities in paint layers executed with green and blue copper pigments, although relatively common, have been studied only little to date. Yet, their proper identification is a powerful tool for classification of paintings, and, potentially, for future provenance studies. In this paper, we present analyses of copper pigments layers from wall paintings situated in the vicinity of copper ore deposits (the palace in Kielce, the palace in Ciechanowice, and the parish church in Chotków) located within the contemporary borders of Poland. We compare the results with the analyses of copper minerals from three deposits, two local, and one historically important for the supply of copper in Europe, i.e., Miedzianka in the Holy Cross Mountains, Miedzianka in the Sudetes, and, as a reference, Špania Dolina in the Slovakian Low Tatra. Optical (OM) and electron microscopy (SEM-EDS), Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have been used for a detailed investigation of the minute grains. Special attention has been devoted to antimony and nickel phases, as more unusual than the commonly described iron oxides. Analyses of minerals from the deposits helped to interpret the results obtained from the paint samples. For the first time, quantitative analyses of copper pigments’ impurities have been described.


2013 ◽  
Vol 150 (6) ◽  
pp. 1103-1126 ◽  
Author(s):  
DETA GASSER ◽  
ARILD ANDRESEN

AbstractThe tectonic origin of pre-Devonian rocks of Svalbard has long been a matter of debate. In particular, the origin and assemblage of pre-Devonian rocks of western Spitsbergen, including a blueschist-eclogite complex in Oscar II Land, are enigmatic. We present detrital zircon U–Pb LA-ICP-MS data from six Mesoproterozoic to Carboniferous samples and one U–Pb TIMS zircon age from an orthogneiss from Oscar II Land in order to discuss tectonic models for this region. Variable proportions of Palaeo- to Neoproterozoic detritus dominate the metasedimentary samples. The orthogneiss has an intrusion age of 927 ± 3 Ma. Comparison with detrital zircon age spectra from other units of similar depositional age within the North Atlantic region indicates that Oscar II Land experienced the following tectonic history: (1) the latest Mesoproterozoic sequence was part of a successor basin which originated close to the Grenvillian–Sveconorwegian orogen, and which was intruded byc. 980–920 Ma plutons; (2) the Neoproterozoic sediments were deposited in a large-scale basin which stretched along the Baltoscandian margin; (3) the eclogite-blueschist complex and the overlying Ordovician–Silurian sediments probably formed to the north of the Grampian/Taconian arc; (4) strike-slip movements assembled the western coast of Spitsbergen outside of, and prior to, the main Scandian collision; and (5) the remaining parts of Svalbard were assembled by strike-slip movements during the Devonian. Our study confirms previous models of complex Caledonian terrane amalgamation with contrasting tectonic histories for the different pre-Devonian terranes of Svalbard and particularly highlights the non-Laurentian origin of Oscar II Land.


2021 ◽  
pp. 014556132110498
Author(s):  
Xiaoli Qu ◽  
Yang Xiao ◽  
Lijing Ma ◽  
Jun Wang

Objectives The lesion distribution of juvenile-onset recurrent respiratory papillomatosis (JORRP) during first-time surgery has been rarely reported. The purpose of this study was to describe the anatomical distribution of papilloma across 25 Derkay sites during initial surgery and to assess the impact of the lesion distribution on disease severity. Methods Surgical videos and medical records of 106 patients with JORRP (27 aggressive and 79 nonaggressive cases) were retrospectively reviewed. Lesion locations were recorded using Derkay anatomical sites. Logistic regression was used to analyze the effect of the lesion distribution on disease severity. Results Among the 106 patients, the true vocal cords (90.6% left, 84.0% right) were the most frequently involved site, followed by the false vocal cords (39.6% left, 35.8% right) and the anterior commissure (26.4%). Two patients (1.9%) had tracheal involvement. Patients with false vocal cord involvement (odds ratio [OR] = 3.425, 95% confidence interval [CI] [1.285, 9.132], P = .014) and a younger age at diagnosis (OR = .698, 95% CI [.539, .905], P = .007) were more likely to require more than 4 procedures in the year following first-time surgery. Conclusions Lesions were most common on the true vocal cords. False vocal cord involvement and a younger age at diagnosis were risk factors for disease severity.


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