scholarly journals REE, Y, Th, U and Mn systematics of Upper Devonian conodonts in the West Uralian Folded Zone (Southern Urals)

LITOSFERA ◽  
2019 ◽  
pp. 250-268
Author(s):  
A. V. Maslov ◽  
O. V. Artyushkova ◽  
R. Ch. Tagarieva ◽  
D. V. Kiseleva ◽  
M. V. Streletskaya ◽  
...  

Research subject. This article presents the results of a study undertaken to investigate the systematics of rare-earth elements (REE), Y, Th, U and Mn in the Upper Devonian conodonts of the Western Ural region of the foreland fold of the Southern Urals (Askyn and Makarovo horizons, Kukkarauk, Ryauzyak and Lemezinsky sections).Methods. The conodonts were isolated from carbonate rocks using the conventional method of their dissolution in organic acids, mainly formic acid. Sample preparation and mass spectrometric analysis were carried out in the class 1000 and 10 000 cleanroom facilities of the Zavaritsky Institute of Geology and Geochemistry. A PerkinElmer ELAN 9000 quadrupole ICP mass-spectrometer was used to determine the concentration of the trace elements under study. Sm and Nd isotope ratios were measured from a 3% nitric acid solution by a Thermo Fischer Neptune Plus multicollector inductively coupled plasma mass-spectrometer. The long-term reproducibility and accuracy of the measurement procedure were evaluated using a standard Merck Nd solution based on the NIST Nd2O3 and yielded 143Nd/144Nd = 0.511720 ± 15 (1 SD, n = 40).Results. The established features of PAAS-normalised lanthanide distributions in the conodont bulk samples (10.4–21.8 mg), Ce-anomalies, high REE values (173–1211 ppm) and a number of other parameters indicate the leading role of late diagenetic processes in the formation of conodont REE systematics. This is also evidenced by the Y/Ho values (≈26–32) specific for the studied conodont samples.Conclusions. In general, the distribution of lanthanides in the conodonts suggests that this process was mainly controlled by a lithogenic (from 90 to more than 99%) REE source. The εNd (t) (–4.0…–2.8) values characteristic of the cono donts of the Askyn and Makarovo horizons suggest that their Nd isotopic composition was either formed under the influence of the open ocean (island arc basin), characterised by a significant share of radiogenic Nd, or due to the entry of radiogenic waters of the ocean into the shelf zone at the peak of the marine transgression that took place in the region under consideration in the Famennian. 

LITOSFERA ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 212-223
Author(s):  
S. V. Pribavkin ◽  
A. V. Коrovko ◽  
I. A. Gottman

Research subject. The geological structure and rock composition of the Nizhne-Sinyachikhinsky plagiogranite massif, which is part of the Alapaevsk-Sukholozhsky zone, is promising for the Cu(Au,Mo)-porphyric mineralization type, were studied. The aim was to determine the formation features of these rocks and compare them with the productive granitoids of Ural porphyry deposits of similar age. Materials and methods. The mineral composition of the rocks was determined using a JEOL JSM 6790LV scanning electron microscope with an INCA Energy 450 X-Max 80 EDS spectrometer and a CAMECA SX-100 electron microprobe analyser. The rock composition was obtained by X-ray fluorescence spectrometry on a SRM-35 and XRF-1800 spectrometers with the titrimetric determination of FeO. The concentrations of rare and rare-earth elements were determined on an ELAN 9000 inductively coupled plasma mass spectrometer at the Geoanalitik Center for Collective Use of the Ural Branch of the Russian Academy of Sciences. Results. For the first time, an early tonalite-plagiogranite series was identified in the structure of the massif. This series is represented by tonalites of the hypabyssal appearance, broken through by the dikes of plagiogranite-porphyry. It was shown that the separation of plagiogranite-porphyry melts from magmas of the mafic composition occurred at the base of the island-arc construction, and their crystallisation was carried out in an intermediate chamber at a pressure of 1.8–2.3 kbar. In contrast, the plagiogranites of the main phase of the massif were separated from the parent melt in an intermediate chamber located at the level of the upper crust, and their crystallisation occurred at a pressure of 1.5–2.0 kbar. Conclusions. A comparison of the main phase plagiogranites and the isolated early-series plagiogranite-porphyry indicates their similar composition, as well as their similarity in age with the granitoids of the Southern Urals, productive in terms of the porphyry mineralisation type. The concentrations of F, Cl and S in the apatites and amphiboles of the rocks under study is an argument in favour of their belonging to andesitoid formations that are productive in terms of the Cu (Au)-porphyry mineralisation type. The absence of the sulphide mineralisation of this type can be explained by a more significant depth of rock formation and their erosion section.


LITOSFERA ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 573-591
Author(s):  
S. G. Kovalev ◽  
S. V. Michurin ◽  
A. V. Maslov ◽  
A. A. Sharipova

Research subject. The object of the study is the Ulyuk-Bar gold deposit ore-bearing rocks, located in the Bashkir meganticlinorium (the Southern Urals). Methods. The article presents the first data on the distribution of rare earth elements (REE), platinum group elements (PGE) and Au, obtained by inductively coupled plasma mass spectrometry (ICP-MS) on “ELAN- 6100 DRC” and “Agilent 7700” with the use of the computer data processing program “TOTALQUANT”, which includes automatic accounting of isotopic and molecular overlays on the mass spectral analytical lines of the determined elements. The chemical composition of ore minerals (native gold, pyrite, pyrrhotite, gersdorfite, chalcopyrite, arsenopyrite, and galena) was determined using an REMMA-202M scanning electron microscope with an LZ-5 X-ray energy-dispersive spectrometer and detectors for secondary and reflected electrons. Results. As a result of the studies, the enrichment of heavy lanthanides from ore-bearing rocks of the Ulyuk-Bar deposit in comparison with the sandstones and shales of the Bolshoi Inzer Formation outside of the ore field was established. It is shown that the noble-metal geochemical specialization of ore-bearing sediments of the Bolshoi Inzer Formation of the Ulyuk-Bar deposit is similar in a number of parameters to rocks of the Mashak Formation of the Shatak complex, formed under the influence of Middle Riphean magmatism on sedimentary rocks of the upper layers of the earth’s crust. Based on the calculation of the age of the minerals thorium and uranium, according to the isotopic studies of Rb-Sr (996 ± 26 Ma) and K-Ar (676–706 Ma) methods and galena by the Pb-Pb method (950 Ma), it was established that mineralization was formed in two stages. The first of which is associated with tectono-thermal activation at the border of the Middle and Late Riphean, and the second was realized about 600 Ma ago. Conclusions. It is concluded that the REE-EPG-Au taxonomy of ore-bearing deposits of the Ulyuk-Bar deposit is due to the polychrony and polygenicity of ore formation processes associated with the Middle Riphean plume magmatism, manifested over a vast territory, and the Late Vendian dynamothermal collisional metamorphism.


2011 ◽  
Vol 48 (2) ◽  
pp. 515-541 ◽  
Author(s):  
Yvon Lemieux ◽  
Thomas Hadlari ◽  
Antonio Simonetti

U–Pb ages have been determined on detrital zircons from the Upper Devonian Imperial Formation and Upper Devonian – Lower Carboniferous Tuttle Formation of the northern Canadian Cordilleran miogeocline using laser ablation – multicollector – inductively coupled plasma – mass spectrometry. The results provide insights into mid-Paleozoic sediment dispersal in, and paleogeography of, the northern Canadian Cordillera. The Imperial Formation yielded a wide range of detrital zircon dates; one sample yielded dominant peaks at 1130, 1660, and 1860 Ma, with smaller mid-Paleozoic (∼430 Ma), Neoproterozoic, and Archean populations. The easternmost Imperial Formation sample yielded predominantly late Neoproterozoic – Cambrian zircons between 500 and 700 Ma, with lesser Mesoproterozoic and older populations. The age spectra suggest that the samples were largely derived from an extensive region of northwestern Laurentia, including the Canadian Shield, igneous and sedimentary provinces of Canada’s Arctic Islands, and possibly the northern Yukon. The presence of late Neoproterozoic – Cambrian zircon, absent from the Laurentian magmatic record, indicate that a number of grains were likely derived from an exotic source region, possibly including Baltica, Siberia, or Arctic Alaska – Chukotka. In contrast, zircon grains from the Tuttle Formation show a well-defined middle Paleoproterozoic population with dominant relative probability peaks between 1850 and 1950 Ma. Additional populations in the Tuttle Formation are mid-Paleozoic (∼430 Ma), Mesoproterozoic (1000–1600 Ma), and earlier Paleoproterozoic and Archean ages (>2000 Ma). These data lend support to the hypothesis that the influx of sediments of northerly derivation that supplied the northern miogeocline in Late Devonian time underwent an abrupt shift to a source of predominantly Laurentian affinity by the Mississippian.


2014 ◽  
Vol 29 (6) ◽  
pp. 1132-1137 ◽  
Author(s):  
Lucia D'Ulivo ◽  
Lu Yang ◽  
Yong-Lai Feng ◽  
John Murimboh ◽  
Zoltán Mester

Accurate quantitation and characterization of organometals are successfully achieved by splitting the gas chromatography (GC) flow to both an electron ionization mass spectrometer (EIMS) and an inductively coupled plasma mass spectrometer (ICPMS).


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