scholarly journals The Overmaraat-Gol Alkaline Pluton in Northern Mongolia: U–Pb Age and Preliminary Implications for Magma Sources and Tectonic Setting

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 170 ◽  
Author(s):  
Vassily Vrublevskii ◽  
Igor Gertner ◽  
Richard Ernst ◽  
Andrey Izokh ◽  
Andrey Vishnevskii

A new Wenlockian zircon U–Pb age (~426 Ma) of the Overmaraat-Gol nepheline syenite (foyaite, juvite) pluton in the SW Lake Hovsgol area (Northern Mongolia) prompts a long history of alkaline magmatism in the western Central Asian Orogenic Belt, exceeding the duration of the Devonian and Permian–Triassic events. The LILE and HFSE patterns of pluton samples analyzed by X-ray fluorescence (XRF) and inductively coupled plasma (ICP-MS) methods indicate intrusion in a complex tectonic setting during interaction of a mantle plume with accretionary-collisional complexes that previously formed on the active continental margin. As a result, the parent magma had a heterogeneous source with mixed mantle (PREMA and EM) and crustal components. This source composition is consistent with Nd–Sr isotope ratios of the Overmaraat-Gol alkaline rocks, from −0.1 to −1.2 εNd(t) and from ~0.706 to 0.707 87Sr/86Sr(t).

2009 ◽  
Vol 60 (6) ◽  
pp. 495-504 ◽  
Author(s):  
Ioan Balintoni ◽  
Constantin Balica ◽  
Monica Cliveţi ◽  
Li-Qiu Li ◽  
Horst Hann ◽  
...  

The emplacement age of the Muntele Mare Variscan granite (Apuseni Mountains, Romania)Like the Alps and Western Carpathians, the Apuseni Mountains represent a fragment of the Variscan orogen involved in the Alpine crustal shortenings. Thus the more extensive Alpine tectonic unit in the Apuseni Mountains, the Bihor Autochthonous Unit is overlain by several nappe systems. During the Variscan orogeny, the Bihor Unit was a part of the Someş terrane involved as the upper plate in subduction, continental collision and finally in the orogen collapse and exhumation. The Variscan thermotectonic events were marked in the future Bihor Unit by the large Muntele Mare granitoid intrusion, an S-type anatectic body. Zircon U-Pb laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) dating yielded a weighted mean age of 290.9 ± 3.0 Ma and a concordia age of 291.1 ± 1.1 Ma. U-Pb isotope dilution zircon analyses yielded a lower intercept crystallization age of 296.6 + 5.7/-6.2 Ma. These two ages coincide in the error limits. Thus, the Muntele Mare granitoid pluton is a sign of the last stage in the Variscan history of the Apuseni Mountains. Many zircon grains show inheritance and/or Pb loss, typical for anatectic granitoid, overprinted by later thermotectonic events.


2017 ◽  
Vol 64 (1) ◽  
pp. 35-52 ◽  
Author(s):  
Emmanuel E. Adiotomre ◽  
Innocent O. Ejeh ◽  
Edwin O. Adaikpoh

Abstract Geochemical analysis of fluvial sediments on the banks of River Ero using inductively coupled plasma mass spectrometry illustrates their maturity, provenance and tectonic setting. The analysed sediment samples show low SiO2/Al2O3 ratios of 2.92-2.99 (units FL_A, FL_B and FL_E) and high SiO2/Al2O3 ratios of 4.064-4.852 (units FL_C, FL_D, FL_F and FL_G). Sediments were geochemically classified as shales (units FL_A, FL_B and FL_E) and greywackes (units FL_C, FL_D, FL_F and FL_G). Variability in sediment maturity (FL_F > FL_G >FL_C >FL_D >FL_A > FL_B > FL_E) parallels a decreasing order in the ratios of SiO2/Al2O3 and K2O/Al2O3, as well as the proportion of quartz grains and matrix components. Evidence from Al2O3/TiO2, K2O, Rb, La/Co, Th/Co, Cr/ Th, Th/Cr, La/Th-Hf, Th-Hf-Co and rare earth element contents of sediment samples suggest felsic protoliths of upper continental crust in a passive margin tectonic setting. An insignificant contribution of mafic components from the source is, however, inferred based on the Ni and Cr contents of the sediment samples. Combined Eu anomalies <0.85 and (Gd/Yb)n ratios <2.0 (1.53- 1.82, average 1.65) suggest post-Archean protoliths.


2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mohammed Olatoye Adepoju ◽  
Yinusa Ayodele Asiwaju-Bello

Chemical whole-rock major oxides and some trace element analyses were done on granitic gneiss rocks located on the southeastern margin of western Nigeria Basement Complex, exposed in parts of Dagbala-Atte District, southwestern Nigeria. This was meant to classify the rocks and to understand the tectonic setting in order to evaluate their crustal evolution. The chemical analyses were done using inductively-coupled plasma mass spectrometer. From the results obtained, these rocks classified into calc-alkaline to shoshonite series with metaluminous to peraluminous varieties, they are I-type granitoids of feroan composition. The granitic gneisses formed from metamorphism of granite and granodiorite. Tectonically, most of the rock samples plotted in the field of island arc, continental arc and continental-collisional granitoids, which indicated that the protolith granite and granodiorite are orogenic and are arc related inferring arc tectonic setting.


1995 ◽  
Vol 52 (7) ◽  
pp. 1421-1430 ◽  
Author(s):  
Anthony J. Fowler ◽  
Steven E. Campana ◽  
Simon R. Thorrold ◽  
Cynthia M. Jones

Retrospective determination of the early life history of fish using the microelemental analysis of their otoliths is dependent upon understanding the factors that affect this elemental composition. Here, juvenile Atlantic croaker (Micropogonias undulatus) were reared under different treatments of temperature and salinity to determine their impacts on elemental inclusion rates in otoliths. Solution-based inductively coupled plasma mass spectrometry (ICPMS) was used to measure 21 isotopes in each otolith: isotopic concentrations ranged over seven orders of magnitude, and differed significantly amongst the temperature–salinity regimes. Univariate analyses identified 13 isotopes that contributed to these multivariate differences; the influence of temperature was stronger than that of salinity. Within each treatment there was a significant relationship between otolith microchemistry and otolith size. To some extent this confounded the interpretation of the between-treatment effect of temperature. In contrast, both the otolith and somatic growth rates were similar between the two salinity treatments, indicating that differences in elemental fingerprints were unambiguously related to the salinity difference, probably a response to the elemental concentrations in the tank water. Overall the study highlighted the current poor understanding of the mechanism of contamination of otoliths by trace elements and their incorporation into the otolith microstructure.


2021 ◽  
Author(s):  
Ariuntsetseg Ganbat ◽  
Tatsuki Tsujimori ◽  
Laicheng Miao ◽  
Inna Safonova ◽  
Daniel Pastor-Galán ◽  
...  

The Mongol–Okhotsk Belt, the youngest segment of the Central Asian Orogenic Belt, formed by the evolution and closure of the Mongol–Okhotsk Ocean. The oceanic closure formed two volcanoplutonic belts: Selenge Belt in the north and Middle Gobi Belt in the south (in present day coordinates). However, the origin and tectonic evolution of the Mongol–Okhotsk Belt in general, the origin and formation age of the Middle Gobi Belt in particular, remain enigmatic. To better understand the history of the magmatic activity in the Middle Gobi Belt, we conducted geochemical, U–Pb geochronological, zircon Hf, whole-rock Nd isotopic analyses of volcanic and plutonic rocks of the Mandalgovi suite, the major component of the Middle Gobi Belt. Our results show that the Mandalgovi suite consists of (i) 265 ± 2 Ma biotite-granite; (ii) 250 ± 3 Ma hornblende-granitoids; (iii) their volcanic equivalents of both: and (iv) gabbro-diorites. The geochemical compositions indicate that their precursor magmas were derived from crustal source. The protoliths of the biotite and hornblende-granitoids were metagraywacke and metabasalt, respectively. They are characterized by positive whole-rock εNd(t) and zircon εHf(t) values, indicating the molten protoliths were juvenile crust. The biotite-granites formed by remelting of fore-arc sediments by ridge subduction and later hornblende-granites were emplaced at an intra-oceanic arc by the subduction of the Mongol–Okhotsk Ocean. We conclude that the magmatic rocks of the Middle Gobi formed in an active continental margin and/or intra-oceanic arc setting.


Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1034
Author(s):  
Chang Liu ◽  
Heng Xie ◽  
Lei Nie ◽  
Hong Wang ◽  
Yuanyuan He

Pottery is a gem in the history of human civilization and a crystallization of human wisdom. Yunnan Jianshui purple pottery is one of the four famous types of pottery in China, with a long history and superb craftsmanship. Used as tableware, research on the composition and element dissolution of pottery is extremely significant for production and health. This paper takes Jianshui purple pottery as its research object, samples its raw ores and finished products, and conducts X-ray fluorescence, scanning electron microscopy, inductively coupled plasma mass spectrometry experiments, and dissolution tests. The chemical composition, microstructure, and trace element concentrations of pottery before and after firing were measured. Results show that the dissolution of purple pottery under various use scenarios is low and meets health requirements. Combined with the characteristics of purple pottery, the composition changes and the mechanism of change before and after firing are discussed, which can be used as the theoretical basis for improving pottery production in the future.


2019 ◽  
Vol 13 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Karim Jafari ◽  
Saeed Rahimzadeh ◽  
Somayeh Hekmatfar

Background. Mouthwashes are widely used as adjuncts to mechanical oral hygiene procedures. Nonetheless, there is little information regarding the effect of various mouthwashes on the amount of ions released from the nickel-chromium (Ni‒Cr) alloys used in the fabrication of fixed prostheses. Therefore, the present study was conducted to evaluate the effect of two types of mouthwash on the release of Ni ions from dental alloys. Methods. Forty-two disk-shaped specimens were prepared with a diameter of 10 mm and a height of 2 mm. Two mouthwashes were examined in this study: Oral B and Listerine. A control group was also considered using distilled water. Each Ni‒Cr disk was immersed in the mouthwashes and distilled water in polypropylene test tubes, and then incubated at 37°C to simulate the oral temperature. After 45 days of incubation, the samples were tested for Ni ions using inductively coupled plasma mass spectroscopy. Data were analyzed using ANOVA. Results. In the Halita group subjects exhibited 2.04±0.65 reduction in OLS. OLS reduction in the chlorhexidine group was 1.95±0.74. Statistical analysis showed no significant difference between the two groups (P>0.05). Conclusion. As the results indicated, the amount of ion release was within the safe limits in the two experimental groups. However, it is recommended that prescribe Listerine mouthwash should not be prescribed for the patients with a history of Ni allergy.


Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 415
Author(s):  
Nadezhda Krivolutskaya ◽  
Boris Belyatsky ◽  
Bronislav Gongalsky ◽  
Alexander Dolgal ◽  
Andrey Lapkovsky ◽  
...  

The origin of the Siberian trap province is under discussion even though numerous models of its formation have been created over the last three decades. This situation is mainly due to lack of modern geochemical data on magmatic rocks around the province. These data are a very important tool to reconstruct of magmatic evolution within the province in time and space and to understand a mechanism of province formation. Geochemical study has only been carried out so far for the Norilsk and Meimecha–Kotuy areas. For the first time, we have studied the geochemical and mineralogical characteristics of magmatic rocks at the Kulyumber river valley located 150 km to south from the Norilsk ore district, in the junction of the Tunguska syneclise and Norilsk–Igarka zone. It comprises three sites, i.e., Khalil, Kaya, and Kulyumber. The geochemical data on the magmatic rocks of the Khalil and Kaya sites were published earlier (Part I). This article (Part II) regards geochemical and mineralogical data on igneous rocks at the Kulyumber site. Seventeen intrusive bodies (41 samples) and six samples of sedimentary rocks were studied by X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). Isotopes analyses (Sr, Nd, Pb) were conducted for 12 samples. These data were compared with data for intrusions of the Norilsk area, the Dzhaltulsky massif, Kureyka river, and intrusions in Angara river valley published earlier. The whole list of analyses includes 102 items. Three groups of intrusive rocks were recognized: (1) Mafic rocks with elevated K2O without negative Ta-Nb and Pb-positive anomalies, with (Gd/Yb)n = 2.0 and εNd = −1.0; attributed to a new Kulyumbinsky complex; (2) subalkaline rocks with elevated SiO2,TiO2, P2O5, and K2O with small negative Ta-Nb and positive Pb anomalies and (Gd/Yb)n = 1.8, εNd = −3.8; Ergalakhsky complex; and (3) mafic rocks with strong Ta-Nb and Pb anomalies and (Gd/Yb)n = 1.2–1.4, εNd = +0.4–+2.2. The third group is rather nonhomogeneous and includes intrusions of the Norilsk, Kuryesky, Katangsky, Ogonersky, and Daldykansky complexes differing in MgO content and trace element distribution (values of Ta-Nb, Pb, and Sr anomalies). Three groups of intrusive bodies had different magma sources and different condition of crystallization reflecting their origin in rift and platform regimes.


2021 ◽  
Author(s):  
Michael Edirin Okiotor ◽  
EDeh Desiree Ogueh

Abstract The present study investigates the Anambra Basin shales to determine the provenance and maturity of the sediments using standard geochemical techniques. Twelve (12) representative samples recovered from shale sequences of The Mamu Formation and Nkporo Group of The Anambra Basin were studied to determine the sediment provenance, paleoenvironment, diagenetic conditions, maturity as well as the tectonic setting. To consider in detail and establish the inherent constituents of the Major minerals, Trace and Rare Earth elements, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analyses techniques was employed. The detrital minerals determined are Al2O3 (18.27% and 21.16%), TiO2 (1.73% and 1.63%) and Fe2O3 (2.78% \ and 2.85%), for Nkporo Group and Mamu Formation respectively. The enrichment of SiO2, Al2O3 and TiO2 (1.14, 1.94, 3.67 respectively) supported by Chemical Index of Alteration (CIA) of 93.54 & 39.55 and Rb/Sr ratio of 0.57 & 0.40, indicate that the Anambra Basin sediments are matured. TiO2/AL2O3 binary plots, Th/Co Vs La/Sc crossplots, Th-Sc-Zr triplots and Cr, Ni concentration suggest mixed provenance of felsic to mafic source rocks for these sediments. From the log (K2O/Na2O) Vs SiO2 crossplots, a passive margin tectonic setting was determined for these sediments.


1993 ◽  
Vol 39 (8) ◽  
pp. 1650-1655 ◽  
Author(s):  
J Yoshinaga ◽  
Y Shibata ◽  
M Morita

Abstract Flow injection-inductively coupled plasma mass spectrometry has been evaluated for determining the distribution profile of trace elements along a single strand of hair. Hair was cut into several mm long sections from follicle to the distal end. Each section was solubilized in a capped 1.5-mL polypropylene tube with small volume of nitric acid (typically 50 microL) at room temperature. After dilution an aliquot (50 microL) was introduced into the mass spectrometer by flow injection. The limit of determination was typically 5-50 pg with 5-10% precision (CV), depending on the element examined; this corresponds to sub-microgram/g concentrations of these elements in hair segments. Recent exposure and intake history of individuals to thallium or mercury could be reconstructed by this system.


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