Melt inclusions in olivines from phoscorites and olivinites of the Kovdor massif.

2020 ◽  
Author(s):  
Anna Redina ◽  
Cora Wohlgemuth-Ueberwasser ◽  
Julia Mikhailova ◽  
Gregory Ivanyuk
Keyword(s):  
Melt Inclusions ◽  
Trace Element Composition ◽  
Russian Science ◽  
Silicate Mineral ◽  
Mineral Phases ◽  
Icp Ms ◽  
Kola Alkaline Province ◽  
Negative Crystal ◽  
The Baltic ◽  
Silicate Carbonate

<p>The Kovdor massif is a part of the Paleozoic Kola alkaline province and located in the eastern part of the Baltic Shield. Kovdor carbonatites host a unique complex baddeleyite-apatite-magnetite deposit from which iron ores and zirconium have been mined. New data on melt inclusions in olivine crystals from phoscorites and olivinites of the ore complex are presented in this contribution. Daughter minerals in crystallized melt inclusions were identified by Raman spectroscopy and scanning electron microscopy. The trace element composition of inclusions was determined using LA-ICP-MS.</p><p>Melt inclusions in olivine from Kovdor phoscorites are negative crystal or round in shape, with sizes ranging from 5 to 50 microns. They form groups or line up. According to the mineral composition, two types of melt inclusions can be distinguished: carbonate and silicate-carbonate. In the first type, Ca-Na-Mg- (Sr?) - REE carbonates are dominant among daughter phases. In the second one, silicate phases (phlogopite, monticellite, diopside), Ca-Na-Mg carbonates and magnetite are found together. Melt inclusions in olivine from olivinites are isometric or elongated, 5–25 μm in size. They form groups or occur as isolated inclusions. Benstoneite, geylussit, ankerite, calcite and hydroxyl-bastnesite along with phyllosilicates (phlogopite, paragonite?) were identified among daughter minerals.</p><p>The rare earth elements composition of melt inclusions from both types of rocks is characterized by the predominance of light REE. The content of REE, especially light ones, in inclusions from phoscorites is higher. Strontium and barium contents in most melt inclusions have negative correlations with niobium and zirconium concentrations.</p><p>Melt inclusions from phoscorites and olivinites contain carbonate and silicate mineral phases in various proportions, which may imply heterogeneous trapping of crystalline phases and two immiscible melts, silicate and carbonatite. Inclusions from phoscorite represent a more evolved magma with higher concentrations of rare metals.</p><p>This work was supported by the Russian Science Foundation, grant No 19-17-00013.</p>

scholarly journals Polygenic Nature of Olivines from the Ultramafic Lamprophyres of the Terina Complex (Chadobets Upland, Siberian Platform) Based on Trace Element Composition, Crystalline, and Melt Inclusion Data

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 408
Author(s):  
Anastasiya Starikova ◽  
Ilya Prokopyev ◽  
Anna Doroshkevich ◽  
Alexey Ragozin ◽  
Vasily Chervyakovsky
Keyword(s):  
Melt Inclusions ◽  
Melt Inclusion ◽  
Trace Element Composition ◽  
Mantle Metasomatism ◽  
Negative Slope ◽  
Positive Slope ◽  
Melt Evolution ◽  
Different Sources ◽  
Two Populations ◽  
Silicate Carbonate

Olivine from the deep mantle-derived rocks, such as ultramafic lamprophyres, carries important information about the composition of the mantle source, the processes of mantle metasomatism, the origin of specific silicate-carbonate melts, as well as the composition and mechanisms of crystallization of these rocks. Textures and compositions of olivine from the carbonate-rich ultramafic lamprophyres (aillikites) of the Terina complex, along with their mineral and melt inclusions, exposed that olivines have different sources. Two populations of olivines were considered: macrocrysts (>1 mm) and groundmass olivines (<1 mm). Groundmass olivines are phenocrysts and characterized by weak variations in Mg# (84–86.5), a sharp increase in Ca and Ti contents, and a decrease in Ni and Cr from core to rim. They have higher concentrations of Li, Cu, Ti, and Na compared to macrocrysts. Among the macrocrysts, the following populations are observed: (1) high-Mg olivines (Mg# 89–91) with high Ni and low Ti contents, which are interpreted as xenocrysts from the slightly depleted lherzolite mantle; (2) high-Ca olivines (Mg# 84–88, CaO 0.13–0.21 wt %), which have patterns similar to groundmass olivines and are interpreted as cumulates of early portions of aillikite melt; (3) macrocrysts with wide variations in Mg# (73–88), low CaO contents (0.04–0.11 wt %), and positive slope in Ca vs. Al and negative slope in Ca vs. Mn, which are interpreted as disintegrated megacrysts from the Cr-poor megacryst suite. The megacryst suite could have been formed in the pre-trap period during the melting of the metasomatized subcontinental lithospheric mantle (SCLM). The aillikite melt evolution is traced by secondary melt inclusions in olivine macrocrysts: early phlogopite-diopside-calcite-apatite association, containing Ti-magnetite and ilmenite, is followed by an association with magnetite and sulfides (pyrrhotite and pentlandite); finally, at a late stage, inclusions with a predominance of Ca-Na-carbonates and sulfates and enriched in U, Th, Y, REEs, Sr, and Ba were captured.

A Raman spectroscopic study of the natural carbonophosphates Na3MCO3PO4 (M = Mn, Fe, and Mg)

2021 ◽  
Author(s):  
Ekaterina Fomina ◽  
Evgeniy Kozlov ◽  
Mikhail Sidorov ◽  
Vladimir Bocharov
Keyword(s):  
Natural Increase ◽  
Mineral Species ◽  
Raman Shift ◽  
Russian Science ◽  
Epma Data ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Mineral Phases ◽  
Vibrational Bands ◽  
Global Carbon

&lt;p&gt;Along with some other Na-minerals, carbonophosphates indicate a high initial Na activity in carbonatite and kimberlite melts, which is beneficial for petrological reconstructions. Because carbonophosphates are capable of incorporating large-ion lithophile and rare earth elements (REEs) in their structure, they can participate in the transport of these elements. Moreover, due to the presence of both [PO&lt;sub&gt;4&lt;/sub&gt;]&lt;sup&gt;3&amp;#8722;&lt;/sup&gt; and [CO&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;2&amp;#8722; &lt;/sup&gt;groups in carbonophosphates, these mineral phases play an important role in the Earth's global carbon and phosphate cycles. With all these properties, carbonophosphates have long attracted the attention of geologists. Raman spectroscopy appears to be one of the most suitable tools for their diagnosis, since they commonly present in rocks as small inclusions in other mineral grains. Despite this profit, only a few publications contain Raman characteristics of either natural or synthetic carbonophosphates.&lt;/p&gt;&lt;p&gt;We studied and compared Raman spectra of three natural carbonophosphate phases (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na&lt;sub&gt;3&lt;/sub&gt;MCO&lt;sub&gt;3&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; (M = Mn, Fe, and Mg, correspondingly). These spectra showed from 21 to 24 vibrational bands, of which the two most intense (963&amp;#177;5 cm&lt;sup&gt;-1&lt;/sup&gt; &amp;#1080; 1074&amp;#177;3 cm&lt;sup&gt;-1&lt;/sup&gt;) correspond to the &amp;#957;1(P&amp;#8211;O) and &amp;#957;1(C&amp;#8211;O) modes. These two bands split due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. A natural increase in the Raman shift was observed for most bands assigned to the same vibrations (the smallest shift in the spectrum is characteristic of sidorenkite, an intermediate - of bonshtedtite, and the largest - of bradleyite).&lt;/p&gt;&lt;p&gt;We propose the following algorithm for the diagnosis of carbonophosphates:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Checking minerals for belonging to the group of carbonophosphates by the main bands and the characteristic profile of the spectrum;&lt;/li&gt; &lt;li&gt;Testing the hypothesis that the mineral of question is bradleyite based on the analysis of the estimated shift of the main bands;&lt;/li&gt; &lt;li&gt;Diagnosis of a mineral species by peaks located between the main bands;&lt;/li&gt; &lt;li&gt;Validation of the diagnostics by considering the position of the bands at 185&amp;#177;9 cm&lt;sup&gt;-1&lt;/sup&gt;, 208&amp;#177;7 cm&lt;sup&gt;-1&lt;/sup&gt;, 255&amp;#177;5 cm&lt;sup&gt;-1&lt;/sup&gt;, and 725&amp;#177;6 cm&lt;sup&gt;-1&lt;/sup&gt;.&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;The proposed algorithm allows one to perform Raman diagnostics of carbonophosphates in inclusions even in the absence of EPMA data. In the study of carbonatites, kimberlites, and other rocks, the diagnostics of the mineral species of the carbonophosphate group can be important in the petrological aspect.&lt;/p&gt;&lt;p&gt;This research was funded by the Russian Science Foundation, grant number 19-77-10039.&lt;/p&gt;

Deconvolution of the composition of fine-grained pyrite in sedimentary matrix by regression of time-resolved LA-ICP-MS data

2020 ◽  
Vol 105 (6) ◽  
pp. 820-832 ◽  
Author(s):  
Aleksandr S. Stepanov ◽  
Leonid V. Danyushevsky ◽  
Ross R. Large ◽  
Indrani Mukherjee ◽  
Irina A. Zhukova
Keyword(s):  
Trace Elements ◽  
Regression Analysis ◽  
Trace Element ◽  
Sedimentary Rocks ◽  
Trace Element Composition ◽  
Element Composition ◽  
Silicate Matrix ◽  
Time Resolved ◽  
Icp Ms ◽  
Wide Range

Abstract Pyrite is a common mineral in sedimentary rocks and is the major host for many chalcophile trace elements utilized as important tracers of the evolution of the ancient hydrosphere. Measurement of trace element composition of pyrite in sedimentary rocks is challenging due to fine-grain size and intergrowth with silicate matrix and other sulfide minerals. In this contribution, we describe a method for calculation of trace element composition of sedimentary pyrite from time-resolved LA-ICP-MS data. The method involves an analysis of both pyrite and pyrite-free sediment matrix, segmentation of LA-ICP-MS spectra, normalization to total, regression analysis of dependencies between the elements, and calculation of normalized composition of the mineral. Sulfur is chosen as an explanatory variable, relative to which all regressions are calculated. The S content value used for calculation of element concentrations from the regressions is calculated from the total, eliminating the need for independent constraints. The algorithm allows efficient measurement of concentrations of multiple chalcophile trace elements in pyrite in a wide range of samples, including quantification of detection limits and uncertainties while excluding operator bias. The data suggest that the main sources of uncertainties in pyrite composition are sample heterogeneity and counting statistics for elements of low abundance. The analysis of regression data of time-resolved LA-ICP-MS measurements could provide new insights into the geochemistry of the sedimentary rocks and minerals. It allows quantification of ratios of elements that do not have reference material available (such as Hg) and provides estimates on the content of non-sulfidic Fe in the silicate matrix. Regression analysis of the mixed LA-ICP-MS signal could be a powerful technique for deconvolution of phase compositions in complex multicomponent samples.

Typomorphic gold features as criteria of placer association with primary gold-silver-type sources (example from Mnogovershinnoye ore placer cluster)

2020 ◽  
pp. 3-23
Author(s):  
Igor Migachev ◽  
Olga Minina ◽  
Vadim Zvezdov
Keyword(s):  
Crystal Morphology ◽  
Gold Cluster ◽  
Primary Source ◽  
Trace Element Composition ◽  
Element Composition ◽  
Primary Sources ◽  
X Ray ◽  
Icp Ms ◽  
Gold Silver ◽  
Comprehensive Study

A comprehensive study of native gold from Mnogovershinnoye gold cluster ores and placers (granulometry, crystal morphology, internal structure, nature of exogenetic transformations, fineness and trace element composition) was performed to define placer association with primary sources. Using ICP-MS method and X-ray spectrographic analysis, new data on geochemical gold features was obtained, which expands and clarifies the evidence of gold typomorphism from a gold-silver deposit primary source and its association with placers.

Marine macrophytes retain microplastics

2020 ◽  
Author(s):  
Irina Chubarenko ◽  
Elena Esiukova ◽  
Olga Lobchuk ◽  
Alexandra Volodina ◽  
Anastasiya Kupriyanova ◽  
...  
Keyword(s):  
Sea Water ◽  
Free Water ◽  
Russian Science ◽  
Southeastern Part ◽  
Marine Litter ◽  
Hand Pump ◽  
Marine Macrophytes ◽  
Zone Depth ◽  
The Baltic ◽  
Coccotylus Truncatus

&lt;p&gt;Plastic contamination of marine beaches, sediments, water is widely reported. It is known that lot of plastic debris appears on marine shores after storms together with natural marine litter, like ragged vegetation, pieces of wood, etc. The goal of our field campaign in the southeastern part of the Baltic Sea was to check whether growing macrophytes also concentrate and retain plastics, particularly that of microplastic (MP, 0.2-5 mm here) size range. Three summer expeditions were conducted (July 30, August 5 and 7, 2019) in sea coastal zone (depth down to 10 m), where communities of attached macroalgae (&lt;em&gt;Furcellaria lumbricalis, Coccotylus truncatus, Polysiphonia fucoides, Cladophora rupestris&lt;/em&gt;) are developed on underwater boulders off the Cape Taran. Samples were collected at 8 stations, covering areas with filamentous algae (at depths of 3.2 and 4 m) and with perennial algae furcellaria (depths of 5.6 and 8.2 m). Along with sampling of growing algae (from area 25x25 cm2 in triplicate), a hand pump was used to sample 20-100 liters of sea water from both algae thicket and algae-free water in surrounding area.&lt;/p&gt;&lt;p&gt;The samples were processed and examined in laboratory. Microplastic particles were found in all the collected samples. Preliminary analysis shows 1.3-5.3 times higher microplastic contamination in water samples taken from algae thicket than in samples taken in free water nearby. The majority of microparticles are fibers, mainly colorless and blue, but also red, black, golden, and yellow.&lt;/p&gt;&lt;p&gt;Investigations are supported by the Russian Science Foundation, grant No. 19-17-00041.&lt;/p&gt;

Arsenopyrite and As-bearing pyrite from the Roudný deposit, Bohemian Massif

2004 ◽  
Vol 68 (1) ◽  
pp. 31-46 ◽  
Author(s):  
J. Zachariáš ◽  
J. Frýda ◽  
B. Paterová ◽  
M. Mihaljevič
Keyword(s):  
Laser Ablation ◽  
Fluid Inclusion ◽  
Electron Microprobe ◽  
Gold Deposits ◽  
Fluid Inclusion Data ◽  
The Core ◽  
Trace Element Chemistry ◽  
Mineral Phases ◽  
Icp Ms ◽  
Substitution Mechanism

AbstractThe major- and trace-element chemistry of pyrite and arsenopyrite from the mesothermal Roudný gold deposits was studied by electron microprobe and laser ablation ICP-MS techniques. In total, four generations of pyrite and two of arsenopyrite were distinguished. The pyrite is enriched in As through an Fe (AsxS1–x)2 substitution mechanism. The As-rich zones of pyrite-2 (up to 4.5 wt.% As) are also enriched in gold (up to 20 ppm), lead (commonly up to 220 ppm, exceptionally up to 1500 ppm) and antimony (commonly <600 ppm, rarely up to 1350 ppm). Positive correlation of As and Au in the studied pyrites is not coupled with an Fe deficiency, in contrast to Au-rich As-bearing pyrites in Carlintype gold deposits. The As-rich pyrite-2 coprecipitated with the Sb-rich (1 –4.2 wt.%) and Au-rich (40 –150 ppm) arsenopyrite-1. The younger arsenopyrite-2 is significantly less enriched in these elements (0 –70 ppm of Au).The chemical zonality of pyrites in the Roudný gold deposits reflects the chemical evolution of orebearing fluids that are not observed in any other mineral phases. The data available suggest relatively high activity of sulphur and low activities of arsenic and gold during crystallization of the older pyrite generation (pyrite-1). Later, after particular dissolution of pyrite-1, Au-rich As-bearing pyrite-2 and arsenopyrite precipitated. These facts suggest a marked increase in the arsenic and gold activities in ore-bearing fluids. The As-content of pyrite-2 decreases in an oscillatory manner from the core to the rim, reflecting changes in the As activity or/and in the P-T conditions. The As-bearing pyrites were formed at temperatures of at least 320–330°C, based on arsenopyrite thermometers and fluid inclusion data.

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