MINERAL FORMATION CONDITIONS IN ACID MAGMATIC SYSTEMS RELATED TO THE FORMATION OF MASSIVE SULFIDE DEPOSITS OF THE URALS AND ALTAI-SAYANY AREA
Studies of melt inclusions in quartz indicate the similarity of acid magmatic systems of massive sulfide deposits in the Urals and Altai-Sayany region. The melts of normal alkalinity corresponding to rhyodacite and rhyolite compositions related to the tholeiitic series are dominant in all the deposi...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
South Urals Federal Research Center of Mineralogy and Geoecology UB RAS
2021-12-01
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| Series: | Минералогия |
| Subjects: | |
| Online Access: | https://journal.mineralogy.ru/wp-content/uploads/2021/12/2021_7_4_1.pdf |
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| Summary: | Studies of melt inclusions in quartz indicate the similarity of acid magmatic systems of massive sulfide deposits in the Urals and Altai-Sayany region. The melts of normal alkalinity corresponding to rhyodacite and rhyolite compositions related to the tholeiitic series are dominant in all the deposits considered. The magmas are characterized by the same type evolution with a decreasing content of main oxides (TiO2 , Al2 O3 , FeO, MgO, CaO, Na2 O, K2 O) and an increasing SiO2 content. Our results show the accumulation of Cu in relatively low-H2 O acidic melts of ancient (Cambrian) deposits of the Altai-Sayany region and low metal contents in the intermediate (Silurian–Devonian) and H2 O-saturated magmas of the Urals. The youngest (Devonian) magmas of Siberia evolve simultaneously along these two directions. The analysis of melt inclusions in quartz suggests that the minimum contents of trace and rare earth elements are characteristic of the SilurianDevonian acid melts of the Urals, with their maximum contents in the youngest (Devonian) magmas and the intermediate contents of ancient (Cambrian) magmatic systems of the Altai-Sayany region. The features of rare and rare earth element patterns in melt inclusions in quartz indicate the similarity of acid magmatic systems of massive sulfide deposits in the Urals and Altai-Sayany region with present-day suprasubduction melts in the ocean-continent transition zones. Computational modeling using data on melt inclusions in quartz confirms our previous conclusions (Simonov, Maslennikov, 2020) that the occurrence of contrasting (basic and felsic) volcanic complexes with massive sulfide deposits in the Urals and Altai-Sayany region is a result of evolution of basaltoid magmas. |
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| ISSN: | 2313-545X 2782-2044 |