Sapphire-bearing magmatic rocks trace the boundary between paleo-continents: A case study of Ilmenogorsky alkaline complex, Uralian collision zone of Russia

Gem corundum (mainly ruby) occurrences are commonly associated with orogenic belts. Corundum deposits of metamorphic origin are known as robust indicators of continent-continent collision tectonic events. Although sapphire-bearing primary magmatic deposits are also found in orogenic belts, their link to continental collision process remains poorly understood. Here we show that primary igneous blue sapphire occurrences in the Ilmenogorsky alkaline complex of Ilmen Mountains in Uralian orogenic belt are indicative of the continent-continent collision processes among Kazakhstania, Laurussia, and Siberia 330 &#8211; 250 Ma ago (Sorokina et al. 2017).The results of geochemical, mineralogical, and geochronological research of corundum syenite pegmatites demonstrate that in situ primary magmatic corundum-bearing mineral assemblages can be used to evaluate the formation conditions and the time constraints of magmatic processes imposed by tectonic activity during orogenesis.Thus, the corundum syenite pegmatites have recorded a multistage evolution of the Ilmenogorsky complex. They crystallized at temperatures of 700 &#8211; 750&#176;C at 275 and 295 Ma ago (in situ LA-ICP-MS U-Pb zircon dating) within the timeframe of the continental collision of the Uralian orogeny. The isotopic signatures show a geochemical link of these deposits to nepheline syenites &#8211; miaskites of the main igneous body in Ilmenogorsky complex. While, some corundum syenite-pegmatites express the metamorphic overprint at temperatures of 700 &#8211; 780&#176;C occurred 249 &#177; 2Ma ago (TISM Rb-Sr isotopy) during limited post-collision stretching period in the area of Ilmenogorsky complex (Sorokina et al. 2021). Hence, these results imply that primary magmatic corundum deposits can be used as an important indicator of continental collision events.References:<div> 1.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Sorokina E.S., Botcharnikov R., Kostitsyn Yu.A., R&#246;sel D., H&#228;ger T., Rassomakhin M.A., Kononkova N.N., Somsikova A.V., Berndt J., Ludwig T., Medvedeva E.V., Hofmeister W. (2021). Sapphire-bearing magmatic rocks trace the boundary between paleo-continents: a case study of Ilmenogorsky alkaline complex, Uralian collision zone of Russia. Gondwana research 2021 (in press). 2.&#160; Sorokina, E.S., Karampelas, S., Nishanbaev, T.P., Nikandrov, S.N., Semiannikov, B.S., (2017). Sapphire Megacrysts in Syenite Pegmatites from the Ilmen Mountains, South Urals, Russia: New Mineralogical Data. Canadian Mineralogist 55, 823&#8211;843 </div>

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Application of the Method of Statistical Comparison of XRD-and XRF-Data for Identification of the Most Representative Rock Samples: A Case Study of an Extensive Collection of Carbonatites and Aluminosilicate Rocks of the Kontozero Alkaline Complex (Kola Peninsula, NW Russia)

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/609/1/012050 ◽

2020 ◽

Vol 609 ◽

pp. 012050

Author(s):

Ekaterina Fomina ◽

Evgeniy Kozlov

Keyword(s):

Kola Peninsula ◽

Alkaline Complex ◽

Statistical Comparison ◽

Rock Samples ◽

Extensive Collection

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Genesis and stability of accessory phosphates in silicic magmatic rocks: a Western Carpathian case study

Mineralogia ◽

10.2478/v10002-008-0004-6 ◽

2008 ◽

Vol 39 (1-2) ◽

pp. 53-66 ◽

Cited By ~ 5

Author(s):

Igor Broska ◽

Igor Petrík

Keyword(s):

Oxidation State ◽

Physical Factors ◽

Early Stages ◽

Magma Composition ◽

Magmatic Rocks ◽

The Stability ◽

Degree Of Differentiation

Genesis and stability of accessory phosphates in silicic magmatic rocks: a Western Carpathian case studyThe formation of accessory phosphates in granites reflects many chemical and physical factors, including magma composition, oxidation state, concentrations of volatiles and degree of differentiation. The geotectonic setting of granites can be judged from the distribution and character of their phosphates. Robust apatite crystallization is typical of the early magmatic crystallization of I-type granitoids, and of late magmatic stages when increased Ca activity may occur due to the release of anorthite from plagioclase. Although S-type granites also accumulate apatite in the early stages, increasing phosphorus in late differentiates is common due to their high ASI. The apatite from the S-types is enriched in Mn compared to that in I-type granites. A-type granites characteristically contain minor amounts of apatite due to low P concentrations in their magmas. Monazite is typical of S-type granites but it can also become stable in late I-type differentiates. Huttonite contents in monazite correlate roughly positively with temperature. The cheralite molecule seems to be highest in monazite from the most evolved granites enriched in B and F. Magmatic xenotime is common mainly in the S-type granites, but crystallization of secondary xenotime is not uncommon. The formation of the berlinite molecule in feldspars in peraluminous melts may suppress phosphate precipitation and lead to distributional inhomogeneities. Phosphate mobility commonly leads to the formation of phosphate veinlets in and outside granite bodies. The stability of phosphates in the superimposed, metamorphic processes is restricted. Both monazite-(Ce) and xenotime-(Y) are unstable during fluid-activated overprinting. REE accessories, especially monazite and allanite, show complex replacement patterns culminating in late allanite and epidote formation.

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Anatexis of former arc magmatic rocks during oceanic subduction: A case study from the North Wulan gneiss complex

Gondwana Research ◽

10.1016/j.gr.2018.04.016 ◽

2018 ◽

Vol 61 ◽

pp. 128-149 ◽

Cited By ~ 12

Author(s):

Xiucai Li ◽

Manlan Niu ◽

Chris Yakymchuk ◽

Zhen Yan ◽

Changlei Fu ◽

...

Keyword(s):

The North ◽

Magmatic Rocks ◽

Gneiss Complex

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Volume characteristics and element transfer of fenite aureoles: a case study from the Iivaara alkaline complex, Finland

Lithos ◽

10.1016/s0024-4937(99)00075-4 ◽

2000 ◽

Vol 51 (1-2) ◽

pp. 75-93 ◽

Cited By ~ 15

Author(s):

Sven Sindern ◽

Ulrich Kramm

Keyword(s):

Alkaline Complex ◽

Volume Characteristics ◽

Element Transfer

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Uranium in South Africa and South West Africa (Namibia)

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1979.0029 ◽

1979 ◽

Vol 291 (1381) ◽

pp. 307-319 ◽

Cited By ~ 12

Keyword(s):

South Africa ◽

West Africa ◽

Alkaline Complex ◽

Metamorphic Belt ◽

Small Bodies ◽

Ore Formation ◽

Clastic Rocks ◽

Magmatic Rocks ◽

South West ◽

South West Africa

A number of genetically different uranium deposits occur in South Africa and South West Africa in rocks of widely differing ages. Early Proterozoic clastic rocks contain sedimentary uraninite, whose deposition in auriferous quartz-pebble conglomerates and carbon seams can be related to fluvial fans and algal mats. Recently discovered deposits of uranium in the Phanerozoic Karoo Supergroup occur as widespread but small bodies in channel sandstones of fluvial association. Carnotite deposits are developed in Cainozoic calcretes in the western, more arid, regions of southern Africa in which the uranium has been precipitated epigenetically from circulating groundwater. Uranium mineralization in magmatic rocks is present to a small extent in phoscorite and carbonatite of the middle Proterozoic Phalaborwa Igneous Complex, and is associated with alkaline lavas and intrusive rocks in the Pilanesberg alkaline complex of middle-late Proterozoic age. Multicyclic processes of ore formation have produced extensive deposits of uraninite-bearing alaskitic pegmatitic granites, of Phanerozoic age, in the Pan-African Damara metamorphic belt.

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The method of anisotropy of magnetic susceptibility: theory and applications. A case study from the Rhodope massif

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17233 ◽

2001 ◽

Vol 34 (4) ◽

pp. 1393

Author(s):

I. ZANANIRI

Keyword(s):

Magnetic Susceptibility ◽

Physical Property ◽

Anisotropy Of Magnetic Susceptibility ◽

Magnetic Fabric ◽

Low Field ◽

Magmatic Rocks ◽

Internal Structures ◽

Scalar Properties ◽

Magnetic Foliation

The anisotropy of magnetic susceptibility is a physical property of the rocks widely used in petrofabric studies and other applications. It is based on the measurement of low-field magnetic susceptibility in different directions along the sample. From this process several scalar properties arise, defining the magnitude and symmetry of the AMS ellipsoid, along with the magnetic foliation and lineation, namely the magnetic fabric. A case study is presented, dealing with the deformation of the Mont-Louis-Andorra pluton. Finally, the method was applied in Tertiary magmatic rocks from the Rhodope Massif, revealing their magnetic character and internal structures.

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