<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The Ukrainian Shield (USh) is a typical province of Proterozoic alkaline magmatism where about 50 massifs and occurrences of alkaline rocks and carbonatites have been found. In spite of the wide distribution of Devonian basaltic- and alkaline magmatic rocks in the Dnieper-Donetsk depression adjacent to the USh, and in a marginal zone of the USh adjacent to folded Donbass, only alkaline rocks of Proterozoic age (1.8-2.1 Ga) that have been identified in the central interior of the USh. Some discrete bodies of 2.8 Ga subalkaline rocks also occur in Bogdanivka massif (Azov area). Occurrences of both Proterozoic (prevailing) and Phanerozoic (Devonian) alkaline rocks and kimberlites are only found in the eastern part of the USh (Azov area). Kimberlites in the central part of the Ukrainian Shield (Kirovograd region) are also of Proterozoic age (ca 1.8 Ga). It is this predominance of Precambrian rocks that makes the USh so different from other alkaline provinces where Phanerozoic alkaline rocks and kimberlites commonly prevail over Precambrian rocks. The lack of Phanerozoic alkaline magmatism on USh is poorly understood. </p><p>Two main complexes of alkaline rocks - alkaline-ultrabasic (carbonatitic) and gabbro- syenitic - are distinguished in the USh. There are also rare occurrences of rock types such as alkaline- and alkaline-feldspar granites that may represent one separate alkaline-granite complex. Alkaline rocks present in the Eastern (Azov) province and in the Western province display essentially different geochemical character. Those of the Eastern province show characteristics typical of alkaline-ultrabasic rocks (e.g. high contents of incompatible rare elementssuch as Nb, REE, Zr, Y, Sr, whereas those in the Western province are characterized by low contents of Nb and Zr, and REE in some cases. This fact is interpreted as reflecting different geodynamic conditions of their origin. The Eastern rocks were formed in rift settings, the Western rocks in crustal compressional settings (collision, subduction). Various mineral deposits of phosphorus (apatite), niobium, REE, yttrium and zirconium, including unusually rich ores of REE, Y and Zr (Azov and Yastrybetsky) are associated with the alkaline rocks and carbonatites of the USh. </p></abstract>

The Ukrainian Shield (USh) is a typical province of Proterozoic alkaline magmatism where about 50 massifs and occurrences of alkaline rocks and carbonatites have been found. In spite of the wide distribution of Devonian basaltic- and alkaline magmatic rocks in the Dnieper-Donetsk depression adjacent to the USh, and in a marginal zone of the USh adjacent to folded Donbass, only alkaline rocks of Proterozoic age (1.8-2.1 Ga) that have been identified in the central interior of the USh. Some discrete bodies of 2.8 Ga subalkaline rocks also occur in Bogdanivka massif (Azov area). Occurrences of both Proterozoic (prevailing) and Phanerozoic (Devonian) alkaline rocks and kimberlites are only found in the eastern part of the USh (Azov area). Kimberlites in the central part of the Ukrainian Shield (Kirovograd region) are also of Proterozoic age (ca 1.8 Ga). It is this predominance of Precambrian rocks that makes the USh so different from other alkaline provinces where Phanerozoic alkaline rocks and kimberlites commonly prevail over Precambrian rocks. The lack of Phanerozoic alkaline magmatism on USh is poorly understood. Two main complexes of alkaline rocks - alkaline-ultrabasic (carbonatitic) and gabbro- syenitic - are distinguished in the USh. There are also rare occurrences of rock types such as alkaline- and alkaline-feldspar granites that may represent one separate alkaline-granite complex. Alkaline rocks present in the Eastern (Azov) province and in the Western province display essentially different geochemical character. Those of the Eastern province show characteristics typical of alkaline-ultrabasic rocks (e.g. high contents of incompatible rare elementssuch as Nb, REE, Zr, Y, Sr, whereas those in the Western province are characterized by low contents of Nb and Zr, and REE in some cases. This fact is interpreted as reflecting different geodynamic conditions of their origin. The Eastern rocks were formed in rift settings, the Western rocks in crustal compressional settings (collision, subduction). Various mineral deposits of phosphorus (apatite), niobium, REE, yttrium and zirconium, including unusually rich ores of REE, Y and Zr (Azov and Yastrybetsky) are associated with the alkaline rocks and carbonatites of the USh.

Alkaline rocks of the Ukrainian Shield: Some mineralogical, petrological and geochemical features

Institute of Geochemistry, Mineralogy and Ore Formation M.P.Semenenko, NAS of Ukraine Director of Institute, Corresponding member NAS of Ukraine, 34, Palladina av., Kiev-142, 03680 Ukraine

Institute of Geochemistry, Mineralogy and Ore Formation M.P.Semenenko, NAS of Ukraine Senior Research Scientist, Candidate of science, 34, Palladina av., Kiev-142, 03680 Ukraine

Taras Shevchenko National University of Kyiv, Geological faculty Docent, Candidate of science, 90 Vasyl'kivska str., Kyiv 03022 Ukraine

Mineralogia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The Ukrainian Shield (USh) is a typical province of Proterozoic alkaline magmatism where about 50 massifs and occurrences of alkaline rocks and carbonatites...

Alkaline rocks of the Ukrainian Shield: Some mineralogical, petrological and geochemical features

Publié en ligne: 31 juil. 2014

Pages: 115 - 124

Reçu: 30 déc. 2010

Accepté: 16 mars 2014

DOI: https://doi.org/10.2478/mipo-2013-0008

Mots clés
Ukrainian Shield, alkaline magmatism, Proterozoic, Devonian kimberlites

© by Aleksandr N. Ponomarenko

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Alkaline rocks of the Ukrainian Shield: Some mineralogical, petrological and geochemical features

Publié en ligne: 31 juil. 2014

Pages: 115 - 124

Reçu: 30 déc. 2010

Accepté: 16 mars 2014

DOI: https://doi.org/10.2478/mipo-2013-0008

Mots clésUkrainian Shield, alkaline magmatism, Proterozoic, Devonian kimberlites

© by Aleksandr N. Ponomarenko

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Mots clés
Ukrainian Shield, alkaline magmatism, Proterozoic, Devonian kimberlites