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Korsakova O.P., Kolka V.V., Savchenko S.N.

Block structures of the Kola Peninsula, their resistance under the conditions of natural and technical systems (by the example of the Khibiny and Lovozero Mountains)

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Abstract. The paper presents the results of comprehensive geological and petrographic, isotope geochemical (U-Pb, Sm-Nd, REE) and geochemical exploring investigations of the Monchetundra intrusion rocks. The studied cumulative stratigraphy for the intrusive rocks forms the basis for the division of the vertical rock sequence into three zones. The lower zone is dominated with orthopyroxene and olivine cumulates. The middle zone consists of pyroxene-plagioclase and plagioclase cumulates. And the upper one is mainly composed of plagioclase cumulates. The internal structure of the intrusion displays the lateral increase in differentiation degree from the eastern flank southwards (for the lower zone) and westwards (for the middle and upper zones). A new manifestation of noble metal stratiform mineralization has been found. It is confined to the horizon of the trachitoid gabbronorite (the middle zone). The mineralization locates in the western part of the intrusion that readily agrees with internal structure. The U-Pb dating has allowed revealing two intrusive phases for the rocks of the upper part: an earlier, 2.47 Ga, and an older, 2.45 Ga, one. The initial magma for the rocks of the middle and upper zones has been found to differ. The initial magma for the rocks of the lower zone of the Monchetundra intrusion was slightly enriched both with light and heavy rare earth elements. The rocks of the middle and upper zones were formed of the primary melts that were close in composition being slightly enriched with LREE. The differences in the REE fractionation have been shown for the different zones of the intrusion, including the initial magma close in composition that yielded the rocks of the middle and upper zones of the intrusion in the course of differentiation and crystallization. Thus, the REE fractionation coefficient, (La/Yb)N directly correlates with the content of Al2O3, CaO, total and particular iron content in the rocks of the upper zone, that is not characteristic of the middle zone rocks. It has been concluded that the collected data on REE, and U-Pb and Sm-Nd isotopy assume the formation of the Monchetundra intrusion as a result of subsequent emplacement, differentiation, and crystallization of the melts from the single anomalous source with possible minor contribution from the depleted source.

Keywords: block structure, morphotectonic structure, morphometric methods, topography, lineaments, landscape and geological indicators of tectonic zones, elastic resistance of rocks, numerical simulation, natural-engineering systems

Printed reference: Korsakova O.P., Kolka V.V., Savchenko S.N. Block structures of the Kola Peninsula, their resistance under the conditions of natural and technical systems (by the example of the Khibiny and Lovozero Mountains) // Vestnik of MSTU. 2009. V. 12, No 3. P. -.

Electronic reference: Korsakova O.P., Kolka V.V., Savchenko S.N. Block structures of the Kola Peninsula, their resistance under the conditions of natural and technical systems (by the example of the Khibiny and Lovozero Mountains) // Vestnik of MSTU. 2009. V. 12, No 3. P. -. URL: http://vestnik.mstu.edu.ru/v12_3_n36/articles/12_korsak.pdf.

(In Russian, p.14, fig. 9, ref 18, Adobe PDF)