DOI: https://doi.org/10.24028/gzh.0203-3100.v37i4.2015.111132

The age of monzonites of the eastern part of the Korsun-Novomirgorod pluton (Ingul megablock of the USh)

E. Shestopalova, L.M. Stepanyuk, T. Dovbush, I.N. Kotvitskaya

Abstract


The article presents the results of monzonites research of the eastern part of Korsun-Novomirgorod pluton. The pluton is situated in the northwestern part of the Ingul megablock. Besides basic rocks varieties — gabbro-anorthosite and rapakivi granites the rocks of monzonite composition of different genesis are widely presented here. Small bodies of monzonites form outputs among rapakivi granites of Shpola massif at the junction of tectonic structures of different rank. Monzonite is a hybrid rock which contains xenoliths of frame rock and possibly ancient dyke formations. Zircon is represented by several generations, which are distinguishable by optical studies, as well as by different U / Th ratio. Some grains contain a nuclei and zircon inclusions, appearance of which was determined by the process of contamination. All fractions obtained discordant zircon age values.  Dating calculated by isotope ratio 207Pb / 206Pb has been taken as the most reliable. Due to the presence of relict zircons received isotopic age of the figures are overstated and do not reflect the formation of monzonite. As the maximum possible monzonite age we can take a minimum age, calculated by 207Pb / 206Pb — 1.740 Ma. The assumption about the formation of monzonite melt as a result of contamination of basic magma by ancient crustal rocks of acid composition has been given, which does not contradict the results of the study of the isotopic composition of strontium, neodymium, and geochronological data.


Keywords


monzonites; zircon; generations; dating; isotopic age; Korsun-Novomirgorod pluton

References


Bartnitskiy E. N., Bibikova E. N., Verkhoglyad V. M., Legkova G. V., Skobelev V. M., Terets G. Ya., 1995. IGMR-1. The international standard for zircon uranium-lead isotope studies. Geokhimiya i rudoobrazovanie (21), 164—167 (in Russian).

Dovbush T. I., Skobelev V. M., Stepanyuk L. M., 2007. Guidelines for uranium-lead, rubidium, strontium and samarium-neodymium isotopic dating of geological sites in the PGR. Kyiv: UkrDGRI Publ., 84 p. (in Ukrainian).

Dovbush T. I., Stepanyuk L. M., Shestopalova E. E., 2009. Crystallogenesis and age of zircons from gabbro Korsun-Novomirgorod pluton (Ukrainian shield). Geokhimiya i rudoobrazovanie (is. 27), 20—24 (in Russian).

Kononov Yu. V., 1966. Gabbro massifs Ukrainian shield. Kyiv: Naukova Dumka, 99 p. (in Ukrainian).

Kononov Yu. V., 1985. Metallonosost habbrovыh breeds Ukrainian shield. Kyiv: Naukova Dumka, 152 p. (in Russian).

Lyakhovich V. V., 1979. Accessory minerals of rocks. Moscow: Nedra, 294 p. (in Russian).

Mitrokhin O. V., 2011. Anorthosite-rapakivi granite formation of the Ukrainian Shield (geology, material composition and conditions of formation): Autoabstract of Dis. Dr. geol. Sci. Kyiv, 36 p. (in Ukrainian).

Sveshnikov K. I., 1981. Age sequence of rocks of Korsun-Novomirgorod pluton. Geologicheskiy zhurnal 41(4), 62—68 (in Russian).

Tarasenko V. S., Kirikilitsa S. I., 1987. Laws of formation and placement of phosphate-titanium mineralization in gabbro-anorthosite massif of the Ukrainian shield. In: Geology and Minerageny anorthosite association. Vladivostok: Publ. USSR AS FEB, P. 107—116. (in Russian).

Shestopalova O. E., Stepanyuk L. M., Dovbush T. I., 2010. U-Pb (for orthite) age granites rapakivi pluton Korsun-Novomirgorod: Abstracts of the Int. Sci. and Pract. Conf. «The stratigraphy, geochronology and correlation of rock complexes foundation nizhnedokembriyskih East European platform». Kiev, 2010. P. 245—248.

Shestopalova E. E., Stepanyuk L. M., Dovbush T. I., Kovtun A. V., 2014. About the age of white anorthosite massif Novomirgorod Korsun-Novomirgorod pluton (Ukrainian shield). Geofizicheskiy zhurnal 36(2), 150—161 (in Russian).

Shestopalova E. E., Stepanyuk L. M., Dovbush T. I., Kotvitskaya I. N., 2014. Isotopic zircon age granitoid pluton Korsun-Novomirgorod (Ingul megablock SHIELD). Mineralogichnyy zhurnal 36(4), 95—106 (in Russian).

Shestopalova E. E., Stepanyuk L. M., Dovbush T. I., Kotvitskaya I. N., 2015. Isotopic age zircon Gorodishchenskoye gabbro massif (Korsun-Novomirgorod Pluto Ingul megablock SHIELD). Mineralogichnyy zhurnal 37(2), 63—76 (in Russian).

Shumlyanskyy L. V., 2012. Petrology and geochronology of waste facilities Northwest region of the Ukrainian Shield and its western slope (in Ukrainian). Autoabstract of Dis. Dr. geol. Sci. Kyiv, 35 p. (in Ukrainian).

Shcherbak N. P., Artemenko G. V., Lesnaya I. M., Ponomarenko A. N., Shumlyanskyy L. V., 2008. Geochronology Early Precambrian Ukrainian board. Proterozoic. Kiev: Naukova Dumka, 238 p. (in Russian).

Krough T. E., 1973. A law contamination method for hedrotermal decomposition of zircon and extraction of U and Pb for isotopic age determination. Geochim. Cosmochim. Acta. 37(3), 485—494.

Ludwig K. R., 1989. Pb Data for MS-DOS, version 1.06. U.S. Geol. Survey Open-File Rept. 542(88), 40 р.

Stasey J. S., Kramers I. D., 1975. Approximation of ter-restrial lead isotope evolution by a two-stage model. Earth Planet. Sci. Lett. 26, 207—211.


Refbacks

  • There are currently no refbacks.


Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Creative Commons License
Geofizicheskiy Zhurnal is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Flag Counter