SIMS AGE OF PLUTONITES OF THE FASTIVSKYI COMPLEX (ROCK ASSOCIATION OF THE YAROSHIVSKYI QUARRY)
This article presents the results of U–Pb dating of zircons by SIMS from quartz monzodiorite and leucocratic biotite granite of the Fastivskyi complex. They were discovered in the Yaroshivkskyi quarry (Fastiv district, Ukraine). Quartz monzodiorites are characterized by a typical mineral composition...
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| Date: | 2025 |
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| Main Authors: | , , , , , , , |
| Format: | Article |
| Language: | Ukrainian |
| Published: |
Institute of Geological Sciences, NAS of Ukraine
2025
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| Subjects: | |
| Online Access: | http://geojournal.igs-nas.org.ua/article/view/340584 |
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| Journal Title: | Geological journal |
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Geological journal| Summary: | This article presents the results of U–Pb dating of zircons by SIMS from quartz monzodiorite and leucocratic biotite granite of the Fastivskyi complex. They were discovered in the Yaroshivkskyi quarry (Fastiv district, Ukraine). Quartz monzodiorites are characterized by a typical mineral composition (plagioclase, potassium feldspar, biotite, amphibole, quartz). Zircon is observed mainly in the form of prismatic crystals with rounded edges. In polished sections, the crystals are characterized by a well-developed “magmatic” zoning. In individual grains, relict nuclei of rounded, occasionally elongated-prismatic forms are observed, which indicates the participation of crustal material in the formation of the melt. Leucocratic granite is represented by a grayish-pink, medium-grained rock of massive structure with perthite and recrystallized textures. It also contains relict cores in zircon crystals, which are interpreted as evidence of crustal melting. SIMS dating of zircon crystals from quartz monzodiorite and granite, conducted at the Australian National University (Canberra), gave concordia ages of 2048 ± 20 Ma for monzodiorite and 2061.5 ± 8.8 Ma for granite, reflecting a Paleoproterozoic magmatic event. The quartz monzodiorite and granite exposed by the Yaroshivskyi quarry were formed during the Zhytomyrskyi stage of magmatic activity (2048 ± 20 Ma and 2061.5 ± 8.8 Ma), respectively. The presence of relic cores within the zircon crystals of quartz monzodiorite and granite suggests a crustal source of the parent granitic melt. |
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