The Structure of the Crystalline Basement and Age of Geological Events of the Fore Range Zone of the Greater Caucasus
Abstract
Blyb metamorphic complex is the largest salient of crystalline basement of the Fore Range zone, which is exposed at the basins of the Big and Small Laba rivers. Within Blyb metamorphic complex the Balkan Formation cut by Balkan metadiorites massif of the Ediacaran age, 549-574 Ma [1], and the Armovka Formation are distinguished. In the area of the Balkan Formation we also identified the granitic massif of the Early Carboniferous age, 319 ± 3.8 Ma [1]. Rocks of Balkan Formation are garnet-amphibole-biotite gneisses metamorphosed up to amphibolites facies. Metamorphic rocks of the Armovka Formation are presented by both metapelites and metabasites: garnet-mica schists, sometimes containing kyanite, epidote-garnet amphibolites. Mineral paragenesis of the Armovka Formation rocks indicates high-pressure metamorphism. The structural, isotopic, petrographic and rock-magnetic data confirm the tectonic coupling the Balkan and Armovka Formations.
We obtained the new U-Pb (SHRIMP) data from linear intrusive body of monzodiorites, contouring the southern boundary of the Blyb complex, and garnet-mica schists of the Armovka Formation. Monzodiorites yielded an age of 393.7 ± 1.7 Ma (the Middle Devonian). Armovka schists gave the Late Devonian age (362.2 ± 1.9 Ma) probably corresponding to the metamorphic event. Comparison of identified magmatic events with detrital and magmatic zircons data from adjacent regions (Mediterranean belt) reveals the predominance of Ediacaran magmatic provenance among detritus of peri-Gondwanan terranes. We assume that Ediacaran magmatism in the Fore Range zone is related to the northern margin of Gondwana and indicates the Cadomian orogeny. At the same time, the Early Carboniferous magmatism can be related to the accretion of Gondwana-derived terranes to the southern margin of East European platform. So, we can conclude that the Blyb salient has Gondwana origin. Besides, in the Fore Range zone there are Middle-Late and Late Devonian metamorphic and magmatic events which are not widely spread within adjacent regions and therefore can be the subjects for further research. 1. Kamzolkin V., Latyshev A., Vidyapin Yu., Somin M., Smul'skaya A., Ivanov S. Late Vendian complexes in the structure of metamorphic basement of the Fore Range zone, Greater Caucasus. Geotectonics. 2018. 52(3): 331-345- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T21H0350L
- Keywords:
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- 5475 Tectonics;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 8102 Continental contractional orogenic belts and inversion tectonics;
- TECTONOPHYSICS;
- 8108 Continental tectonics: compressional;
- TECTONOPHYSICS;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS