Publication details
Želešice amphibolite complex - characteristic and position
| Authors | |
|---|---|
| Year of publication | 2018 |
| Type | Appeared in Conference without Proceedings |
| MU Faculty or unit | |
| Citation | |
| Description | The active quarry near the Želešice is situated in the Želešice amphibolite complex, that is still assigned to the central basic belt (Štelcl and Weiss, 1986; Hanžl and Melichar, 1997; Buriánek, 2005). The central basic belt is separated into two parts: volcanic part on the east and plutonic part on the west. Leichmann and Höck, (2008) define the origin of the central basic belt as an ophiolite. The origin of the amphibolite complex is still ambiguous. Buriánek, (2005) define this complex as the volcano-sedimentary complex which forms the uppermost part of the ophiolite. In active quarry near the Želešice was found rock association that represents variety of the whole amphibolite complex. In quarry were earmarked 6 rock types. Epidote amphibolite with quartz biotite gneiss, epidote amphibolite, fine-grained amphibolite, epidote-biotite-amphibole schist and massive epidote amphibolite. Typical mineral association is zonal amphibole (actinolite, hornblende), plagioclase (albite to bytownite), epidote, chlorite, quartz, apatite, sphene, biotite, from heavy minerals is common magnetite and less common ilmenite. Biotite gneiss is very specific. It consists of quartz, albite, biotite and accessory apatite and tourmaline (dravite/schorl). Heavy minerals represent magnetite. It does not contain amphibole. The minerals have probably metamorphic origin, that makes interpretation of the origin of the rocks difficult. Some rocks have banded layer structure, some rocks have massive structure. In this rock association we have six rock types and every rock type is different. There are differences in structure, in microstructure, in mineralogical association, in chemical composition and evolution of minerals. That varied rock association looks like some volcanic sequence, which was metamorphic overprinted and differences between rocks point to variability in volcanism. This idea corresponded to the theory of the volcano-sedimentary complex by Buriánek, (2005). The position of that complex is very specific. The amphibolite complex border with diorites from the plutonic part on the east. The contact with diorites is probably tectonic. Therefore, the amphibolite’s are probably not higher member of volcanic complex, because of the volcanic complex is located east from the diorites. The amphibolite complex is strongly metamorphosed then the volcanic complex, where relic of primary minerals e.g. pyroxenes, and primary volcanic fabrics are rarely present. Based on a above mentioned facts, amphibolite complex may not be a part of the any part of the central basic belt and it can be a separate unit. |