mineralogy, petrology and geochemistry of allanite-bearing granites of Khrami crystalline massif

Author: Zaur Makharashvili
Keywords: mineralogy, allanite, granites, Khrami crystalline massif
Annotation:

The Khrami сrystalline massif is part of the Black Sea – Central Transcaucasian terrain. It represents the outwashed section of a horst-like uplift of the Artvin–Bolnisi belt and crops out on an area of 500 km2. It is exposed in the River Khrami basin and its tributaries: Chociani, Kldeisi and Aslanura. The massif is built up by gneiss-magmatite complex, Lower Paleozoic metagabbros, Late Variscan migmatic and volcanogenic-sedimentary formations. Precambrian serpentine rocks and Paleozoic metasandstones with very low grade metamorphism are rarely represented as well. The topic of the presented worck is the study of the petrology and geochemistry of Late Variscan allanit-bearing granites of the Khrami crystalline massif. These granites are intruded into the oldest rocks of the massif and overlie the gneiss-migmatitic complex. Late Variscan granitoids of the Khrami massif are represented by four types: biotite-hornblende-alanite-, biotite- and biotite-garnet-bearing granites and aliaskites. Although these granites have been well studied by a number of scientists, their research is relatively less comprehensive from a geochemical point of view. The aim of the presented paper was to conduct researches of geochemical content. The aim of the work is the petrologic and geochemical study of Late Variscan allanite-bearing granites. The data available today require the clarification of a number of petro-mineralogical issues; Geochemical analysis data is rather small. The content of rare and rare-earth elements and the regularities of their distribution have only been partially determined by previous researchers. Both traditional and laboratory methods which was conducted using modern equipment of investigations were applied in the implementation of the mentioned research. In particular, field work was carried out, a key section was selected, rock outcrops were mapped using GPS technologies, and structural schemes of the outcrops were drown on site. Up to 20 thin sections were described microscopically; full chemical analysis of 5 samples was performed and X-ray fluorescence study of 5 samples was conducted by means of XRF. Both classic and modern classification and discrimination-tectonic diagrams were built using the obtained data. Based on the interpretation of the diagrams, certain conclusions have been obtained that will to some extent contribute to the study of Late Variscan allanite-bearing granites.

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ანოტაცია [ka]