Precambrian metamorphites as part of the petrographic diversity of Rila Geopark

Abstract

The petrographic diversity of Rila Mountain is an important prerequisite for the development of Rila Geopark and its nomination for UNESCO Geopark. According to the principle of the thematic geodiversity, the leading theme of the geopark – glacial landscapes, is complemented by the remarkable petrographic diversity of igneous and metamorphic rocks, in which alpine glacial forms are developed. Following a recent review of the intrusive rocks that make up the Rila-West Rhodope Batholith, the concept of Rila Geopark would not be complete without a retrospective of the metamorphic rocks that are an integral part of its petrographic diversity. The different approaches (lithodemic and lithotectonic) to the mapping of the Rila-Rhodope Massif divided the geologists into two camps. This led to a discrepancy in terminology and nomenclature of the metamorphic units, which is unacceptable in the context of the educational priority of the geopark. For the purpose of geotourism, clear and understandable interpretations are required to provoke the visitors’ interest in geological processes and phenomena, rather than confusion and perplexity. This article is a historical overview of the geological study of the metamorphic terrains in Rila Mountain with a scheme of lithodemic units based on the existing lithostratigraphic nomenclature. This approach allows the preservation of the names of the lithostratigraphic units, whose toponymic adjectives derive from well known geographical features in the Rila-Rhodope Massif. The rank term is replaced by a lithological or descriptive term, which frees the nomenclature from the dogmatic restrictions of the stratigraphic code and reduces the distance between the strictly scientific and popular science approach used for interpretation of geological information in a popular language accessible to the general public. This methodology is consistent with the approach recommended for mapping of non-stratified bodies on the Geological Map of the Republic of Bulgaria at a scale 1:50 000.