Indications of Devonian basic volcanism in Southwest Bulgaria

Vonska klippe from the Penkjovci Nappe (Southwest Bulgaria) has a complicated internal structure. The allochthon consists of Lower Paleozoic rocks, preserved as separate klippe relics around the southern periform of Glavička anticline, as a klippe in synformal position, and as klippe relics partially fossilized by the Paleogene of Glogovica graben. The upper part of the section of Vrabča Formation is dated as Upper Emsian – Lower Eifelian with the conodonts Polygnathus serotinus Telford, 1975; Polygnathus cooperi cooperi Klapper, 1971; Polygnathus costatus patulus KIapper, 1971. Below these packets carbonatized and barytized lapilli tuffs have been found. Three rock types (according to texture) have been observed: spilites of weilburgite type with intersertal to subophitic, variolitic, and (probably) hyalopilitic texture (texture I); globular texture (texture II); transitional texture (texture III). The finding of Lower Devonian basic volcanism raises new problems about the tectono-magmatic character of the Paleozoic in Southwest Bulgaria and its possible relations with Devonian volcanics of the Lahn type and the Rheno-Hercynicum of Central and Western Europe. The metallogenic importance of this volcanism is also discussed. It is suggested that the first stage of barite formation was possibly related to the Devonian volcanism, and the Late Alpine barite veins may be bound to re-deposition during the Paleogene along fault structures.