14 research outputs found
Evolution of monogenetic rhyolite volcanoes: Vinicky, Eastern Slovakia
Four essential volcanic units have been recognized
in the late Middle Miocene rhyolite complex at
the southern side of the ZemplĂn horst next to the
village ViniÄŤky. A succession of ash/pumice flow,
surge and fall deposits separated by horizons of
eolian dust and paleosoil in total thickness >15
m forms the lower unit. It represents distal facies
deposits of subplinian/plinian/phreatoplinian type
eruptions at unidentified centers. The second
unit rests upon the lower one with unconformity
marking a
period of erosion.
It
consists of coarse
phreatic/phreatomagmatic pyroclastic rocks with
fragments of basement rocks and glassy dacite/
rhyodacite. They represent proximal facies of a
phreatomagmatic pyroclastic ring. Both units are
truncated by a rhyolite extrusive dome, formed
of perlite and perlitic breccias at its margin.
Emplacement of the dome concluded activity of
local centers northwest of ViniÄŤky. An extensive
rhyolite coulee represents the fourth, uppermost
volcanic unit. It is 40 – 70 m thick, formed of
felsitic rhyolite with perlite and perlitic breccia
at the base. Orientation of flow banding implies
that the Borsuk extrusive dome 1
km northeast
of ViniÄŤky was a source of the coulee. The dome
and coulee form together one rhyolite body of the
dome-flow type. With exception of the distal facies
tuffs at the base the rhyolite complex represents
most probably products of three overlapping
monogenetic volcanoe