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Time-space evolution and volcanological features of the Late Miocene-Quaternary Calimani-Gurghiu-Harghita Volcanic Range, East Carpathians, Romania. A Review.

Szakács, A.

Seghedi, I.

Pécskay, Z.

Mirea, V.

Popa, R.G.

2014

QE05 Historical geology. Stratigraphy / Földtörténet, rétegtan

The Carpathian-Pannonian Region (CPR) hosts
one of the major Cainozoic volcanic provinces of
Europe extending in space over 6 eastern European
countries.The lithospheric evolution of this large
area governed by large-scale asthenospheric
processes is recorded by products of volcanic
activity occurred during a time interval of more
than 21 million years. According to their surface
occurrence areas, ages and composition the
Neogene volcanics of CPR were systematized in
three main groups: 1) mostly explosive products
of felsic magmas generated at the beginning of
volcanism in the whole CPR and in their particular
occurrence areas (21-12 Ma) developed in the
actual intra-Carpathian Pannonian Basin, 2) mostly
intermediate calc-alkaline rocks emplaced in both
the intra-Carpathian areas and along the arcuate
Carpathian fold-and-thrust belt, and 3) Na- and K-
alkaline and ultra-alkaline products clustered in a
number of monogenetic volcanic fields across the
whole intra-Carpathian realm developed in the final
stages of volcanic activity of the CPR as a whole
and of their particular occurrence areas. The ca.
160 km long Călimani-Gurghiu-Harghita volcanic
range (CGH) developed as part of the intermediate
calc-alkaline volcanism closely related in space
with the fold-and-thrust belt of the Carpathians,
representing the south-eastern segment of the CPR.
Although its map view and general petrochemical
and volcanological characteristics are quite similar
with those of other segments of the orogene belt-
tied calc-alkaline volcanic segments, at a closer
look CGH displays a number of unique features.
The time-space evolution of CGH is particular
not only in that it is the youngest (10.5 to < 0.05
Ma) dominantly calc-alkaline segment in CPR
but also it shows a transient character. Unlike
other segments along which volcanism occurred
simultaneously forming true subduction-related
400 to 800 km long volcanic fronts which were
stable in time for millions of year, in CGH
volcanic activity migrated continuously along the
range from NW to SE. So, during any given 1 Ma
time interval active volcanism was restricted to
very limited areas and to just a few active volcanic
centers. The along-range shift of volcanic foci
was concurrent with progressively lower volumes
of magma erupted and decreasing magma output
rates. As a result, gradually lower-volume and
less complex volcanic edifices were built up.
Moreover, at the range-ending and youngest South
Harghita sub-segment, magma compositions
gradually changed from normal calc-alkaline to
high-K calc-alkaline and shoshonitic, and adakitic
features emerged at the end of volcanic activity,
after a time gap of 0.5 Ma. This marks a major
geodynamic event in the development of the East
Carpathians themselves. During the transient
volcanism of CGH, edifices of varying volume and
complexity were built up forming a row of tightly-
packed adjoining stratovolcanoes/composite
volcanoes whose peripheral volcaniclastic aprons
complexly juxtaposed, overlapped and merged
with each other. The largest ones (Călimani
caldera, and Fâncel-Lăpuşna) developed until
caldera stage. Some of them (Rusca-Tihu in the
Călimani Mts., Vârghiş in the North Harghita
Mts.) became unstable during their growth and
collapsed, generating widespread large-volume
debris avalanche deposits. Edifice instability was
solved by volcano-basement interaction processes,
such as volcano spreading, at some large-volume
volcanoes (in particular those in the Gurghiu Mts.).
Volcano typology changed at the smaller-volume
constructs toward the southeastern terminus of the
range in the South Harghita Mts. from typical large
stratovolcanoes to smaller composite volcanoes,
dome clusters and isolated domes and simpler
internal structures. As a whole, CGH displays an
extremely particular evolutionary pattern strongly
suggesting a transient character and decreasing to
extinguishing volcanic activity along its length
from NW to SE.

Conference or Workshop Item

PeerReviewed

text

http://real.mtak.hu/21272/7/time_space_evolution.pdf

Szakács, A. and Seghedi, I. and Pécskay, Z. and Mirea, V. and Popa, R.G. (2014) Time-space evolution and volcanological features of the Late Miocene-Quaternary Calimani-Gurghiu-Harghita Volcanic Range, East Carpathians, Romania. A Review. In: XX congress of the Carpathian-Balkan Geological Association, 2014. Szeptember 24-26., Tirana, Albania.

http://www.cbga2014.org/doc/PCBGASSAV1.pdf

http://real.mtak.hu/21272/