Arkell.1956.Jurassic..

CHAPTER 7
THE BALKAN PENINSULA
EASTERN CARPATHIANS, TRANSYLVANIAN ALPS, BANAT
From the headwaters of the River Theiss, in Bukovina, the Carpathian
arc turns SSE. and then south, fronted by its own flysch zones with
remnants of the klippe chain on their inner edge. At the knee-bend, where
eastern Carpathians turn west into Transylvanian Alps, these zones are
cut off as it were by a mighty tear system. Under the Wallachian plain
there seems to lie a rigid spur which has underthrust WNW. and produced
the great loop of mountains in which the Transylvanian Alps on the north
and the Balkan Mountains on the south face one another across the lower
Danube plain and join at the Iron Gates. Stille (1953) calls this the Wallachian
spur and visualizes it as the western tip of a sunk block underlying
the Black Sea (the Euxinic Swell of Stille, 1953, p. 156, Pontic Mass of
Wilser, 1928, p. 216).
The eastern Carpathians and Transylvanian Alps, and the associated
mountains of Banat to the west and SW., enclose the basin of Transylvania
(Siebenbiirgen, part of which is Szeklerland of the older geological
literature), and Jurassic outcrops, important out of proportion to their small
size, occur in the mountains on east, south and west sides of the basin.
The Jurassic is characterized by patchy Lias, largely in the near-shore
Gresten facies, overlain by transgressive Lower Kimeridgian or Tithonian;
but in places thin, condensed cephalopod beds of Upper Oxfordian,
Middle Callovian, or Bathonian dates begin the transgressive series, after
what appears to have been almost complete regression in the Bajocian.
Thus the area epitomizes many of the principal transgressions that occurred
in many parts of the world. From Bathonian to Oxfordian, both inclusive,
there was non-deposition or retarded deposition and condensation, as in
many other parts of the Mediterranean region. Strong deposition began
only with the Tithonian (reef limestones up to 340 m. thick). The
ammonite faunas are all markedly Mediterranean, with abundance of
Phylloceratids and Lytoceratids at all levels, but with a strong mixture
of north-European forms in the Bathonian, Callovian and Oxfordian.
The clastic materials in the Gresten facies of the Lias are believed
to have been derived from a Liassic landmass called by Mojsisovics the
Oriental Island (Pompeckj, 1897). It covered the southern part of Transylvania
and the southern part of the Hungarian plain (Pannonian basin)
and was continued through Serbia to include the south-eastern part of the
Balkan peninsula and the Aegean. It is noticeable that the Wallachian-
Bulgarian gulf postulated by Pompeckj for Liassic times nearly coincides
with the rigid Wallachian spur postulated by Stille (1953) on tectonic
grounds. The Liassic outcrops considered by Pompeckj, however, lie
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