Guidebook - Ispra

Volume n° 1 - from PR01 to B15
B12
B12 -
Leader: M. Sandulescu
roxene- and hornblende-andesites of Upper Pliocene
? – Lower Pleistocene age, which belong to the calcalkaline
volcanic arc of the East Carpathians. After
crossing the Ciucul de Jos (Lower Ciuc) Quaternary
Depression, the Olt River (and the fieldtrip) crosses
the south-east end of the volcanic chain. At Tușnad
spa, east of the valley, the Sfânta Ana volcanic structure
is well preserved. It is a very young volcano of
Pleistocene or even Holocene age. Downstream, in
the Micfalău area, on the right-hand slope of the Olt
Valley, two subvolcanic bodies of basaltoid andesites
(Lower Pleistocene) are exposed in two large quarries.
On the left-hand slope and tributaries, Lower
Cretaceous flysch formations of the Ceahlău Nappe
are developed. At Malnaș the tectonic contact between
the Ciuc Digitation and the Bodoc Digitation
(both sub-units of the Ceahlău Nappe) is crossed.
From Ghidfalău the Olt River runs within the Sfântu
Gheorghe Quaternary Depression, filled - as the
whole complex developed Quaternary depressions of
the inner part of the Carpathian Bend Area - with Upper
Pliocene-Pleistocene formations.
Between Hărman and Brașov, south of the Depression,
it is possible to reconstruct (if the weather is
favourable), along the skyline, a cross-section of the
Ceahlău Nappe and the front of the Getic Nappe.
Stop 3.1:
Săcele - Jurassic formations in the front of the
Getic Nappe.
In the town of Săcele, the main part of Bonloc Hill
is built up of Jurassic formations similar to those of
the whole Postăvaru Mts.-Codlea-Piatra Craiului
Mts. area, which belong to the Getic Nappe. After
a few siltic black shales of the Grestner Lithofacies
of the Lower Jurassic, Middle Jurassic quartzitic
sandstones follow, hosting a sill of trachytes, also
of Middle Jurassic age. The Upper Jurassic is represented
by massive neritic limestones. The absence of
the Callovian-Oxfordian radiolarites which are usually
developed in the other parts of the Getic Domain,
accentuates the existence of a stratigraphic gap in the
frontal part of the Getic Nappe.
The Săcele Jurassic Getic formations are overthrust
above the Piscu cu Brazi Formation (see Stop 2.4)
of the Ceahlău Nappe.
Brașov is one of the main towns of Transylvania. It is
an early medieval city with many important vestiges.
The Black Church is a famous Catholic church built
in the XV th century in Gothic style. The building
material consists of limy sandstones, which were
worked out from quarries around Teliu village (east
of Brașov) and are massive sandstones intercalated in
the Piscu cu Brazi Formation of the Ceahlău Nappe.
The organ of the church is one of the biggest organs
in the Catholic or Protestant churches in Transylvania.
Council Square is the old centre of the burg, with a
city museum. South of the Black Church, upstream, is
the Orthodox Saint Nicholas Church, where the first
Romanian printing occurred.
Stop 3.2:
Brașov – Ladinian limestones in Dealul Melcilor
Quarry.
Dealul Melcilor Hill is the northern end of Tâmpa
Hill, not far from the centre of town. On its eastern
slope Ladinian organogenous massive limestones
are exposed in an old quarry. They constitute the core
of an E-W oriented anticline belonging to the Getic
Nappe. Above the Ladinian limestones the Gresten
Lithofacies of the Lower Jurassic follows (black siltic
shales dominate with intercalations of quartzitic sandstones);
a sill of arfvedsonite granite porphyry is intruded
in a black siltic sequence. The Middle Jurassic
is represented by quartzitic sandstones, while the
Kimmeridgian-Tithonian by the massive Stramberg
limestones. Tâmpa Hill consists of these limestones
as does the north slope of the Dealul Melcilor.
From Brașov the fieldtrip proceeds to the village of
Cristian (6 km toward south-west) situated in the
western foothills of the Postăvaru Mts.
Stop 3.3:
Cristian – Anisian limestones (Guttenstein type).
North of Râșnov, at the southern margin of the village
of Cristian in an old quarry, well layered limestones
crop out, blackish or dark-grey, slightly bituminous
(“stinking”), frequently with diaclases. Their Anisian
age is documented by ammonitic fauna and by the
palynological assemblages. The Guttenstein-type Triassic
was folded before the Lower Jurassic; Grestentype
formations overlie the Triassic formations with
angular discordance .
The Anisian limestones of Guttenstein type, of the
Cristian-Vulcan area, may be correlated with the Anisian
dolomites and limestones of the Iacobeni quarry
(Stop 1.12). Consequently it is possible to correlate
the Getic Nappe (to which the Cristian section belongs)
with the Infrabucovinian nappes of the Central
East Carpathians.