CARLO AROLDI
(REZUMAT)
Alpii sunt, în cadrul modelului tectonicii placilor, rezultatul convergentei
mesozoic/cainozoice a Africii cu Europa. În succesiunea sud-alpina, apartinând
marginii continentale africane, ciclul alpin începe in Permian cu depuneri
de formatiuni molasice provenite din lantul hercinic ridicat. La sfârsitul
Permianului si al Triasicului, procesul de rift a început si s-a dezvoltat
cu depunerea preponderenta a sedimentelor platformei carbonatice. Jurasicul reprezinta
o perioada de drift, având ca rezultat formarea unei cruste oceanice si
stabilirea unor conditii pelagice. Cretacicul inferior reprezinta un moment de
convergenta între cele doua placi, cu subductia celei europene sub placa
africana. Cretacicul târziu, Eocenul superior si Oligocenul superior reprezinta
cele trei momente în care activitatea tectonica si ridicarea lantului alpin
au atins un maxim, cu formarea, în timpul acestora sau dupa, a depozitelor
de flisch si molasa. În timpul Oligocenului inferior s-a produs intruziunea,
pe fracturi generate de tensiuni extensionale, a corpurilor granitice, granodioritice
si dioritice. O linie tectonica importanta, liniamentul periadriatic, cu evidente
de miscari de decrosare separa Alpii sudici de unitatile austrice. Se examineaza întreaga
succesiune sedimentara de-a lungul unui profil N-S pe o structura, cu formatiunile
mai tinere amplasate la sud de lacul Iseo, si cu cele mai vechi, asezate pe
fundamentul cristalin, localizate la nord de valea Camonica.
Key words: tectonics, stratigraphy, South Alpine Units
Stratigraphic and structural evolution of the South-Alpine units along Lago
d'Iseo-Camonica Valley profile (Central-Oriental Lombardia). The Alps are the
result of the Mesozoic-Cainozoic Africa/Europe convergence in the framework
of the plate tectonics model. In the south-alpine succession, belonging to
the African continental margin, the alpine cycle begins in the Permian with
the deposition of molassic formations originated from the uplifted Hercynian
belt. During the end of Permian and the Triassic, the process of rifting started
and developed with prevalent deposition of sediments of carbonatic platform.
The Jurassic represents a period of drifting with formation of an oceanic crust
and the establishing of pelagic conditions. The Lower Cretaceous represents
a moment of convergence between the two plates, with the subduction of the
European plate under the African one. The Late Cretaceous, the Upper Eocene
and the Upper Oligocene represents the three moments in which the tectonic
activity and the uplifting of the alpine belt reached the highest peak, with
formation, during or after them, of flysch and molassic deposits. During the
Lower Oligocene the intrusion, along fractures generated by extensional stresses,
of granitic, granodioritic and dioritic bodies, occurred. An important tectonic
line, the Periadriatic Lineament, with evidences of strike-slip movements,
divides the Southern Alps from the Austridic Units .
The entire sedimentary succession was examined along a south-north profile,
transversal to the units, with the younger formations located to the south
of the Iseo Lake and the older formations, resting on the top of the crystalline
basement, located toward the north of the Camonica Valley.