In the Agordo area the Valsugana Thrust, the main structure of the Eastern Southern Alps extending 100 km from Trento to Cadore, is a sharp fault plane running N40 between the Variscan crystalline basement of the Southern Alps (Poli & Zanferrari, 1991) and the Mesozoic cover. The hangingwall consists of graphitic phyllites with quartz veins of the Fm. di Col di Foglia Upper Cambrian in age, while the footwall is made of Dolomia Principale Upper Triassic in age. In the N40 trending Imperina Valley to the South of Agordo (the same direction of the fault), until 1962 were exploited copper pyrites mines from 1482. Recently the works to renovate the mines area, permitted us to study a new outcrop which preserve a perfect assemblage of mesostructures (striae and kinematic indicators) over the principal plane of the Valsugana Line. The fault dips 75° towards NW and are preserved the graphitic phyllites spreading on the plane. The kinematic indicators show right lateral movement of the fault surface. A system of left lateral transfer fault N330 trending cause several little throws (few decimeters) of the principal fault plane. This structural association points out an E trending compression acting during Pliocene- Pleistocene as in Cornuda area in the foothills of the Venetian Plain. This reactivation totally erased the structures of the previous Serravallian-Tortonian compression that created the Valsugana Thrust made of N70 frontal ramps and N20-40 left-lateral oblique ramps, exactly like the Agordo ramp which inverted from left to right lateral fault. This outcrop confirms that the E-trending compression (Adriatic event) involves not only the Venetian Plain foothills but also the interiors of the chain. References Poli E. & Zanferrari A., 1991 – Rend. S.G.I., 14, 1, 127-134
A NEW OUTCROP OF THE PRINCIPAL FAULT PLANE OF THE VALSUGANA LINE IN AGORDO AREA: IMPLICATIONS FOR TECTONIC EVOLUTION OF THE EASTERN SOUTHERN ALPS
SELLI, LUIGI;CASTELLARIN, ALBERTO;
2005
Abstract
In the Agordo area the Valsugana Thrust, the main structure of the Eastern Southern Alps extending 100 km from Trento to Cadore, is a sharp fault plane running N40 between the Variscan crystalline basement of the Southern Alps (Poli & Zanferrari, 1991) and the Mesozoic cover. The hangingwall consists of graphitic phyllites with quartz veins of the Fm. di Col di Foglia Upper Cambrian in age, while the footwall is made of Dolomia Principale Upper Triassic in age. In the N40 trending Imperina Valley to the South of Agordo (the same direction of the fault), until 1962 were exploited copper pyrites mines from 1482. Recently the works to renovate the mines area, permitted us to study a new outcrop which preserve a perfect assemblage of mesostructures (striae and kinematic indicators) over the principal plane of the Valsugana Line. The fault dips 75° towards NW and are preserved the graphitic phyllites spreading on the plane. The kinematic indicators show right lateral movement of the fault surface. A system of left lateral transfer fault N330 trending cause several little throws (few decimeters) of the principal fault plane. This structural association points out an E trending compression acting during Pliocene- Pleistocene as in Cornuda area in the foothills of the Venetian Plain. This reactivation totally erased the structures of the previous Serravallian-Tortonian compression that created the Valsugana Thrust made of N70 frontal ramps and N20-40 left-lateral oblique ramps, exactly like the Agordo ramp which inverted from left to right lateral fault. This outcrop confirms that the E-trending compression (Adriatic event) involves not only the Venetian Plain foothills but also the interiors of the chain. References Poli E. & Zanferrari A., 1991 – Rend. S.G.I., 14, 1, 127-134I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
