Statistical Analysis of Directional Features - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 297

rotated by about 50 (Channell and Doglioni 1994 ) and there were very significant
Oligocene-Miocene dextral shear movements along the Periadriatic Lineament
(Ratschbacher et al. 1991 ). South vergent faulting and folding within and around
the Dolomites commenced in the late Miocene. For example, the overthrust sheet
near Strigno associated with the Valsugana Lineament rests partly on Upper
Miocene sediments. Its origin may have involved neo-Alpine sliding motion
along slightly S dipping quartzphyllites south of the Permian Cima d'Asta intrusion
( cf . Agterberg 1961 , Fig. 83). Laubscher ( 2010 ) discusses late Miocene sinistral
strike-slip movement totalling about 70 km along the Giudicaria Line, which forms
the western boundary of the Dolomites Synclinorium.
Castellarin et al. ( 2006 ) have reviewed structure of the lithosphere beneath the
Eastern Alps (southern sector of the TRANSALP profile). Participants in the
TRANSALP Working Group ( 2002 ) originally proposed two different interpreta-
tive models of the Vibroseis depth-migrated data called “Crocodile Model” and
“Ductile Extrusion Model”, respectively. The two interpretations are similar except
in the segment of crust below the Periadriatic Lineament. In the second model, a
N-dipping break transparent zone in the Vibroseis depth-migrated data was
interpreted as the downward extension of the Periadriatic Lineament. In the first
model such a thrust fault was not recognized. The deformation patterns of the
quartzphyllites indicated by the unit vector field fittings described in the previous
two sections support the “Ductile Extrusion Model” in its interpretation that the
Periadriatic Lineament in its final stage was a thrust fault that reactivated Hercynian
s -planes to the south of it by strong neo-Alpine compression between the
Austroalpine units to the north and the Permotriassic of the Dolomites to the
south. The eastward convergence of the boundaries of these more rigid rocks
resulted in upward squeezing out of the more ductile Pustertal quartzphyllites.
The Vibroseis depth-migrated data from the TRANSALP profile across the
Periadriatic Lineament also show a number of non-reflective volumes indicating
presence of intrusions similar to the Permian Brixen batholith and, to the north of
the Periadriatic Lineament, the Oligocene Rieserferner tonalite intrusion. Between
these intrusions and the downward extension of the Periadriatic Lineament there are
many clearly developed south-dipping high-amplitude reflecting intervals, which
are probably equivalent to the south-dipping quartzphyllites of the basement of the
Dolomites in most of the Brixen area (to the SW of Fig. 8.12 ). In accordance with
the “Ductile Extrusion Model”, these rocks would constitute the northern edge of
the Adriatic indenter (Castellarin et al. 2006 ). Immediately below the TRANSALP
profile south of Bruneck, there are no well-developed high-amplitude reflecting
intervals. This is probably because of the subvertical attitudes of most s -planes in
this area. Similar interpretations can be based on the CMP stack section and post-
stack depth-migrated section shown and discussed by L¨schen et al. ( 2006 , Figs. 6
and 8).
Castellarin et al. ( 2006 ) estimated that upper crustal total shortening in the belt of
quartzphyllites between the “Dolomite Synclinorium” and the Periadriatic Linea-
ment amounts to about 15 km and that most of this shortening is due to rotation of
the quartzphyllites from low-dipping to high-dipping attitudes. According to the