Statistical Analysis of Directional Features - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 296

other newly obtained results on tectonics of the Alpine realm involving movements
of the Adria microplate (Picardi et al. 2011 ) of which the current northern boundary
at the surface approximately coincides with the Periadriatic Lineament.
As mentioned in the Introduction, the quartzphyllites of the Dolomites basement
were folded during the Hercynian Orogeny. Most B-axes in the Brixen crystalline
basement West of the TRANSALP profile and in the Cima d'Asta and Agordo areas
south of the Dolomites are relatively low-dipping and have N-S to NNW-SSE
orientations. These parts of the Dolomites basement underwent less Alpine defor-
mation than the quartzphyllites in the San Stefano and Pustertal areas (Figs. 8.6 and
8.16 ). During the early Neogene, the Dolomites and their basement had been
subjected to anti-clockwise rotation of about 50 (Channell and Doglioni 1994 )
indicating that, originally, the Hercynian folds had NE-SW to E-W orientation.
According to Vai ( 2002 ) the Italian region contains three different segments of
Hercynian mountain chain: (1) Carnian-Dinaric, (2) central-western Southalpine
and (3) Apenninic, surrounding a Baikalian or Panafrican consolidated
microcraton, roughly corresponding to the core of to-day's Adria microplate.
North to northeast directed Hercynian structural axes are almost coaxial with
those of Alpine age in the Apennines (3) but cross at high angles in the Southern
Alps (2). From the patterns of Fig. 8.6 (San Stefano area) and Fig. 8.16 (Pustertal) it
can be inferred that the angle between Hercynian and Alpine structural axes
decreases eastward toward the Carnian Alps and southeastward toward the
Dinarides (1) where they become subparallel with E-W to SSE-NNW orientations,
respectively.
Picardi et al. ( 2011 ) provide a recent outline of the Adria microplate, which is a
nearly closed basin comprising a Meso-Cenozoic continental block that represents
the foreland of the Apennines and Dinarides-Hellenides mountains, two
sub-parallel orogenic belts with opposing vergences. Its core is the region currently
occupied by the Adrian Sea. The northern boundary of Adria coincides with the
Periadriatic Lineament. To the north and south of the Dolomites, the Alpine
vergence is southward. The southern boundary of the crystalline basement of the
Dolomites consists of the Valsugana Lineament, which is a major thrust fault, in the
Strigno area (Fig. 1.1 ) accompanied by a south vergent overthrust sheet (Agterberg
1961 ; Castellarin and Vai 1982 ; Castellarin et al. 2006 ). The Alpine anticlinal
structure in the San Stefano area (Fig. 8.6 ) has vergence intermediate between the
S vergence of the Dolomites and the WSW vergence of the Dinarides. Current
deformation in the Adriatic region does not simply reflect the N-S shortening
between Africa and Eurasia. Adria's recent motion controls the distribution of
earthquakes and tectonic deformation across a broad area of South-central Europe.
As in the past, Adria moves in response to the combined motions of the African
Plate, Eurasian Plate, Anatolian block, and Hellenic Arc (Picardi et al. 2011 ). At
present it moves north-eastward (Lippitsch et al. 2003 ).
Stampfli and Hochard ( 2009 ) describe the wander path of Adria during the past
180 million years. Initially Adria moved ESE-ward. After about 60 million years, it
commenced an anticlockwise rotation moving eastward, northward and
NNW-ward. During this motion, the Italian Dolomites and their basement were