Geoscience Reference
In-Depth Information
Fig. 2.49
Geological scheme of the region of Vaucluse (after Mudry and Puig
1991
) 1—Bedoulien terrain; 2—Lower Cretaceous
limestones; 3—Neocomian marls; 4—fault; 5—spring
to
the
Pliocene
transgression
(Depambour
and
case studies, most convenient for the development of
the karst process are these fractures that are perpen-
dicular to the minimum tectonic stress axis (tectonic
extension). These fractures (tensional fractures) are
the least resistant to the water current and they are
most effectively widened when dissolution of the
limestones is going on (Dreybrodt
1988
).
Guedon
2004
).
From hydrogeological point of view, the role of the
spring of Vaucluse (Fig.
2.50
) for the draining of
underground waters is well studied (Murdy and Puig
1991
). It is necessary to note also that the hydro-
geological unit Luberon-Vaucluse continues below
the syncline of Cavaillon (Gouvernet et al.
1971
) and
this was confirmed by the borehole near Chene, 5 km
westwards from the town of Apt.
Karst Galleries Orientation
The diagrams of the orientation of the karst galleries
could be useful for indication of the main preferred
ways of the underground waters. Mostly, this is the
direction of the open fractures and the practice has
shown that this type of fractures in the recent active
karst systems is normally connected with the youn-
gest tectonic stress field.
2.3.4.2
Methods of Study
Fracturing
Mass measurements of the space elements of joints
(dip direction and dip angle) in different outcrops of
the rock massif were done and they provide the basic
data for applying the method of Nikolaev (
1977
) for
reconstruction of the main axes of the tectonic stress
fields. As shown above, when presenting the different
Earthquakes
The most appropriate method for determining the
main directions of the contemporary tectonic stress
