May I suggest that you look into a couple of text books on rock mechanics
and geo-mechanics, I give you two titles of Georg Mandl, but other books
will give you the same info:
Mandl G., 1988. Mechanics of Tectonic Faulting: Models and basic concepts.
Book: Developments in Structural Geology, 1 (Series editor: H.J. Zwart).
Elsevier, ISBN 0-444-42946-8(Vol.1).
Mandl G., 2000. Faulting in Brittle Rocks. ISBN 3-540-66436-x Springer
In brittle rocks the angle (a) between an active fault (shear zone) and
the maximum stress (Sigma I) is determined by a simple relationship: a=
45 is in degrees, Phi is the internal friction angle. 25 < Phi < 45, with
the Phi of most brittle rocks around 30 to 33 degrees.
Phi is a rock property that is generally not affacted by the parameters
that you mention. Overpressure may have an effect in clays by lowering Phi
for increasing pore pressure. This needs to be treated carefully because
this i svery quickly no longer the brittle rock environment for which the
relationship is valid.
At very low stresses (e.g. at very shallow depth) Phi gradually changes
and becomes larger untill it reaches a maximum of 90 degrees at the far
left end of the Mohr-Coulomb failure envelope.
For relatively weak rocks Phi tends to be low and strong rocks tend to
have a higher Phi (e.g., slightly consolidated sandstone 30 or 33 degrees,
strong quartzitic sandstone 38 to 40 degrees, granite 42 to 45 degrees
(Look up in literature, these values are of the top of my head).
The most common reason for changes in the dip of faults is a change in
orientation of Sigma I.
Regards, Dirk Nieuwland
> Hi Ladies and Gentilmen,
> Does anyone know any paper/book about the factors controlling dip angle
> of faults such as temperature-pressure-water content-geothermal
> full references or comments will be appriciated.
> kind regards,
> Aydin CICEK