ZOBECNĚNÁ METODA KLÍNŮ PALEONAPJATOSTNÍ ANALÝZY: ZÁVISLOST NA LODEHO PARAMETRU
Roč.9,(2002)
Abstrakt
Klíčová slova:
inversion; paleostress analysis
Two old basic graphical methods of paleostress reconstructions include right dihedra method (Angelier – Mechler 1977) and M-plane method (Arthaud 1969). These two methods are two marginal cases of general inverse method based on one-fault inverse analysis. Using fault coordinate system, where l-axis is stria lineation, n-axis is normal to fault plane and m-axis complete right-hand orthogonal system lmn, it is easy to derive equation for Lode parameter μL = (2σ2 - σ1 - σ3)/( σ1 - σ3) in dependence on direction of σ1 and σ3 respectively. This function limits field of possible σ1-directions with decreasing of μLmax (Fig. 2a) and σ3-field with increasing of μLmin. The field of σ1 is equivalent to right dihedra quadrant for μL ≤ 1 as one extreme and it is reduced to part of M-plane for μL = -1 as the second extreme (Fig. 1). Base on it we can make equal-area plot for fields of σ1 and σ3 with isolines of μL (Fig. 2b, c). With these plots we can determine upper and lower limits of μL (μLmax, μLmin), and coresponding fields of σ1 and σ3 respectively.
inversion; paleostress analysis
Reference
Angelier, J. – Mechler, P. (1977): Sur une méthode graphique de recherche des contraintes principales également utilisable en tectonique et en séismologie: la méthode des diedres droits. – Bull. Soc. géol. France, 19, 6, 1309–1318. Paris.
Arthaud, F. (1969): Méthode de détermination graphique des directions de raccourcissement, ďallongement et intermédiaire ďune population de failles. – Bull. Soc. géol. France, 11, 729–737. Paris.