Azimuthal resistivity soundings over a steeply dipping anisotropic formation - A case history in central Tunisia

Myriam Schmutz (1) , Pierre Andrieux (2) , Alexeiev Bobachev (3) , Jean-Pierre Montoroi (4) , Slah Nasri (5)

1 Géoressources et environnement
2 SISYPHE - Structure et fonctionnement des systèmes hydriques continentaux
3 Department of Geophysics [Moscow)
4 Bioemco - Biogéochimie et écologie des milieux continentaux
5 INRGREF - Institut National de Recherche en Génie Rural Eaux et Forêts

Azimuthal Resistivity Soundings (ARS), using the so-called "Arrow-type array" as proposed by Bolshakov et al. were carried out in Central Tunisia, together with azimuthal resistivity tomography, because of the known anisotropic behaviour of the nearly vertical formations. First, the developments designed by Bolshakov et al. are reviewed: they deal with the separation between the effects of anisotropy and of heterogeneities, the design of the Arrow-type array and the introduction of the azimuthal spectral analysis. Second, the main methodological results obtained near Gouazine Lake are presented: (1) the clear effect of a quasi-vertical contact and (2) the characterisation of the anisotropic substratum below a thin superficial layer in one site close to the axis of the valley: the strike direction (alpha = 50 degrees N), and a rather high anisotropy coefficient (lambda approximate to 4) are determined. And lastly two directions for further developments are suggested. (C) 2006 Elsevier B.V. All rights reserved.

Mots clés: direct current; Tunisia; anisotropy; ARS azimuthal resistivity sounding

Domaines: Interfaces continentales, environnement; Milieux et Changements globaux

Myriam Schmutz, Pierre Andrieux, Alexeiev Bobachev, Jean-Pierre Montoroi, Slah Nasri. Azimuthal resistivity soundings over a steeply dipping anisotropic formation - A case history in central Tunisia. Journal of Applied Geophysics, 2006, 60 (3-4), pp.213-224. ⟨10.1016/j.jappgeo.2006.05.003⟩. ⟨bioemco-00454595⟩