Application of Electrical Tomography to Put in Evidence the Thickness and Structure of the Filling of Dayet Iffer (Middle Atlas, Morocco)

Bouchra Lemdeghri Alaoui,Mohamed Chibout,Fatima Zahra Faqihi,Anasse Benslimane,Abdennasser Baali

doi:10.4236/ijg.2020.114010

Abstract

The Dayet Iffer belongs to the Dayets of tectono-karst origin of the Northern Middle Atlas. After its watershed genesis of middle altitude during the Quaternary, two lacustrine formations were deposited on the surface while other thick formations exist in depth. The detailed sedimentological study of the soltanian and holocene lithological sections on the surface and the 14C datings helped recognize part of the history of the watershed. The geophysical study allowed to detect the thickness of the superficial geological formations as well as the various geological phenomena (tectonic and/or karst) that affected them from the genesis to the present. The current shape of the watershed where the Dayet Iffer exists is only the result of an evolution where sedimentary, tectonic and karst phenomena interfere. The tomography obtained with Res2DInv software, performed for the first time at the Dayet Iffer, reveals the presence of three ranges which can be interpreted as three resistive, intermediate and conductive zones with a large set of faults. These results helped determine the thickness (over 160 m) of the sedimentary filling. This shows that the hydrological behavior of the Dayet Iffer takes into account both horizontal flows at the stratification and/or karstic joints and the movement of sub-vertical fractures.

Highlights

IntroductionThe studies undertaken on the lake basin of the Dayet Iffer, proceed from a qualitative approach of the contributions; this one concerns the filling whose sedimentation is continuous during the end of the Upper Pleistocene (Soltanian) and the Holocene
The present study aims to specify the thickness, the shape and the structure of the sedimentary filling and the relations between the different bodies of the filling by a recent geophysical method, namely the electric tomography performed for the first time at the Dayet Iffer
The results presented in this paper show that electrical tomography is a geophysical tool well suited to the detection of fills and the mapping of lake basins in karst areas

Summary

Introduction

The studies undertaken on the lake basin of the Dayet Iffer, proceed from a qualitative approach of the contributions; this one concerns the filling whose sedimentation is continuous during the end of the Upper Pleistocene (Soltanian) and the Holocene. On this site, the work allowed to recognize the lithostratigraphy and the morphology of the watershed, to identify the nature and the geometry of the sedimentary filling, to specify the age and to establish correlations with the climatic [4] [5] [6] [7] [8]. The present study aims to specify the thickness, the shape and the structure of the sedimentary filling and the relations between the different bodies of the filling by a recent geophysical method, namely the electric tomography performed for the first time at the Dayet Iffer (high resolution imagery and better detection of lateral and vertical variations in electrical resistivity)

Methods

Results

Conclusion