Structural control on Ypresian karstic aquifer revealed by an integrated geophysical and geological approach: the Mateur imbricated thrust zone (Northern Tunisia)

Abstract

We present the characterization of a poorly studied karstic aquifer, documenting the geometry, resistivity properties and the control of structural discontinuities affecting the outcropping Ypresian limestone in the Mateur imbricated thrust zone in Northern Tunisia. The karst system was produced by meteoric diagenesis. Geophysical methods and field investigations were useful in extracting geologic features. First, our findings suggest that the N110 to N140 directions are the preferred dissolution paths oriented parallel to strike-slip and extensional faults. Second, the gravity data analysis (regional-residual separation, horizontal gravity gradient, and Euler deconvolution) show a particular tectonic node as a junction of NE-SW and NW-SE directions. Third, the 2D electrical resistivity models exhibit the various karstification typologies with high (more than 1000 Ω m), medium (between 200 and 1000 Ω m) to low (less than 100) electrical resistivity zones. These electrical resistivity models contributed to the establishment of the conceptual structural model of the global karst features. Finally, 2D ERT and 1D time domain electromagnetic analysis highlighted the presence of potential water zones integrated into the aquifer. Thematic collection: This article is part of the Karst: Characterization, Hazards & Hydrogeology collection available at: https://www.lyellcollection.org/topic/collections/karst