Structure of the Büyük Menderes Graben systems from gravity anomalies

Abstract

The Büyük Menderes Graben (BMG) of western Turkey is bounded by E–W oriented normal faults and has been a depositional center for thick sedimentary layers since the Miocene. Four Mio-Pliocene depressions (from west to east, the Çine, Bozdoğan, Karacasu, and Denizli basins) having overall N–S trends are situated just south of the BMG. In this study, we focused on the structural characteristics of the BMG using Bouguer gravity data covering the area between 37°N and 39°N and 26°30′E and 30°E and gravity data along 4 profiles to estimate the discontinuous basement relief of the BMG. Our main objectives were to investigate the geometry of the faults bounding the BMG and surrounding faults, and to describe the extent of the cross-graben structures. Boundary analysis, analytical signals, and second derivative methods were applied to Bouguer gravity data in order to determine tectonic border lines. The 2D inversion of gravity data together with the analysis of the power spectrum for each profile exposed an image of the subsurface. As a result of both methods, the thickness of the sedimentary cover was determined to be 1.44–2.3 km in the BMG. According to model geometry, the thickness of the sedimentary deposits decreases to the south of the graben.