Inverting gravity anomalies over the Burdur sedimentary basin, SW Turkey

Abstract

The study area comprises the NE–SW trending Burdur Basin situated at the tectonically active northeastern part of the Fethiye–Burdur Fault Zone (FBFZ), SW Turkey. The basin demonstrates a half graben geometry hosting lacustrine sedimentary deposits from the Late Miocene onward and is bounded by normal faults on its southern side namely the Burdur Fault Zone. In this study, gravity anomalies over the Burdur sedimentary basin were inverted for the first time in terms of mapping its basement relief. The algorithm used for inverting the gravity anomalies provides accuracy depth estimates by incorporating an exponential increase in density with depth at its inversion procedure. Thus the obtained depth configuration yields also a major improvement on the results of depth content of the sedimentary infill reported previously by other studies that used a constant density contrast in their interpretation. Along the east of Burdur Fault from south to north, the basement depth to the southern end of Burdur Basin is ca 1.8 km and gets shallower to ca 0.6 km towards the north around the Burdur city. The deepest section of the basin is ca 3.2 km to the western side of the Burdur Fault close the southern end of the Burdur Lake. Towards north, out of the depression area of the Burdur Basin, the sedimentary infill is about in range of 0.4–1.2 km. The lateral limits of the basin structure have also been outlined by a recent edge detection method based on the logistic function of the total horizontal gradient (LTHG). The LTHG map related to the Burdur Basin shows maximal amplitudes trending NE–SW as two major lines that clearly delineates the segments of the Burdur Fault Zone to the S-SE of Burdur Lake. The inverted basin depth model by a cross-section perpendicular to the regional strike of the basin represents two-step depositional area of the sedimentary fills confirming a geometry of a half graben structure.