Modelling of Thrace Basin, NW Turkey using gravity and magnetic anomalies with control of seismic and borehole data

Abstract

In this study, tectonic features and subsurface structures in the Thrace Basin located in the European part of Turkey were investigated by using gravity, magnetic, well and seismic reflection data in integration. The Thrace Basin is filled by the Tertiary clastic sediments with maximum thickness of about 7.5km and the basin is very prolific for natural gas potential. In this respect, firstly gravity anomaly map was evaluated and then 3km upward continued map was prepared. Analytic Signal was applied to the upward continued map. The gravity anomalies were modelled in three and two dimensional methods with the seismic and borehole data control. When the results are compared to the regional geology in the basin, it is determined that the deepest section of the basin is 7.5km to the north of Hamidiye and around Luleburgaz. In general, average sedimentary thickness of the basin is about 4.5km.3km upward continuation and analytic signal techniques are also applied to the aeromagnetic data. As a result of these applications, it was suggested that the sources of deep seated anomalies observed in the basin are caused by the palaeohighs and the basin is surrounded by the massifs with intensive magnetic anomalies caused by magmatic intrusions. Metamorphic basement outcrops on the Strandja Mountains are evident with the gravity and aeromagnetic responses. However, in contrast, there is a region to the north-northwest of Kirklareli represented by the low gravity contours. It indicates an existence of buried depression on the 3D model. This is explained with the presence of 2 to 3km thick meta-sedimentary units beneath the Strandja Massif.