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

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 7.5 km and the basin is very prolific for natural gas potential. In this respect, firstly gravity anomaly map was evaluated and then 3 km 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 7.5 km to the north of Hamidiye and around Luleburgaz. In general, average sedimentary thickness of the basin is about 4.5 km.3 km 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 3 km thick meta-sedimentary units beneath the Strandja Massif.

► The Thrace Basin is the most important gas-prone basin in Turkey.
► Different geophysical data and methods are consistently used in integration.
► Sedimentary thickness in Thrace Basin is accurately determined.
► The Thrace Basin is modelled 3-dimensionally for the first time.
► Results will be a base for future unconventional activities.