INTEGRATED GEOPHYSICAL STUDIES OF EASTERN SIRT BASIN AND SOUTHWESTERN CYRENAICA PLATFORM, LIBYA

The present day deformation of northern Libya is the result of the Eurasian-African continental collision. The tectonic evolution of Libya, located at the northern extreme of the African continent, has yielded a complex crustal structure that is composed of a series of basins and uplifts. The area under investigation covers the southeastern part of Sirt basin and the southwestern part of Cyrenauca platform. The present study represents a comprehensive seismic and gravity investigations aimed to provide qualitative and quantitative information that would assist in the interpretation of the tectonic and structural history of the area under investigation.

Seismic data used in this study represents four different surveys with different sources including dynamite and vibroseis. The grid density of these data was also varies. Due to these facts quality control and mis-tie had to be precisely performed. Depth conversions were constructed using six interval velocities resulting in depth seismic sections and depth maps. The gravity database for this study was collected from different sources. These data were used to generate the Bouguer anomaly map as well as other specialized gravity maps used in the detailed gravity investigations.

Major structural trends were very well reflected in both seismic and gravity results. These trends include a NE-SW trend which represents the Cyrenaica platform and a NW-SE trend that represents the Sirt basin rift system. Pre-rift, Syn-rift and post rift stratigraphic units have been distinguished into three phases in Sirt basin area using seismic data. However, there are limited distributions of some horizons due to the poor quality of data. Gravity data shows the possibility of dextral strike-slip faults with NE-SW trending direction which has been developed during the formation of Sirt basin.