The Biga Peninsula, the complex geological structure of which has attracted intense attention so far, is located in the north-western part of Anatolia, Turkey. The Peninsula is tectonically very important region where different tectonic zones meet and comprises various kinds of sedimentary, metamorphic and igneous rocks. Among these rocks, igneous rocks occupy a considerably amount of areas in the Biga Peninsula and they are mostly associated with geothermal systems and mineral deposits, and therefore they play an important role in the geology of the Peninsula. In this paper, derived results concerning the geological features and subsurface structures of the igneous rocks in the Peninsula are presented based on analyzing the airborne magnetic anomalies. To this end, a MATLAB-based toolkit named as Gravity and Magnetic Interpretation (GMINTERP) that is composed of a set of linked functions in conjunction with a graphical user interface was developed and used for the interpretation of the airborne magnetic anomalies. Some linear transformations and derivative-based techniques were performed to process the potential field data-set and also to help build a general understanding of the geological details. The close agreement between the derived geophysical anomaly maps and the well-known surface geology map of the Biga Peninsula helped us discuss the geological implications of the geophysical traces. This study also indicated that the developed interactive data processing toolkit may assist geological interpretation even in the areas whose subsurface structure is poorly known.