Investigation of the geologic and tectonic structures of Bafa Lake and Akbuk Gulf (terrestrial and marine areas) by means of gravity and magnetic methods

Abstract

Geologic units of Bafa Lake and Akbuk Gulf, which have very importance in point of geologic and tectonic structure, are generally are classified by high-grade metamorphic units of the Menderes Core Complex, Cycladic Complex (schist, marble, eclogite), Afyon zone meta sedimentary and Pan-African basement rocks, Neogene volcanic-sedimentary rocks and alluvium. As for tectonic structures of study areas are; Izmir-Balikesir Transfer Zone also affected the Buyuk Menderes Graben, Bornova Flysch Zone, Menderes Massif and Lycian Nappes. Regional researches were studied to reveal using Turkey Bouguer Anomaly and Turkey Aeromagnetic regional map with gravity method used for geologic structures analysis and magnetic method used to explain main structure, tectonic conditions of underground. General geologic structure and tectonic lineaments of region were examined and interpretated compatibility with gravity and magnetic values. When the geologic and tectonic structures on the terrestrial areas are generally investigated, graben systems and linearities are clearly seen on the Bouguer Anomaly map. Positive values are seen in the Bornova Flysch Zone and Menderes Massif areas at the north of study areas arising from high-density ophiolitic and metamorphic units. Graben areas in the Menderes Massif are observed negative gravity values on the low-density young alluviums. Positive gravity values are increased up to 50-60 mgal on the metamorphic rocks that are named Cycladic Complex located southwest of study areas.At the aeromagnetic regional magnetic map, gamma values about -100 observed on the Menderes Massif region are indicated metagranite rocks that are Paleozoic crystalline structure. Gamma values, which are changed between -100 and +100 at the transition areas granite with schists, are obviously revealed this transition region. Located northwest of study areas Upper Miocene-Pliocene aged from sedimentary rocks on the terrestrial carbonates and nonsegregated terrestrial clastics units +100 gamma values are interpreted as values observed on the sedimentary rocks. For the marine geologic and tectonic structures, at the total magnetic field measurements mapped weren’t quite run across to residual values. Gamma values that are changed between -60 and +400 acquired at the marine magnetic datas with gamma values that are changed between -100 and +300 in lake at the aeromagnetic anomaly map are very close values each other. In the lake, high anomaly datas are caused by islands. Showing between -100 and +100 of gamma values observed in the Akbuk Gulf are interpreted as to see effects of terrestrial geologic units at the environment in the gulf. Also, Akbuk Gulf marine magnetic datas will be collected for the detailed study.