An aspect of the subsurface structure of the Burdur-Isparta area, SW Anatolia, based on gravity and aeromagnetic data, and some tectonic implications

Abstract

Gravity and aeromagnetic analyses were conducted in the Burdur-Isparta area of Turkey in order to identify the subsurface structure and tectonics of the region independent of surface cover. The analytic signal of the aeromagnetic anomalies was first calculated to delineate the source fields of these anomalies. The magnetic signatures were found to correlate well with the intrusives associated with the subduction of the African oceanic lithosphere and with the ophiolitic nappes in the region. The residual aeromagnetic anomalies mostly orientate in the N-S direction, implying the presence of remanent magnetization. Based on the shape analysis of aeromagnetic anomalies, the region appears to have rotated clockwise. The magnetic anomalies were found to continue upward to 5 km a.s.l. The upward continued map shows deep effects of the sub-crustal magnetic sources. Based on the Bouguer gravity anomalies, the thickness of the crust in the study area is between 33 and 37.5 km. Major extensive NE-and NW-as well as N-trending faults are identified that coincide with the Lake Burdur, Lake Beysehir and Kovada grabens, respectively. Lake Egirdir is also devoid of any magnetic sources. As a final step, the maxima of the horizontal gradient of the gravity data were calculated. The maxima show that the major geological formations and the structural trends in the area are remarkable. The boundaries of the various geological formations can be identified based on the boundary analysis of the gravity and the analytic signal of the aeromagnetic data. The change in the nature of the anomalies reflects the imprints of intense deformation associated with major tectonic activity of the African-Eurasian plate convergence zone.

Geophysical and geological imprints of southern Neotethyan subduction between Cyprus and the Isparta Angle, SW Turkey

“…The crust in southwestern Anatolia thins from 34 km in the east to 22 km in the Aegean Sea (Saunders et al, 1998). Crustal thickness in the Isparta Angle area is 30-37 km (Kalyoncuoglu, 2001;Dolmaz, 2007;Erduran, 2009). For this reason, we assumed that earthquakes in the depth range 0-35 km occurred within the crust.…”

What is the reason for the high Bouguer gravity anomaly at Çumra, Konya (Central Anatolia)?

“…Aside from high Bouguer gravity anomalies due to their high densities, ophiolites have strong effects on magnetic anomalies due to their high magnetic susceptibilities (Rao et al, 2016). Numerous studies show that ophiolites usually have positive magnetic anomalies (Kane et al, 2005;Dolmaz, 2007;Rao et al, 2016); thus, comparing magnetic and Bouguer gravity anomaly maps of the Çumra area would support the buried ophiolite thesis. An examination of the area's aeromagnetic data points out a strong magnetic anomaly around the Çumra region as seen in Figure 10 (MTA, 2007).…”

Teleseismic inversion of crustal S-wave velocities beneath the Isparta Station

“…Therefore, our LVZ is interpreted to represent a body of partial melt in the lower-crust, which is consistent with patterns of volcanism at the surface. Comparable magmatic bodies within extensional provinces with graben development in SW Turkey, as pointed out by Ates¸et al (1996), and also highly magnetized bodies in the upper crustal levels revealed by Dolmaz (2007) through the examination of the crust thermal structure in the Burdur-Isparta area using the CPD estimates from aeromagnetic data, may indirectly point to the presence of lower-crust partial melts.…”

“…Dolmaz (2007) suggested from an analysis of Bouguer gravity anomalies that the crustal thickness in SW Anatolia changes between 33 km and 37.5 km. Gürer and Bayrak (2007) reported that the depth to the Moho discontinuity is ∼40 km in the vicinity of station ISP, based on electrical resistivity observations.…”

“…Ates¸et al, 1996Ates¸et al, , 1999Kalyoncuoglu and Özer, 2003;Gürer et al, 2004a,b;Meier et al, 2004;Dolmaz et al, 2005;Aydın et al, 2005;Zhu et al, 2006;Akyol et al, 2006;Erduran et al, 2007;Dolmaz, 2007;Gürer and Bayrak, 2007;Salah et al, 2007). Here, we employ the joint inversion of teleseismic P receiver functions and surface wave group velocities to improve our knowledge of the crust and uppermost mantle seismic velocity structure beneath the Isparta Angle.…”