Crustal thickness variations in the Aegean region and implications for the extension of continental crust

Abstract

[1] We installed 5 broadband and 45 short-period temporary seismic stations, distributed partly as a dense, 100-km-long, N-S linear array and partly as a regional network, throughout the Menderes Massif of western Turkey in order to study crust-upper mantle structure and seismicity. In this study, we have combined teleseismic waveform data from these stations with data from several permanent seismic stations to determine crustal thickness variations in the Aegean region. Receiver function studies at seven broadband stations, using the H-k stacking method, have yielded crustal thicknesses and V p /V s ratios over a broad region of the Aegean. A more detailed crustal image was obtained in the central Menderes Massif, where we applied common conversion point stacking to receiver functions obtained from the N-S linear array. The results show a general trend of westward crustal thinning from 36 km in central Anatolia to 28-30 km in the central Menderes Massif to 25 km beneath the Aegean Sea. The results also indicate that crustal thinning in the Aegean is not uniform in the N-S extensional direction. The crust is thinner in the central Menderes Massif (28-30 km of crustal thicknesses) and the Cycladic Massif (25-26 km) than in surrounding regions where crustal thicknesses are 32-34 km. The longlived elevated Moho under the metamorphic core complexes suggests that the lower crust in the Aegean region is at least 3 times more viscous than that in the Basin and Range Province, where the Moho is much flatter.

Shallow and Deep Structure of a Supradetachment Basin Based on Geological, Conventional Deep Seismic Reflection Sections and Gravity Data in the Buyuk Menderes Graben, Western Anatolia

“…This finding is consistent with the idea that 6 km of the Western Anatolian lithosphere may be more resistant to the stresses induced by scaled geological flexure over long time scales (Pamukçu and Yurdakul 2008). The results obtained in this study are consistent with the results of the seismological studies performed by Zhu et al (2006) and Akyol et al (2006), with the gravity study conducted by Ankaya and Akçıg (1998) and with the isostasy study carried out by Pamukçu and Yurdakul (2008). In almost all of these studies, the mean crustal thickness was determined to be 33 km.…”

Receiver function images of the Hellenic subduction zone and comparison to microseismicity

“…These results are in good agreement with those obtained from the previous PRF studies in western Anatolia, Peloponnese and in central Aegean (e.g. Sodoudi et al, 2006;Zhu et al, 2006;Karabulut et al, 2013;Vanacore et al, 2013). Relatively thin crust beneath the Aegean and adjacent areas likely shows the extensional tectonics that affected the whole Aegean since the Oligocene time (∼ 30 Ma) (e.g.…”

Recent behavior of the North Anatolian Fault: Insights from an integrated paleoseismological data set

“…Paleomagnetic directions in the west Anatolian extensional province are rotated clockwise [Piper et al, 2008], which we attribute to rotations associated with extension. The plate thickness in the east Anatolian contractional province is 40-50 km [Zor, 2008], in the central Anatolian Ova province 36-40 km thinning toward the southern edge [Zor, 2008], and in the west Anatolian extensional province spot thicknesses are generally in the range of 22-30 km [Tirel et al, 2004;Zhu et al, 2005], with a thickness of only 8 km in the Sea of Marmara [Bécel et al, 2009]. We assume that the thickness of the plate in the central Anatolian Ova province is approximately that of the whole region prior to the present tectonic regime (i.e., at least 13 Ma.).…”