Akademik Veri Yönetim Sistemi
Uluslararası Katılımlı 75. Türkiye Jeoloji Kurultayı, Ankara, Türkiye, 10 - 14 Nisan 2023, ss.1-2
Volcanic eruptions that occurred during the Quaternary period in the northern part of the Erzincan pull-apart basin controlled by the North Anatolian Fault Zone (NAFZ) created more than 10 volcanic eruptions. These volcanic centers erupted along a NW-SE trending deformation zone. This sector of the NAFZ keeps shaping the pull-apart basin with an annual westward block movement of 20 mm. When the mineral chemistry data obtained from previous studies are re-evaluated, rhyolites and dacites are sourced from 12-16 km; andesite and trachyandesitic rocks were calculated to have initial crystallization depths of 15-20 km. Radiometric age data obtained from previous studies (by applying Ar-Ar and K-Ar techniques) show that volcanism intensifies in the range of approximately 300-50 ka. The faults associated with the NAFZ gradually deform the basin in the form of a lens with right-lateral movement, and if the slip rate of approximately 20 mm/year continues in the Erzincan block, it seems possible that this deformative tectonics might trigger new volcanic activities through the region. In this study, the answer to this question was investigated by performing three-dimensional (3-D) numerical modeling analyzes on the basis of the finite element method. Solid mechanical modeling studies were modeled based on time-dependent. The existence of a 20x3x3 km magma chamber has been proposed considering both spread of volcanic centers throughout the field and unpublished seismic tomographic models at a depth of about 15 km. Stress accumulation behavior for 1000 years has been analyzed with dynamic modeling, taking into account the faults in the region, along a domain representing the upper crust of the region with dimensions of 120x60x40 km, where the aforementioned magma chamber is located. In the model created, the magma chamber is formed as a cavity suppressed by a pressure (Pe) of 5 MPa. The following mechanical constants were used for the surrounding rocks: Young's modulus (E): 25 GPa; Poisson’s ratio (ν): 0.25; Density: 2700 kg m-3. In the model, the domain’s base is fixed, the surface is free, the southern sector of the 3D block model is defined as 20 mm/year velocity movement from east to west. The transient solid mechanical modeling results reveal the minimum principal compressive stress (tensile) and Von Mises shear stress distributions in the region. According to these results, although both stress accumulations intensified above 10 MPa along the fault in the first 60 years, a stress of 5 MPa which is excess pressure for the magma chamber could not be followed, which in turn, around the magma chamber. The solid mechanical results indicate that a stress accumulation of at least 10 MPa and above, reaching the surface from the magma chamber after about 350 years, may be possible through the eastern part of the basin. Therefore, according to the results of 3D numerical modeling, it seems possible for volcanic activity to occur within 500 years at the location between Altınbaşak and Tanyeri in the eastern part of the basin.