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Structural Control on the Salmas Geothermal Region, Northwest Iran, from Fractal Analysis and Paleostress Data
Author(s) -
BEHYARI Mahdi,
NOURALIEE Javad,
EBRAHIMI Davar
Publication year - 2018
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13673
Subject(s) - geology , geothermal gradient , seismology , fractal dimension , tectonics , petrology , fault (geology) , subduction , fractal , crust , fracture (geology) , fracture zone , fractal analysis , geophysics , geotechnical engineering , mathematical analysis , mathematics
The Salmas geothermal field is located in NW Iran. Subduction of Neo‐Tethys oceanic crust beneath the Iranian microcontinent caused to propagation of the magmatic‐Arc. Fractures and faults in the convergent zone have created path‐ways for the circulation of geothermal fluid. Fracture concentration in the Salmas geothermal field has been characterized using of the fractal method and creation of a fracture density map that shows the highest concentration in the central part of the study area. The permeability of fractures has been evaluated by analyzing their orientation in respect to the paleostress axes. Also, the fractal analyzing result indicates the maximum fractal dimension (1.96) is around the thermal spring outlet. Paleostress analyzing revealed that in the central part of the study area, σ1 axes orientation is S90°W/10° and the σ2 dip is near to the vertical in this stress field, where strike slip faults can be propagated. In the SE part near the recharge of the thermal springs, the σ3 plunge increases to 70° and σ1 orientation is N15°E/20°, in this local tectonic regime thrust fault developed. Fractures have an important role in the circulation of fluid and the fractal dimension increases near the thermal springs in the Salmas geothermal field. Regarding the paleostress data fracture with N‐S direction such as the F1 fault zone (parallel to the σ1 axes), a suitable pathway for deep circulation of geothermal fluid flow has been created.