Stress and pore pressure analyses using spatial pattern of quartz veins, SE Hamedan

In this research orientations of quartz veins of Zaman Abad area at the south eastern of Hamedan are used to determine the relative principal stresses (σ1, σ2, σ3) and fluid pressure (Pf) conditions by constructing 3D Mohr circle. The poles distributions of quartz veins in the stereograph projection have a wide range of orientation and mainly show the girdle pattern. 3D Mohr circle construction for quartz veins suggest Pf>σ2 condition and shows high value of fluid pressure (Pf=885.7 to 1044.4) near to the maximum principal stress (σ1). Driving pressure ratio (R΄) and stress ratio (Ø) were calculated as R΄=0.82 to 0.93 and Ø=0.77 to 0.81, for quartz veins respectively. Results show that the occurrence and evolution of quartz veins are related to the latest stress phases due to Alvand Batholith intrusion. Also according to the results it revealed that quartz veins were generated in the 3-D oblate stress ellipsoid conditions.