Writers : Sahabi.F
Refference : Geosciences Scientific Quarterly Journal,No.:31-32,P.:2
Publishing Year : 1378

Abstract :
Volcanic activity in Sabalan started in Eocene and resumed in Pliocene by erruption of trachy - andesitic andesitic lava flow through the main caldera. Four major bithostratigraphic units were defined in the studied area in the following order:
Dizu Formation(Quaternary alluvium and terraces), Kasra Formation(post-caldera, Late Pliostocene), Taos Formation(syn-caldera. Early plistocene) Valhazir Formation (pre- caldera, Pliocene).
The Sabalan Volcanic Complex, structurally consists of:
- A central caldera of 14 x 12 km, partially filled by post - caldera trachyanclesite-trachydacite lava flows.
- Linear faulting trending NE - SW, N-S and WNW-ESE.
- Arcuate structures forming an inner and outer fractures to the caldera.
Resistivity measurements(DC, TEM and MT) was carried out to identify subsurface resistivity anomalies. Five significant anomalie! (5-10 ohm. m)were defined as follows:
- Gheynarjeh(NW. Sabalan)
- DoIlar(SE.Sablan)
- Toas-Hooshang Meidan (WNW.Sabalan)
- Ghotur Suii(N.Sabalan)
- Sar- e em (SE Sabalan)
The main hydrothermal alteration exposed at the surface is confined to the valhazir (pre -caldera) formation and is of two types.
- Low temperature alteration developed in the vicinity of the surface thermal springse. g., Gheynarjeh.
- Alteration, indicative of pre - existing hydrothermal system, in which temperature was at least 180 ° C.
Subject List : Volcano, volcanic rocks