Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Sabalan Volcanic Complex with special reference to the hydrothermal resources in Meshkinshahr area, NW. Iran

Author
Fereydoun Sahabi
Geoscience Research Institute, Geological Survey of Iran, Tehran, Iran
Abstract
Volcanic activity in Sabalan started in Eocene and resumed in Pliocene by eruption of trachy - andesitic andesitic lava flow through the main caldera. Four major lithostratigraphic units were defined in the studied area in the following order: Dizu Formation (Quaternary alluvium and terraces), Kasra Formation (post-caldera, Late Pleistocene), Taos Formation (syn-caldera, Early Pleistocene) 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 trachyandesite-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 anomalies (5-10 ohm. m)were defined as follows:
-Gheynarjeh (NW. Sabalan)
-Dollar (SE. Sablan)
- Toas-Hooshang Meidan (WNW. Sabalan)
- Ghotur Suii (N. Sabalan)
- Sar-e ein (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 springs. e. g., Gheynarjeh.
- Alteration, indicative of pre-existing hydrothermal system, in which temperature was at least 180° C.
Keywords
hydrothermal resources
Sabalan
Meshkinshahr

Subjects

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Scientific Quarterly Journal of Geosciences
Volume 8, 31-32
Spring & Summer 1999, vol. 8, No. 31-32
Summer 2000
Pages 2-15