Structure, geochemistry and U-Pb isotopic age of Kor-e-Sefid Gneiss (Neyriz metamorphic complex)

Category Tectonic & Seismotectonic
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      Gneissic rocks in the Kor-e-Sefid area are among the major units of the metamorphic complex of Neyriz area. They are situated at the base of regional lithostratigrahic column.
   From structural point of view they are at the cores of large scale successive antiforms which their limbs consist of micaschsit, marble, greenschsit and amphibolite. These rocks are intruded by anatexis granite. The structural studies show the locally normal shear contact between gneiss and overlying rocks( schist, marble,?.).
   Geochemical analysis indicate the magmatic origin (granite) for these rocks.
   Isotopic dating from separated zircon grains show :
   a) Morphologically, the zircon grains are near-euhedral with large prismatic shape typical of derivation from an igneous source. This confirm the result of geochemical data.
   b) The absolute age of the gneiss based on U-Pb method obtained from zircon is 520 Ma. This shows a granitization period in Cambrian at the south-west margin of central Iran which is comparable with the same age magmatic activity in another part of this zone.