Environment of Deposition and Sedimentary Petrology of the Cambrian System in a Part of South Central Alborz, Iran

Faculty of Science, University of Tehran
For the purpose of this study 160 rock thin sections, as well as many
hand - specimens, were studied and examined. The Cambrian system in the
area is consisting of the Labun and the Mila Formations. R. L. Folk's classification
scheme have been used in the sedimentary petrologic study of the specimens.
General conditions of the sedimentary environment during the Cambrian
time has been described and interpreted.
The Labun Formation which is consisting of three members, has a
composition varying from quartzite to arkose, and its maturity is ranging from
mature to sub mature. Few local dikes of diabasic composition have been
recognized in this Formation. It is concluded that the environment of deposition
of this Formation was of oxidizing conditions and the deposits are of platform
kind.
The Mila Formation does not have complete outcrop of the four members
present in this area at every locality. This is mainly due to faulting, which
has caused the omission of some of the members of this Formation. Mila Formation
is a typical deposit of marine origin The conditions of deposition of this
formation was of varying depth and general reducing environment.