Chemical Characteristics, Provenance Determination and Genesis Conditions of Clay Deposits of Kahrizak Formation (Early-Late Pleistocene), East of Tehran, Iran

Z. Valiani ., P. Rezaee .


The Early-Late Pleistocene deposits in South-East of Tehran (Kahrizak Formation) consist of gravel, sand and clay facies which are related to alluvial fan deposits. The XRD analysis on fine grained deposits of the formation indicated the existence of clay minerals including montmorillonite, illite and chlorite; also quartz, calcite and anorthite are present as the minor components. We determined provenance and paleoclimate condition of the deposits based on clay minerals type. Montmorillonite and illite were used as the provenance indicator showing volcanic rock as the source rock. All clay minerals indicate low to moderate leaching in temperate to cold climatic setting. Their ICV values are >1 indicating negligible recycling or weathering of the clays. K2O/ Al2O3<0.4 and ternary plot of CaO+Na2O-Al2O3-KO2 suggests the deposits compositions same as basalt. Also that displays weathering trend. Low ICV values of the deposits exhibit low to intermediate degree of weathering for the parental rock. Based on Bhatia diagram, using DF1 and DF2and K2O/Na2O versus SiO2, its tectonic setting was determined as being active continental margin.


Kahrizak Formation; clays; paleoclimate; active continental margin

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