Geochemistry of siliciclastic sediments of the Semnan Province and NE of Isfahan Province (Iran), implication for provenance

Abstract

Some 43 samples collected from surficial sediments of Semnan Province (Alborz zone) and NE Isfahan Province (Central Iran zone) were analyzed, for constrains on provenance. Sand fraction were analyzed by XRF analyzer Philips Model PW 2450 in the laboratory of the Geology Survey Iran (GSI). Precision was 0.01%. Furthermore, 8 selected sediment samples and 8 samples from rock units from surrounding area were also analyzed for REE content via ICP-MS in the GSI Lab. in Karaj branch. Interpretations of the major elements suggest intermediate to mafic igneous composition for both of the study area. Samples of the Semnan Province represent PCM and those of the NE Isfahan Province show OA, CIA, and ACM setting for their provenance. The sediments are enriched in LREE in compare to HREE for both of the study area. Results also purpose that the Karaj Fm. was important source that impelled sediment in the Semnan Province. Ultramafic source is more plausible for the NE Isfahan Province. Ultramafic of the Anarak, altered ultramafic rocks of Proterozoic to early Paleozoic of the Anarak – Khor and ophiolites exposed along major faulty in the region (e.g. Nain – Dehshir - Baft Fault) are the possible source for this area.