Biological marker geochemistry of selected oils and possible source rocks from central Alborz Basin

Document Type : Research Paper


Research Institute of Petroleum Industry, Tehran, Iran


Surface oil seeps from Alasht, Lapur and Jenesem share many compositional affinities including distributions and concentrations of
normal alkanes, terpanes and steranes. These oils also show many similarities with that of Jurassic sediments (Shemshak Group, Klariz
Formation) systematically sampled from the Galandrud Coal Mine. Recent geochemical studies in this area indicated that the
Shemshak Group is rich in organic matter and has potential to generate oil and chiefly gas. The Kalariz Formation here is composed of
350 m of mudstones, siltstones and fine-grained sandstones with over 30 coal seams. This formation is thought to have sourced Alasht
and Lapur oil seeps. GC and GC-MS chromatograms of Jenesem oil are unique and show no any similarities with that of above
mentioned oils or the Shemshak Formation. This indicates that the Jenesem oil has been generated from a different source rock but its
origin is still unknown.