Geochemical investigation and determination of the origin of fluvial terrace deposits of Qolyan River in Qalikuh region of Lorestan, high Zagros

Authors

1 M.Sc, Geological Operations, Exploration Management, National Iranian Oil Company, Tehran, Iran

2 Head of Hydrocarbon Systems Department, Exploration Management, National Iranian Oil Company, Tehran, Iran

3 Head of Geochemistry Studies Department, Exploration Management, National Iranian Oil Company, Tehran, Iran

Abstract

Qalikuh region of Lorestan is very important in the geology of Iran due to the spread of oil shales deposits. The Qolyan River flows in the bed of these deposits. In order to investigate the elemental geochemistry, to determine the origin and to investigate the relationship between the concentration of elements and the amount of organic matter, 15samples from the fluvial terrace sediments of the Qolyan River and 15samples from the surrounding oil shales were collected and subjected to petrographic and geochemical analysis. The results showed that the most depletion of main oxides in sediments is related to Na2O and there is enrichment only in relation to CaO. Enrichment of minor elements Sb,As,Ni,V related to shales and Sr is related to the dispersion of clay minerals and lime layers. The depletion of Rb is the consequence of feldspars breaking in process of alteration. Nb, Zr elements are present in sedimentary minerals in minor form. The origin of minor and rare earth elements is related to the place of formation, weathering in the deposits and the amount of total organic carbon in the oil shales scattered in the region. The samples are in the range of litharenite, arkose to shale, which are related to the environments of active continental margin and collisional. According to the Th/U ratio, the sediments were formed from source rocks with the least weathering. The amount of PIA and ICV index of the samples shows the effect of low weathering on sediments related to active tectonic environments.

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History

  • Receive Date: 26 December 2023
  • Revise Date: 06 July 2024
  • Accept Date: 17 July 2024

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