Biostratigraphy and lithostratigraphy of Tarbur Formation (Upper Cretaceous) in southwest of Khorram Abad (southwest Iran)

• Autores: Ahmad Abyat, Massih Afghah, Amir Feghhi
• Localización: Carbonates and Evaporites, ISSN 0891-2556, Vol. 30, Nº. 1, 2015, págs. 109-118
• Idioma: inglés
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• Resumen

  • To study lithostratigraphy and microbiostratigraphy of Tarbur Formations in southwest Khorram Abad (Lurestan), one stratigraphic section of the Tarbur Formation was selected in Cham-e Sangar area. Lithostratigraphic studies reveal limestone, dolomitic limestone, sandy limestone, shale and marl in this section. Identified index lithofacies in this section include grainstone, packstone and wackstone. Microbiostratigraphy studies provided on 67 thin sections from 77.3 m of Tarbur Formation sediments in Cham-e Sangar section indicate the existence of 12 genera and 23 species of benthic foraminifers. Based on assessment of an existing set of foraminifera, Omphalocyclus-Loftusia assemblage zone has been proposed for the Cham-e Sangar section. Micropaleontological studies suggest middle-Maastrichtian to late Maastrichtian age for Tarbur Formation in southwest Khorram Abad. The studies were performed for the first time in Lurestan province, Tarbur Formation where index lithology and fauna of Maastrichtian interbeds in the clastic-conglomerate deposits of Amiran Formation base as a tongue, or a projecting part of a lithostratigraphic unit extending out beyond its main body. This study indicates the age of the Amiran Formation basal part as Maastrichtian.