Introduction
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Figure 1
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[2] The Khan Formation established by Afghanabati (1977) to the west of the town of Tabas
stretches along the large Kalmard fault dividing the Posht Badam and Tabas tectonic blocks
(Figure 1). The formation lies with a hiatus on the Lower Carboniferous Gachal Formation and under
the Lower Triassic Sorkh Shale Formation. Fusulinids of the formation were first described by Kahler
[1977], who identified them as subspecies "Pseudofusulina alpina antiqua" and "Triticites primarius isfarensis", known previously from the Upper Carboniferous deposits of the Alps and
Fergana. Finds of fusulinids ( "Schwagerina", "Pseudofusulina", "Staffella",
"Brevaxina") were reported by Afghanabati [1977] and used as an evidence for Early Permian
age of the formation.
Arefifard and Davydov [2004]
studied several exposures of the formation. Based on preliminary fusulinid identifications they
concluded on Asselian (possibly Sakmarian) age of its middle and upper parts. V. I. Davydov also
indicated similarity of these fusulinids to those of Central Pamirs (pers. comm.).
[3] We studied only one incomplete section of the formation but peculiar endemic fusulinid
assemblage found in its upper part is of great interest in terms of age refinement and
paleobiogeographic reconstruction. 115 oriented thin sections are stored in the Laboratory of
Micropaleontology of the Geological Institute of Russian Academy of Sciences (collection number
4782).
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