Until now Bashkirian and Moscovian deposits had been recognized in Eastern Iran, the eastern part of Central Iran, and eastern Alborz (Figure 4). Beyond these regions, these rock units were either not deposited or were eroded away during the Late Pennsylvanian (Kasimovian-early-middle Gzhelian) and Early Permian (late Sakmarian) marine regressions (Leven and Taheri 2003). Bashkirian-Moscovian strata also occur in other areas of Central Iran (Abadeh area) where they underlie the Asselian-Sakmarian Vazhnan Formation and contain the Moscovian fusulinid Ozawainella mosquensis (Baghbani 1993). Although no details on the Moscovian in the Abadeh area are known.

The Bashkirian and Moscovian deposits of eastern Alborz have received thorough biostratigraphic characterization (Jenny et al. 1978; Lys et al. 1978; Vachard 1996). The deposits constitute the Bagherabad and Gheselghaleh formations. The former is mainly composed of varying limestone up to 260 m thick. Only the upper 30-40 m of the limestone is related to the Bashkirian. Laterally, this portion is substituted by the lower beds of the Gheselghaleh Formation (G1) and overlain by higher beds of this formation (G2). The Gheselghaleh formation is 242 m thick and consists of bioclastic limestone, sandstone, and marl. Upwards in the section, Gheselghaleh Formation is replaced by sandstone and limestone of the Dorud Formation (Asselian in age, although the basal most strata of Dorud Formation could be late Gzhelian).

Comparative analysis of the sections reported here and the eastern Alborz section shows their great similarity. The Sardar Group and Gheselghaleh formations both are represented by shallow-water carbonate and carbonate-siliciclastic deposits of approximately equal thicknesses. They lie on predominantly Devonian-Lower Carboniferous, carbonate deposits and below the uppermost Gzhelian-Asselian transgressive deposits (the Zaladu and Dorud formations). A significant stratigragraphic hiatus exists between the Moscovian and the latest Gzhelian-Asselian. In all three regions the Bashkirian-Moscovian sequences are well characterized by foraminifers, including fusulinids, the fossil group that provides precise interregional correlations. The eastern Alborz foraminiferal biostratigraphy was reported by Bozorgnia (1973), Lys et al. (1978), and Vachard (1996). In the Bashkirian through the Moscovian interval, Lys et al. (1978) established several foraminiferal zones, which were slightly modified by Vachard (1996). Figure 4 shows the strong correlation of these zones to the foraminiferal zones in the Zaladu and Anarak sections. Some discrepancies exist because the eastern Alborz section is not known as well as the others. Another feature common to all sections in these regions is the poor foraminiferal content of upper Moscovian deposits.

Well-exposed Bashkirian and Moscovian sequences in the regions bordering Iran on the west occur only in Turkey. In eastern Taurus, there is a para-autochthonous occurrence represented by sandstone and bioclastic foraminiferal limestone blocks nearly 100 m thick. Seven fusulinid zones were established for this interval (Altiner 1981). In western Taurus, in the Hadim-Tashkent area, Bashkirian-Moscovian deposits occur in the Aladag and Bolkar Dagi nappes. Here they are represented by Mantar Tepe Beds (quartzitic sandstone and bioclastic, oolitic and micritic limestone, 250 m thick) of the Yaricak Formation where eight fusulinid zones were established (Altiner and Özgül 2001). The highly fossiliferous Taurus sections can readily be correlated with the Iranian sections (Figure 4). The Bashkirian-Moscovian deposits are likely widespread in the Anatolia region of Turkey, as suggested by the occurrence of corresponding foraminifers in limestone blocks of the Karakaya Complex (Leven and Okay 1996), however, no sections suitable for study have been discovered there.

In Afghanistan, just east of the Iranian border, Bashkirian-Moscovian deposits have a restricted distribution and are poorly studied. Reliably dated foraminiferal facies are only known in northern Afghanistan. In the province, Fariab, in the Maimana area and in Firuzkoh Ridge, north of the Herirud River, Pennsylvanian strata are exposed below thick red deposits from the Upper Carboniferous-Permian. Bashkirian-Moscovian strata also occur on the northern slope of western Hindu-Kush in the Sourkhob River basins (Dronov 1980). These strata are represented by a 200 m limestone sequence that unconformably overlies pre-Carboniferous deposits and is overlaid by a lower Permian flysch. These exposures have not been studied and therefore cannot be correlated.

Vachard (1980, 1996) correlated the Carboniferous sequences of the Tabas area to those of Central Afghanistan and the eastern Alborz section to the Band-e-Bayan Ridge sequences in the north Afghanistan. These correlations are problematic, however, because they are not substantiated by direct evidence. The Serpukhovian-Gzhelian deposits of the Tabas section were correlated to those of the Bokan section of Central Afghanistan on the basis of their siliciclastic lithology and almost absolute absence of fossils. Vachard's correlations seemed to be valid because the Sardar Group had not received adequate paleontological characterization. Presently, rich foraminiferal assemblages are known to occur throughout the Sardar Group; these occurrences lend no support to Vachard's hypothesis. There is less evidence to correlate the Alborz section to the Band-e-Bayan sections. In these locations the Bashkirian-Moscovian deposits either cannot be distinguished from the virtually barren, thick shaly Siakhkoh Formation (as in the Khodja Murod and Karganau tectonic zones) or they are completely missing as in the Khaftkala tectonic zone (Dronov 1980; Leven 1997).

The statement above contradicts the paleoreconstruction of the Iran-Afghanistan territory of Central Asia proposed by Vachard (1980, figure 56; and 1996). According to this reconstruction, Eastern Iran was confined to the western part of a narrow "Sinus Tezakien" bay, which was connected somewhere in the east of the Pamirs with the Sinus Tethysien parallel basin in the southern margin of which existed the Alborz Basin. This supports the hypothesis that Eastern Iran was isolated from Alborz by a wide stretch of land in Central Iran. In light of the new data presented in this paper, Vachard's reconstruction is likely no longer correct. The Bashkirian-Moscovian sections of Alborz and Eastern Iran are in every respect alike. It is evident that these regions were located within a single basin. This basin can also be correlated with the Taurus and Anatolia basins in the west, Central Asia in the east, and basins of the Donets, Russian platform, and Urals in the north (Davoudzadeh and Weber-Diefenbach 1987). This hypothesis is supported by the non-endemic character of the Iranian foraminiferal assemblages throughout Bashkirian-Asselian time. The differences in diversity can be attributed to more complete taxonomic studiest in the Russian sections. The Eastern Iranian basins might have been connected with basins that existed in Afghanistan territory, but additional studies are required to confirm this linkage.