Upper Carboniferous--Permian stratigraphy and fusulinids...

Brief Characteristics of the Section

Figure 3

[4] The discussed section is located on the southern slope of Mount Kuh-e-Bande Abdulhussein, 1625 m high, about 25 km southeast of the Anarak town (Figures 1 and 3). At the base of the slope there is a small separate outcrop of limestone bearing the following fusulinids from the lower zone of the Gzhelian: Schubertella sp., Ozawainella sp., Schwageriniformis sp., Triticites aff. ishimbaji, T. ex gr. simplex, T. ex gr. secalicus, T. nefandus, T. aff. samaricus, Rauserites rossicus, R. ex gr. postarcticus, R. variabilis, R. persicus, Rauserites sp. 1, Rugosofusulina aff. elliptica, and Rugosofusulina sp. 1 (Sample RL). Upward the slope the limestone likely related to the Upper Permian Jamal Formation is recovered, which is evidenced by the involved small foraminifers Geinitzina, Pachyphloia, Langella, and others. Further upward from the base the uninterrupted sequence of limestones of the Zaladou Formation occurs (Samples AC9-P13 and C1-C47). The top of the mountain is composed by dolomites of the Tighe-Maadanou Formation.

[5] Below is a brief characteristics of the sequence of the Zaladou Formation (upward from the base).

[6] 1. Light grey clayey shale bearing beds of shaly, silty and sandy, biomicritic, biosparitic, and oobiosparitic limestone, rarer of coarse-grained sandstone. Numerous Reitlingerina bradyi and scarce, non-identified more precisely Triticites occur (Samples AC9-AC13). The total thickness is 15.5 m.

[7] The relationship of the member with the sediments located down the slope is unclear. Considering the probable relation of the latter to the Jamal Formation, the contact between them should be of tectonic origin. However, this was not recorded in describing the section.

[8] 2. Clotted, thin- or medium-bedded limestone (silty and sandy biosparite, oobiosparite, packstone, scarcely grainstone); small coral bioherms (Samples AC14-AC16, C1-C12). The limestones bear single corals, bryozoans, brachiopods, and fusulinids. Among the latter Eostaffella aff. acuta, Seminovella ex gr. carbonica, Eoschubertella obscura, Schubertella sp., Quasifusulina sp., Schwageriniformis aff. perstabilis, Sch. ex gr. kairakensis, Sch. aff. gissaricus depressa, Sch. cf. perlongus, Triticites aff. ishimbaji, T. globoides, T. ex gr. ohoiensis, Rauserites variabilis, R. aff. samaricus, R. (?) persicus, Rugosofusulina uralica, R. (?) iranica, and R. (?) elongata were encountered at the base of the member (Samples AC14, C1, C2). The overlying sediments yield Eostaffella sp., Eoschubertella obscura, Reitlingerina aff. tachtavica (Sample AC16), and fragments of ferruginated and likely redeposited Schubertella ex gr. kingi, Schwageriniformis (Tumefactus) sp., Montiparus (?) sp., Triticites sp., and Pulchrella sp. (Sample C12). The thickness is 16.5 m.

[9] 3. Grey medium- and coarsely bedded limestone (biomicritic or dismicritic packstone) with two thick beds, at the base and in mid-member, of coral prereef breccia (boundstone) (Samples AC17-AC21, C13-C16). Fusulinids are missing. The total thickness is 22.3 m.

[10] 4. Grey, brownish, coarsely bedded, in places dolomitized limestone (biomicritic or sparitic, sometimes oomicritic packstone, rarer grainstone and rudstone) (Samples AC22-AC26, C17-C24). Small mud mounds of algae-fusulinid limestone occur in the upper part. The limestones of the member are mostly poor in organic remains, however, certain beds are overfilled with fusulinids. One of them is in the middle part of the member and contains numerous Schwageriniformis acutatus n. sp. (Sample AC25). The limestone mud mounds located slightly above yield Rauserites elongatissimus, R. cf. erraticus, and Jigulites cf. formosus (Samples C20-C24). Reitlingerina bradyi, Triticites aff. shikhanensis, Rauserites aff. postarcticus, R. karlensis, and R. (?) stepanovi were found nearby the top of the member (Samples AC22-AC26). The total thickness is 15.6 m.

[11] 5. Rose-colored marl, 4.3 m thick.

[12] 6. Light grey, brownish, medium bedded limestone (biomicritic and biosparitic floatstone and rudstone) bearing numerous fusulinids and fragments of bryozoans, crinoid columns, algae, corals, and echinoid spines. At the base the limestone is overfilled with Ruzhenzevites ferganensis (Samples AC27 and R-3). The overlying beds contain Reitlingerina sp., Anderssonites aff. zarjae, A. aff. nanus, U. bosbytauensis distincta, and Ultradaixina (?) aff. kozui (Samples AC28, AC29, and C27). The thickness is 3.7 m.

[13] 7. Grey, medium- and coarsely bedded, in places dolomitized, ferruginated and recrystallized algae-fusulinid limestone (biosparitic wackestone, packstone, occasionally floatstone); coral bioherms at the base of the member. Small foraminifers, brachiopod valves, and bryozoans occur together with fusulinids and algae. Among fusulinids Eostaffella sp., Schubertella sp., Ozawainella (?) sp., Ultradaixina bosbytauensis distincta, U. kosvaensis, U. (?) kozui, Likharevites esetensis, L. aff. paranitidus, Anderssonites anderssoni, A. pseudoanderssoni latiterminosa, A. paraanderssoni, and A. nanus were identified; nearby the top Rugosofusulina directa and R. mutabilis were recorded (Samples P1-P9, C29, C30, ML, and others). The thickness is 11.4 m.

[14] 8. Algae-fusulinid limestone analogous to that of Member 7. In the lower part fusulinids Sphaeroschwagerina sp., Ruzhenzevites subcylindricus, R. zaladuensis zaladuensis, R. zaladuensis brevis, and Praepseudofusulina kljasmica were found (Samples P10, P11). The overlying beds yield Eoschubertella sp., numerous Likharevites gracilis, and L. kokpectensis and Pseudofusulina aff. conspiqua (Samples C38, C39, P12, R1, R2, RupA, Rup2, Rup3). The uppermost beds contain Schubertella sp., Boultonia sp., Ozawainella sp., Quasifusulina longissima, Rugosofusulina cf. directa, Likharevites inglorius, Pseudoschwagerina ex gr. extensa, Ps. robusta, Ps. sp. n., Sphaeroschwagerina shamovi primitiva, Sph. shamovi gerontica, Sph. pavlovi, Sph. ex gr. sphaerica, Sph. moelleri, Sph. notabilis, Sph. ellipsoidalis, Sph. fusiformis, Pseudofusulina (?) narjanmarica, Rugosochusenella paragregaria, and Praeskinnarella (?) huangchuigouensis (Samples P13, Rup, C42-C47, PR1). The thickness is 5.85 m.

[15] The total (incomplete) thickness of the Zaladou Formation is 95 m.

[16] The Zaladou Formation grades into the dolomitic Tighe-Maadanou Formation of about 80-100 m thick. It is overlain by the 8-10-m-thick loose quartz sandstone and the 2-m-thick shaly argillite. The latter is sharply unconformably overlain by the limestone Jamal Formation that bears the Upper Permian fusulinids ( Staffella, Nankinella, and Chusenella) and small foraminifers, which are going to be described later.