Bazardarin Gr

Includes in SE Murghab district (Mynkhadjr type), SE Murghab district (Istyk type (Dunkeldyk area), SE Murghab district (Gurdumdin type), SE Murghab district (Gurdumdin type Kastanatdjilga, Buryukurmes rivers), SE Murghab district (Gurdumdin type Shin and Igrymiyu rivers), SE Murghab district (Gurdumdin type Gurumd and Kattamardzhana rivers).

It is identified by G. A. Dutkevich (1937). Divided into a lower Urzbulak Fm and an upper Tashkazyk Fm by Novikov (1976).

Synonym: Bazardarin suite, Базардаринская свита

The exposed upper Carboniferous and pre-Kungurian (uppermost Lower Permian) of SE Pamir is the Bazardara Gr of cold-water siliciclastic deposits. It is composed of alternating dark gray and black siltstone and claystone, containing interbeds and lenses of sandstones, conglomerates, gravelites, and limestones. The incomplete thickness is 1800 m.

It is divided into a lower Urzbulak Fm of black claystones capped by immature sandstones and an upper Tashkazyk Fm (300 to 980 m) of several units of sandstone-siltstone-claystone (generalized as siltstone).

In this subsequence, at different times, numerous remains of bryozoans, crinoids, brachiopods, pelecypods, corals, ammonoids, known from the lower, middle, upper Carboniferous, and lower Permian deposits (Dutkevich, 1937; Gushchin, 1966; Leven, 1967; Pavlov, 1967, 1972; Grunt and Dmitriev, 1973) were collected. The remains were collected in separate exposures, the stratigraphic relationships of the rocks in which are not always clear now, since the identification of the above-mentioned subsequences and thicknesses under conditions of significant uniformity of rocks is possible only with sequential geological mapping of the entire area of the Southeastern Pamir, which has not yet been done.

QUOTED (from Russian) from Baratov, R. B. (1976): No organic remains have been found in the Kishtau layer, and in the fields of development of the Kilil layer, in unclear layers of the section, in two points, remains of Namurian Goniatites were collected. The first point is located in the upper reaches of the river Northern Karadjilga. N.I. Bondarenko in 1967 in the scree found here a fragment of limestone with Homoceras sp., Payettevilles sp., Syngastrioceras sp. The second is located in the upper reaches of the river Djarjilga. In a lens of calcareous claystones among sandstone-claystone rocks, B.S. Sviridov and E.Ya. Leven in 1972 collected remains of Homoceras sp., Ramosites sp., Syngastrioceras sp., Stenopronorites sp.

QUOTED from ANGLIOINI et al. (2015) from their review and field study – See the two formations for more detail: “The Uruzbulak Formation contains cold-water bivalves,

conulariids, bryozoans and rare ammonoids of Carboniferous age (Leven, 1967; Pavlov, 1972). At the top of the formation, we collected a very well preserved assemblage of the infaunal bivalve Oriocrassatella sp. consisting of articulated shells mostly in life position. The Tashkazyk Formation comprises conulariids, crinoids, bryozoans, ammonoids (Metapronorites sp., Marathonites sp., Emilites sp.), bivalves (Pseudomyalina sp., Megadesmus sp.) (Leven, 1967; Pavlov, 1972) and very abundant brachiopods. According to Grunt and Dmitriev (1973) and to our own analysis, brachiopods from the Tashkazyk Formation comprise species of Costatumulus, Permochonetes, Reticulatia, Spirelytha, Tomiopsis, and Trigonotreta. We have found conodonts in a sample collected about 100mbelow the top of the Tashkazyk Formation at Mudzubulak. They comprise Mesogondolella monstra, Streptognathodus sp., Sweetognathus bucaramangus, S. cf. merrilli, S. cf. behnkeni, and S. whitei (Table 2c; Supplementary Fig. S1). Although S. whitei has normally been associated with an Artinskian age, it was determined that the holotype of S. whitei is older (Lucas, 2014; Henderson, 2014). Such older forms from Nevada (Ritter, 1987) and Bolivia (Suarez Riglos et al., 1987) are now ascribed to the late Asselian and early Sakmarian. According to Chernykh (2005) Mesogondolella monstra is typical of the Tastubian or early Sakmarian substage and the S. merrilli Zone

See Tashkazyk Fm

LOWER AND UPPER UNITS -- QUOTED (from Russian) from Baratov, R. B. (1976): “As a result of recent lithological studies by V. P. Novikova, as well as by T. A. Khakhina and G. V. Kuznetsov, who conducted geological mapping in the North-Alichursky Ridge, the Bazardarin suite has been divided into two parts, and the latter - into a series of more fragmented units. The nomenclature of all these subdivisions is not yet established. If it is subsequently proven possible to map them across the entire area of the Southeast Pamir, then, probably, the understanding of the two parts of the Bazardarin suite (самостоятельных свит) as independent suites, combined into the Bazardarin series, as proposed by B. M. Gushchin (1969) will be adopted. The smaller subdivisions can be named as sub-suites. For now, we consider the two parts of the Bazardarin suite as sub-suites, and the more fragmented units - as thicknesses.

In the North-Alichursky Ridge, three thicknesses have been identified in the lower sub-suite of the Bazardarin Fm (базардарннской свиты), each with a thickness of 150-250 m. The lower thickness is composed of claystones, feldspathic-quartz and greywacke claystones and sandstones. The middle thickness includes clayey feldspathic-quartz and greywacke sandstones and gravelites. The greywacke sandstones and gravelites consist of 30-60% of fragments of rocks: calcareous claystones and claystones, clayey limestones, cherts, quartzites, gneisses, various crystalline slates, feldspars, spilites, plagio-granites, granosyenites, and granite-porphyroids. Almost all of the listed rocks, especially sedimentary and intrusive, are found as separate evenly scattered pebbles up to 20 cm in size. The upper thickness is composed of characteristic banded quartz-feldspathic claystones with distinct horizontally- and wavy-bedded textures. In addition to the described formations in the lower sub-suite of the Bazardarin suite (бaзардаринской свиты), there are also volcanogenic rocks, which have a clearly subordinate significance. They form small lenses up to 1-1.5 m thick, represented by diabase porphyrites, andesites, and andesite-dacites. The incomplete thickness of the lower sub-suite reaches 800 m. No identifiable organic remains have been found in it.

The upper sub-suite of the Bazardarin Fm (базардаринской свиты) is composed mainly of feldsparSpat-quartz siltstones, chlorite-hydromica claystones, to a lesser extent - fine-grained sandstones, in composition corresponding to siltstones, and often approaching oligomict quartzites. A significant place among these sediments is occupied by rocks of mixed granulometric composition, or pattums, often containing carbonate admixture. These rocks rhythmically alternate with each other. In the lower half of the upper subsequence, there is a typical phyllite interlayering of sandstones and claystones; the power of rhythms in the upper half of the subsequence varies from 7-10 to 30-35 m. In general, the upper subsequence can be divided into several cartographic thicknesses, the number of which reaches six. At the base of the upper subsequence, there is a characteristic boulder-cobble package of very variable power, varying from 20 to 150 m. It is formed by strongly deformed siltstones, inside which there are large boulders and cobbles of various rocks, similar to the rocks of the lower subsequence of the Bazardarin suite. Sometimes among the siltstones, small lenses of basalts, apo-diabases, and andesite-dacites, as well as small lenses of conglomerates with fragments of granosyenite-porphyres and syenite-porphyres, are found. The power of the upper subsequence of the Bazardarin suite varies from 500 to 1000 m, increasing to the southeast.

This section also describes the deposits developed in the eastern part of the Pshart Range, which were previously not attributed to the Bazardarin Fm (during medium-scale geological surveying works, they were tentatively correlated with the Triassic Bardarin suite of the Rushan Range, the characteristics of which are presented below). As a result of field studies by V. I. Dronev in 1968, he came to the conclusion that the deposits considered below have certain similarities with the Bazardarin suite and therefore can conditionally be attributed to it. The deposits have a two-membered structure. The lower part, designated by V.I. Dronov as the Kishtau layer, is exposed on the northern slope of the ridge, in the lower and middle parts of the rivers Akdjilga, Kenjiliga, Northern Gumbezkol, Northern Karadzklga, and others. It consists of dirty-red and gray, variably-grained, predominantly quartz and quartz-feldspathic sandstones with interlayers of dark gray claystones. The thickness is 300-500 m. The lower contact of the layer remains unclarified. Above, conformably lying is the Kilil layer. It forms the larger part of the northern slope and the watershed part of the eastern half of the Pshart ridge. The layer is composed of dark gray claystones with interlayers of quartz-feldspathic sandstones. At the top of the layer, among the claystone rocks, there are scattered well-rounded pebbles (from 0.5 to 10 cm) of plagiogranites, plagiogranite porphyries, quartz porphyries, and their tuffs, liparites, felsitic porphyries, quartzites, sandstones, cherts, and clay slates. The thickness is 300-500 m.

AGES – -- QUOTED (from Russian) from Baratov, R. B. (1976): “Taking into account the entire complex of organic remains collected in the Bazardarin suite and its subordination to the deposits of the Kuberghandinsky horizon of the lower Permian, it is most reasonable to consider this suite Lower Carboniferous - Lower Permian, including the formations of the Karachatur and Uluk horizons.

The listed fauna remains indicate that the Kilil layer includes Namurian layers, but their volume and position in the section are unclear. From the conformable lying of the layer under the faunistically characterized deposits of the Kubergetin-Pamir horizons, it follows that the upper age boundary of it corresponds to the boundary of the Ulyuk and Kubergetin horizons or passes within the latter. The Kishtau layer by its position in the section is below the Kilil layer or is Namurian, or even more ancient - Visean-Tournaisian.

The described variant of the correlation of the Kishtau and Kilil layers with each other and with the surrounding deposits, as well as the interpretations of their age, is not the only one. In the exposures of the lower parts of the rivers Akdjilga, Karadjilga, Northern Gumbezkol, Northern Karadjilga, it can be seen that the Kishtau layer together with the Kilil layer lies geographically and structurally higher than the white massive marble-like limestones with early Kubergetin fusulinids. If this lying is not the result of a thrust, then the age of the Kishtau and Kilil layers must be considered post-late Kubergetinian, and the previously listed remains of Namurian goniatites are either re-deposited, or belong to some other layer, currently located in tectonic wedges within the Kilil layer.

According to the materials of E. Ya. Leven and B. R. Pashkov, who studied the eastern part of the Shartokoy Range in 1970-1973, only the Kilil layer relates to the Carboniferous - Lower Permian. The Kishtau layer is considered by them to be bounded by faults to the south and north and is conditionally attributed, without confirmation by fossil remains, to the Lower Cretaceous. In addition, these same geologists conditionally (also without the collection of organic remains) distinguish Upper Triassic and Jurassic deposits, similar in lithological composition to the Kilil layer.”