Marguzor Fm

Includes in Hisar-Zarafshan ranges, and Obisafit, Turkparidin, Chakykalya typesections.

It was established in 1967 by D.R. Muchaidze, D.A. Starchinin, and A.I. Lavrushevich. Previously, it was considered as the upper formation or "upper part" of the Pushnevatskaya suite (Martyshev, 1956, 1970; Resheniya..., 1959). By distinguishing the Pushnevatskaya suite in the western part of the Zeravshano-Hissar district (approximately to the west of Mount Chimtarga) in the same volume as the Agbasay and Marguzor suites are currently distinguished there, V.R. Martyshev and a number of other researchers in the eastern part of this district related to the Pushnevatskaya suite (fully or partially) still those sediments, which in this work are related to the Yagnob suite of the Vendian?-Lower Paleozoic.

Synonym: Marguzorskaya suite, Маргузорская свита

Reference section:

It is composed of dark gray polymictic sandstones and clay slates that are irregularly alternating, containing lenses of conglomerates and gravels, less frequently siliceous rocks and limestones. There are re-deposited blocks of more ancient rocks found within it. The thickness is 700-1200 m.

According to the observations of V.N. Shvanov, carried out in 1972 and 1973 on several cross-sections, sandstones and slates form layers from 10-15 cm to 3-4 m in thickness, with sandstones, in general, prevailing. They are of variable grain size, often debris-bearing, and include scattered pebbles. Sandstones belong to the quartz-polymictic greywackes. In the fragments within them, there are limestones of Ludlow, Devonian, and Tournaisian, clay slates, claystones, fine-grained sandstones, quartzitic sandstones of the type of Ordovician-Lower Silurian, siliceous rocks of the Agbasay suite type, metamorphic quartzites, white quartz, effusives of aphanitic and diabase porphyrites type. There are very few fragments of plagioclases. Accessory minerals include zircon, rutile, garnet, leucoxene; chromian spinelides are especially abundant, the content of which reaches 200-350 g per ton of rock. Clay slates contain magnesian-iron chlorite, a little muscovite. In them, there is always a feldspathic or sandy admixture.

Conglomerates are found throughout the section of the Marguzor Fm (марrузорской свиты), but most often - in the middle of it. In addition, the largest number of them is concentrated along the southern edge of the Zeravshano-Hissar district. The thickness of the conglomerate lenses is from 1-3 to 15-20 m. Fragments in them (0.5-2.0) cm, less frequently up to 5 cm) are represented by slates of the type that are developed in the Yagnob Fm of the Vendian? -Lower Paleozoic (sericite-chloritic-siliceous, quartz-phyllosilicate, etc.), as well as quartz sandstones, quartzites, siliceous slates, jaspers, marls, dolomites, limestones, magmatic. Rocks of these types. In 1966-1969, D. A. Stashnin collected over 600 cobbles and boulders of intrusive rocks from sections of the Marguzor suite at various locations (sections of the Honaqo, Agbassay, Sarimmat river basins, at the Tavasang pass, along the Gurdara, Bilfurak, Chashmanyat, Nofin, Tiogly, Boyymurad rivers, in the Chakylykalyan mountains). Almost all the cobbles belong to the plutonic rocks of the plagiogranite series. Comparing the cobbles of magmatic rocks from the Marguzor Fm with the granitoid clasts from the later described Upper Moscow - Upper Carboniferous Darakhtisurkh Fm, where granite cobbles are also found, reveals a striking difference. The latter belong to the formation of normal granites (adamellites). Therefore, the dominance of plagiogranite clasts in the conglomerates of the Marguzor Fm, according to D. A. Stashnin, can serve as a reliable indicator for its identification.

Organic remains are found everywhere in the Marguzor suite, mainly in a redeposited state: in cobbles, boulders, and blocks of limestones. The oldest of these are rugose corals of the Upper Ordovician, found among shales at the Magian pass. Often, redeposited remains of middle to late Devonian and early Tournaisian foraminifera are encountered. At the same time, remains of Tournaisian foraminifera Endothyga cf. primaeva Raus., E. latispiralis Lip., Tournayella cf. gigantea Lip., and others; Tournaisian-Visean rugose corals Amygdalophullum aff. columellare Pickett., Keyserlingophyllum ex. gr. oblicuum Stuck., and others; tabulate corals Syringopora cf. ramulosa Goldf., are present in carbonate cement.