On the biostratigraphy and cyclostratigraphy of the Moscovian Stage in the type area Marya Kh. MAKHLINA Geocentre Moscow, Varshavskoye shosse, 39a, 113105 Moscow (Russia) Marya N. SOLOVIEVA t & Natalia V. GOREVA Geological Institute of the Russian Academy of Sciences, Pyzhevsky per., 7, 109017 Moscow (Russia) Makhlina M. Kh., Solovieva M. N. & Goreva N.V. 1997. — On the biostratigraphy and cyclostratigraphy of the Moscovian Stage in the type area, in Crasquin-Soleau S. & De Wever P. (eds), Peri-Tethys: stratlgraphic correlations, Ceodiversitas 19 (2) : 235-245. ABSTRACT Moscovian Stage deposits are widespread in Russia. The stage was established in 1890 by Nikitin. It is subdivised in four horizons: Vereya, Kashira, Podol'sk and Myachkovo. The subdivisions of the stage ate based on studies of brachipods, foraminifera, conodonts, ammonites, bivalves, rugosans and KEYWORDS Moscovian, plants. In this paper, new data are due to the cottection of the standatd sec­ Carboniferous, tion of the Moscovian Stage and its new interpretation. Cyclostratigtaphy biostratigraphy, analysis based on the geological history of the region and its eustatics is a new cyclostratigraphy, Moscow Syncline. aspect of the research presented in this paper. RESUME Les dépôts du Moscovien sont largemenr répandus en Russie. Cet étage a été défini en 1890 pat Nikitin. Il est subdivisé en quatre horizons : Vereya, Kashira, Podol'sk et Myachkovo. Les subdivisions de l'étage sont fondées sut l'étude des btachiopodes, foraminifères, conodontes, ammonites, bivalves, MOTS CLES Moscovien, rugueux et plantes. Dans cet article, les nouvelles données proviennent de la Carbonifère, révision de la coupe standard de l'étage et de ses nouvelles interprétations. biostratigraphie, cyclostratigraphie, L'analyse cyclostratigraphique fondée sur l'histoire géologique de la région et synclinal de Moscou. de son eustatisme est un nouvel aspect de la recherche présenté ici. GEODIVERSITAS • 1997 • 19(2) 235 Makhlina M. Kh., Solovieva M. N. t & Goreva N. V. The Moscovian Stage deposits as well as the were caused by the discovery of a gap in the stra- Middle Carboniferous ones as a whole are wides­ totype section of the Kashira Horizon, where pread in Russia and mineral deposits, including deposits of the Tsna unit, established by oil and gas, are rather common in these sedi­ Solovieva (1984, 1986) in the Tsna River basin ments. Subdivision and correlation of the (Ryazan-Saratov depression) in the eastern part Moscovian polyfacial deposits connected with of the Moscow Syneclise, ate absent. Cyclostrati- different climatic zones (subtropical and boreal) graphical analysis of the Moscovian Stage based represent the essential element of geological on the geological history of the region and its mapping and exploitation. Tendency to adequate eustatic tectonics is the new aspect of the resear­ reliability, precision of stratigraphic scales and ch presented in this paper. high degree of correlations achievement caused the necessity to reinvestigate of the stage and The Moscovian Stage in the type atea is represen­ substage stratotypes. ted by marine deposits, i.e. by continuous series The Moscovian Stage was established by Nikitin of transgressive deposits (130-150 m thick), in in 1890 in the vicinity of Moscow. The upper which sands and clays are gradually replaced by limit of the stage was defined at the base of clayey and pure limestones. Subhorizontal bed­ Gzhelian limestones. ding and cyclicity of deposits give opportunity to The Moscovian, accotding to the ideas of Ivanov identify and follow up horizons, formations and (1926) who had established the fundamental relatively small subdivisions (subformations and principles of the modern views on the volume of members) in this region, and to identify cycles of this stage and its subdivisions based on the stu­ diffetent order. dies of the depositional sequence in the southern If the Carboniferous system is considered to be a part of the Moscow Syneclise, was subdivided cycle of the third order, Middle and Upper into four horizons: Vereya, Kashira, Podol'sk and Carboniferous (Pennsylvanian) are cycles of the Myachkovo. The Tegulifera Horizon (the fourth order. The Middle Carboniferous corres­ Kasimovian Stage) was considered to be a part of ponds to a tectono-eustatic cycle of the fifth the Upper Carboniferous. Faunal assemblages of order, the Moscovian and Kasimovian stages to the Moscovian as a whole, as well as those of its cycles of the sixth order (Table 1). According to subdivisions based on studies of brachiopods, Tikhomirov (1988), the latter includes the three foraminifers, conodonts, ammonites, bivalves, units corresponding to three phases of the trans­ rugosans, plants, ate relatively well known, zonal gression: initial (a), maximum (|3) and terminal, scales being established on the basis of some of or regressive phase (y). Cycles of the sixth order these studied groups. Numerous publications are may be complete or shortened, the former devoted to the Moscovian Stage in the type area, consisting of three cycles of the seventh order, which most important are those by Ivanov the lartet of two cycles of the same order, the ini­ (1926), Ivanova & Khvorova (1955), Rauser- tial phase being absent. These cycles could be Chernousova et al. (1951). Some papers are followed up in diffetent facies throughout a published during the last 20 years by Shik region, and their formation corresponds to the (1971), Makhlina (1972, 1976), Makhlina & maximum tectono-eustatic changes of basin Shik (1983), Makhlina et al. (1984), Goreva level. The Aza, Vereya and Tsna subdivisions (1984), Solovieva (1984, 1986). apparently correspond to the cycle of the seventh New data included in the present paper were order, or to the initial phase of the transgression obtained by the correction of the standard sec­ (oc) (Table 1). The combined Kashira, Podol'sk tion of the Moscovian Stage and its new inter­ and Myachkovo horizons correspond to the cycle pretation. of the seventh order, or to the maximum phase of the transgression ((3), whereas thtee horizons The lower boundary of the Moscovian Stage, of the Kasimovian Stage of the Upper according to the traditional views, coincides with Carboniferous correspond to a regressive phase the lower boundary of the Veteya Horizon. (y). Within the cycles of the seventh order thete Changes in the standard section interpretation 236 GEODIVERSITAS • 1997 • 19(2) Bio-cyclostratigraphy of the Moscovian Stage TABLE 1. — Subdivision of the Moscovician of the Russian Platform. Regional Local scale Cyclostratigraphy scale scale Moscow Syncllse order of cycles IX VIII VII VI V IV III Horizon Formation Subformation Member Horizon Substage m s m e (Formation) Stag Serie Syste Subsyste Voskresensk n r Krevyakino Krevyakino Suvorovo Krevyakino Krevyakinian V Uppe Kazimovia Myachkova Peski Peski Myachkovian C IN Novlinskoe Novlinskoe [33 10 Shchurovo Shchurovo T= o Podolsk Podol'sk Ulitino Ulitino Podolskian CD i— -c Vas'kino Vas'kino [32 CD CO CD Smedva Smedva Smedva > 5 > - Rostlslavl' O o >. c Lopasnya Lopasnya Lopasnya Kashirian ß o _l Kashira Kashira Khatum </> CO o Nara P1 o c cz Nara Polustova Nara Gora CD CO Tsna Tsna Tsnian? Q_ Ü a3 Upper Ordynka a Vereya Vereya Alyutovo Vereyan Lower Shat «2 Melekess Aza Aza a1 are smaller cycles - those of the eighth order, cor­ environments. Periodicity in the distribution of responding to separate horizons (substages in the faunal assemblages, which always show maxi­ proposed cyclostratigraphic scale, Table 1) and mum diversity in a transgressive part of a cycle those of the first order, corresponding to subfor­ and low diversity in its regressive part (Makhlina mations (horizons in the proposed cyclostrati­ & Shik 1983), is a characteristic feature of all graphic scale, Table 1). simultaneously formed polyfacial stratigraphie units corresponding to the cycles (Figs 1-3). Every stratigraphie unit of any rank can be sub­ Boundaries between these units correspond to divided into two parts: lower, corresponding to historico-geological changes of sedimentation the transgressive phase of sedimentation, and patterns, i.e. to changes in abiotic environment upper, corresponding to the regressive phase. taking place simultaneously in the whole region Contemporaneous stratigraphie units of different (Makhlina 1996). facies, which were formed in the paleobasin as a The main criteria for distinguishing and tracing lateral sequence of rocks reflect, near-shore, per- of transgressive-regressive cycles in which combi­ iferal, shallow-water and relatively deep-water nation form stratigraphie units (formations, sub- GEODIVERSITAS • 1997 • 19(2) 237 Makhlina M. Kh., Solovieva M. N. t & Goreva N. V. formations) are the following: sedimentological N. bassleri, Diplognathodus coloradoensis, and faunistic content, features of textute, perio­ D. orphanus, Streptognathodusparvus. dicity in the distribution of all groups of fauna in According to Solovieva (1984) and Alekseev the section, as well as biostratigtaphical characte­ (1994), the Vereya Formation sensu Ivanov ristics for the definition of the geological age of (1926) is only chatacterized by the Alyutovo the units. The sufficient methodical significance fusulinid and conodont assemblages. The over­ of the lithological-palaeoecological criteria, ela­ lying and underlying Shat and Ordynka mem­ borated by Osipova & Belskaya (1967), should bers (Table 1) do not contain any other faunistic be emphasized in this respect. complex except Alyutovo age. Leaving