STRATIGRAPHY AND SEQUENCE STRATIGRAPHY OF THE MOSCOVIAN, KASIMOVIAN AND GZHELIAN IN THE MOSCOW BASIN

The Moscovian deposits form a second order sequence (5-6 m.y.) with a complete cycle of tectono-eustatic variations including a lowstand sys tem tract (LST), a transgressive system tract (TST) and a highstand sy stem tract (HST). The Moscovian deposits are subdivided into four form ations or third order sequences (1 m.y.) named Vereia, Kashira, Podols k and Myachkovo by the Russian stratigraphers; which can be further su bdivided into members or fourth order sequences (about 500 k.y.); whic h in turn can be further subdivided into elementary sequences (about 1 00 k.y.). Vereia shows two fourth order sequences, Kashira four, Podol sk three and Myachkovo two. The Kasimovian deposits Form a second orde r sequence (3-5 m.y.) with a complete cycle of tectono-eustatic variat ions. They are subdivided into three formations or four third order se quences (1 m.y.) named Krevyakino, Khamovnichi, Dorogomilovo; which ca n be further subdivided into members or fourth order sequences (about 600 k.y.); which in turn can br further subdivided into elementary seq uences (about 250 k.y.). Each third order sequence shows two fourth or der sequences, the first more transgressive and the second more regres sive. The Gzhelian deposits form a second order sequence (5-6 m.y.) wi th a complete cycle of tectono-eustatic variations. They are subdivide d into five formations or five third order sequences (1 m.y.) named Re chitsy, Amerevc, Pavlov-Posad, Noginsk and Melekhovo; which can be fur ther subdivided into members or fourth order sequences (about 600 k.y. ) which can be in turn further subdivided into elementary sequences (a bout 200 k.y.). Each third order sequence shows two fourth order seque nces, the first more transgressive and the second more regressive. At whatever order, the sequences present a similar organization: the TST consists mainly of limey deposits. The overlying deposits are more cla yey and dolomitic: they represent a HST with terrigenous supply. In or der to check the continuity of the sequences, our data have been compa red with previously described boreholes located on West-East cross-sec tions. Except for the Tsna Member known only eastwards, the same fourt h order sequences number is recorded within the basin. During the Mosc ovian and Kasimovian time, the Moscow Basin presents a thinner western border and a eastern trough. During the Gzhelian time, some inversion s in subsidence occur. For the mechanisms of genesis of these sequence s. their continuity proves the allocyclicity. However, the tectonics a nd the eustasy interfere. The tectonic subsidence is low or moderate i n the Moscow Basin. The fourth order sequences are more prominent than the third order sequences, which would be characteristic of an eustas y produced by the melting of polar ice cap located in Gondwanaland dur ing the late Carboniferous. However, the stratigraphic completeness an d the associated preservation of the sequences are low at the western border of the basin and better eastwards.