Arkell.1956.Jurassic..

RUSSIA 485
The highest limestones, being without ammonites, are only vaguely
dated but are probably Lower Kimeridgian. There follow some variegated
clays and there is then a big gap in the succession, the next deposits being
Cenomanian sands, which form a continuous ring round the older rocks
and overstep them all transgressively. Between the Kimeridgian and
Cenomanian there occurred a minor phase of folding which, unfortunately,
cannot be accurately dated (Stepanov & others, 1937, pp. 25, 30).
The Donetz Jurassic resembles that in the rest of Russia in lacking
characteristic Tethyan ammonites. No Phylloceratid or Lytoceratid
has been recorded. The following citations of ammonites refer to the
monograph by Borissjak (1908) except where stated otherwise.
UNDATED
Variegated clays with plant-remains.
LOWER KIMERIDGIAN
Thick shelly limestones with Nerinea, Nerinella and other gastropods
(Borissjak, 1917, p. 13, figs. 10, 11), in places coralline.
UPPER OXFORDIAN
Bimammatum Zone. Limestones with Amoeboceras bauhini (Oppel)
and brachiopods, and below that beds with Decipia ? aff. achilles (d'Orb.)
and echinoids, including Paracidaris florigemma, Nucleolites scutatus
and N. dimidiatus (Makridin, 1951).
Transversarium Zone (Plicatilis Zone). To this zone belong beds at
Mount Kremenez with large Arisphinctes (Borissjak, 1908, pi. vi) and
Perisphinctes s.s. (pi. ii, fig. 14). The supposed fragment of Peltoceras
(Gregoryceras) cf. transversarium (p. 77, pi. iii, fig. 3) comes from an
Upper Callovian locality and could equally well belong to a Rursiceras
sp. nov.; but Makridin (1951) records G. cf. transversarium from beds
with Upper Oxfordian Perisphinctes (not figured).
LOWER OXFORDIAN
Cordatum Zone. To this zone is to be assigned Euaspidoceras nikitini
(Borissjak) (pi. ix, fig. 1), which occurs in England in the Cordatum
Subzone s.s.; also probably E. indorossicum (pi. vii, fig. 4) and the assemblage
of small Cardioceratids of the subgenera Plasmatoceras and Subvertebriceras
from Mogilni Ravine (pi. i, figs. 7, 9-13), though at least
some of them might be a little later, being reminiscent of the Arngrove
Stone faunas.
Mariae Zone. To the Praecordatum Subzone belong Scarburgiceras
subexcavatum Maire (pi. i, fig. 6) and Pavloviceras nalivkini (Borissjak)
(pi. i, figs. 4, 5), both from Uski Ravine. To the Mariae Zone are also to
be assigned the large Scarburgiceras sp. (pi. i, fig. 8), Euaspidoceras ivesense
Spath (pi. iii, fig. 7), and Q. cf. mariae (p. 63), all from Chutor Sawodski.
http://jurassic.ru/