Shallow-Marine Carbonates - Trace Fossils as Indicators of Sedimentary Environments - page 693

FIGURE 3 Sawn section through the Middle Ordovician Dikari unit in the Babino quarry, approx-
imately 150 km east of St. Petersburg, Russia. The bed numbers correspond to the bed nomenclature
of Fig. 2 .
FIGURE 4 Bed-by-bed correlation of sections of the Middle Ordovician Volkhov Formation
(Dapingian) along the Baltic-Ladoga Glint Line (Estonia-Russia).
been adopted for subdivision of the succession into numerous elementary units
that, to a significant degree, are traceable over the eastern part of the Baltic-
Ladoga Glint (a Holocene coast cliff) over a distance of more than 300 km
( Jaanusson, 1976; M ¨ nnil, 1966; Dronov et al., 1996, 2000 ; Fig. 4 ). In total,
29 lithostratigraphic units (parasequences) can be recognized in the Volkhov
Formation ( Figs. 2 and 3 ).
The Volkhov Regional Stage is interpreted as a single depositional sequence
bounded by distinctive erosional surfaces with associated stratigraphic gaps.
Sequence boundaries coincide with the hardground surfaces at the base and
the top of that sequence ( Fig. 2 ). The lowermost part of the Dikari Limestone