in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
Upper Jurassic Oil Shale Deposits of Aiyuva Shale-Bearing Basin
386
L. Selkova * , S. Lyurov
Institute of Geology of Komi SC of Ural Division of RAS, Syktyvkar, Russia (E-mail: laselkova@geo.komisс.ru; lsv@geo.komisc.ru)
Three lithological strata were determined in the
section. For the first time the deposits from the Aiyuva
outcrop are characterized by miospores and dinocysts.
Aiyuva-1 outcrop is located 3 km downstream
Three lithological strata were determined in the
section. The description of the outcrop is given from
bottom to top.
The first stratum is represented by aleuritic, grey,
light grey with greenish hue, carbonate non-plastic clay
with shell detritus, belemnite and bivalve fauna and
undetermined pyritized nuclei of ammonite shells.
Innumerous foraminifers (stratum base) include:
Astacolus aff. suprajurassicus (Mjatl.), A. sp.,
Lenticulina aff. nedulosa Jak., L. sp., Citharina aff.
lepida (Schwag.), Marginulina cf. robusta Reuss,
Guttulina (?) sp. The forms are characteristic for the
Late Jurassic Early Kimeridgian (J3km1).
Fern spores are found: Cyathidites australis Coup.,
C. triangularis Rom., Gleicheniidites laetus (Bolch.), G.
senonicus Ross, and also conifer pollen: Pinus-
pollenites pernobilis (Bolch.), Podocarpidites major
(Naum.), P. multesimus (Bolch.), Sciadopityspollenites
mesozoicus Coup., Classopollis classoides Pflug, C.
minor Coup.
Apart from the miospores, Jurassic dinoflagellate
cysts (dinocysts) are abundant: Gonyaulacysta jura-
ssica (Defl.) Norris et Sar. subsp. adecta Sarj., G.
jurassica (Defl.) Nor. et Sarj. subsb. jurassica, G.
jurassica (Defl.) Nor. et Sarj. subsp. adecta Sarj. var.
longicornis (Defl.) Sarj., Gonyaulacysta sp., Lepto-
dinium sp., Ctenidodinium ornatum (Eis.) Defl.,
Rhynchodiniopsis cladophora (Defl.), Fromea am-
phora Cook. et Eis., Pareodinea sp., P. ceratophora
Defl., Chytroeisphaeridia sp., Olygosphaeridium sp.,
Hystrichosphaeridium sp. Alongside the organic
from the village of Kerka on the left bank of the Aiyuva
river (Fig.1). Samples on microfauna and palynological
analysis were taken to determine the age of deposits.
Fig.1 Map of the study area
remains of very small foraminifers are found -
Microforaminifera sp.
On the top the following foraminifers are
determined: Lenticulina infravolgaensis (Furss. et Pol.),
L. aff. kaschpurica (Mjatl.), L. media (Furss. et Pol.), L.
sp., Saracenaria pravoslavlevi Furss. et Pol., S. ex gr.
alta K. Kuzn., Planularia poljenovae K. Kuzn.,
Astacolus obliteratus (Furss.), Marginulina robusta
Reuss, Vaginulinopsis embaensis (Furss. et Pol.),
Citharina raricostata (Furss. et Pol.), Dentalina sp.
Miospores and dinocysts are represented by the
same taxa.
The second stratum is represented by intercalation
of dark grey, carbonate clays with numerous fragments
of rostra of belemnites, fragments and unbroken shells
of bivalves and grey-brown oil shales. The shales
contain many prints of ammonites and bivalves.
Foraminifers include here: Evolutionella aff.
emeljanzevi Schleif., Kutsevella cf. labythnangensis
(Dain).
Single fern spores are found: Foveosporirtes
pseudoalveolatus Coup., Osmundacidites jurassicus
(K.-M.), and also pollen grains: Piceapollenites
variabiliformis (Mal.), Classopollis sp., Sciadopity-
spollenites mesozoicus Coup. Dinocysts are present:
Gonyaulacysta jurassica (Defl.) Nor. et Sarj. subsp.
adecta Sarj., G. jurassica (Defl.) Nor. et Sarj. subsb.
jurassica, Cribroperidinium sp., Pareodinea prolon-
gata Sarj., Chytroeisphaeridia sp., Pterospermella sp.
The third stratum – intercalation of grey, light grey,
low plastic, carbonate clays with abundant fauna