Arkell.1956.Jurassic..

AZERBAIJAN 305
a series of limestones and marls with numerous pelecypods and other
fossils which appear to carry on high into the Kimeridgian, but ammonites
are not yet known. (For discussion see Uhlig, 1911, pp. 379-80.) The
Neocomian contains a well-developed Polyptychites horizon, also of
northern affinities (Luppov, 1935).
Farther east, in Bokhara, exposures are few and far between and little
known. A facies resembling the Alpine 'Couches a Mytilus' occurs
(Borrisjak, 1910), but the only ammonite figured is the Callovian Grossouvria
bucharica (Nikitin, 1889, pi. viii).
(Some references for this section are listed with those for European
Russia.)
AZERBAIJAN
The old name Azerbaijan is the most convenient for a region of
mountains south of the Caucasus and now partly in NW. Persia, partly
in Turkey (Armenia) and partly in the modern Armenian and Azerbaijan
republics of the U.S.S.R., where important but little-known Jurassic
outcrops occur.
Julfa Gorge
Where the River Aras or Araxes, draining the highlands of Armenia,
flows down between the Little Caucasus on the north and Mount Ararat
on the south, it passes near Julfa on its way to the Caspian Sea by a rocky
gorge. The Julfa (Djoulfa) Gorge, about 75 miles NW. of Tabriz,
is just on the Russian side of the frontier with Persia. It exposes a
succession from Carboniferous to Oligocene (Bonnet, 1912, 1912a, 1947).
On Lower and Middle Trias there succeeds up to perhaps 1000 m.
of compact black limestones and more or less cavernous black dolomite
without fossils. Owing to its likeness to the Alpine dolomites Bonnet
considered this series Upper Triassic, but by comparison with Persia
and Baluchistan a partly Liassic age cannot be excluded. It is overlain
conformably by 100-200 m. of basalt, and that in turn, also conformably,
by Middle Jurassic sediments. Then follow a conglomerate and about
700 m. more basalts and tuffs, which are interstratified with the unconformable
Cretaceous.
The Middle Jurassic is about 150-200 m. thick, and consists of limestones
and shaly marls with Middle Bajocian to Lower Callovian ammonites.
Bonnet deciphered the following succession. In the absence of illustrations
of ammonites his own nomenclature is retained, with remarks on dating
in square brackets.
6. Grey marls like No. 2, with Phylloceras flabellatum Neumayr,
Sphaeroceras bullatum (d'Orb.), Sph. microstoma (d'Orb.), Macrocephalites
and Perisphinctes orion (Bonnet, 1947, p. 87). [Upper Bathonian-Lowei
Callovian.]
3-5. Grey limestones, 30-40 m., with a rich, well-preserved fauna
Three ammonite levels were recognized:—•
5. A level with abundant Oppelia aspidoides; also Phyllocera
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