Gaurdak Fm

Includes in Dushanbe-west Shirkent-Luchob, east Shirkent-Luchob. It was allocated in 1931 by V. A. Miroshnichenko.

Synonym: Gaurdak suite, гаурдакской свитами, Гаурдакская свита

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It is composed of gypsum and anhydrites with interbeds of red sandy clays, as well as layers and lenses of rock salt. The thickness in outcrops is 100-300 m, according to drilling data, the thickness of salts reaches up to 700 m.

In the listed regions, the Gaurdakskaya suite is the oldest, it is most often exposed along major fractures from beneath the overlying Cretaceous red rocks. In all such cases, the lower part of the Gaurdakskaya suite - the sulfatic subsuite, has not been traced to the surface anywhere, hence there are suggestions of a detachment during folding of the entire Mesozoic-Cenozoic folded complex from its base along the anhydrite deposits of this suite. In the Kulob region, the Gaurdakskaya suite forms large domes (Khodja-Sartis, Khodja-Mumin, Tanapchi, etc.), which probably have a diapiric origin. In the domes, rock salt predominates.

V. S. Luchnikov refers, by the similarity of the rock composition and their position beneath the Lower Cretaceous, colorful gypsum-bearing and salt-bearing deposits, exposed in the northeastern part of the Vakhsh region in the valley of the Surkhob River, to the Gaurdakskaya suite. Their incomplete thickness is about 300 m, the lower contacts are tectonic. Some researchers have distinguished these deposits as the independent Surkhobskaya suite (Grigoryev, 1958; Kafarsky and Pyzyanov, 1963). They contain interbeds and lenses of yellowish or white limestones up to 15-30 cm thick.

Organic remains in the Gaurdak Fm in the listed regions were found only in these limestones, outside the territory of Tajikistan, in the basin of the river Allindara and near the confluence of the rivers Qyzylsu and Koksu (Grigoryev, 1958). In the first case, bryozoans characteristic of Jurassic deposits (A. V. Grigoryev does not provide their names) were found, in the second – remains of the gastropod Acktaeonella sp. nov., characteristic for the Titonian according to B. F. Gelyntsev.

In the lower half of the Gaurdak suite in Dushanbe, remains of Kimmeridgian bivalves Astarte pontica Pcel., Camptonectes grenieri Contej., C. duabensis Rep., Anomia monsbeliardensis Contej. are found.