Title: A New Gas Field of Eastern Turkmenia-Bayram-Ali
Abstract: The upper part of the known section to the Cenomanian inclusively is typical for all the platform part of southeastern Turkmenia. Thick variegated continental deposits of the Neogene-Quaternary overlap eroded Paleogene (on the periphery) and Senonian (at the crest) sediments. The Paleogene sediments consist of argillaceous Eocene rocks with a thickness up to 96 m and Paleocene limestones of the Bukhara stage with a thickness of 110-120 m. The lower occurring Senonian, Turonian, and Cenomanian sediments, which have thicknesses of 384-410, 308-355, and 372-406 m, respectively, have similar lithologic characteristics. They consist of alternating strata of gray and greenish gray sandstones and greenish gray clays. The thickness of some sandstone strata reaches several tens of meters, and that of the clays - 100 m. It should be noted that the problem of the presence of deposits of the Danian stage here, as on many other structures of eastern Turkmenia, remains unclear. An angular discordance has not been established between sediments of the Bukhara stage and the Senonian super-stage in all cases. The Lower Cretaceous section is separated from the Upper Cretaceous sediments by carbonates; moreover, their quantity increases with depth. In the Albian part of the section with a thickness of 550-566 m carbonates are found in a unit of black clays and in individual strata of gray sandstone; they occur in the form of individu al thin beds of limestone. The Aptian sediments (thickness of 82-84 m) consist of gray politic limestones with thin beds of gray sandstones and clays. The thickness of the sediments of Barrem age is 123-127 m. The upper half consists of dark gray dense clays with beds of gray limestone; the lower–gray oolitic limestones with beds of dark gray clay and sandstone. Undifferentiated Valanginian-Hauteriv sediments with a thickness of 165-171 m consists of gray pelitic limestones with beds of gray (upward) and red (downward) argillites, sandstones, dolomites, and anhydrites. An abundance of carbonates in the Lower Cretaceous section is distinctive of the Bayram-Ali structure and adjacent areas of the Murgab region in contrast to the Amu Dar’ya region where clastic deposits predominate in the sediments of the Lower Cretaceous. Valanginian-Hauteriv limestones rest on an unfossiliferous clastic unit of brick red sandstones and clays with beds of very compact sandstones, limestones, dolomites, and anhydrites. The position of the unit between the carbonates of Lower Neocomian age and the underlying Kimmeridgean-Titonian Gaurdak formation, the similarity of facies to facies of the Karabil formation studied in outcrops of the Gaurdak-Kugitan region and in wells of the Amu-Dar’ya region (Kerki-Dag, Narazym, Farab) and of the Repetek region, the same order of thickness, the absence of organic remains as is characteristic of the Karabil formation in all the prospecting areas of eastern Turkmenia–all this indicates that the redbed unit at Bayram-Ali is an analog of the Karabil formation. Just as at Kerki-Dag, in the Bayram-Ali area no angular unconformity is found between the Karabil formation and the overlying Lower Cretaceous sediments. At Narazym and Farab there is a large angular unconformity, which indicates a Jurassic age for the Karabil formation. The thickness of the Karabil formation at Bayram-Ali ranges from 448 to 464 m.
Publication Year: 1962
Publication Date: 1962-01-01
Language: en
Type: article
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