New data on the Geochemistry of Gases in the Potash Deposits

• Main Authors: I. I. Chaykovskiy, O. V. Ivanov
• Format: Article
• Language: English
• Published: Perm Sate National Research University 2014-12-01
• Series: Vestnik Permskogo Universiteta: Seriâ Geologiâ
• Subjects: Верхнекамское месторождение; состав газов; первичные и вторичные соли
• Online Access: http://geology-vestnik.psu.ru/index.php/geology/article/view/49

The composition of the gas phase of salt rocks from a number of potash deposits located in Europe (Verkhnekamskoe, Starobinskoe) and Asia (Tubegatanskoe, Zhylyanskoe Satimolinskoe) was studied. It allowed dividing them into two groups. In Asian deposits, only authigenic dry gases were formed by diagenetic decomposition of organic matter. Structural exposure of these deposits led to the oxidation of methane and hydrogen and enrichment by carbon dioxide. European deposits were not structurally exposed to the oxidation process, but were exposed during salt rock formation. They experienced influx of heavy hydrocarbons from the underlying strata. The history of the formation of gas regime at the Verkhnekamskoe potash deposit could be divided into three stages. First stage may be characterized by a syngenetic capture of deep gases and authigenic organic matter converted during diagenesis to methane, which percentage gradually increases with an increase of the thickness of impermeable salt strata. Then the deep gases invaded the salt formation during sedimentation of the upper carnallite layers and top salt rock. Third stage was associated with folding processes accompanied by a mobilization of fluids scattered in the gas-fluid inclusions, and with probable influx of heavy hydrocarbons and carbon dioxide resulted in formation of the secondary salt zones. Replacement of carnallite layers leads to the release of isomorphous ammonium ion and formation of a hydrogen.