Geology, geography and global energy

Scientific and Technical Journal

Vertical hydrogeochemical zoning of underground water of Caspian basin

2013. №4, pp. 59-65

Myazina Natalya G.  - C. Sc. in Geology and Mineralogy, Associate Professor, Orenburg State University, 13 Pobeda ave., Orenburg, 460018, Russian Federation,, geologia@mail.osu.ru

In this article the vertical hydrogeochemical zoning Caspian basin as development salt dome tectonics. Part of the post-salt sedimentary cover includes hydrogeological complexes intense, difficult and highly hindered water exchange top pressure, Hydrogeodynamic system. Relatively water-resistant sulfate-halogen Kungurian thickness separates the top tier of the hydrodynamic system of post-salt strata from the bottom. In the lower part there is the subsalt subsalt Hydrogeodynamic system, which consists of zones kvazizastoynogo regime and brackish waters of the crystalline basement. Within the North Caspian region artbasseyna intensive water exchange is territorial confined to the valley of the rivers Volga and Akhtuba. She is represented by groundwater bicarbonate, sulfate and chloride, the chloride, a different cation composition with mineralization 3.1 g/dm3. Is confined to the alluvial-marine Khazar Khvalynskaya and srednechetvertichno-modern alluvial deposits. Area of difficulty Hydrogeodynamic regime represented sulfate-chloride and chloride-sulfate, chloride salt water with a salinity of 1-36 g/dm3. It is developed throughout the Cenozoic sediments. Zone rather hindered water exchange is represented by two major geochemical and genetic types: 1) sodium chloride brine leaching infiltrogennymi rock salt in the areas adjoining to salt domes and ridges, 2) chloride sodium-calcium (calcium-sodium) sedimentogene brines with mineralization 36-350 mg /dm3. Halogen salt (waterproof) floor before magnesium chloride (sodium and magnesium) relict Permian paleobasins mother liquor to the value of mineralization 349-540 g/dm3. Subsalt lower floor consists of two zones kvazizastoynogo regime and water zones of the crystalline basement. The first zone is located in the sediments of the Carboniferous and Upper Devonian sediments in the second subband Riphean and Lower Devonian is represented by two major geochemical and genetic types: 1) sodium chloride, calcium (calcium-sodium) sedimentogene pickles, 2) sodium chloride brine leaching infiltrogennymi diffusion rock salt in Artinskian-Asselian verhnekamennougolnyh and sediments with mineralization up to 100-150 in some cases 200 g/dm3. In the crystalline basement are desalinated water with a salinity of several to tens g/dm3. In forming paleoavlakogenov, palaeorift, thrust structures separating their faults occur in the fluid movement of the faults and the surrounding cover and crustal blocks.

Key words: underground hydrosphere,North Caspian artesian basin,vertical zonation,water exchange zone,relatively water-resistant sulfate-halogen sequence,hydrodynamics,paleoavlakogeny,palaeorift,thrust structures,fluids,brines,chemical composition

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