8
N E W S of the Academy of Sciences of the Republic of Kazakhstan
sink to a depth of 50-100 m, and in the Prekaratau valley to 700-800 m and more. They are overlapped by
Upper Cretaceous, Paleogene and Neogene sediments, the upper part (Upper Miocene-Pliocene) of which
composes the daily surface of the Southern Mangystau and Ustyurt plateaus. In some areas, in particular, in
the North Mangystau depression there are sand massifs.
Aquifers, aquifer systems and other groundwater data are mapped in Kazakhstan on the maps taking
into account the requirements for displaying geographical objects on digital hydrogeological maps [17-22].
The main aquifer complexes and horizons of the region containing low-salinity water are the following
sediments: Alb-Cenomanian, Upper Cretaceous, Upper Miocene-Pliocene and eolian sands. Groundwater
of Alb-Cenomanian deposits is the most widespread and water-bearing among all aquiferous deposits in
the basin and represented by different-grained sands and sandstones with interlayers of clay sediments, and
come out to the day surface in Prekaratau valleys and in bottoms of some drainless depressions. Depth of
occurrence of underground water complex in the basin as a whole varies from absolute levels of 100-150 m in
the Prekaratau valleys to minus 800 m in the South Mangystau and Ustyurt. In the zones of outcrop of water-
bearing rocks the discharge of springs does not exceed 1.5-2 L/sec. With dipping of the stratum and with the
increase of groundwater head their productivity increases: in Prekaratau valleys self-discharge well flow rates
are 5-40 L/sec, in the south and north of Mangystau reach 40-55 L/sec. Water-bearing complex of Upper
Cretaceous deposits containing groundwater of marl-chalk sediments with mineralization up to 5 g/L is spread
in the region on the limited area. Such waters are uncovered within the North and South Aktau monoclines.
Flow rates of water points do not exceed 1-1.5 L/sec under small drops in water level. Here their salinity is
1.5-5 g/L. Water-bearing complex of Quaternary sediments with salinity up to 5 g/L is connected mainly with
uncemented and weakly cemented sand massifs and in some limited in area sections of marine Quaternary
sediments in the form of lenses and interlayers in clay strata. Weakly mineralized groundwater is established
in the northern part of Ustyurt, in the northwest of the South Mangystau plateau, as well as in different parts
of the Bozashi Peninsula. The Sam sand massif is the largest with a total area of 2320 km
2
in the northern
part of Ustyurt. The sand massifs of the northwestern part of Southern Mangystau (Sauskan-Bostankum,
Tuyesu, Baskudyk) and the Bozashi Peninsula (Kyzylkum, Zhilimshik, etc.) have small areas (150-500 km
2
each). The productivity of wells, laid especially in the sands in the north-west of Southern Mangystau and
Sam massif, varies from 0.2 to 6 L/sec at lowering the water level by 1.5-10 m. Mineralization of water in the
most part of massifs is mainly 0.2-1 g/L, and in their marginal parts and near salt depressions increases from
1.5-3 to 5 g/L. Weakly mineralized groundwater of marine Quaternary deposits in some parts of the central
upland part or in flat depressions of the relief, near lake and other depressions is revealed only in the South
and Central Peninsula Bozashi [23].
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