Geology Reference
In-Depth Information
of the Tersk-Caspian Foredeep (trough) of inverse hydrochemical zoning
due to a mandatory ground water salinity decrease in the subsalt clastics
underneath the evaporites.
Analysis of the ground water position, manifestations and spatial distri-
bution of its salinity and component composition suggests that the major
mechanism forming spatial hydrochemical zoning in the lower sediment
cover of the Tersk-Caspian Foredeep (trough) is powerful interformational
fluid cross-flows through the system of large faults. In the Upper sediment
cover the main role belongs to hydrochemical effects caused by the infiltra-
tion nature of its water-exchange.
2.2.4 heZagrosForedeep
The penetrated section in the region is mostly carbonates. It includes high-
salinity (80-130 g/l) chlorine-calcium waters with the secondary salinity
factor of 17-39%-equiv. (Table 2.20).
The major waterhead complexes in the trough are Jurassic (Hami
Series), Upper Cretaceous (Bangestan Series), Oligocene-lower Miocene
(Asmari formation). The regional water-barriers are formed by the marl
sequence of a Middle Jurassic Druma formation, by the evaporite forma-
tion of the Upper Jurassic Hiyon Stage, clay formations Kazdumi (Albian
Stage, Lower Cretaceous), clayey-marly rocks of the Tabur and Gurpi
formations (Maastrichtian Stage, Upper Cretaceous), Pabdeh Paleocene-
Eocene formation and evaporite-clay sequence of the Fars Formation
(Middle Miocene).
he
Jurassic
complex (Hami Series) is composed of organic limestones
(Marat and Arab formations) and is saturated with brines (420-455 mg-
equiv. - 120-130 g/l) of the chlorine-calcium type with the secondary salin-
ity factor of 35-30%-equiv. The sulphate-ion content is 1.7-3.6 mg-equiv.
he
Upper Cretaceous
complex (limestones and marls of formations
Sarwak and Ilam - Bangestan Series) includes ground waters with the
salinity 350-402.5 mg-equiv. (100-115 g/l), secondary salinity factor
25-32%-equiv. and the sulphate-ion content 1.5-3.1 mg-equiv..
he
Oligocene-Lower Miocene
complex (reef limestons of the Asmari
Fm.) is saturated with 280-315 mg-equiv. salinity waters (80-90 g/l) and
secondary salinity factor 17-22%-equiv.; the sulphate content is 1.0-2.3
mg-equiv.
he
Middle-Upper Miocene
water-saturated reservoir lenses within the
evaporite-clay sequence of ther Lower Fars formation (Middle Miocene),
some limestone, marl and sandstone beds of the Middle Fars formation
(Middle Miocene) and reservoirs in the clastic Upper Farsа Fm. (Upper
