Geology Reference
In-Depth Information
montmorillonite clay. This fact together with recorded temperature val-
ues at the curve intersection points (9
-107°С), which is optimum for the
start of intense dehydration, suggests two important conclusions.
On the
one hand, it establishes the Miocene-Oligocene interval in the region
as the upper boundary of the alkaline waters' generation and prevail-
ing occurrence zone. On the other hand, it confirms the hydrodynamic
association between the Pliocene and overlying sediments with the
underlying ones.
General conclusions may be made based on the reviewed materials:
2
1. Average values of geothermal gradients in the depth inter-
val 500 to 6,000 m in the mobile belts' Alpine basins range
between 1.55 and 3.71°С/100 m.
2. Maximum sediment cover heating is recorded in the regions
with features of eugeosynclinal evolution, relatively slow
deposition and shallow basement.
3. Minimum sediment cover heating is recorded in the deepest
miogeosynclinal depressions and troughs with maximum
sediment cover thickness, high-rate Recent deposition and
deeply buried consolidated crust surface.
4. Geotemperature
parameters
of individual regions
do not
display clear correlation with their tectonic nature (depres-
sions, troughs). Patterns of temperature distribution in their
sections are defined in each specific case by the regime of
geotectonic evolution, deposition rate, sediment cover
thickness and by the ratio within the sediment cover of heat-
generating
and
heat-insulating intervals,
i.e., by the condi-
tions of conductive heat transfer.
5. Zones of abnormally-high (compared with the background)
temperature in all fields and prospects are usually associated
with areas of intense faulting, diapirism, mud volcanism,
elevated fracturing with active shows of thermal ground
waters of the injection/cross-flow penetration.
6.
Caeteris paribus
(all other conditions being equal) average
geothermal gradients in the sections of fields and prospects
are minimal in zones of conducting faults and minimal in
the obstructed discharge areas of geo-fluid-dynamic system
(see Chapter 5).
7. At the same depths within individual structures, temperature
in the crestal (most faulted) portions is higher than over the
