A. NEGUT
Universitatea din Bucuresti
IMPLICATIONS OF THERMAL FIELD STRUCTRE IN MUNTENIA AND OLTENIA
(Abstract)
The needs for a good knowledge of the whole thermal field distribution – temperature,
geothermal gradient and heat flow – is connected first, with understanding
that the main processes of Earth's interior are dependent on thermal events
and second, with the practical and economic targets of the identification and
evaluation of mineral resources. The thermal field distribution knowledge is
o particular interest for geothermal source of energy evaluation.
The thermal field distribution in Muntenia and Oltenia has been obtained by
processing and synthetising about 4,300 temperature values from wells drilled
in oil and gas zones and structures.
The morphology and structure of the thermal field have been defined by means
of both, primary and regional geoisothermes and average geothermal gradient
maps.
Analysis of geothermal maps in connection with factors affecting the thermal
state and other geological and geophysical information on the studied area,
permitted to evidence the following characteristics:
– The complexity of the thermal field according to the geological structure
of the main geological units represented by the Moesian Platform and the Carpathians
Fore-deep;
– Wide range variation of the average geothermal gradient for minimum values
of 1.2–1.3°C/100 m to the values higher than 5.5°C/100 m;
– Different thermal condition of the east and west side of the Moesian
Platform. The average geothermal gradient in the west side is about two times
higher than in the east one; the limit between the two zones is materialized,
approximately, by the Dambovita Valley;
– A regularity in the geothermal anomalies orientation in the platform
zone, namely: general SE–NW orientation in the east side, along some "dobrodjean" directions
and SW – NE orientation in the west side, converging to the Carpathians
Foredeep;
– Because small differentiation of sedimentary rocks from cover formations
by thermal conductivity, prevailing factors which affect the thermal state are:
the depth and relief of crystalline basement, the formations structure and the
main fractures of fracture systems in the crystalline basement and/or in the
sedimentary cover; in addition, the presence of magmatic rock bodies may be included.
The particular significance of some regularities in the thermal field distribution
are outlined in the paper; also, the main problems concerning temperature and
geothermal gradient implications are specified.
Finally, the main direction of future efforts in the geothermal research in
Romania are discussed.
Key words: thermal field, temperature, geothermal gradient, heat flow, geothermal maps.