Parametry geotermiczne rejonu Krzemianki i Udrynia na tle ziemskiego pola cieplnego NE Polski
Abstract
GEOTHERMAL PARAMETERS OF THE KRZEMIANKA AND UDRYŃ AREA ON THE BACKGROUND OF THE THERMAL FIELD OF NE POLAND
Summary
The paper presents results of geothermal studies covering the area of NW-Polish section of the East European Precambrian Platform. The measurements taken in the areas of Krzemianka and Udryń, where boreholes about 2.2 km deep penetrated a 1.4 km section of Precambrian intrusive iron-bearing norite-anorthosite rocks, are analysed in detail. Values of heat flow and the geothermal gradient are determined for these areas. Table III shows newly obtained as well as already published heat flow values. Tables I and II show temperatures recorded at various depth and geothermal gradients determined for the areas of Krzemianka and Udryń. An analysis of geothermograms from Krzemianka and Udryń boreholes has shown the occurrence of disturbances in the heat field at the depths to 0.6 km. The disturbances are related to successive glaciation epochs and to the Holocene period of climate amelioration. Temperatures higher than the mean annual temperature on the surface were recorded at the depth of 20 m. It is assumed that the distribution of temperatures in upper layers of sedimentary stage was also influenced by changes in the climate during the last 1000 years, including a period of climate deterioration (following a local climate amelioration) from the late Medieval times. Interdependances between the distribution of geothermal parameters for NW Poland and the tectonics are found. The lowermost values were recorded in the elevated basement of the Mazury-Białoruś massif, and higher values - in the areas of the Marginal Depression, Peribaltic syneclise and Podlasie trough. Low values of heat flow are presumably related to low generation of radiogenic heat in the area studied and to the low value of subcrustal heat flow, which is typical of Precambrian Platform areas (QO = 0.6•10-6 cal/cm2s - see Fig. 5). Low values of temperatures recorded in the crystalline massif and negative values of geothermal gradient from its sedimentary blanket are highly advantageous for iron mining in the areas of Krzemianka and Udryń.
Summary
The paper presents results of geothermal studies covering the area of NW-Polish section of the East European Precambrian Platform. The measurements taken in the areas of Krzemianka and Udryń, where boreholes about 2.2 km deep penetrated a 1.4 km section of Precambrian intrusive iron-bearing norite-anorthosite rocks, are analysed in detail. Values of heat flow and the geothermal gradient are determined for these areas. Table III shows newly obtained as well as already published heat flow values. Tables I and II show temperatures recorded at various depth and geothermal gradients determined for the areas of Krzemianka and Udryń. An analysis of geothermograms from Krzemianka and Udryń boreholes has shown the occurrence of disturbances in the heat field at the depths to 0.6 km. The disturbances are related to successive glaciation epochs and to the Holocene period of climate amelioration. Temperatures higher than the mean annual temperature on the surface were recorded at the depth of 20 m. It is assumed that the distribution of temperatures in upper layers of sedimentary stage was also influenced by changes in the climate during the last 1000 years, including a period of climate deterioration (following a local climate amelioration) from the late Medieval times. Interdependances between the distribution of geothermal parameters for NW Poland and the tectonics are found. The lowermost values were recorded in the elevated basement of the Mazury-Białoruś massif, and higher values - in the areas of the Marginal Depression, Peribaltic syneclise and Podlasie trough. Low values of heat flow are presumably related to low generation of radiogenic heat in the area studied and to the low value of subcrustal heat flow, which is typical of Precambrian Platform areas (QO = 0.6•10-6 cal/cm2s - see Fig. 5). Low values of temperatures recorded in the crystalline massif and negative values of geothermal gradient from its sedimentary blanket are highly advantageous for iron mining in the areas of Krzemianka and Udryń.