Madrid, Spain Abstract
4. DRAWING UP OF MAPS
4.3. Analysis of the resolution of radiometric maps
Using the aforementioned characteristics the radiometric map of Salamanca province was drawn up with the same resolution as the national map (1 piece of data per 35 kmj), Fig. 4. The same map with a resolution of 1/100 km2 may be seen in Fig 5.
E X T R E M A D U R A
Uranium mine
FIG. 4. Radiometric map of the Province of Salamanca. Resolution: 1 Radiometric datum/35 km2.
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Hoja 36 1 200000
E X T R E M A D U R A
Uranium mine
FIG 5 Radwmetric map of the Province of Salamanca Resolution 1 Radiometnc datum/100 km2
If both maps are compared with the geological scheme in Fig 2 it can be seen that, in the first case, the geological macroformatlons (entities of over 100 km2) are quite well drawn, whereas in the second case only the limits of these macroformatlons can de seen approximately (Ciudad Rodngo basin, northern zone of Lumbrales and southern zone, Sierra de Gata)
Fig 6, shows the sheet no H-36 (Vitigudmo) 1 200 000 , with resolutions of 1/4, 1/9, and 1/25, (one 1 200 000 sheet is made up of 4 x 4 1 50 000 sheets)
From a comparative analysis with the geological sketch in Fig 2 it is deduced that
With a 1/1 resolution the position of the uranium mines (Fe and Retortillo mines), the Almendra reservoir and its extension over a great distance, minor (quaternary north of the reservoir) and major geological formations, clear edges between radiometncally well characterized geological formations, and even the influence of the metamorphic gradient over the residual Palaeozoic of the northern part of the Ciudad Rodngo basin are perfectly in evidence
With a 1/4 resolution the tail of the reservoir disappears and the Retortillo mine has not been captured
With a 1/9 resolution the foregoing details can still be seen, albeit more faintly
Resolution : 1 radiometric datum/4 Km2
Resolution : 1 radiometric datum/9 Km2
Resolution : 1 radiometric datum/25 Km2
FIG 6. Radiometic mapof the H. 36 Vitigudino 1: 200 000 with different resolutions.
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With resolutions of 1/25 and 1/35 the radiometnc contacts become fainter and fainter Anomalies of less than 25-35 km2 might not be captured and if they are they offer a sharpening of kilometric forms
5 CONCLUSIONS
With regard to data extraction
The problem with the data-extraction mesh in our MARNA Project is similar to that of the calculation of the optimum sampling
Each surface factor must be studied statistically and the number of data increased until an acceptable confidence limit is reached in all cases Should any of the samples fail to fulfil the error limit, the mesh on its surface will be closed until the confidence limit can be brought down to within acceptable or admissible margins, otherwise the item of data will be dispensed with
With regard to the drawmg-up of maps On a 1 200 000 scale
From the experience gained in drawing up maps on 130 000 km2 of Spanish territory, it is inferred that for resolutions included between 1/1 and 1/9 km2 very acceptable resolutions are obtained, versus geology and orography [15], [16], [17]
On a 1 1 000 000 scale
A resolution of 1/35 km2 is very acceptable, and a resolution of 1 100 km2 deforms important geological and geographic irregularities
With regard to the geology/radiometry correlation Very good with the resolution 1/1 km2 (mines detected) With regard to the quantitative determination of contaminations
Once the preoperational radiometnc map has been drawn up, an eventual contamination may be quantified by means of similar comparative methods
The extension and variability in intensity of the contamination will govern the size of the sampling
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XA9745940 NATURAL BACKGROUND RADIATION IN JORDAN