A.A. Qureshi

Preliminary radon concentration-survey in some houses of Islamabad

Abstract Measurements of radon and its daughter products have been carried out in 13 houses in the city of Islamabad (Pakistan). Both CR-39 and CN-85 detectors were installed in bed rooms, kitchens and drawing rooms of the chosen houses and were exposed to radon and its daughters over a period of about four months. All the exposed detectors were processed employing the optimized etching conditions. Significant variation in radon concentration has been observed in the houses under investigation.

Determination of uranium contents in rock samples from Kakul phosphate deposit, Abbotabad (Pakistan), using fission-track technique

Abstract Some times high uranium contents are present in the phosphate rocks used for the manufacturing of fertilizer. In view of the harmful effects on human health due to the processing and use of such fertilizers in agriculture, it is important to analyse phosphate rocks for uranium content determination. Ten representative rock samples from Kakul phosphate deposit exposed near Abbotabad, Pakistan which are used for the manufacturing of fertilizers were studied for uranium content determination with the help of fission track and neutron activation analysis techniques. Each sample was split into three parts. The first and second parts (solid slabs and pellets) were subjected to fission track analysis, while the third part was analysed using neutron activation analysis technique for comparison. On the average a uranium content of 37 ppm was found in the phosphate rocks. The results of uranium content determinations with the help of fission track and neutron activation analysis techniques show a remarked resemblance up to ±0.1%. This indicates that the fission track analysis technique of uranium content determination is a reliable method inspite of its simplicity. The uranium content in the Kakul deposits is within the permissible limit allowed for the mining and processing of the phosphate rocks for the manufacturing of fertilizers.

Radon signals for geological explorations

Abstract Laboratory and field work concerning radon measurements have shown that radon signals can be used to locate oil, uranium deposits, faults, for earthquake prediction and many other studies. The SSNTD-Laboratory (PINSTECH) is carrying out experiments relating to radon diffusion/migration in different media of interest and is presently exploiting it for uranium exploration, earthquake predition and to locate geological faults in Pakistan.

Emplacement time of Salai Patai carbonatite, Malakand, Pakistan, from fission track dating of zircon and apatite

Based on fission track dating of zircon and apatite, the emplacement history of Salai Patai carbonatite has been traced. It has been estimated that the carbonatite was emplaced along the thrust plane associated with the Indian-Eurasian plate collision during the Oligocene period followed by some thermal/tectonic episode during Early Miocene. This negates the previous proposal that all carbonatites found in Pakistan are a part of a 200 km long alkaline province associated with the rifting of Peshawar Valley during Late Cretaceous or Early Tertiary.

Radon concentration in some houses of Islamabad and Rawalpindi, Pakistan

Abstract 222 Rn concentration in almost fifty houses of Islamabad and Rawalpindi has been measured using box type radon dosimeters containing CN-85. The concentration has been measured in various locations of the houses. The geometric mean of radon concentration comes out 29±14 Bq/m 3 for bed rooms, 28±11 Bq/m 3 for sitting rooms, and 33±16 Bq/m 3 for stores. The minimum and maximum value of radon concentration found from all the rooms, is 11 Bq/m 3 and 83 Bq/m 3 , respectively.

The study of crystalline etch products of CR-39

Abstract The study of etch products is highly desirable for economical re-use of etchants and for the better etching efficiency of detectors used in solid state nuclear track detection technique. A variety of inorganic and organic compounds, formed in the reaction of CR-39 detector with sodium hydroxide solution have been studied. Out of different possible compounds, a crystalline etch product was examined through macroscopic, microscopic and XRD studies. This was identified as mineral “Thermonatrite”.

Unroofing history of the Sillai Patti granite gneiss, Pakistan: constraints from zircon fission-track dating

Abstract A group of alkaline igneous rocks is exposed in the north of the Peshawar Plain, extending from Tarbela in the east up to Loe–Shilman near the Pakistan–Afghanistan border in the west. The alkaline rocks consist mainly of granites, syenites, gabbros, ijolites and carbonatites. Granitic gneisses of Paleozoic age are exposed at the Malakand and further westward at Sillai Patti. However, the fission-track dating studies on zircon, based on the present work, indicate that the age of the Sillai Patti granite gneiss is less than the absolute age of granite gneisses. Therefore, the zircon fission-track age of 24.28±2.97 Ma of the Sillai Patti granite gneiss, represents a time of post-metamorphic denudation history of the area, when these rocks passed through the 210°C isotherm, corresponding to a depth of about 6.7 km inside the earths crust from their present position if a paleogeothermal gradient of 30°C/km is assumed to have prevailed. Our average fission-track zircon age of 24.28±2.97 Ma is very similar to the average fission-track zircon age of 25.4±0.7 Ma of Mansehra granites. Average cooling rates of the Mansehra and Sillai Patti granite gneisses have been computed to be (8.00±0.22)°C/Ma and (8.00±0.98)°C/Ma, while the average denudation rates of the Mansehra and Sillai Patti granite gneisses have been computed to be (0.262±0.007) and (0.274±0.034) mm / yr , respectively, on the basis of zircon fission-track ages for the period between 25 Ma and the present time. This indicates that the two complexes have experienced similar average cooling/uplift-induced denudation histories during the last 25 Ma or so.

Application of solid state nuclear track detection technique in the study of fossil bones

Mammalian fossil bones have been discovered in the rocks of 16 my old Siwalik System in Pakistan. These bones belonging to some animal similar to the rhinoceros of our present days, have been studied using petrography, X-ray diffraction, γ-spectrometry, fission track dating, and α-autoradiography techniques. Presence of uranium in bones, now petrified to apatite, has been identified by fission track and alpha autoradiography methods. Interestingly, the petrified bones still contain well preserved bone cells and blood vessels in their original shape and red colour, perhaps due to the sudden burial of the animal in an anaerobic atmosphere.

Uranium exploration in Pakistan using alpha sensitive plastic films (ASPF)

Abstract The ASPF technique has been successfully developed in Pakistan. Studies concerning optimisation of tube size, exposure time, position of detector in tube, etching conditions, type of detector, etc. have been done in the laboratory. Some studies like effects of depth, size and grade of ore body and water table were carried out in the field. The application of this technique was fairly successful in sandstone areas. Based on this technique, subsurface uranium occurences were established in D.G. Khan and Isa Khel. The ASPF-results were confirmed by subsequent drilling and other methods. The technique has been found to be workable and inexpensive. It has been found to supplement the conventional exploration methods, and if applied as a part of normal exploration programme may reduce overall project cost substantially. This paper briefly describes the methodology, parameters, applications and results of the ASPF technique in the field of uranium prospecting and exploration in Pakistan.

Radon measurements in coal mines using polymeric nuclear track detectors

Abstract Radon and its airborne daughter products are prevalent in our natural environment. They constitute significant hazards when concentrated in some enclosures such as mine, cave, etc. We have carried out radon measurements using both passive and active techniques in the Makarwal coal mines, situated in the “Sur Ghar” range of Pakistan. The passive method consisted of using CR-39 detectors alongwith dosimeters from KfK (Karlsruhe, F.R. Germany) which were mounted at different locations in the mines. Whilst in active method, an air pump was employed to draw the air through a filter paper. The alpha activity of radon decay products trapped in the filter was counted using Thomas and Kusnetz techniques. Our studies indicate that the radon concentration inside the coal mines is about 5–10 times greater than that of radon levels outside the mines.