No abstract

A part of Mansehra Granite was selected for the assessment of radiological hazards. The average activity concentrations of (226)Ra, (232)Th and (40)K were found to be 27.32, 50.07 and 953.10 Bq kg(-1), respectively. These values are in the median range when compared with the granites around the world. Radiological hazard indices and annual effective doses were estimated. All of these indices were found to be within the criterion limits except outdoor external dose (82.38 nGy h(-1)) and indoor external dose (156.04 nGy h(-1)), which are higher than the world's average background levels of 51 and 55 nGy h(-1), respectively. These values correspond to an average annual effective dose of 0.867 mSv y(-1), which is less than the criterion limit of 1 mSv y(-1) (ICRP-103). Some localities in the Mansehra city have annual effective dose higher than the limit of 1 mSv y(-1). Overall, the Mansehra Granite does not pose any significant radiological health hazard in the outdoor or indoor.

All human beings are exposed to primordial radiation. The main source of primordial radiation has been naturally radioactive building materials. In Pakistan, among building materials, granites are most commonly used. This paper reviews the previous studies conducted for the estimation of natural radioactivity of granites from Rustam-Koga, Shewa-Shahbazgarhi, Bunair, Mansehra, and Nagarparkar. The techniques used for these studies include gamma spectrometry and field surveys. To assess the radiation hazards associated with granites of Pakistan, primordial radionuclides and corresponding radiation hazards have been estimated. Most of these granites are found to be safe except Rustam-Koga granite, which presents high excess lifetime cancer risk.

This study aims to analyze the lineaments using the field data and a remote sensing approach, to describe their relationship with the folds, faults, and regional tectonic stress of the central Sulaiman Fold-Thrust Belt. Joint data, from nine anticlines, has been collected using the scanline method and classified into three sets (JS1, JS2, and JS3) based on their geometrical relationships. Lineaments extracted from the 30 m digital elevation model have been classified subsequently into three lineament sets (LS1, LS2, and LS3) based on the azimuths from the corresponding joint sets. A very high correlation coefficient (rs = 0.97), between the azimuths of the field joints and the remotely sensed lineaments, has been observed which validates that the lineaments are the regional representation of the local field joints. The geometrical relationship of the lineament sets with the fold hinges indicates that the older LS1 and LS2 are strongly related to the regional folding episode, while the younger LS3 is a result of local shears. The chronological interpretation of the deformational events responsible for the lineament sets is constrained by the presence of the Kingri Fault, which induces a strike-slip component within the study area. Furthermore, the controls on the joint and lineament sets, established using multivariate statistics to decipher the effects of lithological and structural contrasts on the lineament density, reveal that an increase in the lineament density can be attributed to the competence and thickness of the rock units as well as the variable local stresses across the different folds. Based on the orientations of these lineament sets, the cumulative direction of the compressive event in the NW-SE direction (310–320) coincides with the regional stress direction of the SFTB.

<p>The western Himalaya-Karakoram region in northern Pakistan has such hydrothermal features as hot springs and alteration zones. The heat source for these features remains unclear, with suggested mechanisms including radiogenic heat production from minerals, frictional heating caused by shearing along faults, residual heat from Miocene plutonic intrusions, metamorphic heat caused by tectonic collision, and heat advection related to rapid exhumation. In this study, we provide a quantitative estimation of the radiogenic heat production of 158 locations from different crystalline lithologies exposed in the three distinct tectonic domains of the western Himalayan-Karakoram region, i.e., Nanga Parbat-Haramosh Massif, Kohistan-Ladakh Batholith, and Karakoram Batholith. The radiogenic heat production values are calculated from the concentrations of the uranium (ppm), thorium (ppm), and potassium (wt%), which are determined directly in the field using a portable gamma spectrometer on exposures of Proterozoic to Tertiary crystalline rocks. The radiogenic heat production in the Nanga Parbat-Haramosh Massif ranges between 0.72 and 18.46 µWm<sup>-3</sup>, with mean and median values of 7.12 and 6.74 µWm<sup>-3</sup>, respectively. Furthermore, Proterozoic gneisses, Tertiary granites, and pegmatites within the Nanga Parbat-Haramosh Massif have mean radiogenic heat production values of 7.86, 10.67, and 6.47 µWm<sup>-3</sup>, respectively. The radiogenic heat production in the Kohistan-Ladakh Batholith ranges between 0.42 and 5.16 µWm-3, averaging at 2.49 µWm<sup>-3</sup> with the highest mean of 3.68 µWm<sup>-3</sup> in granites and lowest 0.74 µWm<sup>-3</sup> in tonalites. The radiogenic heat production of the Karakoram Batholith ranges between 1.04 and 23.54 µWm<sup>-3</sup> with a mean of 5.84 µWm<sup>-3</sup> and a median of 4.45 µWm<sup>-3</sup>. Within the Karakoram Batholith, the Tertiary granites have the highest mean radiogenic heat production of 11.17 µWm<sup>-3</sup>,  while the lowest mean radiogenic heat production of 2.86 µWm<sup>-3</sup> is found in the Cretaceous diorites. Our results suggest that the Nanga Parbat-Haramosh Massif, which is composed of Proterozoic Indian plate basement rocks, has high concentrations of uranium, thorium, and potassium, and consequently a higher radiogenic heat production. This also correlates with similar high radiogenic heat-producing basement rocks exposed in southern India. The presence of high radiogenic heat production in Tertiary granites and pegmatites indicates mobilization and enrichment of incompatible uranium and thorium due to crustal evolution processes related to the Himalayan Orogeny. We suggest that high radiogenic heat production in Proterozoic rocks may have contributed significantly to the enhanced heat flux in the active Himalayan Orogen.</p>