Natural radioactivity in rocks of the Modane-Aussois region (SE France)

The activity concentrations of 40K, 232Th, and 238U in the characteristic rocks of the Modane-Aussois region (Western Alps, France) were determined using an HPGe gamma-ray spectrometry system. The activity concentrations of 40K varied from 18 Bqkg-1 (limestone dolomite) to 392 Bqkg-1 (calcschist), while those of 232Th varied from 0.7 Bqkg-1 (limestone dolomite) to 18 Bqkg-1 (calcschist). The activities associated with 238U ranged from 9 (quartzite) to 29 Bqkg-1 (dolomite). In the investigated rock samples, concentrations of 238U (ppm) and 40K (%) had a strong negative correlation

222Rn and 220Rn concentrations in soil gas of the Izera Massif (Sudetes, Poland) as a function of sampling depth

This research presents soil gas 222Rn and 220Rn concentrations measured at 17 locations in the Izera Massif of southwest Poland. The average 222Rn concentrations at sampling depths of 10, 40 and 80 cm were 8, 78 and 224 kBq m–3, respectively. The average 220Rn concentrations for the same depths (10, 40 and 80 cm) were 6, 10 and 13 kBq m–3, respectively. Profiles of the concentrations versus depth can be fitted by exponential, linear and polynomial functions for soils developed on fault zones, above uranium mineral deposits, and above faulted uranium deposits, respectively. Soils developed on bedrock without fault zones or uranium mineralisation exhibit concentrations that follow a power function with an exponent of p <1

222Rn and 220Rn concentrations in selected soils developed on the igneous rocks of the Kaczawa Mountains (Sudetes, Poland)

This study presents the preliminary results of 222Rn (radon) and 220Rn (thoron) concentrations that were measured in the soils developed on igneous rocks including mafic (pillow lavas, basalts and melaphyre) and acid (keratophyre, rhyolite and rhyolitic tuff) rocks at ten locations in the Kaczawa Mountains (SW Poland). The measurements were carried out at sampling depths of 10, 40 and 80 cm using a RAD7 portable radon system. The highest concentrations of radon (222Rn) were mainly observed in the soils overlaying acid igneous rocks. The highest value of 11 kBq m-3 was obtained at a depth of 10 cm for soils overlaying melaphyre. At depths of 40 and 80 cm, the averages of 222Rn concentrations showed the same values of 3.6 kBq m-3 for all of the soils investigated. The highest concentrations of thoron (220Rn) were observed in soils overlaying acid igneous rocks, i.e. the value of 49 kBq m-3 at a depth of 40 cm for soils overlaying rhyolitic tuff. In the soils developed on basalts, the average concentrations of 222Rn increased with the sampling depth, whereas the average concentrations of thoron (220Rn) decreased with increasing sampling depth. Positive correlations were found between 232Th activity in the parent rocks and soil gas 220Rn concentrations at all of the sampling depths, whereas a positive correlation between soil gas 222Rn and the 238U activity concentration in the parent rocks was only found at a depth of 40 cm

Depositional architecture of marginal multiple-source ramp of the Magura Basin (Eocene Flysch formation, Outer Western Carpathians)

The Zembrzyce Beds were studied to interpret the environments and facies in the western part of the Siary Subunit. New sedimentological data were obtained for the reconstruction of the depositional architecture of the Zembrzyce Beds. Based on detailed facies analysis, 9 facies and 4 facies associations were recognized. The facies associations represent different architectural elements of a submarine fan, such as: termination of distributary channel with transition to depositional lobe (distal part of mid-fan/outer fan sub-deposystem), lobes and distal lobes (outer fan sub-deposystem). According to the classification of Reading & Richards (1994) the fan deposystem can be classified as mud/sand-rich ramp. This system consists of several elongated lobes that formed synchronously, migrated laterally, and then retreated or decayed. The depositional system was supplied from the north and north-east. The inner-fan sub-deposystem was not detected. The sediments were deposited by high- and low-density turbidity currents and hyper-concentrated density flows sensu Mulder & Alexander (2001) with participation of the depositional background processes (pelagic settling). The sedimentary conditions of the Zembrzyce Beds during the Late Eocene were controlled by tectonic movements, the progress of the subduction and the global sea level changes

Krater Ngorongoro największą atrakcją geoturystyczną ryftu Gregory’ego (północna Tanzania, Afryka) - uwarunkowania geograficzne

The caldera of an extinct Ngorongoro volcano is the largest unflooded and not destroyed type of this form on Earth. The depression itself occupies an area of nearly 300 km2, while the Crater -walls tower afew hundred metres (400--610 m) above the floor of the caldera. Almost all typicalforEast Africaplants and animals, as -well as rare, endemic and often endangered species can observed in the crater. The -unique richness and diversity of natural -world of the Xgorongoro Crater is caused exceptionally by favourable weather and hydrological conditions. These factors depend on local conditions, associated -with significant relief of this area. Probably, the most important is the richness of the Cgorongoro Crater in -water. There occur springs, perennial and seasonal rivers, marshes, swamps, as -well as reservoirs of fresh and sally -water. Essential is also the presence of the local autochthonous population of theMaasai people, -which raises the attractiveness of that localization adding so important cultural values. Due to its -unique natural and touristic -values, the Cgorongoro Conservation Area (NCA) has been established in 1959. The area was also included into the UNESCO World Cultural and Natural Heritage List. This paper presents only the geographical setting of the Ngorongoro Crater, which should be understood as its morphology, hydrological and climatic conditions, -wildlife and indigenous localpeople

In situ gamma-ray measurements of 40K, 232Th and 238U in high-grade meta morphicrocks from the Sowie Mountains (Sudetes, SW Poland)

This paper reports on the abundance of primordial radionuclides (40K, 232Th and 238U) in characteristic lithologies from the Sowie Mountains (SW Poland). In situ gamma-ray measurements were conducted at 12 localities hosting exposed augen gneiss, flaser gneiss, granulite, homophanized gneiss, hornblendite, layered gneiss, layered migmatite, migmatic gneiss, mylonitic gneiss and mylonitic granulite. The activity concentration of 40K varied from 180 Bq kg–1 (mylonitic granulite) to 845 Bq kg–1 (layered gneiss). The activity concentrations associated with 228Ac (232Th) varied from 10 Bq kg–1 (mylonitic granulite) to 53 Bq kg–1 (homophanized gneiss), while activity associated with 226Ra (238U) varied from 9 Bq kg–1 (mylonitic granulite) to 43 Bq kg–1 (layered gneiss). An augen gneiss adjacent to the Intra-Sudetic Fault showed the highest combined Th + U activity (89 Bq kg–1). The average Th/U ratio (3.6) calculated for gneiss outcrops of the Sowie Mountains falls within the range reported for biotite gneiss (3.5–4). Subsurface outcrops from the Walim-Rzeczka underground complex did not give noticeably higher 238U activities. The results obtained for the Sowie lithologies are compared with those obtained by similar methods for similar rocks as reported in literature sources

Krater Ngorongoro największą atrakcją geoturystyczną ryftu Gregory’ego (północna Tanzania, Afryka) - dziedzictwo geologiczne

The Ngorongoro Crater is the largest unflooded and not destroyed collapse volcanic caldera of the shield volcano on Earth. It attracts many visitors each year not only because of the undoubted -wealth of the -wildlife and breathtaking views, but also due to the geotouristic attractiveness of this definite location. The Crater is in fact a specific example of geological processes, relevant to the development of planet Earth. In a relatively small area one can observe rocks of different types and ages: Precambrian igneous and metamorphic rocks, -volcanic rocks formed in the Pliocene, Pleistocene, and even nowadays, as -well as sedimentary rocks, up to those currently forming -within the caldera floor. The origin and development of the Ngorongoro -volcano, and lately caldera, is closely related to the activity of rifting processes occurring along the Gregory Rift, belonging to the East African Rift System. It represents one of the three arms of the Afar triple junction associated -with the located here hotspot. Due to the geotouristic attractiveness, as -well as a richness of living nature and archaeological sites -with discoveries of our ancestors, -which illustrate an important stage in the history of mankind, the area of the Ngorongoro Crater was designated a UNESCO World Cultural and Natural Heritage Site

The Ngorongoro Crater as the biggest geotouristic attraction of the Gregory Rift (Northern Tanzania, Africa) – geological heritage

The Ngorongoro Crater is the largest unflooded and not destroyed collapse volcanic caldera of the shield volcano on Earth. It attracts many visitors each year not only because of the undoubted wealth of the wildlife and breathtaking views, but also due to the geotouristic attractiveness of this definite location. The Crater is in fact a specific example of geological processes, relevant to the development of planet Earth. In a relatively small area one can observe rocks of different types and ages: Precambrian igneous and metamorphic rocks, volcanic rocks formed in the Pliocene, Pleistocene, and even nowadays, as well as sedimentary rocks, up to those currently forming within the caldera floor. The origin and development of the Ngorongoro volcano, and lately caldera, is closely related to the activity of rifting processes occurring along the Gregory Rift, belonging to the East African Rift System. It represents one of the three arms of the Afar triple junction associated with the located here hotspot. Due to the geotouristic attractiveness, as well as a richness of living nature and archaeological sites with discoveries of our ancestors, which illustrate an important stage in the history of mankind, the area of the Ngorongoro Crater was designated a UNESCO World Cultural and Natural Heritage

In situ measurements of natural radioactivity in selected igneous rocks of the Opava Mountain region

In situ gamma-ray measurements of four igneous rocks were taken in the Opava Mountains (Eastern Sudetes, Poland). The activity of naturally occurring radionuclides was measured using a portable GX3020 gamma-ray spectrometry workstation. The activity concentrations of 40K varied from 914 ± 17 Bqkg-1 (gneiss, Kamienna Góra) to 2019 ± 37 Bqkg-1 (weathered granite, Sławniowice), while those of 232Th from 7.5 ± 0.6 Bqkg-1 (weathered granite, Sławniowice) to 68 ± 0.9 Bqkg-1 (migmatitic gneiss, Nadziejów). The activities associated with 238U decay series ranged from 10 ± 0.4 Bqkg-1 (weathered granite, Sławniowice) to 62 ± 1.6 Bqkg-1 (gneiss, Kamienna Góra). The results will be used in compiling Radiological Atlas of the Sudetes