Using radiometric data to identify æolian dust additions to topsoil of the Hillston district, western NSW

The identification and characterisation of æolian dust additions to Australian soil profiles has been attempted using a wide range of analytical techniques. Such techniques are often reliant on specialised equipment and operator expertise, but do not necessarily yield information on the spatial distribution of deposited dust across the landscape. An airborne geophysical technique which measures naturally occurring gamma-rays may now assist in the rapid assessment of dust accumulation sites at the catchment scale. This technique, known as gamma ray spectrometry or radiometrics, assesses the potassium (K), uranium (U), and thorium (Th) contents of the Earth's surface, and may potentially distinguish æolian sediments from the underlying rock or in situ developed soil profile by their differing K, U, and/or Th-bearing mineral suites. This paper summarises a study of this technique for identifying æolian dust in topsoils of the Hillston district in western New South Wales. Using airborne with follow-up ground-based radiometric data, a variable relationship was established between large K signatures and apparent topsoil dust accumulations, which were identified as containing appreciable feldspar and illite. The previously established correlation between topsoil clay content and eTh (equivalent Th) concentration was also observed in this region, indicating that the technique may allow for rapid identification of landform features with significant clay and silt enrichment, as often occurs with dust accession. Despite the ubiquity of æolian sediments in this region, the radiometric data were moderately effective in discriminating different dune systems and may therefore represent a useful initial technique for discerning likely areas of dust accumulation in this environment. However, in areas influenced by fluvial sediments, the radiometric signatures were not necessarily indicative of the topsoil dust content.

Download Full-text

Gamma-ray spectrometry observations to monitor a presumed meteoritic signature at Maâdna crater (Talemzane, Algeria)

10.5194/egusphere-egu2020-2677 ◽

2020 ◽

Author(s):

Atmane Lamali ◽

Lamine Hamai ◽

Sid Ahmed Mokhtar ◽

Abdelkrim Yelles-chaouche ◽

Abdeslam Abtout ◽

...

Keyword(s):

Gamma Ray ◽

Sedimentary Rocks ◽

Clay Content ◽

Gamma Ray Spectrometry ◽

Gamma Spectrometer ◽

Geophysical Method ◽

Impact Cratering ◽

High Level ◽

The Impact

<p>By measuring changes in radioelement concentrations, gamma-ray spectrometry is increasingly emerging as an efficient geophysical method that allows such changes to be geologically mapped according to lithology and soil type. At Ma&#226;dna crater in southern Algeria, this method has been used to monitor any changes in the composition of the target rocks that may be associated with the impact cratering process. For this purpose, several measurements were carried out in situ using a portable field gamma spectrometer. As a result, most predominantly calcareous surface lithologies, exposed on the rim and flanks of the crater, showed a very low emitted radiometric response over the three channels (K, Th, U). However, no more than 90 Cps were counted both inside and outside the crater. Such a rate is indeed expected in sedimentary rocks with low clay content, and this remains valid, as long as other exogenous mineralogical enrichments are excluded. On the other hand, the contoured radioelement concentrations maps, have demonstrated an anomalous enhanced gamma radiation levels of potassium-dominated peaks over the central part of the crater and in the surrounding wadis. Nevertheless, the central potassium anomaly is well correlated with the shallower magnetic one that has been described in previous studies (see e.g. Lamali et al., 2016). Therefore, either near the surrounding wadis or in the central part of this crater, this anomalously high level of radioactivity may be linked to an accumulation of later altered deposits. Consequently, there are no objective criteria to link these results to an impact event occurring at the Ma&#226;dna structure, similar to what was done at the Serra da Cangalha crater (Vasconcelos et al., 2012).</p>

Download Full-text

Distributions and Risk Assessment of the Natural Radionuclides in the Soil of Shoubra El Kheima, South Nile Delta, Egypt

Atmosphere ◽

10.3390/atmos13010098 ◽

2022 ◽

Vol 13 (1) ◽

pp. 98

Author(s):

Randa Osman ◽

Yehia H. Dawood ◽

Ahmed Melegy ◽

Mohamed S. El-Bady ◽

Ahmed Saleh ◽

...

Keyword(s):

Gamma Ray ◽

Nile Delta ◽

Natural Radionuclides ◽

Agricultural Practices ◽

Clay Content ◽

Gamma Ray Spectrometry ◽

Distribution Maps ◽

Activity Concentrations ◽

Chemical Attributes ◽

Physical And Chemical

Due to heightening concern about radiation hazards protection, activity concentrations of 226Ra, 232Th, 40K in forty soil samples collected from Shoubra El Kheima in the South Nile Delta were measured using gamma-ray spectrometry. The mean activity concentrations of 226Ra and 40K were higher in 20% of the considered samples than the world average values. A comprehensive comparison with up-to-date data was carried out. Spatial distribution maps of the measured radionuclides and radiological parameters were generated. The distributions of natural radionuclides were influenced by the soil organic matter, clay content, and scavenger metals oxides, as well as differences in the physical and chemical attributes and solubility of these radionuclides. The results revealed that industrial activity and agricultural practices in the study area caused an incremental increase in 226Ra and 40K activity concentrations. It can be deduced that although there are intensive industrial activities in this area, the natural radiation that comes from the soil is normal and does not pose a significant radiological hazard to the public. The natural radioactivity of soil in this area needs to be monitored periodically to prevent unnecessary radiation exposure to inhabitants.

Download Full-text

Lithofacies, diagenesis and reservoir quality of Upper Shu’aiba reservoirs in northwestern Oman

GeoArabia ◽

10.2113/geoarabia1904145 ◽

2014 ◽

Vol 19 (4) ◽

pp. 145-182

Author(s):

Naima Al Habsi ◽

Mohammed Al Shukaili ◽

Sabah Al Tooqi ◽

Stephen N. Ehrenberg ◽

Michaela Bernecker

Keyword(s):

Gamma Ray ◽

Clay Content ◽

Total Porosity ◽

Bulk Rock ◽

Vertical Wells ◽

Wide Range ◽

Saddle Dolomite ◽

Lower Porosity ◽

Local Supply ◽

Calcite Cement

ABSTRACT Core and log data from Lower Cretaceous limestones of the Upper Shu’aiba Member were used to characterize the distribution of lithofacies, clay and porosity within two low-angle clinoforms that form the reservoirs for an oilfield of northwestern Oman. Data from 15 vertical wells, including four with core, and four horizontal well cores were projected into a dip-oriented cross-section derived from a static reservoir model as a basis for visualizing the above variations. Each clinoform consists of a basal “argillaceous zone” and a thicker “reservoir zone” of clean limestone, together reflecting fourth-order cycles of progradation along the margin of the Bab intra-shelf basin. Lithofacies vary in a proximal direction from mudstone and wackestone (mid-ramp) to mud-dominated packstone (slope) to mud-rich floatstone, rudstone and boundstone (ramp crest) and are arranged in a pattern of decreasing water depth and increasing energy both upwards and landward within each clinoform. In contrast, the reservoir zone of a younger clinoform from a nearby oilfield consists of well-sorted grainstone and grain-dominated packstone, illustrating the wide range of depositional conditions that occurred in the ramp-crest facies belt of different units. Except within the proximal extent of the younger clinoform, where values are transitional toward reservoir zone values, the argillaceous zones have total porosity mostly < 10% and baseline-normalized gamma-ray (GR) activity > 23 API units, reflecting clay contents of around 10–18%. In contrast, most parts of the reservoir zones have GR of 15–23 API units and porosity of 10–35%. Higher clay content is suggested to be linked with lower porosity through facilitation of both mechanical and chemical compaction, the latter providing a local supply of calcite cement. XRD analyses show that the clays are kaolin, illite/smectite and illite, similar to the clays in the overlying Nahr Umr shale. Most former macropores have been filled by blocky calcite cement in the main oilfield studied, but all lithofacies have similar wide ranges of total porosity of 8% to > 30%. The cores were also studied for evidence of diagenesis related to the contact with the overlying Nahr Umr Formation, but profiles of stable-isotope ratios, bulk-rock strontium, petrography and porosity-permeability data show no trends indicative of upward-increasing meteoric diagenesis below this sequence boundary. Meteoric leaching could nevertheless be pervasive throughout the Upper Shu’aiba reservoirs, at least partially accounting for extensive aragonite dissolution and low Sr and δ18O values. Two of the cores show trends of upwards-increasing bulk-rock uranium, manganese and iron, possibly indicative of sea-floor authigenesis. In addition, saddle dolomite near the tops of these cores may reflect late influx of magnesium derived from clay in the Nahr Umr Formation.

Download Full-text

Generation and interpretation of geophysical images with examples from the Rae Province, northwestern Canada shield

Geophysics ◽

10.1190/1.1442927 ◽

1990 ◽

Vol 55 (8) ◽

pp. 977-997 ◽

Cited By ~ 17

Author(s):

H. John Broome

Keyword(s):

Gamma Ray ◽

Shear Zones ◽

Gamma Ray Spectrometry ◽

Data Sets ◽

Aeromagnetic Data ◽

Different Types ◽

Geologic Maps ◽

Vertical Gravity ◽

Shaded Relief ◽

Radiometric Data

Different types of images generated from gravity, magnetic, and gamma ray spectrometry data from the Rae Province of the Canadian shield were compared with each other and geologic maps to evaluate their effectiveness for displaying the geologically relevant content of the data sets. Shading methods were useful for enhancing weak directional anomalies in the aeromagnetic data. Multi‐directional, shaded‐relief images produced by overlaying three colored, shaded‐relief images are useful for analysis of anomalies associated with structure. Vertical gravity derivative images display a continuous gravity feature linking the Wager Bay and Amer Lake shear zones that is obscured on the Bouguer gravity intensity image. Detailed vertical magnetic derivative images of the shear zone clearly displayed anomalies associated with the internal structure. Composite images generated using three different geophysical parameters show correlations between the magnetic, gravity, and radiometric data which can be related to the geology. Subtle variations in uranium, thorium, and potassium concentrations determined by gamma ray spectrometry can be effectively displayed using ternary radioelement images

Download Full-text

Incomplete mass transfer processes in 28Si +93Nb reaction

International Journal of Modern Physics E ◽

10.1142/s0218301318500106 ◽

2018 ◽

Vol 27 (02) ◽

pp. 1850010 ◽

Cited By ~ 1

Author(s):

R. Tripathi ◽

S. Sodaye ◽

K. Ramachandran ◽

S. K. Sharma ◽

P. K. Pujari

Keyword(s):

Mass Transfer ◽

Gamma Ray ◽

Incomplete Fusion ◽

Gamma Ray Spectrometry ◽

Complete Fusion ◽

Small Contribution ◽

Reaction Products ◽

Transfer Processes ◽

Mass Transfer Processes ◽

Wide Range

Cross sections of reaction products were measured in [Formula: see text]Si[Formula: see text]Nb reaction using recoil catcher technique involving by off-line gamma-ray spectrometry at beam energies of 105 and 155[Formula: see text]MeV. At [Formula: see text][Formula: see text]MeV, the contribution from different incomplete mass transfer processes is investigated. Results of the present studies show the contribution from deep inelastic collision (DIC), massive transfer or incomplete fusion (ICF) and quasi-elastic transfer (QET). The contribution from massive transfer reactions was confirmed from the fractional yield of the reaction products in the forward catcher foil. The present results are different from those from the reactions with comparatively higher entrance channel mass asymmetry with lighter projectiles, for which dominant transfer processes are ICF and QET which involve mass transfer predominantly from projectile to target. The [Formula: see text] values of the products close to the target mass were observed to be in a wide range, starting from [Formula: see text] of the target ([Formula: see text]Nb) and extending slightly below the [Formula: see text] of the composite system, consistent with the contribution from DIC and QET reactions. At [Formula: see text][Formula: see text]MeV, a small contribution from QET was observed in addition to complete fusion.

Download Full-text

Gamma-Ray Spectrometric Analysis of Some Trace Elements in the Human Articular Disc of the Mandible

Nuklearmedizin ◽

10.1055/s-0037-1621214 ◽

1963 ◽

Vol 03 (02) ◽

pp. 175-182 ◽

Cited By ~ 1

Author(s):

Bo Bergman ◽

Rune Söremark

Keyword(s):

Trace Elements ◽

Neutron Activation ◽

Quantitative Data ◽

Thermal Neutron Flux ◽

Gamma Ray ◽

Dry Weight ◽

Gamma Ray Spectrometry ◽

Spectrometric Analysis ◽

Articular Disc ◽

Group Separation

SummaryBy means of neutron activation and gamma-ray spectrometry the concentrations in the human mandibular articular disc of the following elements have been determined: Na, Mn, Cu, Zn, Rb, Sr, Cd, W, and Au. The discs were obtained at necropsy from seven men and nine women, ranging in age from 56 to 71 years.The activation was carried out in a thermal neutron flux of about 1.7 XlO12 neutrons × cm−2 × sec.−1 for about 20 hours. A chemical group separationwas performed before the gamma-ray spectrometry. Quantitative data based on the dry weight of the cartilage samples were obtained by comparing the photo-peak area of the identified elements with those of appropriate standards.

Download Full-text