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Author Stone, A.E.C.; Thomas, D.S.G. url  openurl
  Title Casting new light on late Quaternary environmental and palaeohydrological change in the Namib Desert: A review of the application of optically stimulated luminescence in the region Type Journal Article
  Year 2013 Publication Journal of Arid Environments Abbreviated Journal  
  Volume 93 Issue Pages 40-58  
  Keywords Namib Desert, Optically stimulated luminescence dating, Palaeoenvironment, Palaeohydrology, Quaternary, Southern Africa  
  Abstract (up) The application of optically stimulated luminescence (OSL) dating in the Namib Desert is casting new light on late Quaternary environments. OSL has been applied to: (i) complex linear dunes, alongside ground penetrating radar stratigraphy in order to establish dune migration rates, (ii) fluvial lithofacies associations that distinguish between flood deposits and river end points, in order to constrain the timing of periods of higher discharge and conditions relatively drier than present and (iii) aeolian sand interbedded with carbonate deposits in order to provide chronologies for water-lain interdune sediments. We present and review the contribution of these data to enhancing reconstructions of the palaeoenvironments and palaeohydrology of the west coast of Namibia, particularly the increased confidence in interpretations provided by lithofacies analysis of the river deposits. This includes major silt deposits, which have had a contested palaeohydrological interpretation, such as the Kuiseb River Homeb Silts. We conclude that OSL should remain a key chronological technique to further elucidate the palaeoenvironmental history of southern Africa.  
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  ISSN 0140-1963 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ stone_casting_2013 Serial 98  
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Author Boulesteix, T.; Cathelineau, M.; Deloule, E.; Brouand, M.; Toubon, H.; Lach, P.; Fiet, N. url  openurl
  Title Ilmenites and their alteration products, sinkholes for uranium and radium in roll-front deposits after the example of South Tortkuduk (Kazakhstan) Type Journal Article
  Year 2019 Publication Journal of Geochemical Exploration Abbreviated Journal  
  Volume 206 Issue Pages 106343  
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  Abstract (up) The approximate determination of average Ra/U disequilibria in orebodies is one of the most common causes of errors in U reserve estimations. In roll-front deposits, the disequilibria are however frequently distributed following complex geometries, which must be fully understood to prevent major U reserve overestimates and costly unproductive extractive operations. The processes responsible for disruption of the radioactive equilibria and the U and Ra carriers in such complex natural systems remain poorly constrained. In this contribution, we propose an innovative approach, mixing orebody to sub-grain scale studies to unravel the distribution of U and Ra and the processes responsible for their concentration and uncoupling. Using mineral separations, gamma spectrometry and mineral-chemical analyses, we identified the Fe-Ti clusters (altered ilmenite + pyrite/marcasite) as the microsites for coffinite precipitation and Ra concentration. To understand the influence of such clusters on the distribution of U and Ra at the deposit scale, whole-rock Ra/U disequilibria were measured and mapped at a series of ten drill holes along a profile crosscutting the studied roll-front. The main Ra/U disequilibria are encountered around the mineralization in low U content zones. They are controlled by two main processes. (1) In the oxidized zones, the immobility of 230Th with respect to the U produces patches of Ra disequilibria (carried by the altered U minerals). (2) In the immediate vicinity of the roll-front, the dissolution of the mineralization produces an Ra flux trapped by the alteration products of ilmenites, as definitely confirmed by direct SIMS measurements. Such a process is responsible for the Ra disequilibria envelope located downstream of the richest ores, also known as Ra halo. The highest Ra/U ratios correspond to oxidized upstream samples, but most other high Ra/U ratios are from reduced downstream samples close to the mineralization. Such a low to medium U content envelope with high Ra/U ratios constitutes the main cause of U reserve overestimations.  
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  ISSN 0375-6742 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ boulesteix_ilmenites_2019 Serial 181  
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Author Wilson, G.B.; McNeill, G.W. url  openurl
  Title Noble gas recharge temperatures and the excess air component Type Journal Article
  Year 1997 Publication Applied Geochemistry Abbreviated Journal  
  Volume 12 Issue 6 Pages 747-762  
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  Abstract (up) The calculation of a groundwater recharge temperature based on the dissolved concentrations of Ne, Ar, Kr and Xe requires a correction for noble gas supersaturation due to excess air entrainment. This entrainment is commonly attributed to the recharge process or to air contamination at the wellhead during sample collection. With the exception of some local studies, most work has concentrated on interpretation of the recharge temperature or quantification of the radiogenic content for palaeoclimatic and dating purposes. The magnitude and source of the excess air is not directly relevant to these studies and so is often ignored. In this work, excess air Ne and other data have been calculated from new and published noble gas data sets for several groundwater systems. For younger groundwaters which have been recharged under one broad climatic regime, the amount of air entrainment increases according to lithology in the order granites, sandstones and limestones respectively. A negative correlation between precipitation and excess air entrainment is identified in at least one aquifer, and some of the mechanisms which may influence the entrainment process are discussed.  
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  ISSN 0883-2927 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Wilson1997747 Serial 281  
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Author Veerasamy, N.; Kasar, S.; Murugan, R.; Inoue, K.; Natarajan, T.; Ramola, R.C.; Fukushi, M.; Sahoo, S.K. url  openurl
  Title 234U/238U disequilibrium and 235U/238U ratios measured using MC-ICP-MS in natural high background radiation area soils to understand the fate of uranium Type Journal Article
  Year 2023 Publication Chemosphere Abbreviated Journal  
  Volume 323 Issue Pages 138217  
  Keywords HBRA, MC-ICP-MS, Monazites, U/U, Uranium  
  Abstract (up) The Chhatrapur-Gopalpur coastal area in Odisha, India is a well-known natural high background radiation (HBRA) area due to the abundance of monazite (a thorium bearing radioactive mineral) in beach sands and soils. Recent studies on Chhatrapur-Gopalpur HBRA groundwater have reported high concentrations of uranium and its decay products. Therefore, the soils of the Chhatrapur-Gopalpur HBRA are reasonably suspected as the sources of these high uranium concentrations in groundwater. In this report, first the uranium concentrations in soil samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) and they were found to range from 0.61 ± 0.01 to 38.59 ± 0.16 mg kg−1. Next, the 234U/238U and 235U/238U isotope ratios were measured to establish a baseline for the first time in Chhatrapur-Gopalpur HBRA soil. Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) was used for measurement of these isotope ratios. The 235U/238U ratio was observed to be the normal terrestrial value. The 234U/238U activity ratio, was calculated to understand the secular equilibrium between 234U and 238U in soil and it varied from 0.959 to 1.070. To understand the dynamics of uranium in HBRA soil, physico-chemical characteristics of soil were correlated with uranium isotope ratios and this correlation of 234U/238U activity ratio indicated the leaching of 234U from Odisha HBRA soil.  
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  ISSN 0045-6535 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ veerasamy_234u238u_2023 Serial 149  
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Author Carrión, A.; Fornes, A. url  openurl
  Title Underground medieval water distribution network in a Spanish town Type Journal Article
  Year 2016 Publication Tunnelling and Underground Space Technology Abbreviated Journal  
  Volume 51 Issue Pages 90-97  
  Keywords Water distribution, Underground cistern, Medieval tunnel  
  Abstract (up) The city of Alcudia de Crespins, in the centre of the Valencia province (east of Spain), has an exceptional water distribution system that in the past served fresh water to many houses in the town. This system is formed by more than one km of tunnels and underground cisterns, and dates probably in the late medieval times, while it has been in use and suffering modifications until 1955. This paper presents the structure and characteristics of such exceptional system, and explains the functioning parameters of the infrastructure.  
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  ISSN 0886-7798 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Carrion201690 Serial 264  
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