Formation of Secondary Uranium Minerals in the Koongarra Deposit, Australia

1993 ◽  
Vol 333 ◽  
Author(s):  
Hiroshi Isobe ◽  
Rodney C. Ewing ◽  
Takashi Murakami
Keyword(s):  
Northern Territory ◽  
Accessory Mineral ◽  
Migration Behavior ◽  
Graphite Layer ◽  
Uranium Mineral ◽  
Oxidation Condition ◽  
Uranyl Phosphates ◽  
Alteration Processes ◽  
Uranyl Silicates ◽  
Uranium Minerals

ABSTRACTSecondary uranium minerals from the Koongarra deposit, Northern Territory of Australia, were examined in order to understand the formation and alteration processes of the uranium minerals and their relevance to the migration behavior of uranium, lead, calcium and rare earth elements in the weathered zone. In most of the secondary ore zone, the only stable uranium mineral was saléeite (Mg(UO2)2(PO4)2·10H20), occurring as euhedral platy crystals up to 1 mm in length in veins and at surfaces. Apatite (Ca5(PO4)3F), an accessory mineral of the host rock, has saléeite reaction rims, suggesting formation at the expense of apatite. Ca-uranyl phosphates, such as autunite (Ca(UO2)2(PO4)2·10H2O), were not identified, and Ca-rich uranyl silicates are also absent in the primary ore zone. Pb-bearing uranyl phosphates were found only in the graphite layer cross-cutting the secondary ore zone. In the graphite layer, the local low oxidation condition and high hydrocarbonate content of ground water have affected the formation of uranium minerals and the migration behavior of uranium.

Redistribution of U, Pb and REE in association with alteration of uranium minerals from the Koongarra deposit, Northern Territory, Australia

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Kenji Horie ◽  
Hiroshi Hidaka
Keyword(s):  
Northern Territory ◽  
Migration Behavior ◽  
History Of ◽  
Alteration Processes ◽  
Uranium Minerals ◽  
Uranium Matrix

SummaryIn order to investigate migration behavior of REE in uranium matrix by alteration, and to understand a chronological history of the alteration processes,

Alteration of Natural Uranyl Oxide Hydrates in Si-Rich Groundwaters: Implications For Uranium Solubility

1991 ◽  
Vol 257 ◽  
Author(s):  
R.J. Finch ◽  
R.C. Ewing
Keyword(s):  
Corrosion Products ◽  
Dissolved Silica ◽  
Uranyl Phosphates ◽  
Uranyl Silicates ◽  
Solid Phases ◽  
And Control

ABSTRACTThe uranyl oxide hydrates are common initial corrosion products of uraninite (nominally U02+x) during weathering. In the presence of dissolved silica these early-formed phases alter to uranyl silicates (most commonly soddyite, U2SiO8-2H2O, and uranophane, CaU2Si2O11·6H2O). Uraninite, however, usually contains radiogenic Pb, and the earlyformed Pb-poor uranyl oxide hydrates alter incongruously to uranyl silicates plus Pb-enriched uranyl oxide hydrates such as curite. Similar to dissolved silica, radiogenic Pb may also serve to limit the mobility of U in nature by fixing U in solid phases. Curite may also play an important role in the formation of uranyl phosphates, which are significantly less soluble than the uranyl silicates, and control U solubility in many groundwaters associated with altered U ore.

scholarly journals Niobium and rare earth minerals from the Virulundo carbonatite, Namibe, Angola

2012 ◽  
Vol 76 (2) ◽  
pp. 393-409 ◽  
Author(s):  
L. Torró ◽  
C. Villanova ◽  
M. Castillo ◽  
M. Campeny ◽  
A. O. Gonçalves ◽  
...  
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Second Generation ◽  
Accessory Mineral ◽  
Vein Formation ◽  
Rare Earth Minerals ◽  
Late Generation ◽  
Alteration Processes ◽  
Hydrothermal Replacement ◽  
First And Second Generation

AbstractThe Virulundo carbonatite in Angola is one of the largest in the world and contains pyrochlore as an accessory mineral in all of the carbonatite units (calciocarbonatites, ferrocarbonatites, carbonatite breccias and trachytoids). The primary magmatic pyrochlore is fluorine dominant and typically contains about equal molar quantities of Ca and Na at the A site. High-temperature hydrothermal processes have resulted in the pseudomorphic replacement of the primary pyrochlore by a second generation of pyrochlore with less F and Na. Low-temperature hydrothermal replacement of the first and second generation pyrochlore, associated with quartz-carbonate-fluorite vein formation in the carbonatite, has produced a third generation of pyrochlore, with a high Sr content. The Sr appears to have been released by low-temperature hydrothermal replacement of the primary magmatic carbonates. Finally, supergene alteration processes have produced late-stage carbonates, goethite, hollandite and rare earth element (REE) minerals (mainly synchysite-(Ce), britholite-(Ce), britholite-(La), cerite-(Ce)). Cerium separated from the other REE s in oxidizing conditions and Ce4+ was incorporated into a late generation of supergene pyrochlore, which is strongly enriched in Ba and strongly depleted in Ca and Na.

scholarly journals Geophysical and geological field work on fault structures at the Igaliko peninsula, South Greenland

1983 ◽  
Vol 115 ◽  
pp. 75-79
Author(s):  
P Nyegaard ◽  
L Thorning
Keyword(s):  
Field Work ◽  
Uranium Mineral ◽  
Geophysical Field ◽  
Base Camp ◽  
Electromagnetic Methods ◽  
Uranium Exploration ◽  
Fault Structures ◽  
Uranium Minerals ◽  
Logistic Support ◽  
Geological Work

Uranium exploration carried out in South Greenland by the Syduran project in the last few years (Armour-Brown et al., 1981) has indicated that certain major E-W fauIt structures are features worthy of attention in this connection. During August 1982 geological and geophysical field work was carried out 10 km south-south-east of Igaliko (fig. 25) around a fauIt zone which had earlier given indications of the presence of uranium mineral occurrences. The object of the geological work was to map the surface within the geophysical grid and to make a gamma-radiation survey of the area. Pitchblende veins, found in connection with geochemical prospecting, were traced by trenching and were sampled. The object of the geophysical work was firstly to evaluate the usefulness of various electromagnetic methods for locating and mapping the structures in the Julianehåb granite which contain uranium minerals and secondly to evaluate the extent of the known uranium mineral occurrences. Logistic support was supplied by the Syduran project base camp at Dyrnes.

Radioelement distribution in the Tertiary Lundy granite (Bristol Channel, UK)

1995 ◽  
Vol 132 (4) ◽  
pp. 413-425 ◽  
Author(s):  
Richard S. Thorpe ◽  
Andrew G. Tindle ◽  
Olwen Williams-Thorpe
Keyword(s):  
Gamma Ray ◽  
Coarse Grained ◽  
Accessory Mineral ◽  
Rock Composition ◽  
Plagioclase Feldspar ◽  
Gamma Ray Spectrometer ◽  
Replacement Product ◽  
Original Rock ◽  
Southern Half ◽  
Alteration Processes

AbstractThe radioelement distribution and content of the Lundy granite, a coarse-grained megacrystic granite of Tertiary age, has been measured using a portable gamma-ray spectrometer in order to assess fractionation and alteration processes in the granite. Results indicate a systematic variation of K, Th and U (with a few notable exceptions) that follows a partially concentric distribution to lower concentrations inland. The plateau region of the island (particularly the southern half) is relatively depleted in all radioelements. Over the island, measurements of K vary from 1.3–4.9 wt %, Th varies from 5.0–20.3 ppm and U varies from 2.0–12.5 ppm. A petrographic, electron microprobe and autoradiography examination of the granite indicates that the radioelements mainly reside in discrete major and accessory minerals, of which K-feldspar (K), biotite (K), monazite (Th), xenotime (U), tungsteniferous columbite (U) and uraninite (U) are the most important. Uraninite is rare, being preserved only in fresh samples which come mainly from abandoned quarries. Mass balance modelling indicates that up to 76.6% of uranium could reside in uraninite and where this has been leached by secondary processes such as hydrothermal alteration or weathering then the present radioelement content no longer reflects the original rock composition. Fission track evidence is presented to show the pathways along which uranium has been mobilized from or within the granite. Secondary sites of radioelements include fractures cross-cutting all major minerals (but especially quartz), grain boundaries, altered cores of plagioclase feldspar and occasionally yellowy brown mixed chlorite/smectite replacement product after biotite. Biotite itself may exhibit secondary tracks along cleavage traces. Combined effects of crystal fractionation (primary variation) and secondary alteration best explain the distribution of radioelements, with K controlled by fractionation of the major phases K-feldspar and biotite, Th by fractionation of the accessory mineral monazite (±xenotime and uraninite) and U contents by uraninite and tungsteniferous columbite. Secondary processes have removed much of the uraninite leaving behind indeterminate Fe—U material along fractures and residual U (and Th) enrichment within altered major minerals. There is some evidence to suggest that late radioelement-bearing fluids precipitated monazite and uraniferous zircon along fractures during the waning stages of magmatic activity.

Spectroscopic properties of uranium(VI) minerals studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

2000 ◽  
Vol 88 (9-11) ◽  
Author(s):  
Gerhard Geipel ◽  
G. Bernhard ◽  
M. Rutsch ◽  
V. Brendler ◽  
Heino Nitsche
Keyword(s):  
Data Base ◽  
Fluorescence Spectra ◽  
Fluorescence Emission ◽  
Spectroscopic Properties ◽  
Coordination Shell ◽  
Time Resolved ◽  
Crystal Water ◽  
Uranyl Phosphates ◽  
Band Spacing ◽  
Uranium Minerals

We studied the fluorescence properties of 120 uranium minerals in order to provide a data base of potential secondary solids that may form in the flooding process of defunct uranium mines. This data base may provide a link of the fluorescence spectra of the minerals to solution spectra containing so far unknown tertiary and quaternary solution complexes in environmental uranium(VI)-containing waters. In our initial effort to establish the data base, we are focusing on phosphate- and arsenate-containing uranium(VI) minerals. Except for chernikovite [(HWe found hypsochromic shifts of the fluorescence emission for the uranyl phosphates and bathochromic shifts for the uranyl arsenates. The band spacing of the fluorescence emissions from the 20502 cmIn both series, the fluorescence lifetime decreases with decreasing crystal water. This is different compared to solution spectra where the lifetime increases as water is displaced from the inner coordination shell.Comparing the fluorescence data of the mineral troegerite [H

SIMS Analysis of Lead Isotopes in the Primary Ore Body of the Koongarra Deposit, Australia: Behavior of Lead in the Alteration of Uranium Minerals

1997 ◽  
Vol 506 ◽  
Author(s):  
H. Isobe ◽  
H. Hidaka ◽  
T. Ohnuki
Keyword(s):  
Isotopic Composition ◽  
Lead Isotope ◽  
Isotope Composition ◽  
Lead Isotopes ◽  
Alpha Decay ◽  
Sulfide Minerals ◽  
Migration Behavior ◽  
Ore Body ◽  
Sims Analysis ◽  
Uranium Minerals

ABSTRACTLead, the final decay product of uranium, is found in natural uranium ore deposits. The isotope composition of lead in uranium-bearing minerals reflects their age and the migration behavior of lead. Secondary Ion Mass Spectroscopy (SIMS) can be used to analyze the isotopic composition of minerals. SIMS analysis of lead contained in the Koongarra uranium deposit, Australia, revealed that uraninite and uranyl minerals with different chemical composition in the primary ore region have homogeneous lead isotope, from the highest grade area to a uranyl silicate zone at a distance of 6.1m. Uranyl minerals, which have good crystallinity and retain stoichiometric composition, have “old” lead isotope composition identical to that of uraninite. Uranyl minerals keep exchanging lead with ground water in the primary ore region through metamictization and recrystallization by alpha-decay damage. Sulfide minerals just outside the primary ore body contain only radiogenic lead with an isotopic composition different from that of uranium minerals. Lead that migrated from the primary ore body formed sulfide minerals in a specific geological event. Since then, lead produced from uranium decay has been retained in the primary ore body, in spite of recrystallization of uranyl minerals and exchange and homogenization of lead isotopes. Uranium minerals may retain minor elements despite intense alpha-decay dose.

Mechanism of Saleeite Formation at the Koongarra Secondary Ore Deposit

1995 ◽  
Vol 412 ◽  
Author(s):  
Takashi Murakami ◽  
Hiroshi Isobe ◽  
Toshihiko Ohnuki ◽  
Tsutomu Sato ◽  
Nobuyuki Yanase ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Host Rock ◽  
Thermodynamic Calculations ◽  
Accessory Mineral ◽  
Uranium Mineral ◽  
Ore Deposit ◽  
Rock Samples ◽  
Iron Minerals ◽  
Ground Waters ◽  
20 Nm

AbstractRock samples in the secondary ore deposit at Koongarra, Australia, were examined mineralogically to clarify the formation mechanism of saléeite (Mg(UO2)2(PO4)2.10H2O), a major secondary uranium mineral in the secondary ore deposit. Sklodowskite (MgSi2U2O11.7H2O) veinlets, present upstream of the ore deposit, are partially replaced by saléeite. Most grains of apatite (Ca5(P04)3F), an accessory mineral of the host rock, are also replaced by saléeite. Thermodynamic calculations by EQ3NR showed that the present Koongarra ground waters are undersaturated with respect to saléeite and also suggested that saléeite can be precipitated under the condition of higher U or P concentrations. Such conditions can be created at the reaction interfaces of dissolving sklodowskite, which releases U, or dissolving apatite, which releases P. The present study indicates that saléeite is formed by local microscale saturation upstream of the secondary ore deposit, which is different from the formation mechanism of saléeite downstream of the ore deposit, where saléeite microcrystals of 1 – 20 nm in size form by catalysis on iron minerals, the weathering products of the host rock.

Changing patterns of migration to Australia's Northern Territory: Evidence of new forms of escalator migration to frontier regions?

2013 ◽  
Vol 10 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Catherine Martel ◽  
Andrew Taylor ◽  
Dean Carson
Keyword(s):  
Young People ◽  
Life Events ◽  
Career Advancement ◽  
Work And Family ◽  
Northern Territory ◽  
Population Ageing ◽  
Men And Women ◽  
Working Lives ◽  
Changing Patterns ◽  
New Perspective

Building on Fielding’s idea of escalator regions as places where young people migrate (often temporarily) to get rapid career advancement, this paper proposes a new perspective on 'escalator migration' as it applies to frontier or remote regions in particular. Life events, their timing and iterations have changed in the thirty years since Fielding first coined the term ‘escalator region’, with delayed adulthood, multiple career working lives, population ageing and different dynamics between men and women in the work and family sphere. The object of this paper is to examine recent migration trends to Australia's Northern Territory for evidence of new or emerging 'escalator migrants'.

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