... calcification des champs opalifères australiens concorde avec un âge tertiaire de formation. (Traduit par la Rédaction) Abstract The composition and microstructure of opalized saurian bones (Plesiosaur) from Andamooka, South Australia, have been analyzed and compared to saurian bones that have been partially...

... opal-A samples from the Andamooka (South Australia) and Yowah (Queensland) precious opal fields, using petrographic microscopy, XRPD, SEM, and EPMA to identify and characterize opaline silica, the mineral assemblage, and the host rock. Opal-A consists of submicrometer-sized silica spheres...

...Figure 1 —Map, showing geographic position of Andamooka, South Australia, and a list of marine reptile taxa recorded from the locality. Abbreviations: Ples, Plesiosauria; Ich, Ichthyosauria ...

.... West Australia nil n.d. Table 4. OH-sharing octahedral cation-pair concentrations (normalized absorbance intensity) in five ferruginous smectites as determined from decomposition of the OH-bending region. Fraction of normalized absorbance Andamooka Redhill Nibost...

...Médard Thiry; Anthony R. Milnes; Véronique Rayot; Régine Simon-CoinÇon Abstract Detailed studies of morphological, micromorphological and geochemical characteristics of silcretes in the deep bleached and weathered regolith across a large area of inland Australia have provided a new...

...FIGURE 3. Original Bouguer gravity data from the Stuart Shelf, shaded to highlight anomalies. Magnetic anomalies 1 and 2 in Figure 2 are at the NE and SW ends of the large Bouguer gravity anomaly near Andamooka opal field. The Bouguer gravity anomaly associated with the known copper...

... . Horwitz , R. C. , 1962 , The geology of the Arrowie military sheet : South Australia Dept. Mines Geol. Survey Rept. Inv. , no. 21 , 18 p. Johns , R. K. , 1968 , Geology and mineral resources of the Andamooka-Torrens area : South Australia Dept. Mines Geol. Survey Bull. , no. 41...

... that are too small (<140 nm) also would not diffract visible light. We encountered only two opal-AG samples (from Dubník, Slovakia and Andamooka, Australia) with spheres smaller than those required for diffraction (~80 nm in diameter), but these spheres also were not stacked in an ordered array (Fig. 2e...

...., Hiern, M. N. & Nixon, L. G. 1966. Andamooka Sheet SH 53–1 , SH 53–12 . 1:250.000 Series, Geol. Surv. S.Aust., Dep. Mines, Adelaide. Johnson, W. 1965. Copper and lead ore deposits of South Australia In: McAndrew, J.(ed) Geology of Australian Ore Deposits, 1 2nd Ed 8th Commonwealth Mining...

... of an orebody, it starts at the exploration stage. This long period of cash expenditure is high-risk, as it will result in total loss if an economic discovery is not made. The average cost of each economic discovery in Australia from 1955 to 1986, as shown on Table 1 , was US$36 million ( Mackenzie...

... of the evidence Minerals Science and Engineering 1973 5 81 91 Mount, T. J. 1975. Diapirs and diapirism in the Adelaide Geosyncline, South Australia. PhD thesis, University of Adelaide Murrell, B. 1977. Stratigraphy and tectonics across the Torrens Hinge Zone between Andamooka and Maree, South...

... Precious opal, a rare gem, is an ordinary mineral in Australia, the central part of which (more than 1000 km 2 ) is opal-bearing throughout. The Australian opal deposits are superior to all other occurrences of precious opal (Czechoslovakia, USA, New Mexico). Veinlets and nests of this mineral occur here...

... 1996 Geological Society of London Tertiary Australia landform evolution silcretes weathering References Alley, N.F. 1995.Tertiary stratigraphy. palaeoenvironments and geological evolution of the Lake Eyre Basin. Palaeogeography, Palaeoclimatology, Palaeoecology. in press...

..., Gawler craton, South Australia, 2001–2003 : Geo-science Australia Record , v. 2005/20 , 197 p. Johns , R.K. , 1968 , Geology and mineral resources of the Andamooka-Torrens area : Geological Survey of South Australia , Bulletin 41 , 103 p. Johnson , J.P. , and Cross , K.C...

... ), silicified bones in Australia ( Pewkliang et al . 2008 ) or silicified wood from Slovakia ( Papp et al . 1998 ) and other localities. In such deposits, opal fills-in voids of wood cells or makes up wood cast. These silicification phenomena are diagenetic processes that occur after sediment burial...

.... Tonkin D. , eds., Excursion A1—Basement geology of the Stuart shelf region, South Australia : South Australia Department of Primary Industries and Resources, Report Book 86/51 , p. 27 . Paterson H.L. Muir P.M. Uppill R.K. Hinde J.S. Arden P.J. , 1986 , Andamooka, Stuart...

...C. C. Von Der Borch; R. Smit; A. E. Grady ABSTRACT A well-exposed series of major basin-slope submarine canyons of late Proterozoic age occur within the mixed carbonate and siliclastic Wonoka Formation of the Adelaide Supergroup (“Adelaide geosyncline”), Flinders Ranges, South Australia. They were...

...Roger G. Skirrow; Evgeniy N. Bastrakov; Karin Barovich; Geoffrey L. Fraser; Robert A. Creaser; C. Mark Fanning; Oliver L. Raymond; Garry J. Davidson Abstract The eastern Gawler craton hosts Australia’s premier uranium-bearing iron oxide copper-gold (IOCG) belt, the >500-km-long Olympic Cu-Au-(U...