Добірка наукової літератури з теми "Andamooka"

ABSTRACT The presence of a copper-containing dissimilatory nitrite reductase gene (nirK) was discovered in several isolates of β-subdivision ammonia-oxidizing bacteria using PCR and DNA sequencing. PCR primers Cunir3 and Cunir4 were designed based on published nirK sequences from denitrifying bacteria and used to amplify a 540-bp fragment of the nirK gene fromNitrosomonas marina and five additional isolates of ammonia-oxidizing bacteria. Amplification products of the expected size were cloned and sequenced. Alignment of the nucleic acid and deduced amino acid (AA) sequences shows significant similarity (62 to 75% DNA, 58 to 76% AA) between nitrite reductases present in these nitrifiers and the copper-containing nitrite reductase found in classic heterotrophic denitrifiers. While the presence of a nitrite reductase in Nitrosomonas europaea is known from early biochemical work, preliminary sequence data from its genome indicate a rather low similarity to the denitrifier nirKs. Phylogenetic analysis of the partial nitrifier nirK sequences indicates that the topology of the nirK tree corresponds to the 16S rRNA andamoA trees. While the role of nitrite reduction in the metabolism of nitrifying bacteria is still uncertain, these data show that the nirK gene is present in closely related nitrifying isolates from many oceanographic regions and suggest thatnirK sequences retrieved from the environment may include sequences from ammonia-oxidizing bacteria.

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The Gawler Craton, South Australia hosts the Olympic Dam Iron Oxide Copper Gold deposit as well as a number of other IOCG, copper, gold, and iron ore deposits. In the Stuart Shelf region (eastern Gawler Craton), primary mineralisation is generally hosted within basement granites and volcanics of the Hiltaba Suite. Basement rock, potentially containing mineralisation, on the Stuart Shelf is often overlain and concealed by Adelaidean sequences as well as highly weathered, altered and complex Mesozoic cover sequences. These sedimentary basin sediments can conceal mineralisation and are a major frontier for mineral explorers to overcome. Identification of key physical, chemical and biological interfaces, such as basal gravels, redox zones and palaeosols, within the cover sequences and understanding the processes which have led to their formation can be a useful tool in exploration. Andamooka, South Australia, lies on the Stuart Shelf near the southern margin of the Eromanga Basin. Exposed Mesozoic sediments of the Eromanga basin at Andamooka are in close proximity to the Olympic Dam IOCG deposit and are therefore important in understanding dispersion patterns within the cover sequences of elements and minerals associated with IOCG type mineral systems. This understanding can be used for further exploration in the area, where mineralisation may be concealed by Mesozoic sediments. The purpose of this paper is to describe the Mesozoic sediments around Andamooka, identifying any key interfaces and to devise a geochemical footprint of the Mesozoic sediments in this area, which can be used to aid exploration. Gold, nickel, zinc, lead and copper are found to be elevated in multiple regions within the Mesozoic stratigraphy. Several geochemical conceptual models are presented, including; a detrital source of gold and base metals in the basal region of the Algebuckina Sandstone, and a relationship between base metal accumulation and a major redox zone in the Cadna-owie Formation. Other outcomes of this study include; a proposed structural framework of the region, where extensional block faulting has impacted the landscape structure and the relative positions of Mesozoic sequences, and a revision of previous geological mapping. As well as, a possible mechanism for the formation and distribution of opals within the Bulldog Shale, as a direct result of oxidation of pyrite and organic material causing the breakup of aluminosilicates.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011

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Regolith and sedimentary material overlying potentially enriched basement, is an ever-present obstacle in the highly prospective Olympic iron-oxide copper gold (IOCG) Province, South Australia. The Eromanga Basin, composed of Mesozoic sediments - Algebuckina Sandstone, Cadna-owie Formation and Bulldog Shale - overlies the northern extent of the Stuart Shelf, including the Olympic Dam IOCG province. The closest surface exposures of these sediments to Olympic Dam, is around the opal mining town of Andamooka. The formation and distribution of the precious opal has been previously linked to fluctuating water tables. However, oxidation of pyrite by fluctuating water table height, caused by intracontinental extensional faulting in the area, provides an enhanced interpretation linking opal distribution with the presence of jasper and silcrete lag. Extensional fault boundaries were identified through contrasting regolith and landform components observed from field mapping and remote sensing imagery. ASTER band ratios and relative absorption-band depth ratios complimented field observations with ratios primarily useful in distinguishing high reflectance homogenous mineral groups e.g. opal diggings and sand dunes. A regolith-landform map and digital elevation model over the area identifies the contrasting units, with opal diggings (digitised from ASTER imagery) strongly associated with higher elevations. The potential for secondary economic mineralisation is proposed for the Andamooka area. A source material (Olympic IOCG Province), transport mechanism (extensional duplex faulting), and potential trap rock (REDOX boundaries and varying permeability of Mesozoic units) all contributed to a prospective exploration model for the area.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011