School of Earth Sciences - Theses
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ItemThe geology, petrology and geochemistry of the granitic rocks of Victoria(University of Melbourne, 1973)In the field the granitic rocks of Victoria show a wide variety of characteristics but chemically all are related and are the result of similar processes that occurred cyclically during the Palaeozoic. The granites may be divided into two groups on the basis of whether or not primary hornblende is present in the more basic members of the suite. Rocks of the hornblende-free series concentrate mainly in central Victoria and usually contain biotite that is red-brown in colour. In the granites of the hornblende-bearing group green-brown biotite is generally present. The two different colours appear to indicate unlike oxygen fugacities in the magmas from which the micas crystallized. The rocks of the hornblende-bearing and hornblende-free provinces also vary slightly in chemistry - the most important difference being that the basic members of the first group contain slightly more Ca than those of the second having comparable silica content. The compositions of the Victorian granites is consistent with their derivation by anatexis of a mixture of basic igneous rocks and sedimentary material. The conclusion is drawn that a combination of Cambrian basalts and dolerites and Cambro-Ordovician sediments constitute the source. The explanation of the fact that two chemical trends are observed in the granites may lie in the possible existence of two chemically distinct groups in the Cambrian igneous rocks - the one having lower Ca predominating under central Victoria.
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ItemInvestigations into diamond drilling and rock drillability: microscale and fullscale impregnated bits( 1980)Drill bits having cutting edges formed of a matrix of sintered metal powder impregnated with diamond bort (the so called "impregnated" diamond bits) have the potential to greatly increase the economy of diamond drilling, due to low production costs and long bit life resulting from reconditioning of the cutting edges. However, little detailed research into the performance of impregnated bits has been conducted, and the capacity to predict their field behaviour is limited. As a contribution to the knowledge of impregnated bit performance, this project has studied basic relationships between thrust, rotational speed and the penetration of diamond bits into rock, with particular attention paid to the development of techniques suitable for laboratory testing using miniature impregnated bits. A conventional bench drill and a radial arm drill were modified and instrumented to enable operating conditions to be controlled and drilling parameters to be measured and monitored, for microscale and fullscale drilling using impregnated drill bits. Bit performance and drilling characteristics were studied for four rock types, and rock drillability studies were carried out on seven rock types. Statistical relationships between penetration rate, specific energy, torque and drilling distance that were determined enable projection of drilling data from a standard "sharp" condition. A wear measuring device was developed to assess matrix wear of the impregnated microbits. Reconditioning was done by drilling medium-strength, abrasive Stawell sandstone. Initial penetration rate increases linearly with increases in thrust and/or rotational speed, but only within a limited range, depending on rock type and the other operating parameters. Matrix contact with the rock surface, "clogging" of the diamonds, time-dependency, and strength of diamonds and the diamond-matrix bond play important roles in these phenomena. Comparison of rock drillability between that of microscale and fullscale bits shows a straight-line relationship indicating the possibility to predict drilling performance in the field. Uniaxial compressive strength, tensile strength, and Sklerograf hardness can be used as a preliminary, but not reliable guide, to predict drillability. Petrographic characteristics and the relative scale of diamond size to grain size of minerals affect rock drillability.
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ItemStudies in Victorian Tertiary foraminifera neogene planktonic faunas( 1977)Planktonic foraminiferal faunas are described for the interval late Early Miocene to the Pleistocene, in the Tertiary basins along the southern margin of Victoria, including the Otway Basin, the Port Phillip Embayment, and the Gippsland Basin. Ninety-two foraminiferal taxa are identified. The faunas are dominated in the Early Miocene by globigerinid and globigerinoidid species, by unkeeled globorotalids in the Middle Miocene, and by keeled globorotalids for most of the Late Miocene. Unkeeled globorotalids are again important in the Early Pliocene, but keeled species again reappear in the Late Pliocene and the Early Pleistocene. One Pleistocene, two Pliocene, two Late Miocene, and two Middle Miocene planktonic foraminiferal zones are recognised on the first appearance of the following species: Orbulina suturalis, Globorotalia mayeri, Globorotalia acostaensis, Globorotalia conomiozea, Globorotalia puncticulata, Globorotalia viola, Globorotalia truncatulinoides. Subzones are identified by the extinction of Globorotalia peripheroronda, and by the appearance of Globigerina nepenthes and Globorotalia plesiotumida. Foraminiferal datum levels are used to correlate the Victorian sections with the Italian stratotype sections, the New Zealand late Tertiary, and the N-zonation of Blow, and hence into the palaeomagnetic and radiometric time scales. In the Tertiary basins, the maximum extent of marine deposition occurred in the Early Miocene, and despite subsequent sea level falls, continuous marine deposition is found through the Middle Miocene and most of the Late Miocene in the Otway Basin and the Port Phillip Embayment. Shallowing within the Middle Miocene is reflected by breaks in the Gippsland Basin sections, and lithological changes in other basins. A major sea withdrawal occurred near the top of the Miocene. Small scattered Pliocene deposits indicate short high sea level phases at the base of the Pliocene, in the middle of the Pliocene, and about the Pliocene - Pleistocene boundary.
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ItemMineralogy, geochemistry and origin of the Kalgoorlie gold deposits, Western Australia( 1978)Rich gold-telluride lodes (steeply dipping and flatly dipping) and minor gold-quartz stockwork mineralization characterize the Kalgoorlie gold-field. The origin of these gold deposits, the relationship between deposits and then nature of the host rocks are the major problems considered in this thesis. Extensive diamond drilling at the essentially unmineralized southern end of the field provided excellent material for stratigraphic studies and for country rock analysis whilst ore samples were obtained from both mines and drill core.
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ItemThe Permian glacial sediments of central Victoria and the Murray Basin: their sedimentology and geochemistry( 1986)This study investigates the sedimentology and geochemistry of Permian glacial sediments cropping out in the Bacchus Marsh and Derrinal areas in central Victoria and in the subsurface beneath the Cainozoic Murray Basin in Victoria, New South Wales and South Australia. Facies analysis of the Bacchus Marsh Formation, based on a critical review of literature on glacial sedimentary processes and environments, identifies the following major facies groups: 1. Subglacial tillites deposited beneath wet-based ice. Some of these tillites exhibit structures indicative of a number of subglacial processes such as frictional lodgement of large clasts, subglacial bed deformation, subglacial meltwater flow and subglacial size sorting of clasts. Other subglacial tillites are essentially structureless. 2. Bedded diamictites to sandstones deposited predominantly by ice-rafting of debris into standing water. 3. Fluvial outwash sandstone and conglomerate facies that are finer-grained than typical proglacial outwash facies. 4. Deltas and subaqueous outwash fans vary from sandy sediments deposited by proglacial and subglacial streams to coarse, poorly sorted complexes deposited as debris aprons close to the ice front. Abundant underflow deposits suggest that less than normal marine salinities prevailed in these water bodies, even if they were arms of the sea. 5. Supraglacial tillites consisting of sandy diamictites to pebble conglomerates. Facies in the thickest sequence in the Bacchus Marsh area suggests that the area was covered by a major ice mass at least 8 times. Minor glacial advances took place during predominantly ice-free periods. The Derrinal Formation consists of a basal unit of predominantly subglacial tillite deposited in shallow glacially excavated valleys overlain by a complex of subglacial and supraglacial facies deposited by about 8 minor advances of a small ice tongue. Facies relationships in this part of the sequence are confused by intense deformation of the sediment pile during the melting of buried ice and dewatering of saturated diamictons. A major ice advance then overwhelmed the area depositing thick subglacial tillite. The Urana Formation, beneath the Murray Basin, is dominated by marine ice-rafted diamictite and mudstone. Rhythmically bedded siltstone and claystone, sediment gravity-flow deposits, traction-current deposits, and, possibly, subglacial tillites are also present. Facies assemblages in some drill holes indicate areas that were never covered by grounded glacial ice. Sedimentological and palaeontological evidence suggests that the Urana Formation was deposited towards the end of the glaciation. Ice motion indicators and ice sheet limits inferred from the facies assemblages in the Urana Formation are used to estimate the thickness of the ice over central Victoria during glacial maxima. These estimates support the conclusion drawn from the facies analysis that the ice was a large ice sheet. Comparisons of ice movement directions for central Victoria and formerly adjacent parts of Gondwana suggest that a large ice sheet was centred in North Victorialand. Major and some trace elements analyses of the clay component of marine and non-marine diamictites were used to test a number of methods of distinguishing marine from nonmarine glacial diamictites. None of the methods were clearly successful because sediment detrital mineralogy dominates the geochemical composition though V/Cr ratios may be useful in some circumstances.
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ItemThe nature of the Kapai slate formation and its role in the genesis of gold mineralisation at the Victory gold mine, Kambalda, Western Australia( 1989)Oxide banded iron-formation-hosted gold deposits account for 12.8% of the gold production from greenstone belts in the Yilgarn Block of Western Australia, but rarely occur in the Kambalda-Kalgoorlie area. Western Mining Corporation initial observations indicated that gold mineralisation at the Victory Mine, Kambalda, Western Australia, although part of a much larger mineralised system, was in some way spatially related to an unusual magnetite - rich variant of the Kapai Slate Formation, but little was known on the nature of the Kapai Slate and its role in the genesis of gold mineralisation at the Victory Gold Mine. The Victory Gold Mine consists of an Archaean vein-associated system hosted in a complexly deformed, subvertical segment of the Кapai Slate Formation, intruded by quartz albite dykes. The veins cut all rock types, and wall-rock alteration is restricted to the siliceous magnetite argillite. The Kapai Slate Formation is a persistent, thin (≤ 10 m) regional marker horizon representing a major hiatus between two volcanic events; the Devon Consols Basalt Formation and the overlying Paringa Basalt Formation. These rocks form part of the mafic-ultramafic sequence of the Kalgoorlie Group which is overlain by felsic volcanic and sedimentary rocks of the Black Flag Group. Five sulphide and oxide bearing lithofacies are recognised within the Kapai Slate Formation; i) siliceous magnetite argillite, ii) siliceous pyrrhotite argillite, iii) carbonaceous pyrite argillite, iv) magnetite chert and v) sulphide chert. The argillites are typically thin-bedded (< 10 cm) and contain more than 15 wt% iron of sedimentary origin. The Victory Deposit is hosted by siliceous magnetite argillite but there is no correlation of lithofacies distribution with structural features. Oxygen isotopic composition of the Kapai Slate Formation lies between 9 o/oo to 12 o/oo indicating a strong depletion compared to Precambrian chert ( ≤ 20 o/oo) and recent marine chert (≤ 36 o/oo). These data together with other geologic data indicate that the magnetite facies is not the result of gold-related hydrothermal alteration but may be the result of both seafloor alteration and metamorphism. The Kapai Slate Formation is compositionally and mineralogically different from other Archaean Banded Iron Formations. The Kapai Slate has high Al, Ti, Na, V, Cr, Zr and Ga, low Ti/Zr ratios, and contains zircons derived from a pyroclastic air-fall tuff (Claoue-Long et al., 1988). The nature of the Kapai Slate lithofacies is interpreted to represent a primary facies variation formed in a deep water sedimentary basin during a hiatus in volcanic activity. It may initially have been composed of both air-fall and water-borne detritus derived from a felsic volcanic source as well as chemical precipitates (sulphide and oxide). This material was totally pseudomorphed and/or replaced by silica, sodium and iron minerals during prolonged exposure on the sea floor. The only elements unaffected by the replacement process were immobile elements such as Al, Ti, Zr, Cr and V. Potassium, Mg and Ca were mobile to a certain extent during the replacement process and the chalcophile elements Cu, Co, Zn, etc. were added to the argillite as chemical precipitants along with S. At the Victory Gold Mine three types of vein sets are recognised: i) ribbon veins, ii) subvertical veins and iii) flat lying quartz veins. However, only the flat lying quartz veins are related to gold mineralisation. The mineralised veins which formed during one episode of open/space filling cut all rock types. Pyritic alteration envelopes of the vein walls are restricted to the siliceous magnetite argillite. Magnetite layers are seen to be deformed by earlier deformations and cut by all vein sets. The development of the pyritic alteration envelopes began with the infiltration of hydrothermal fluid into open fractures resulting in the sulphide replacement of magnetite. Sulphide replacement of magnetite led to the mimicking of the primary layering of the siliceous magnetite argillite. Sulphidation of the vein walls ceased before filling of the veins. After the development of pyritic alteration envelopes, mineral coatings of actinolite and albite formed along the vein walls and later bulk quartz deposition filled the vein openings. The paragenetic sequence consists essentially of a concomittent deposition of pyrite, chalcopyrite, sphalerite, galena, tellurobismuthite and gold. Gold, chalcopyrite, sphalerite, galena, molybdenum and tellurobismuthite were subsequently remobilised into fractures and along grain boundaries of pyrite during a postfilling episode of deformation. The Kapai Slate Formation and the distribution of lithofacies had no influence on the localisation of gold mineralisation at the Victory Gold Mine on a regional scale. However the competent and the more iron-rich nature of the siliceous magnetite argillite probably acted as an efficient chemical and structural trap for the hydrothermally donated S and Au.
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ItemVolatile and precious metal geochemistry of the Mount Isa ores and their host rocks( 1986)Geochemical and petrographic investigations of Pb-Zn-Ag mineralization (12 orebody) and Cu-Co mineralization (1100 orebody) from Mount Isa were undertaken. Over one hundred and twenty carefully selected samples were analyzed for major and minor elements and for some or all of the following volatile metals: Au, Ag, Cd, As, Sb, Se, Bi, Co and Tl. A strong Tl enrichment is observed in (pyritic) unmineralized lateral equivalents of 12 orebody for several kilometers to the north of the mine sequence. The Se and As contents, S/Se ratios and S isotope relationships in the Pb-Zn ores and their host pyritic shales preclude a magmatic or deep-seated hydrothermal S Source. The data suggest that sulfide S in the Urquhart Shales was derived from reduction of a “seawater”/evaporitic/pore water sulfate source. Lateral variations in the thickness of mineralized intervals, the nature of the sulfide-gangue textures in the ores, the pervasive K and Tl enrichment in the host rocks and other chemical features of the Pb-Zn ores indicate that much of the Mount Isa mineralization formed epigenetically within the unconsolidated Urquhart Shales. The Pb-Zn-Ag ores contain very little Au and it is argued that this feature is best explained by the hydrothermal solutions that formed the Pb-Zn ores being cool (<<200°C) and moderately oxidized. The “silica dolomite” (the host to all the Mount Isa Cu mineralization) formed from “normal” Urquhart Shale as a result of intense fault-related hydrothermal activity (Perkins, 1984). The alteration has silicified the shales adjacent to the fault, and dolomite, phyllosilicates and “immobile” elements liberated during the silicification have been re-deposited at higher levels up-dip in the silica dolomite bodies. For the most part primary sulfide textures have not been preserved. It is argued that the distribution of several elements (notably Co, Bi, As, Fe and S) in 1100 orebody and its location down-dip from a strongly pyritic section of Urquhart shale are good evidence that stratiform Co (and Cu) mineralization was present in pyritic Urquhart Shales prior to formation of the silica dolomite. Chemical and isotopic evidence suggest that the Cu mineralization had a similar S-source and formed from similar solutions to the Pb-Zn-Ag ores. A new co-genetic model for the Mount Isa Cu and Pb-Zn-Ag deposits in which the mineralization formed from cool oxidized solutions in the upper few meters of the unconsolidated Urquhart Shales is presented. The metal-bearing solutions were expelled from their source rocks (oxidized clastic sediments lower in the Moust Isa Group) during the course of normal basin compaction and dewatering. Base metal sulfides were fixed by sulfate reduction processes occurring in the diagenetic environment of the Urquhart Shales. Weathered mafic volcanic detritus may have been and important component of the source.
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ItemLate Paleozoic glaciations of Eastern Australia( 1959)In a re-analysis of the Late Paleozoic glaciations of Eastern Australia, close review of elements of paleogeography results in many new interpretations. New data appear from field studies of the details (including till fabric analyses in the Heathcote District of Victoria) of glacial stratigraphy in drift sequences of Victoria and South Australia. Analysis of sedimentary volumes in Tasmania and analysis of sedimentation during the Upper Carboniferous and Permian of New South Wales and Queensland adds more new information. Field reviews of sequences in the Finke District of the Northern Territory, Tasmania, New South Wales, and Queensland aid in understanding the effects of glaciations in those regions. All data known to the writer from extensive field examinations and review of published data may be incorporated into a unified history of the glacial times. Many lacunae exist, but analogy with studies of Pleistocene glacial drifts helps to bridge some gaps. Principally during the Middle and Upper parts of the Upper Carboniferous and in the Early Permian, highland centers in the northwest of Tasmania (the Macquarie Mountains) and in northeast New South Wales (the Clarencetown Mountains, a volcanic range) became loci for glacial formation and spread. From the former, glaciers spread east, north, and northwest. Upon advancing northwest, the Mt. Lofty-Kangaroo Island Ranges were encountered. These were breached with the establishment of glacial corridors, and a glacial lobe subsequently pushed about 600 miles further north-north-west. In that region, this glacial [?] [?] [?] joined a sheet from Western Australia. Also, in pushing north from the Macquarie Mountains, the glaciers apparently advanced 900+ miles to the Springsure District of Queensland. From the Clarencetown Mountains, piedmont glaciers radiated east (to the sea near Mt. George, Booral, and Limeburner’s Creek), south, and west to fill subsiding basins with glacial deposits and some volcanic effusions. Additionally, some glaciers spread east from the epi-Kanimblan mountains of New South Wales. Thick drift sequences left by these spreading glaciers have been preserved in favourable sites. Fluvial and lacustrine deposits in the drifts demonstrate the presence of interstadial and interglacial conditions, but the entire interval may be considered a single glacial epoch much resembling the Pleistocene, although that of the Late Paleozoic probably was much longer. After wastage of the glaciers, cold weather (at least during winters) persisted, for many phenomena found in the Permian sediments seem best related to climates which were cold at least part of the year. Notable among these are the erratics so widely distributed through the marine Permian sediments of eastern Australia. Such erratics seem best explained as phenomena resulting from the transport by winter ice floes of material eroded from glacial drift left on the land by earlier glaciations.
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ItemThe geology of the Pyramid and Tonghi Creek areas, East Gippsland( 1984)A study of the geology of the Club Terrace region is being undertaken with two major aims: 1) to provide a clearer picture of the structural geology and geological history of the region and, using this, 2) to investigate Ag, Cu, Pb, and Zn mineralization present in the region with emphasis on producing a model for ore genesis.
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ItemGeology of the Dookie District (Part I) & Trace element distributions within some major stratiform orebodies (Part II)( 1973)Part I: The Cambrian rocks outcropping in the Dookie district consist of a series of altered igneous rocks (diabases), a variety of pyroclastic rocks and cherts. The igneous rocks are thought to have been originally tholeiitic, having undergone low grade burial metamorphism, hydrothermal alteration and possibly contact metamorphism. Field evidence indicates that at least one of the igneous bodies is intrusive, probably a sill. The relation between these rocks and Cambrian rocks elsewhere in Victoria is discussed. The lithology and structure of an area of folded Ordovician and Silurian — L. Devonian sediments outcropping to the south of the main Cambrian massif is reviewed. Part II: Trace elements Tl, Ag and Au abundances in whole rock samples from a number of important stratiform basemetal orebodies have been determined by neutron activation analysis. Suites of samples were taken from the HYC Zn-Pb-Ag deposit at McArthur River, N.T., the Cu-Pb-Zn deposit of Rosebery, Tasmania and a Karoko type orebody from Shakanai, Japan. While the distribution of Au and Ag in the three deposits were found to closely follow those of Cu and Pb respectively, a higher Ag/Au ratio is apparent in the HYC deposit. In the other deposits, probably formed at temperatures greater than 200°, high concentrations of Au are explainable in terms of high temperature transport via chloride or thiocomplexing, while in the HYC deposit, formed below 150°, hydrothermal transport of comparable amounts of Au is considered unlikely. In response to lower temperature, strongly reducing conditions and restricted circulation, Tl concentrations in the HYC deposit are markedly greater than those in the remaining deposits. At McArthur River, significant enrichments in Tl occur up to, 250 metres stratigraphically above the main ore shales, and the geochemical significance and practical value of such metal haloes about stratiform orebodies are discussed.