VIMP Report 37

Geology and prospectivity of the 1:250 000 map sheet area

S. Maher, M.A. Hendrickx, R.J. Boyle and D.J. Brookes

October 1996 Bibliographic reference: MAHER, S., HENDRICKX, M.A., BOYLE, R.J., BROOKES, D.J., 1996. The geology and prospectivity of the Bairnsdale 1:250,000 map sheet area. Victorian Initiative for Minerals and Petroleum Report 37. Department of Natural Resources and Environment.

© Crown (State of ) Copyright 1996 Geological Survey of Victoria

ISSN 1323 4536 ISBN 0 7306 9407 0

This report may be purchased from: Business Centre, Department of Natural Resources and Environment, Ground Floor, 115 Victoria Parade, Fitzroy, Victoria 3065

For further technical information contact: Manager, Geological Survey of Victoria, Department of Natural Resources and Environment, P O Box 2145, MDC Fitzroy, Victoria 3065

Authorship and acknowledgments: Authorship responsibilities for this report are as follows: Chapter 1 S. Maher Chapter 2 M. Hendrickx Chapter 3 S. Maher, R. Boyle ( 1:100 000 map area) Chapter 4 D. Brookes, S. Maher Chapter 5 M. Hendrickx Chapter 6 M. Hendrickx, S. Maher

Information in the Bairnsdale Mine Database was compiled by S. Maher and R. Boyle (Omeo 1:100 000 map area). Ideas in Chapters 3 and 6 were developed following discussion with K. Slater, R. Twyford, S. Haydon, D. Moore and F. VandenBerg. Figures 1, 2, 3 and 4 were produced by R. Jolly and J. Dunleavy. Figures 5, 6 and 7 were produced by D. Brookes. Editing was by R. Buckley and P. O'Shea. Formatting was by G. Ellis. GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 1

Contents Abstract 3 1 Introduction 4 2 Geology 6 2.1 Geological history 7 Lachlan Fold Belt 7 Mid-Cretaceous to the present day 10 2.2 Stratigraphy-sedimentary and volcanic rocks 10 Ordovician 10 Silurian 12 Lower Devonian 13 Upper Devonian-Carboniferous 14 Permian 14 Triassic 14 Cretaceous 15 Tertiary 15 Quaternary 15 2.3 Intrusive Rocks 15 Bega Basement Province 15 Wagga Basement Province 16 Kosciusko Basement Province 18 Howqua Basement Province 20 3 Economic geology 22 3.1 History of 22 3.2 Mineral Production 25 3.3 Precious metal vein deposits 27 Harrietville-Dargo province 30 Benambra gold province 34 3.4 Lower Devonian volcanic hosted metal deposits 36 3.5 Placer gold deposits 40 3.6 Silurian volcanic associated massive sulphide (VAMS) deposits 42 3.7 Porphyry copper deposits 43 3.8 Base metal vein deposits 46 3.9 Red bed copper deposits 47 3.10 Carbonate hosted metal deposits 47 3.11 Nowa Nowa ironstones 49 3.12 Granite hosted tin deposits 50 3.13 Wolframite vein deposits 51 3.14 Brown coal deposits 51 3.15 Non metallics 51 Limestone 51 Dimension Stone 52 Pyrophyllite 52 Barite 52 Talc 53 Semi-precious gemstones 53 Dolomite 53 Feldspar 53 Wollastonite 54 4 Overview of mineral exploration 55 4.1 Gold 55 4.2 Base metals and silver 55 4.3 Other minerals and coal 56 4.4 Soil and stream sediment geochemistry 57 5 Geophysics 58 2 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

6 Mineral resource potential and prospectivity 59 6.1 Precious metal vein deposits 59 6.2 Lower Devonian epithermal precious metal deposits 60 6.3 Placer gold deposits 61 6.4 Silurian volcanic associated massive sulphide (VAMS) deposits 62 6.5 Porphyry copper-gold deposits 62 6.6 Base metal vein deposits 64 6.7 Red bed copper - uranium 64 6.8 Carbonate hosted base metal deposits 64 6.9 Tennant Creek style copper-gold deposits 64 6.10 Granite hosted tin deposits 64 6.11 Skarns 65 6.12 Heavy mineral 65 6.13 Industrial minerals 65 6.14 Diamonds 65 6.15 Buried intrusions 65 References 67 Appendix 1 75 Bairnsdale 1:250 000 map area: Summary of Exploration Licences Appendix 2 82 Bairnsdale 1:250 000 map area: Location of expired Exploration Licences Victorian Initiative for Minerals and Petroleum (VIMP) report series 98

List of figures 1 Recent airborne geophysical surveys and geological mapping, Bairnsdale 1:250 000 map area 5 2 1:500 000 simplified geology, Bairnsdale 1:250 000 map area. (Back pocket) 3 Geology, mineral resources and tenements, Bairnsdale 1:250 000 map area. (Back pocket) 4 Mineral resources within the Bairnsdale 1:250 000 map area 23 5 Primary, alluvial and total goldfield production 28 6 Annual primary and alluvial goldfield production 29 7 Source of gold production 30 8 Gold vein orientations, Bairnsdale 1:250 000 map area 32 9 Cassilis mine, c.1910. Photo, Minerals & Petroleum Victoria collection 35 10 Exploration drilling at Benambra by WMC, c.1975. Photo, Minerals & Petroleum Victoria collection 42 11 TMI image showing mineral resources of the Bairnsdale 1:250 000 map area. (Back pocket)

List of tables 1 Summary of the geological history, stratigraphic units and mineralising events within BAIRNSDALE 8 2 Production from mines within BAIRNSDALE 26 3 Production from the Wilga deposit 26 4 Gold production from goldfields within BAIRNSDALE 27 5 Sources used in calculating gold production within BAIRNSDALE 30 6 Major primary gold producers within goldfields of the Dargo-Harrietville gold province 31 7 Major primary gold producers within goldfields of the Benambra gold province 35 8 Major alluvial gold producers within goldfields of BAIRNSDALE 40 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 3

Abstract

This report summarises the geology and prospectivity of the Bairnsdale 1:250 000 map area (BAIRNSDALE) in eastern Victoria.

New airborne geophysics and detailed geological mapping conducted over BAIRNSDALE as part of the Victorian Initiative for Minerals and Petroleum (VIMP) has enabled a reappraisal of the regional geology and prospectivity of the area. This has been complemented by mineral resource, mineral exploration and exploration geochemistry compilations.

Broad areas with potential to host a variety of styles of mineralisation have been outlined as a result of this reappraisal. These include:

· porphyry copper–gold deposits associated with high level magnetic intrusions; · epithermal precious metal deposits associated with the Volcanics and Mount Elizabeth Caldera Complex; · precious metal vein deposits within and outside goldfields; · additional Wilga style volcanic associated massive sulphide deposits within the Limestone Creek Graben; · Tennant Creek style copper–gold deposits in Nowa Nowa ironstones; · Irish style base metal deposits in the Buchan Rift; · base metal veins associated with caldera fractures; · red bed copper–uranium; · granite hosted tin deposits; · placer gold; and · a variety of industrial minerals. 4 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

1 Introduction parks and roads. This data set is available from the Geological Survey of Victoria. This report summarises the geology, mineral resources and mineral exploration history of the Bairnsdale 1:250 000 map area (BAIRNSDALE) in East Victoria (Fig. 1). This information is designed to aid mineral exploration and mineral resource development. It complements new geological maps and airborne magnetic and radiometric data covering large parts of BAIRNSDALE that have been collected as part of the Victorian Initiative for Minerals and Petroleum (VIMP). New geological maps cover the 1:100 000 map area (VandenBerg et al., 1996), the Mount Elizabeth Caldera Complex (Simpson et al., 1995), the Limestone Creek area (Allen, 1991) and the Murrindal 1:100 000 map area (Orth et al., 1995). Geological interpretation of the new VIMP airborne geophysical data is presented in Sands (1995) covering the Orbost area, Slater (1996) covering the Dargo area, Haydon (1996) covering the Omeo area, and Twyford (1996) covering the Murrindal area. Mineral exploration in BAIRNSDALE, including details on anomalies in geochemical surveys and significant drill intersections, is summarised in Brookes and Boyle (1996).

Detailed location, production and geological information for mines and prospects within BAIRNSDALE accompany this report in the BAIRNSDALE Mine Database. The database, explanatory notes and references are supplied on a 3.5 inch DOS disk in the following formats:

BAIRNSDALE Mine Database Bairmine.mdb Microsoft Access 2.0 format Bairmine.ldb Microsoft Access 2.0 format *.txt Tab delimited ASCII text files derived from the Access Database

Explanatory Notes Readme.doc Microsoft Word 6.0 format Readme.txt ASCII text file format

References Referenc.doc Microsoft Word 6.0 format Referenc.txt ASCII text file format

The mine database is only one theme in the GIS data set covering BAIRNSDALE. Other themes include geology, geochemistry (also available in ASCII text and relational database formats), magnetic and radiometric images, current and expired Exploration Licences (ELs), national

6 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

2 Geology Ordovician and Silurian turbidite sequence that has been deformed during the Quidongan and Tabberabberan deformations. The BAIRNSDALE encompasses a diverse group of Wonnangatta Fault is an important structure rocks deposited in a variety of environments running northwest through the zone. It divides between the Lower Ordovician and Quaternary. the zone into two domains with differing The eastern part of the map sheet, covered by structural styles (Gray et al., 1988). The the MURRINDAL (Orth et al., 1995) and domain southwest of the Wonnangatta Fault ORBOST (VandenBerg et al., 1996) 1:100 000 includes Pinnak Sandstone and Silurian map sheets and MOUNT ELIZABETH Cobbannah Group (Fergusson, 1996). One (Simpson et al., 1996) and LIMESTONE main phase of folding is present. The CREEK (Allen, 1991) 1:50 000 sheets has been enveloping surface is subhorizontal and mapped in detail and it is mainly from these vergence is to the south. The style of reports that this summary of the geology has deformation indicates thin skinned fold thrust been derived. deformation associated with tectonic transport to the south (Gray et al., 1988). This is BAIRNSDALE straddles parts of the probably towards the Governor Fault which Mallacoota, Omeo, Tabberabbera and Buchan occurs at the southwest margin of the structural zones (Figs 2 & 3) which are four of Cobbannah Group under the Avon seven major Palaeozoic structural zones within Synclinorium as indicated by magnetic data the southeastern part of the Lachlan Fold Belt. (Slater, 1996). Each zone is distinguished by different stratigraphic and tectonic histories (Gray et al., The domain northeast of the Wonnangatta 1988). Fault consists of Hotham Group and is characterized by a more complex deformation The Mallacoota Zone extends east from the history with widespread multiple deformation Yalmy-McLaughlan Fault Zone to the New indicative of thick skinned tectonics (Fergusson, South Wales coast. The western margin 1987). The zone also includes the Mitchell coincides with the I-S line of Chappell and Syncline which contains Lower Devonian White (1974). The folded basement sediments shallow marine clastics and minor limestone, are mainly Ordovician with some areas of fault deformed during the Tabberabberan bounded Silurian quartz rich turbidites. Deformation and intruded by the Tabberabbera dyke swarm post deformation. The Omeo Zone occurs between the Kiewa Fault and the Indi Fault. It is comprised The Buchan Zone includes Silurian to Devonian principally of the Omeo Metamorphic Complex, volcanics and sediments between the Indi and which forms the southern extension of the Yalmy fault zones. It comprises the Limestone Wagga Metamorphic Belt (Morand, 1990). The Creek Graben, Yalmy Fold and Thrust Belt and belt includes high grade metamorphic rocks and Buchan Rift which were variously active foliated and non foliated granites. The age of between the Late Silurian and Middle metamorphism in the belt is Middle Silurian, Devonian. corresponding to the Quidongan Deformation. To the north the zone is structurally more The Sedimentary and Volcanic complex and may include metamorphosed Province appears along the western border of Cambrian sedimentary and volcanic rocks the map and encompasses Upper Devonian to (Fleming, pers comm in Oppy et al., 1996). The Lower Carboniferous red beds and subaerial Kiewa Fault accommodated about 50 km of volcanics which were deformed during the dextral displacement during the Late Silurian Kanimblan Deformation. to Early Devonian (Morand & Gray, 1991). The Indi Fault is a major reverse fault which was The coastal sections of BAIRNSDALE are active during the Bindian Deformation (Morand covered by marine and fluviatile Tertiary & Gray, 1991). It links with the Gilmore Fault, sediments which were deposited in rift-like a major sinistral fault in . basins associated with the break up of Gondwana. The Tabberabbera Zone occurs along the western margin of BAIRNSDALE, between the Governor Fault (Mount Wellington Fault Zone) and the Kiewa Fault. It consists of a thick GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 7

2.1 Geological history Ordovician deep marine sedimentation (500- 438 Ma): Hotham Group, Pinnak Sandstone, Broadbent River Sandstone, Bendoc Group. The geological history of BAIRNSDALE, and of Eastern Victoria in general, can be divided into three major episodes: The oldest rocks in BAIRNSDALE were deposited in the Early Ordovician (500 Ma) as an extensive submarine fan system. East of the · Cambrian to Early Carboniferous: Wonnangatta Fault these rocks are part of the development of the Lachlan Fold belt Hotham Group, Pinnak Sandstone and involving cycles of marine and non-marine Broadbent River Sandstone and consist of deposition alternating with folding, sandstones and mudstones which were faulting, intrusion of granites, volcanism deposited by turbidity currents into the deep and metamorphism; marine environment along the eastern edge of

the Australian craton. In the Late Ordovician, · Early Carboniferous to mid-Mesozoic: a turbidite sedimentation was largely replaced by period of apparent tectonic stability quiet accumulation of silt and mud on a deep characterized by extensive erosion which anoxic seafloor (Bendoc Group). The lower part produced a landscape of low to gentle relief of the Bendoc Group (Sunlight Creek over most of southeastern ; Formation) has thin quartz sandstone beds

which appear to be distal turbidites. The · Mid-Mesozoic to the present day: Australia Blueys Creek Formation is similar in its separating from Antarctica and New depositional setting but contains turbidites that Zealand during the break-up of Gondwana. were derived from mafic igneous rocks. The main break-up began in the mid - Warbisco Shale, which occurs throughout Cretaceous when the Tasman Sea began to eastern Victoria and southeastern New South open. Australia's northward migration was Wales is dominated by black, very siliceous also initiated, and continues to the present siltstone, with silica probably derived from day. The southern part of BAIRNSDALE radiolarians. It contains abundant graptolites lay along the coastline of the new and records a long time span, 20-25 million Basin while uplift inland produced a new years, of very quiet pelagic and hemipelagic continental divide. Marine sedimentation sedimentation. The change from Warbisco occurred along the new coast and the Shale to green mudstone (Akuna Mudstone) hinterland has been subject to continuous with a higher clay and detrital content erosion and deep incision, with a brief marked a return to more aerated conditions and period of basaltic volcanism in the Eocene - continent-derived clastics. Oligocene. Early Silurian Benambran Deformation A summary of the geological history and (ca 440 Ma) stratigraphy is presented in Table 1. The two Silurian deformations, Benambran and Lachlan Fold Belt Quidongan, are the main episodes of cratonisation in eastern Victoria. The oldest rocks of southeastern Australia are Cambrian volcanics, volcaniclastics and The Benambran Deformation, at about the end turbidites. These rocks are mainly exposed in of the Ordovician (440 Ma), is most strongly isolated fault bounded belts across much of expressed near Delegate in MALLACOOTA Victoria, west of the Tabberabbera Zone, and where it is marked by an unconformity between are assumed to occur extensively at depth. The Silurian sediments and strongly deformed volcanics do not re-emerge in Victoria east of Pinnak Sandstone. However on BAIRNSDALE the Mount Wellington greenstone belt. There this deformation appears to have had little are no Cambrian rocks exposed in effect, possibly producing a bedding-parallel BAIRNSDALE and their extent at depth is fabric in the Lower Ordovician Pinnak unknown. Sandstone. Table 1 Summary of the geological history, stratigraphic units and mineralising events within BAIRNSDALE

Age Stratigraphy Tectonic Events Mineralisation Sedimentary Volcanic Plutonic Quaternary Recent stream deposits Placer Au Tertiary Sub–volcanic gravels Older Basalt Placer Au Seaspray Group Brown coal Break up of Gondwana Cretaceous Strzelecki Group (not outcropping) Triassic Mount Leinster Complex (The Mount Leinster Complex Sisters Granite) Permian Un-named sediments (not outcropping) Kanimblan Deformation Precious metal veins Lower Carboniferous Mount Tambo Group? Avon River Group Avon River Group Red bed Cu-U (Wellington Rhyolite) Tabberabbera Dyke Swarm Granite Intrusion Upper Devonian Granite related Sn, W, Au Tabberabbera Deformation Remobilisation Buchan Group Wentworth Group Carbonate hosted base metal Mount Elizabeth Caldera Buchan Rift Nowa Nowa Ironstone Lower Devonian Complex Epithermal precious metals Snowy River Volcanics Porphyry copper? Granite intrusion Granite related Au Bindian Deformation Precious metal veins Upper Silurian Enano Group Enano Group Limestone Creek Graben Benambra VAMS (Mount Tambo Group?) Quidongan Deformation Precious metal veins Granite Intrusion Omeo Metamorphic Porphyry copper Complex Lower Silurian Seldom Towanga Yalmy Cobbannah Seen Sandstone Group Group Formation Benambran Deformation Upper Ordovician Bendoc Group Lower Ordovician Pinnak Sandstone Broadbent River Sandstone Hotham Group GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 9

Early Silurian (440-430 Ma): Seldom Seen faults and these appear to be related to Formation, Towanga Sandstone, Yalmy southeast movement of the Omeo Zone (Morand Group, Cobbannah Group & Gray, 1991).

The pattern of deep marine sedimentation Early Devonian rifting and volcanism (410-395 established in the Ordovician continued into the Ma): Buchan Rift, Mount Elizabeth Caldera Early Silurian with deposition of the Seldom Complex, Wentworth Group Seen Formation, Towanga Sandstone and Yalmy Group. The Seldom Seen Formation and Crustal extension in the Early Devonian Towanga Sandstone were probably parts of the produced the Buchan Rift, a trough-like same submarine fan system, with a source area meridional structure extending from the New consisting of Bendoc Group rocks. Although South Wales border to the coastal plain at still relatively deep marine, the depositional Nowa Nowa, into which a mixture of volcanics environment of the Yalmy Group was probably and minor non-volcanic sediments were shallower than during the Ordovician: there are deposited (Snowy River Volcanics). The portion no black shales or mudstones, and the of the rift lying within MURRINDAL has been sandstones are generally much better sorted. described in detail by Orth et al., (1995) and on The Yalmy Group also shows, for the first time, ORBOST by VandenBerg et al., (1996). While prominent lateral facies changes. The the Snowy River Volcanics were being deposited Cobbannah Group consists of a number of as the Mount Elizabeth Caldera Complex was yet un-named sandstone and siltstone packages being formed. West of the Buchan Rift a north- deposited in a deep submarine environment. south trending basin formed and was filled by Palaeocurrents in the group suggests derivation the Wentworth Group, a thick, rapidly from the west (Fergusson, 1996). deposited sequence of shallow marine clastics and minor limestone. Middle Silurian (430-425 Ma): Quidongan Deformation Early To Middle Devonian carbonate deposition (395-385 Ma): Buchan Group The Quidongan Deformation was the major regional deformation event in . At about the beginning of the Emsian, the sea It was responsible for tight folding of the level rose throughout the world (Talent, 1989) Ordovician and Lower Silurian rocks, and a large part of BAIRNSDALE was generation of the Omeo Metamorphic Complex inundated from the south. Rapid transgression and was accompanied by intrusion of I and S changed the region from a terrigenous/ type granites. volcaniclastic environment to one of widespread limestone deposition. After a basal, very Middle to Late Silurian (425-410 Ma): shallow marine dolomitic phase, the region Limestone Creek Graben, Wombat Creek became a shallow marine shelf, on which Graben limestone sands and muds, derived largely from the shells of organisms, were deposited (Buchan In the Middle Silurian rifting caused the Caves Limestone). A further deepening formation of the Limestone Creek Graben. This occurred somewhat later and allowed animals fairly deep marine graben was infilled by the of more open marine habitat (nautiloids, Enano Group. These include acid volcanics polygnathid conodontophores, styliolinids) to (intrusive and extrusive) as well as submarine enter the region. This also caused a change to volcaniclastic breccias and finer grained deposition of marls (calcareous silts). sediments. The base metal deposits at Wilga and Currawong were formed during this time. Middle Devonian (385-380 Ma):Tabberabberan Deformation Late Silurian Bindian Deformation (410 Ma) In the Middle Devonian, the Tabberabberan The Bindian Deformation occurred at the end of Deformation folded and faulted the Buchan Rift the Silurian. Rocks in the Limestone Creek including the Buchan Group, Mount Elizabeth Graben were folded and faulted for the first Caldera Complex and the Wentworth Group time. Earlier fabrics in the Omeo Metamorphic and produced overprinting fabrics in the older Complex were overprinted by new fabrics. The rocks. Further movement occurred on major most significant structures formed during the fault zones in the area including the Kiewa, Bindian include the Kiewa, Ensay and Indi Indi and Ensay Faults. Granites along the 10 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

southern margin of BAIRNSDALE were . This began in the mid - intruded subsequent to deformation. The Cretaceous about 95 million years ago, when Tabberabbera dyke swarm intrudes folded the Tasman Sea began to open, and major Wentworth Group sediments indicating they subsidence occurred in the Gippsland and also post date the Tabberabberan Deformation. Otway basins. This coastal and offshore subsidence was combined with major uplift of a Late Devonian to Early Carboniferous (380-355 broad belt to the north of the coastal plain, and Ma) Mount Howitt Sedimentary Province, Avon it is this juxtaposition of uplifted highlands River Group, Mount Tambo Group close to the subsided lowlands that has influenced the Tertiary history of the region. Upper Devonian to Lower Carboniferous volcanics and sediments unconformably overlie Palaeocene to Recent stream incision and deformed Ordovician and Lower Devonian basaltic volcanism (65 Ma-present day) rocks. Over most of the province, the sequence consists of a single upward fining cycle The Late Cretaceous uplift began a cycle of (collectively known as the Avon River Group) of incision and lateral erosion that continues at conglomerates, sandstones, and red mudstones the present day. The Great Escarpment, with a major interval of bimodal subaerial originally situated at about the latitude of volcanism low in the sequence. Nowa Nowa and Orbost, was virtually destroyed by incision and headward erosion. The Mount Tambo Group may also have been The material removed from the highlands was deposited at this time. deposited mainly offshore, to form the thick Gippsland basin sequence. Onshore, eruption Early Carboniferous Kanimblan Deformation of basalts during the Eocene-Oligocene caused (ca 355 Ma) minor interruption in the erosion process but within the area, their influence was negligible. This was the last deformation to have affected the rocks of the region. The Avon River Group 2.2 Stratigraphy-sedimentary was deformed into open, large wavelength folds. More intense deformation occurs along the and volcanic rocks margins of the Avon River Group. Ordovician Early Carboniferous to Mid-Cretaceous (ca 355-100 Ma) Ordovician rocks on BAIRNSDALE form the basement to the map sheet. In eastern Victoria The uplifts associated with the Tabberabberan the Ordovician consists of two main units: a and Kanimblan deformations began a long lower unit dominated by turbidite sandstones process of erosion that continued to the Late and an upper unit of siltstone and black shale. Mesozoic, and which, by the mid-Cretaceous, In the eastern part of the map sheet these have had produced a land surface of low relief and been subdivided into Broadbent River probably low elevation over most of Sandstone and Pinnak Sandstone and the southeastern Australia. This period of relative Upper Ordovician Bendoc Group. Little is inactivity was broken in the Triassic with the known about the distribution of these formation of the Mount Leinster Complex. formations outside of the MURRINDAL and Rocks in this suite include trachyte lavas and ORBOST 1:100 000 map areas. Where no associated volcaniclastics which were later differentiation has been made the entire intruded by syenite and high level granite Ordovician is grouped into the Hotham Group. porphyry. Hotham Group (Beavis, 1962; VandenBerg and Mid-Cretaceous to the present day O'Shea, 1981)

Late Cretaceous break-up of Gondwana and The Hotham Group (Beavis, 1962; VandenBerg regional uplift (ca 95-65 Ma) and O'Shea, 1981) forms the bedrock to much of the eastern Lachlan Fold Belt, extending, in The history during the last 100 million years Victoria, from the Mount Wellington Fault Zone was controlled by the break-up of the to the east coast. It is an informal name given Gondwanan supercontinent, especially the to the undifferentiated Ordovician sediments separation of Australia from Antarctica and that cover much of BAIRNSDALE. The GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 11

Hotham Group comprises an undetermined thickness of well bedded deep marine Blueys Creek Formation (Allen, 1987) greywacke, quartzwacke, siltstone, slate and mudstone with minor chert. The Blueys Creek Formation (Allen, 1987) occurs as fault bound belts in the northeast Pinnak Sandstone (VandenBerg et al., 1991) corner of BAIRNSDALE. It is characterised by thin bedded chert, black cherty slate and mafic The Pinnak Sandstone (VandenBerg et al., volcaniclastic turbidites, intercalated in a 1991) has been mapped in the eastern part of succession of fine to medium grained quartz BAIRNSDALE. It consists of interbedded sandstone, siltstone and grey to black turbiditic sandstone, green grey slaty mudstone. The overall lithology is very similar mudstones and occasional thin bands of chert. to the Sunlight Creek Formation, the main The sandstones are thick bedded litharenites, difference being the presence of mafic and lithic and feldspathic greywackes with less volcaniclastic turbidites. Conodonts indicate a abundant thin bedded quartzarenites and Gisbornian age (I.R. Stewart in Allen, 1987). quartzwackes. The finer grained interbeds consist of individual beds or packages of thin to Sunlight Creek Formation (VandenBerg et al., thick green slaty mudstone. Thin beds of chert, 1991; Orth et al., 1995) though relatively uncommon, are a characteristic feature of Pinnak Sandstone and This formation comprises rhythmically appear to be confined to the lower portion of the alternating dark green to almost black siliceous formation. The upper portion tends to contain a siltstone and white thin bedded, fine grained higher proportion of finer grained beds. quartzitic sandstones which give the rock a "stripy" appearance. It commonly appears as Conodonts and rare graptolites indicate that narrow slivers marking the presence of major the formation spans almost the entire Lower faults. The formation is a lateral equivalent of Ordovician from the Bendigonian to the the Blueys Creek Formation and spans a short Darriwilian (VandenBerg & Stewart 1992). interval across the Darriwilian-Gisbornian (Da4-Gi1) and hence Early to Late Ordovician Broadbent River Sandstone (Orth et al., 1995) boundary (Orth et al., 1995).

This formation has thus far only been Warbisco Shale (VandenBerg et al., 1991) recognised in a small belt along the Snowy River north of Mackillops Bridge (Orth et al., The Warbisco Shale crops out extensively 1995). The formation consists of medium to throughout the eastern Lachlan Fold Belt thick bedded sandstone interbedded with generally as narrow slices along major faults. intervals of rhythmically alternating thin pale It has thus far been recognised in the eastern sandstone and dark massive mudstone. It part of BAIRNSDALE. The formation consists differs from Pinnak Sandstone in having better of 400-500 m of black shale and siliceous shale sorted sandstones with typically "stripy" thin with very minor pale coloured quartzitic bedded sandstones and dark siltstones between sandstone (VandenBerg et al., 1991). The black thick bedded sandstone. shale is richly fossiliferous throughout and contains a complete late Gisbornian to Bendoc Group (VandenBerg et al., 1991) Bolindian graptolite fauna.

The Bendoc Group is characterized by black Akuna Mudstone (VandenBerg et al., 1991) shales, black and dark grey mudstones and cherts with rare pale coloured sandstones. The Akuna Mudstone has been recognised in the group spans the Upper Ordovician extending northeast of BAIRNSDALE and on into the Llandovery and has been divided into MALLACOOTA. It is likely that the formation four formations: Blueys Creek Formation, occurs elsewhere in eastern Victoria and Sunlight Creek Formation, Warbisco Shale and southern New South Wales. It consists of about Akuna Mudstone, of which the first occurs only 250 m of dark grey and purple laminated in the Limestone Creek region (Cas & mudstone and siltstone. Thin sandstone VandenBerg 1988; VandenBerg et al., 1991). laminations occur higher in the unit. It is likely The Sunlight Creek and Warbisco formations that the formation spans the middle to late are commonly found as narrow belts along Bolindian (VandenBerg et al., 1991). major faults throughout eastern Victoria. 12 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Silurian probably deposited on the upper portion of a submarine fan. Silurian rocks crop out on both sides of the Buchan Rift. They consist of thick marine Towanga Sandstone (Talent, 1964; Orth et al., quartz rich sediments (Yalmy Group, Seldom 1995) Seen Formation, Towanga Sandstone, Cobbannah Group) overlain in places by acid The Towanga Sandstone crops out north of the volcanics and mudstone (Enano Group). Nunniong Pluton and is considered to be part of the same depositional sequence as the Seldom Yalmy Group (VandenBerg et al., 1991) Seen Formation (Orth et al., 1995). It consists of marine thick to thin bedded quartz Yalmy Group describes a thick sequence of sandstone, planar laminated siltstone and Lower Silurian deep marine turbiditic minor conglomerate. Allen (1987) recognised sandstone and mudstone. The total thickness several distinctive lithologies in the Towanga of the group is estimated at about 2,500 m. Sandstone. These include the 30 m thick Rough Graptolites and conodonts indicate a Lower Creek Conglomerate Member and three Silurian age. There are three component units. unnamed facies of siltstone, interbedded These are; sandstone and siltstone and quartz sandstone.

Sy1- a lower unit of sandstone, part of it coarse- Enano Group (VandenBerg et al., 1981) grained, with minor interbedded mudstone; The Enano Group includes the Thorkidaan Sy2- a unit of laminated and massive mudstone Volcanics, the Cowombat Siltstone and the with minor interbedded sandstone and Gibsons Folly Formation, from youngest to quartzite; and oldest, which crop out in the Limestone Creek Graben in the northeast of BAIRNSDALE. The Sy3- an upper unit of sandstone and group has been described in detail by Allen, orthoquartzite turbidites with interbedded 1988 and Orth et al., 1995. The Enano Group mudstone. disconformably overlies the Towanga Sandstone which was deformed during the Middle Silurian Yalmy Group has been recognised only in the Quidongan Deformation (Allen, 1987), eastern portion of BAIRNSDALE and on associated with the onset of rhyolitic volcanism MALLACOOTA to the east. and the beginnings of the Cowombat Rift. The Thorkidaan Volcanics probably formed in a Cobbannah Group (VandenBerg & Stewart, mixture of shallow water, deep marine and sub- 1992) aerial conditions and includes a mix of felsic volcanics and minor marine sediments. The The Cobbannah Group crops out southwest of Cowombat Siltstone is a shallow marine shelf to the Wonnangatta Fault and consists of a lower deeper marine basin slope facies association portion of thick bedded sandstones and an consisting of marine siltstone and minor upper portion of interbedded sandstones and laminated sandstone with occasional limestone shales (Fergusson et al., 1989). The group was lenses. The formation contains several Cu-Pb- assigned an Ordovician age by VandenBerg and Zn prospects. The Gibsons Folly Formation Stewart (1992), however recent work by represents deposition in a deeper marine Fergusson (1996) indicates the group may be environment, perhaps towards the central, Early Silurian equivalent to the Yalmy group deeper parts of the rift (Allen, 1987). It consists which occurs farther east. of at least 300 m of strongly foliated rhyodacite and interbedded siltstone. It contains Seldom Seen Formation (VandenBerg & numerous stratiform lenses of variably altered O'Shea, 1981) andesitic to dacitic lavas intercalated with fine grained turbidites and at least two Cu-Zn-Pb The Seldom Seen Formation crops out south of massive sulphide deposits, Wilga and the Reedy Creek Fault. It is unconformably Currawong. overlain by the Snowy River Volcanics. The Omeo Metamorphic Complex formation consists of about 2,600 m of chert conglomerate and quartz sandstone to lithic The Omeo Metamorphic Complex (Beavis, sandstone with very rare mudstone. It was 1960) is a major feature on BAIRNSDALE, extending in a southeast trending arc from New GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 13

South Wales to Ensay in the south. It consists of Hotham Group metamorphosed during the Mount Elizabeth Caldera Complex (Simpson et Quidongan Deformation. Metamorphic grade al., 1996) ranges from lower greenschist grade at the margins to upper amphibolite grade in the core. The Mount Elizabeth Caldera Complex (MECC) Lower grade rocks at the margins of the is centred on the three peaks that make up complex comprise slate, phyllite and psammite Mount Elizabeth. The caldera has a diameter and are characterised by the presence of of 13.5 km and comprises a central volcanic chlorite and biotite plus cordierite with higher pile, dominated by ignimbrite, surrounded by grades. With increasing grade the rocks show an almost complete ring of granite. The progressive changes into schists and gneisses volcanic stratigraphy of the caldera consists of with andalusite, cordierite, sillimanite and K- two units: the Fainting Range Ignimbrite feldspar the dominant metamorphic minerals. (Simpson et al., 1996), a dark, crystal poor The complex also includes migmatite and pumiceous ignimbrite with minor intercalated syntectonic granites. sedimentary horizons, and the Slater Ignimbrite (Simpson et al., 1996) a red to In the Kuark Metamorphic Complex on purple, densely welded quartz, feldspar MALLACOOTA to the east the metamorphism ignimbrite. is restricted to the Lower Ordovician units (Pinnak Sandstone) with no involvement from Wentworth Group Upper Ordovician formations (Hendrickx et al., 1996). This is probably also the case in the The Wentworth Group is confined to a complex Omeo Metamorphics. synclinal structure in the Tabberabbera area, and lies unconformably on folded Ordovician Lower Devonian rocks. Talent (1963) divided the group into two formations, the Wild Horse Formation and the Lower Devonian rocks overlie the Silurian and Tabberabbera Formation. Ordovician with a sharp angular unconformity which marks the Bindian Deformation. They Wild Horse Formation (Talent, 1963) occupy extensional basins the largest of which is the Buchan Rift, a broad syncline like This unit overlies Ordovician sediments with a depression containing a thick sequence of felsic marked angular unconformity. It consists of volcanics and subaerial to marine sediments 365 m of coarse to very coarse grained quartz (Snowy River Volcanics and Buchan Group) . A sandstone, lithic quartz sandstone and minor thinner sequence is preserved in the Bindi half fine grained sediments with a basal polymict graben (Snowy River Volcanics and Buchan conglomerate. Group); the Mitchell Syncline (Wentworth Group) and the Mount Elizabeth Caldera. Tabberabbera Formation (Talent, 1963)

Snowy River Volcanics (Ringwood, 1955; Orth This formation conformably overlies the Wild et al., 1995; VandenBerg et al., 1996) Horse Formation and is subdivided into three members which together make up a total The Snowy River Volcanics (SRV) is a complex thickness of about 1500 m. The formation is sequence of mainly felsic I type volcanics, characterised by fine grained sediments volcaniclastics and intrusives deposited in including poorly bedded mudstone, claystone, subaerial to subaqueous conditions. They are impure limestone, sandstone, calcareous mainly confined to the Buchan Rift and have a sandstone and minor conglomerate. The sharp angular unconformity with surrounding Wentworth Group was deposited in a rapidly older rock units. The SRVs have been mapped deepening marine basin (VandenBerg, 1988). in detail on MURRINDAL (Orth et al., 1995) and ORBOST (VandenBerg et al., 1996), where they have been divided into nine major Buchan Group subgroups, plus several smaller units; these in turn are subdivided into 56 formations. The Buchan Group is a sequence of carbonate Readers are referred to these reports for and calcareous mudstone which once extended detailed descriptions of individual formations over the entire Buchan Rift. The group and a detailed description of the history of comprises three formations; Buchan Caves deposition of the sequence. 14 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Limestone, Taravale Formation and Murrindal feldspathic sandstones, red to purple siltstone Limestone. and mudstone with intercalated rhyolite and basalt. The group is divided into four Buchan Caves Limestone (Talent , 1956) formations: the Moroka Glen Formation (Talent, 1963), Wellington Rhyolite (Teale, The main portion of Buchan Caves Limestone 1920), Mount Kent Conglomerate (Talent, 1963) consists of grey to black limestone and dolomite. and Snowy Plains Formation (Howitt, 1876). The basal 10-25 m are dolomitic, giving way to normal calcitic carbonates. The limestone Mount Tambo Beds (Howitt, 1876; VandenBerg consists of skeletal or often peloidal grainstones & O'Shea, 1981) to wackestones (after Dunham 1962). Fragments of ostracods, brachiopods, corals, The Mount Tambo Beds crop out along the algal limestone, fish bones, bivalves, conodonts northeast boundary of BAIRNSDALE, about and a few gastropods make up the bioclastic 5 km east of Hinnomunjie. They component of much of the limestone. The unconformably overlie Ordovician rocks to the formation contains a basal clastic member, the east and are intruded by Triassic granites on Creek Member, and a band of andesitic the west - elsewhere they have faulted contacts. volcaniclastics named the Amberley The 3000 m thick sequence comprises a thick Volcaniclastic Member. The Spring Creek basal conglomerate, sandstone and siltstone Member is transitional with the underlying with abundant volcanic detritus, mudstone and Snowy River Volcanics. shale. The formation also contains a 9 m thick rhyolite flow. The age of the unit remains Taravale Formation (Teichert & Talent, 1958) uncertain. It has been variously described as being Upper Devonian or Silurian based on This formation rests conformably on Buchan lithological comparisons with the Avon River Caves Limestone and has a maximum thickness Group and Wombat Creek Group. of about 600 m in the Murrindal Synclinorium (Orth et al., 1995). The formation is Permian characterised by mudstone and nodular limestone. The nodular limestone is blue-grey Permian rocks are known from borehole only when fresh and generally well bedded. The (Duck Bay 1 well about 30 km west of nodules are of secondary origin, due to Entrance, Bowen & Thomas, 1988). They dissolution of carbonate by ground water and consist of 184 m of shale, siltstone and muddy redeposition of the carbonate elsewhere. sandstone, lying directly on deformed Ordovician. Murrindal Limestone (Teichert & Talent, 1958) Triassic The Murrindal Limestone is a lenticular unit restricted to the northern part of the Murrindal Triassic rocks on BAIRNSDALE are limited in Synclinorium. It has a maximum thickness of exposure to the northern margin of the sheet, 290 m. The formation is divided into two northeast of Omeo. Outcrops of porphyritic members, the dark McLarty Limestone Member microgranite at "The Sisters" are part of the and the paler Rocky Camp Limestone Member. Mount Leinster Complex. This is a suite of alkaline igneous rocks and associated Upper Devonian-Carboniferous volcaniclastics comprising porphyritic microgranite, alkali granite, trachyte lava, The Avon River Group (Talent, 1963; Neilson, breccia and pyroclastics, and syenite. The 1964) syenites and granites have an intrusive relationship with their volcanic equivalents. Crops out in the southwestern part of Preliminary work on the Benambra 1:100 000 BAIRNSDALE. The rocks form part of the map sheet (VandenBerg et al., in prep) Mount Howitt Sedimentary and Volcanic indicates that the volcanic rocks were probably Province (Marsden, 1988) which is much more deposited in small calderas which were extensive on WARBURTON to the west. They intruded during caldera resurgence. overlie older rocks with a sharp angular Radiometric age dates of 225±5 Ma (Bowen, unconformity. The group is about 3,500 m thick 1975) or 232±5 (McKenzie et al., 1984) have and consists of non marine fluviatile sediments, been obtained from a biotite hornblende including conglomerates, quartzose, lithic and trachyte from The Brothers on GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 15

TALLANGATTA. Other dates on dunes consist of loose grey sand with cores of TALLANGATTA include a quartz syenite at soft clay. 201±8 Ma (McDougall & Wellman, 1976). 2.3 Intrusive Rocks Cretaceous BAIRNSDALE covers parts of the Bega, Rocks of Early Cretaceous age, assigned to the Kosciusko, Wagga and Howqua basement Strzelecki Group are confined to the subsurface provinces of Chappell et al., 1991. in the Wellington Depression and Gippsland Basin. Their total thickness is not The Bete Belong Group of intrusives in the known but exceeds 2500 m near Lake southeast of BAIRNSDALE are the only Wellington. They consist of blue-green granites cropping out in the Bega Basement feldspathic and chloritic sandstone and possibly Province. They are all I-type intrusives and arkose, and blue-grey to black mudstone with range in composition from granodiorite to some interbedded coarse sandstone, gritstone tonalite. and thin coal bands. In Duck Bay No. 1 Bore about 100 m of altered olivine basalt and minor Most of the granites in the Kosciusko Province basaltic volcaniclastics are interbedded near the have features indicative of derivation from pre- base of the Strzelecki Group (Douglas, 1988). existing sedimentary rocks (ie these are predominantly S-type intrusives and are Tertiary members of the extensive Bullenbalong Suite (Amboyne Granodiorite, Campbells Knob Sub basaltic sediments and Older Volcanics Granodiorite, Suggan Buggan Pluton, Nunniong Pluton, and Barrabilly Adamellite). The older volcanics, primarily olivine and Members of this suite are some of the most alkali-olivine basalt, are confined to the mafic S-type granites in the Lachlan Fold Belt highlands area, where they form extensive (White & Chappell, 1988). Intrusive rocks plateaux and smaller ridge top residuals. Sub- around Mount Elizabeth are Devonian in age. basaltic sediments occur around their margins in most areas, these consist of poorly Granites in the Wagga basement province are consolidated gravel and sand. Radiometric ages poorly studied. The Anglers Rest Granite is the ( Wellman, 1974) indicate basalts were only representative of the Boggy Plains extruded in the Oligocene (Mt Hotham, Dargo Supersuite on the map sheet. area) and Eocene ( area). Other granites appear closely associated with Tertiary Sediments regional metamorphic rocks (Omeo Metamorphic Complex) and were probably The Tertiary sequence is divided into three intruded synchronous or just post the groups: the Group (Eocene - Benambran-Quidongan Deformation. They are Oligocene in the map area; Thomas & S and I type granodiorites and tonalites, Baragwanath, 1949), consisting of non-marine commonly foliated and with metasedimentary sediments including coal beds; the Seaspray inclusions. Intrusions falling into this group Group (Oligocene to early Pliocene; Hocking, include Mount Nugong, Mount Livingstone, 1972) consisting of marine sediments including Bindi, Old Sheep Station, Rileys Creek, Ensay limestone; and the Sale Group (Pliocene; South, Tongio Gap and the Ensay Tonalite. Hocking, 1972) consisting of non-marine sediments. Only the Sale Group and upper Granites in the Howqua basement province Seaspray Group are exposed on BAIRNSDALE. range in age from Late Silurian to Mid Devonian and include S and I types. The Quaternary Castleburn, Dargo and Mount Blomford plutons form a group of granites on the western edge of Rocks of this age consist of present stream and the map. Granites in the Howqua province coastal deposits. The most important alluvial around Bairnsdale are all Middle Devonian in deposits occur near the mouth of the Snowy, age. Mitchell and Avon Rivers. Sediments include conglomerates, gravels and sands. Sand hills Bega Basement Province and dunes are mostly confined to the Munro Plain in the southwest of the map area. Most 16 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

All intrusives Silurian in age. generally deeply weathered forming flat decomposed pavements of quartz and sericitised Bete Belong Group feldspar grains in a green clay rich matrix. The rock consists of euhedral prisms of hornblende Aeromagnetic data shows the Bete Belong up to 2 cm long in a groundmass of interlocking Group to be composed of four main plutons, quartz, plagioclase and orthoclase and these are from east to west, Bete Belong/Double occasional equate biotite grains to 2 mm. Bull, Broken Leg, Feltis Farm and Dysentery. Rocks within the group range from granodiorite Jarrahmond (Sg45; VandenBerg et al., 1996) in the east to tonalite in the west. This range in compositions reflects fractionation processes in The Jarrahmond Granite appears to have been the primary batholith and may indicate the totally unroofed and is surrounded by a normal relative ages of the intrusions with the more hornfels aureole. Aeromagnetic data suggest mafic varieties intruding earlier in the west, that the pluton extends for quite some distance with the eastern intrusions becoming more below the Snowy River plain. The rock is fractioned and intruding later. well exposed in Gunn Creek and is a medium to coarse grained granite, white to green but Three of the four plutons occur on weathering to white. It is characterised by the BAIRNSDALE: presence of large euhedral crystals of hornblende. Large elongate mafic xenoliths, Bete Belong-Double Bull (Sg57; Sg56; White & 10´4 cm, occur occasionally through the rock. Chappell, 1988; VandenBerg et al., 1996) Orbost Tonalite (Sg44; VandenBerg et al., 1996) The granodiorite forms two elongate intrusives, separated by a narrow hornfels ridge along Bete The Orbost Tonalite is a small intrusion Belong Creek northwest of Orbost. covering an area of approximately 4 km2. The rock is medium grained, grey-green when fresh The rock is medium to coarse grained, light and green when weathered. It may be quite coloured when fresh, weathering to dark green. mafic in composition with enclaves of both It has a weak porphyritic texture defined by the mafic composition and rarer (distinctly foliated) presence of coarse grained, euhedral sedimentary material. Some enclaves are hornblende crystals in a slightly finer grained internally variable as shown by dark patches groundmass of intergrown subhedral quartz within enclaves. and feldspar and books of biotite up to 5 mm across. Xenoliths are rare throughout. Eleven Bob Granite (Sg512; Beams & Hough 1979) Feltis Farm (Sg47; Orth et al., 1995) This pluton crops out in the valley of Major Intrusive contacts with the surrounding contact Creek, north of Orbost, and covers metamorphosed Pinnak Sandstone are very approximately 3 km2. It is surrounded by a shallow accounting for the irregular shape of narrow hornfels ridge 1 km wide which widens the tonalite as boundaries follow topography. It to 2 km along the northern margin of the is generally deeply weathered and where granodiorite indicating a shallow, north dipping exposed forms flat friable platforms free of fresh contact. The granodiorite is poorly exposed and rock. deeply weathered consisting of a soft friable, poorly consolidated mix of medium grained In hand specimen the rock is grey when fresh quartz, feldspar crystals and occasional weathering to green. Hornblende forms chloritised biotite flakes to 0.5 mm in a abundant elongate prisms up to 1 cm long set in groundmass of soft grey clay. a medium grained groundmass of intergrown quartz, feldspar and biotite with a small Wagga Basement Province amount of fine grained pyrite. All intrusives Upper Silurian to Lower Broken Leg (Sg46; Beams & Hough, 1979) Devonian in age.

The Broken Leg Granodiorite occurs in a Anglers Rest Granite (Dlg114; Mclaughlin & number of small separate pods near Mount Tattum, 1976) Pinnak 20 km north of Orbost. This granite is GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 17

This body is a massive, homogenous medium Ensay South Granodiorite (Sg135; ; grained pink biotite leucogranite. Numerous VandenBerg & O'Shea, 1981; White & Chappell, pegmatite dykes parallel the margins of the 1988 ) intrusion. The intrusion is dated at 400±16 and This intrusive crops out along the Ensay Fault, 390±16ma (Richards & Singleton, 1981). north of Ensay. It is medium grey and finely foliated near Ensay grading to almost non Mount Nugong Granodiorite (Sg123; foliated near Doctors Flat. The granodiorite is VandenBerg & O'Shea, 1981; White & Chappell, 1988) elongate to the northwest and is dated at 412±13 Ma (Richards & Singleton, 1981). The Mount Nugong Granodiorite consists of Tongio Gap Granodiorite (Sg143; VandenBerg medium grained plagioclase, quartz, interstitial & O'Shea, 1981; White & Chappell, 1988 ) K-feldspar and abundant brown biotite, minor large cordierite crystals. Metasedimentary and The Tongio Gap Granodiorite lies southeast of granitic inclusions have been recorded. Omeo. It is a medium grey weakly to non foliated granodiorite similar in composition to Mount Livingstone Granodiorite (Sg144) the Ensay South Granodiorite. The Mount Livingstone Granodiorite occurs on Ensay Tonalite (Sg128; Simpson et al., 1996) the west side of the Livingstone Creek Fault. It is elongate to the east. Little is known about The Ensay Tonalite occurs north of Mount this granite. Elizabeth. It intrudes well foliated metasediments along its northern margin and Cobungra Intrusion (Sg118) is deformed by the Ensay Shear Zone along its southern margin. A variably developed igneous The Cobungra Intrusion is a poorly studied lineation in the tonalite lies parallel to the pluton on the west side of the Mount lineation in the shear zone indicating intrusion Livingstone Granodiorite. occurred synchronous to deformation. Bindi Granodiorite (Sg121; Mclaughlin & Tattum, 1976) In the less deformed parts of the intrusion the rock is medium to coarse grained and consists This intrusive crops out west of Bindi and is of euhedral plagioclase crystals enclosed by medium to coarse grained and weakly foliated. large poikilitic quartz grains with up to 20 % It consists of quartz, feldspar, biotite and biotite and hornblende. Hornblende crystals cordierite with minor tourmaline and zircon. are randomly to strongly aligned. Rocks Metasedimentary inclusions are common. bordering the Ensay Shear Zone are mylonitised. Old Sheep Station Granodiorite (Sg136; VandenBerg & O'Shea, 1981; White & Chappell, 1988)

This pluton crops out near Doctors Flat. It is a roughly circular body composed of grey, even grained granodiorite which is weakly foliated near the pluton margins. Rileys Creek (Sg137; Mclaughlin & Tattum, 1976; White & Chappell, 1988)

This intrusive crops out around and is also known by this name. The rock consists of a medium grained foliated granodiorite with quartz, feldspar, biotite and hornblende. Elongate bodies of quartz diorite are incorporated into the pluton and large schist xenoliths occur near the margins. 18 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Kosciusko Basement Province Barrabilly Adamellite (Sg77; Talent, 1964)

Silurian Intrusives This small intrusive occurs in the Barrabilly Creek area. The rock is fine to medium grained Amboyne Granodiorite (Sg71; Bruce, 1979; and comprises quartz and feldspar with Sherren, 1979) interstitial fine biotite which imparts a dark colouration to the rock. Cordierite occurs is The Amboyne Granodiorite forms an elongate pseudomorphed by chlorite and sericite. pluton along the . The intrusive is medium to coarse grained with quartz, Nunniong Pluton (Orth et al., 1995) plagioclase, K-Feldspar, cordierite, garnet and rare sillimanite. Inclusions are common and The Nunniong Pluton is the largest intrusion on include quartzite, hornfels, gneiss and schist. BAIRNSDALE. It extends from the western The Amboyne Granodiorite has been dated at margin of the Snowy River Volcanics in the east 407±13 Ma (Richards & Singleton, 1981) and to the Timbarra River in the west. It consists of 427±3 Ma (Henley & Webb, 1990). two intrusions; the Nunniong Granodiorite and the Mellick Munjie Granodiorite. The Mellick Campbells Knob Granodiorite (Sg66; White & Munjie Granodiorite lies fully within and is Chappell, 1988; Orth et al., 1995) therefore probably intrusive into the Nunniong Granodiorite. This intrusive crops out along the Snowy River around Campbells Knob. The rock is a medium Nunniong Granodiorite (Sg125; VandenBerg et al., to coarse grained granodiorite. The main 1984) minerals are euhedral quartz intergrown with plagioclase, K-feldspar and biotite. Accessory The Nunniong Granodiorite is fine to medium minerals include muscovite, apatite and zircon. grained with a dark appearance and contains abundant metasedimentary inclusions. Finer Suggan Buggan Pluton (Orth et al., 1995) grained portions of the intrusion have a porphyritic appearance with large quartz and The Suggan Buggan Pluton is part of an feldspar crystals in a finer "groundmass" of extensive intrusion which extends into N.S.W. quartz, feldspar and biotite. Medium grained It includes two different intrusions; the Suggan portions have a darker appearance and consist Buggan Granodiorite and the Chilpin of equigranular grains of quartz, feldspar and Granodiorite. biotite. Minor minerals include cordierite and rare garnet; accessory minerals comprise Suggan Buggan Granodiorite (Sg74; White & apatite, zircon, and monazite. The Nunniong Chappell, 1988) Granodiorite is dated at 430 ±13 Ma (Richards & Singleton, 1981) and 417±3 Ma (Henley & This intrusion occurs in the headwaters of Webb, 1990). Buchan Creek, and appears to partly surround the Chilpin Granodiorite (Orth et al., 1995). Mellick Munjie Granodiorite (Sg127; Orth et al., The rock consists of coarse grained quartz with 1995) euhedral feldspar and finer scattered biotite with minor altered cordierite. Accessory This intrusive is a north trending ovate body minerals include apatite, zircon and within the Nunniong Granodiorite and crops tourmaline. out along Mellick Munjie Creek. It is a coarse to medium grained granodiorite comprising Chilpin Granodiorite (Sg76; Orth et al., 1995) coarse quartz, feldspar, cordierite and biotite and has a paler appearance than the The Chilpin Granodiorite crops out in Buchan surrounding Nunniong Granodiorite. The Creek. Grain size varies from very fine with an intrusion is dated at 418±3 Ma (Henley & aplitic texture to medium with a slight Webb, 1990). porphyritic texture. The main minerals are quartz and feldspar with minor biotite. The Kaerwut Trondhjemite (Sg516; VandenBerg et presence of epidote and alteration surrounding al., 1996) fractures indicates part of the granodiorite has been affected by hydrothermal alteration. This forms a small intrusion about 3 km north of Spanker Knob. The intrusion comprises an GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 19

"upper" marginal porphyritic phase and a pluton consists of a finer grained, more "lower" equigranular phase – the former is the leucocratic phase and may represent a series of more common. dykes within poorly exposed diorite or alternatively may represent intrusion of a The porphyritic phase consists of plagioclase single pod of fine grained granite. Narrow with less common quartz, biotite and dykes of similar leucocratic granite also occur in amphibole. These are set in a finer grained the adjacent Ordovician metasediments. groundmass of quartz and feldspar. Alteration is common. The diorite is a medium grained rock with well zoned, euhedral plagioclase and hornblende The equigranular phase has a similar crystals with interstitial quartz and minor K- composition, consisting of plagioclase, biotite, feldspar. Accessory minerals include magnetite minor quartz and extremely rare K-feldspar; and sphene. accessories include pyrite and pyrrhotite, and sparse chalcopyrite. Both phases of the Mount Mcleod Tonalite (Sg65; Orth et al., 1995) granitoid show a moderately developed foliation defined by biotite. Most of this intrusion crops out in the catchment of Whisky Creek northeast of Tambo Crossing Tonalite (Sg134; Kok, 1976; Buchan. It intrudes Yalmy Group and has a VandenBerg & O'Shea, 1981) unconformably overlain by Snowy River Volcanics. The intrusion consists of medium This granite intrudes Hotham group sediments grained green to grey tonalite. The dominant on the east side of the Mount Elizabeth. It is minerals are plagioclase, quartz and unconformably overlain by volcanic rocks of the hornblende with interstitial biotite and Mount Elizabeth Caldera Complex and hornblende. Actinolite is present as a intruded by the Patricks Creek Granite. secondary mineral and may be replacing augite. It is dated at 402±12 Ma (Richards & Singleton, 1981). The rock is medium to coarse grained Forlorn Hope Granite (Sg122; VandenBerg et and consists of euhedral to subhedral zoned al., 1984) crystals of plagioclase, interstitial quartz, abundant biotite, scattered euhedral The Forlorn Hope Granite crops out north of hornblende and rare small grains of K feldspar. the Reedy Creek Fault. It is elongate to the southwest and consists of medium to coarse Crohn Granite (Sg515; VandenBerg et al., 1996) grained quartz, feldspar, biotite and muscovite.

This granite crops out over a very small area in Postman Spur Granodiorite (Sg59; VandenBerg Granite Creek, a of Crohn Creek et al., 1991) northwest of Mount Tara. In the south and southeast, the granite has an intrusive This pluton occurs as a small nearly circular boundary with Pinnak Sandstone which shows body in the valley of Mountain Creek. The relatively weak contact metamorphism. To the intrusive is medium grained with euhedral east, the granite appears to be overlain quartz, feldspar, cordierite and biotite. nonconformably by Tara Range Subgroup Inclusions of gneiss, schist and hornfels are quartz ignimbrites but in the west, the major abundant. Gilbert Fault forms the boundary between granite and Snowy River Volcanics. The Granite (Sg60; Orth et al., 1995) granite itself is crossed by several quartz- feldspar porphyry dykes which themselves are This is an I-type intrusive which crops out in a clearly part of the Snowy River Volcanics, thus number of small pods intruding Yalmy Group giving a clear minimum age for the intrusion. sediments along the Rodger River. The rock has a slightly porphyritic texture with large Kenny Creek Diorite (Sg129; Simpson et al., euhedral feldspar, augite and lesser quartz in a 1996) groundmass of finer intergrown quartz, feldspar, biotite and augite. Abundant A small body of poorly exposed hornblende-rich sedimentary and igneous inclusion occur. diorite, approximately 2.5 km long and 1.5 km wide, occurs in the headwaters of Kenny Creek, east of Mt Elizabeth. The southern part of the 20 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Bull Run Gap Adamellite (Sg62; VandenBerg et contains brittle fracture zones which display al., 1991) grain size reduction and strained/recrystallized quartz and feldspar. The Bull Run Gap Adamellite crops out in the headwaters of Camp Creek along the eastern Howqua Basement Province edge of BAIRNSDALE however most of the intrusion is on MALLACOOTA to the east. The Mount Baldhead Granodiorite (Sg139; rock is medium grained with large feldspar VandenBerg & O'Shea, 1981; White & Chappell, crystals intergrown with quartz, feldspar and 1988 ) biotite. This composite granodiorite-diorite body crops Devonian Intrusives out east of the Mitchell Syncline. The granodiorite is medium grained and intrudes a Saint Patricks Creek Granite (Dlg133; Chappell fine to medium grained diorite. et al., 1991) Pheasant Creek (Sg138; White & Chappell, This granite occurs in the ring faults 1988) surrounding the Mount Elizabeth Caldera Complex. The rock consists of medium grained This is a small poorly studied pluton on the quartz, pink K-feldspar, plagioclase and biotite. west side of the Mount Baldhead Granodiorite.

Mount Elizabeth Granodiorite (Dlg126; White & Castleburn Tonalite (Sg142; Mclaughlin & Chappell, 1988) Tattum, 1976)

This granodiorite intrudes volcanic rocks of the The Castleburn Tonalite forms an elongate, Mount Elizabeth Caldera Complex. It post– north trending pluton around Castleburn. It is dates intrusion of the Saint Patricks Creek a medium grained grey rock comprising Granite (Simpson et al., 1996). The pluton is plagioclase, quartz, hornblende and biotite; K- compositionally zoned with a leucocratic phase feldspar is rare. Accessory minerals include occurring within the granodiorite. The main apatite, zircon and sphene. The pluton is phase consists of euhedral plagioclase laths, intruded in the south by a phonolite dyke, hornblende, biotite and interstitial quartz probably Triassic or Tertiary in age (Spooner, intergrown with K-feldspar. Acicular 1995). hornblende crystals up to 1 cm long are characteristic of the intrusion. Dargo Granodiorite (Sg140; Mclaughlin & Tattum, 1976) Mollys Plain Granite (Dlg514; VandenBerg et al., 1996) The Dargo Granodiorite crops out around Dargo forming an elongate northeast trending pluton. This granite occurs along Yellow Waterholes It is similar to the Castleburn Tonalite Creek at the western margin of the Buchan (VandenBerg & O'Shea, 1981, Spooner, 1995) Rift. The granite is medium grained and and consists of medium grained plagioclase, greenish grey, and deeply weathered except in quartz, K-feldspar, hornblende and biotite. The a few places in Yellow Waterholes Creek. intrusion is dated at 402±16 Ma (Richards & Where fresh the rock consists of a graphic Singleton, 1981). intergrowth of quartz and perthitic feldspar, which are so finely intergrown that it is Mount Blomford Granite (Sg141; Mclaughlin & impossible to estimate mineral percentages. Tattum, 1976)

Case Granite (Dmg513; Simpson et al., 1996) The Mount Blomford Granite occurs around Mount Blomford, west of Castleburn. It is This is a small intrusive 5 km long and 3 km coarse grained and dominated by K-feldspar wide cropping out sparsely in Boggy Creek. with lesser quartz, plagioclase and biotite. The granite is strongly altered and fractured, Accessory minerals include zircon, apatite, producing a blotchy green/pink appearance. It fluorite and tourmaline. consists of an interlocking aggregate of plagioclase, quartz, K-feldspar and less than 2% chloritized small mafic grains. The granite GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 21

Devonian Intrusives

Colquhoun Granite (Dmg130; White & Chappell, 1988)

The Colquhoun Granite is poorly exposed over an area of about 85 km2 north of Colquhoun and much of it is covered by a veneer of Tertiary sediments.

The rock is a coarse to medium grained pink granite containing large quartz and perthitic K- feldspar crystals, plagioclase and biotite. Accessory minerals include magnetite, apatite and zircon. The rock also exhibits kinked biotite, strained quartz and thin mylonitic fracture zones close to faults. White & Chappell (1988) reported numerous miarolitic cavities, indicative of a high level of emplacement.

Mount Taylor (Dmg132; White & Chappell, 1988)

This intrusive crops out northeast of Bairnsdale. It is strongly porphyritic with large crystals of K-felspar, plagioclase, and quartz with less common garnet and cordierite set in a finer grained groundmass. The rock is appreciably altered in places.

Clifton Creek Granite (Dmg131; VandenBerg & O'Shea, 1981)

The Clifton Creek pluton is a leucocratic granite with pink orthoclase, quartz, lesser plagioclase and rare biotite. It is dated at 371±11 Ma (Richards & Singleton, 1981).

Tabberabbera Dyke Swarm

The Tabberabbera Dyke Swarm intrudes folded Wentworth Group sediments. The dykes include quartz diorite, hornblende porphyrite and quartz feldspar porphyrite. They are poorly studied. 22 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

3 Economic geology 3.1 History of mining

Mines within BAIRNSDALE have produced in At the end of September 1996, 22 Mining excess of 13.7 t of gold, 45 000 t of copper, Licences, and 12 extractive industry Work 21 000 t of zinc, 15.0 t of silver and unknown Authorities were held on BAIRNSDALE, which quantities of lead, iron and other metals. In in 1994/95 had an approximate production addition to metallic minerals, sales of non value of $45.8M. Modern mining has been metallic minerals produced within dominated by development of the Wilga copper - BAIRNSDALE exceed $2M per annum. lead-silver deposit by Denehurst and Macquarie BAIRNSDALE includes several of Victoria's Resources NL between 1992 and July 1996. At most important mineral deposits, including one stage, this was Australia's fourth largest Wilga - the states largest base metal deposit. copper mine. The history of mining within Mines and exploration prospects where BAIRNSDALE dates back to the discovery of significant mineralisation has been proved are gold at Livingston Creek, near Omeo in 1851 shown in Figures 3 and 4. (Fairweather, 1983).

The following styles of mineralisation are The following summary of mining is largely recognised within BAIRNSDALE: taken from Bannear and Annear (1995).

· precious metal vein deposits; Omeo, Swifts Creek and New Rush Creek · Lower Devonian volcanic hosted metal goldfields deposits within the Snowy River Volcanics and Mount Elizabeth Caldera Complex; Discovery of gold at Livingstone Creek in 1851 · placer gold deposits; led to a small rush of alluvial prospectors, · Silurian volcanic associated massive mostly around the Oriental Claims-Livingston sulphide (VAMS) deposits in the Cowombat Creek area, from Hinnomunjie in the north to Rift; New Rush Creek in the south. Open cut and · porphyry copper deposits; underground alluvial mining continued into the · base metal vein deposits; 1900s when dredges began operating on · red bed copper deposits in the Upper Livingston Creek between Hinnomunjie in the Devonian Snowy Plains Formation; north and the Oriental Claims area 12 km · carbonate hosted metal deposits in the basal south (Fairweather, 1983). Auriferous veins dolostone of the Lower Devonian Buchan were worked west of the Oriental Claims after Caves Limestone; 1882. · Nowa Nowa ironstones; · granite hosted tin deposits; Alluvial gold was first found on Swifts Creek in · wolframite vein deposits; 1854. Four years later an auriferous quartz · brown coal deposits; and vein was discovered at Cassilis; Christie (1993) · various non metallics. reported that this was the first hardrock gold discovered in Gippsland. Hardrock mining was Gold deposits are mainly confined to the sustained within the Swifts Creek goldfield Harrietville-Dargo and Benambra gold from c.1880 to 1918, with the majority of provinces in west and central BAIRNSDALE. production recorded between c.1900 and 1912. These provinces defined by Ramsay and Willman (1988) are shown in Figures 3 and 4, The township of Tongio West was established and have been subdivided into goldfields to aid by the mid-1870s on a site that had been known description of local characteristics of as Chinamans Crossing in the 1860s (Bannear mineralisation. The location of goldfields has & Annear, 1995). A public water-powered been modified after Weston and Nott (1990) to battery was erected at Tongio West in 1883, and take account of more detailed information. helped open the field to mining.

Base metal deposits are dominant in east The township of Cassilis was established to the BAIRNSDALE. Many of these are related to north of Tongio West by 1889. By 1911 there rocks of the Buchan Rift and Limestone Creek were up to 1500 people living in Cassilis Graben. (Fairweather, 1975) and employed at the Cassilis mine (Christie, 1993). Although the Cassilis mine closed in 1918, a dredge

24 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

continued to operate on Swifts Creek until the government battery at Dargo resulted in a early 1920s (Fairweather, 1975). small unsustained revival in mining in about 1900. Grant, Dargo, Dargo High Plains and Cobbannah goldfields Prospecting and mining in these areas was hindered by poor access, and severe winters. In Gold was discovered at within addition, ore at taken from below the Dargo High Plains goldfield in 1852. the water table was pyritic, and required Alluvial mining commenced in 1857, and expensive treatment to recover gold. between 1859 and 1861, 21 mines operated along the river north of Mount Battery. The Haunted Stream and Shady Creek goldfield focus of mining changed to Brandy Creek during the mid 1860s and mining of leads Gold was first found at Haunted Stream in buried by Tertiary basalt commenced in 1867. 1865, and a small alluvial rush followed The main period of mining on Cobungra River (Fairweather, 1975). By 1882 three hardrock commenced in 1884, and coincided with the mines, including the Passover and the Rob Roy, introduction of hydraulic sluicing on Cobungra were being worked at Haunted Stream. The River, Brandy and Murphys creeks. Mining town of Stirling was established in c.1883. A was hindered by lack of water and severe short decline in mining, possibly due to the winters. Nevertheless, the Cobungra (Sluicing ) remoteness of the goldfield, preceded a boom Co., which commenced operation in 1884, between 1886 and c.1900. In 1887, the washed several hundred thousand tonnes of population of Stirling was 300, by the end of the auriferous deep lead gravel from the Brandy century this peaked at about 800 (Fairweather, Creek Lead prior to 1893. Operations ceased in 1975). Stirling, and nearby Dog Town were 1894 because of the expense of treating deserted by World War I (Fairweather, 1975). cemented gravel and/or difficulty tracing the auriferous lead. Very little mining is reported Alluvial mining was undertaken along the after this time. , and its western below Tambo Crossing from c.1854. Gold is reported Alluvial mining is reported on the in of the Tambo River, Shady Creek, at Pikes Creek from 1854. A rush to Crooked Monkey Creek, Lankys (Lankies) Creek, River in 1861 was initiated by the discovery of Ramrod Creek, Stuarts (Stewarts) Creek, Carrs alluvial gold by a government prospecting party Flat and Dead Horse Creek. Sluicing of the on Crooked River and Good Luck Creek in banks of the Tambo River was undertaken from 1860. This was followed by rushes to the Dargo 1873 but was short lived. Fist reported High Plains (Upper Dargo River, 25 Mile Creek, workings at Stuarts Creek date back to 1888. A and 30 Mile Creek) from 1863 to 1864, and rush to Stuarts Creek is reported between 1893 periodic rushes to the Dargo, Crooked and and 1894. This area was reworked between Wentworth Rivers occurred throughout the 1917 and 1918. 1800s. Small scale dredging was undertaken on the Dargo and Crooked Rivers between 1906 Auriferous quartz veins are reported between and 1912. Prospecting for leads buried by Monkey and Ramrod creeks. Prospecting for basalt in the Dargo High Plains was hardrock sources of alluvial gold in the 1880s undertaken between 1882 and 1910, mostly was largely unsuccessful, although a battery is with minimal success. reported on Shady Creek in c.1890.

Auriferous quartz veins were discovered at Deptford and Yahoo Creek goldfields Crooked River in 1864. Within two years in excess of 250 gold bearing veins were found at From the 1850s to the 1930s alluvial mining Crooked, Wongungarra, Wonnangatta and was carried out intermittently along the Dargo rivers, Jungle, Good Hope and Good Nicholson River and its tributaries. Luck creeks, and Grant (Mount Pleasant). The majority of these proved to be uneconomic, and Quartz mining was undertaken between 1866 were abandoned by 1867. Other veins were and 1871 at Store Creek and Deptford. Largest periodically worked throughout the 1800s. The mines were the Tambo at Store Creek and the Good Hope was the most permanent of these Tubal Cain at Deptford. Mines were generally mines, and was worked almost continually abandoned because companies failed to attract between 1864 and 1915. Establishment of a development capital. Mining recommenced at GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 25

Deptford in 1881, and the Hidden Treasure and Several carbonate hosted lead-silver deposits the Great Success produced moderate amounts were discovered within BAIRNSDALE at this of gold before closing in c.1886. time, and mining followed at Back Creek, Spring Creek, Pyramids and Park. Quartz mines within the Yahoo Creek goldfield Mines were worked intermittently until 1928 were worked from 1888 into the 1890s. Mines (Cochrane, 1982). Although significant were revived in c.1900, and sustained until sphalerite occurred with the ore, zinc was not World War I before being abandoned. recovered. The expense of transporting ore made concentration or on-site smelting Between 1890 and 1896, the Deptford desirable; and in the mid 1880s a smelter was Proprietary GMC led the final, best capitalised established at the Hume Park Mine (Adams, campaign in the Deptford goldfield. Overall, 1981). the mine is said to have averaged almost an ounce to the ton, but working costs were high Lead and copper minerals were first reported and calls on investors outweighed dividends. near Deddick in the 1870s, but it was not until 1896 that mining of silver-lead veins In the late 1890s, a government battery was commenced (VandenBerg et al., 1996). Only installed at Store Creek, initiating a brief small quantities of ore were produced prior to revival. Mining also had a brief revival at closure of the mines by c.1900. Remoteness of Yahoo Creek, where new ore shoots were mines, and the high cost of transporting ore discovered. contributed to the abandonment of the mines. The nearby Accommodation Creek copper Tara goldfield deposit was probably first worked in 1899, but main production occurred between 1959 and Reports of the discovery of auriferous veins at 1970 (Cochrane, 1982). Nowa Nowa resulted in a small rush to the area in 1887 (Stirling, 1887). Although prospectors Small workings on base metal veins and were unable to find gold, this rush led to mining alluvial gold deposits within the Campbells of iron ore deposits north of Nowa Nowa. The Knob lead-zinc field suggest small scale mining discovery of silver at Hospital Creek in 1893 in the late 1800s (VandenBerg et al., 1996), was followed by mining of several gold bearing although no production is recorded for the area. quartz veins within the Tara goldfield. Mines Barite and silver were respectively mined at a within the goldfield operated until the 1920s. small scale from veins within the Snowy River Small amounts of gold were mined from Volcanics at the Glen Shiel barite and Glen alluvium of the Loongelaat and Creamy creeks Shiel silver mines. (Anon, 1897). 3.2 Mineral Production Small alluvial gold workings are reported from drainages near the summit of Gil Groggin and a Whilst accurate gold production records are creek draining Campbells Knob (VandenBerg et available for most mines (see below), other al., 1996), although no official production is mineral production has not been systematically recorded for these areas. VandenBerg et al. recorded. An overview of mineral production (1996) also reported a gold mine in hornfels east from BAIRNSDALE is given in Table 2, which of the summit of Gil Groggin. This mine lists only gold and Wilga copper-zinc-silver operated in the late 1950s, and production is production derived from accurate records. not known. Records of base metal production are not Other areas comprehensive. Reported production for the Accommodation Creek copper mine is 3676 t of Gregson (1887) reported testing of iron ore copper ore, grading between 2 and 5% copper discovered north of Nowa Nowa in 1887. (Cochrane, 1982). The majority of this ore was Production from these, and manganese oxide produced between 1969 and 1970. Seventeen deposits since that time has been intermittent tonnes of copper ore was produced from the and small. Cassilis mine in 1909 (Cochrane, 1982). The only recorded production from the Deddick The first discovery of lead ore in Victoria was made near Buchan in 1869 (Adams, 1981). 26 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Table 2 Production from mines within BAIRNSDALE

Commodity Gold (kg) Copper (t) Zinc (t) Silver (kg)

Total production 13 697 44 968 21 031 15 000

Copper, silver and zinc figures are taken from Table 3. Silver values are approximate, and include projections for the 1992/93 period.

Table 3 Production from the Wilga deposit

Period Ore Ore Copper (t) Zinc (t) Silver Source Mined Treated Concentrate Metal Concentrate Metal Sales (kg) (t) (t)

1992/93 149 189 147 000 55 152 8992 0 0 unknown Wilkinson (1995) 1993/94 284 700 270 900 84 056 19 812 3253 1509 4832 Denehurst (1995) 1994/95 254 900 264 300 58 119 13 163 13 157 5947 3717 Denehurst (1995) 1995/96 266 200 255 540 15 998 3001 29 889 13 575 1587 Couller (pers. comm.) Grand 954 989 937 740 213 325 44 968 46 299 21 031 >10 136 Total

lead-silver field is 20 t of lead ore in 1898 under WA 197 at Rocky Camp, Murrindal. (Cochrane, 1982). Combined production from Rhyodacite aggregate is quarried by Boral carbonate hosted base metal mines is 796 t of Resources from the Snowy River Volcanics lead ore. Most produced between 1870 and under WA 86 at Nowa Nowa. This operation is 1877. Silver produced as a by-product from a relatively minor producer with the majority of smelting of galena is not recorded. production derived from other operations. Additional operations, primarily sand and Current production gravel pits operated by the former Department of Conservation and Natural Resources are an Modern mining has been dominated by important local source of road surfacing development of the Wilga copper-lead-silver material. deposit by Denehurst and Macquarie Resources NL between 1992 and July 1996. Production Only one mine, MIN 4665 at Brookville, from the Wilga deposit is listed in Table 3. For produced greater than 0.2 kg of gold in 1994/95. the 1995/96 period, metals worth approximately It contributed 0.651 kg, or 0.02 % of Victoria's $31M were produced from Wilga (Couller, pers. gold production (Department of Natural comm.) Resources & Environment records).

Construction materials worth approximately Historic gold production $2.2M were extracted in 1994/95 under the Extractive Industries Act 1996 (Department of Since its discovery in 1851, in excess of 13.7 t of Natural Resources & Environment records). gold has been mined within BAIRNSDALE. Granite aggregate is extracted by Boral Production for each goldfield is listed in Table Resources under Work Authority (WA) 70 from 4, and shown in Figures 5 and 6. Production for the Sarsfield Granite north of Bairnsdale. mines which have not been located to within a Limestone and sandstone used for agriculture specific goldfield, but were listed under a and aggregate is extracted by R Herman P/L, Historic Mining Division, have been included in P. Nelson and G. Tucker from the Seaspray and the total figures for that Historic Mining Sale Groups between Bairnsdale and Orbost Division. Prior to c.1940, official gold under WAs 260, 357 and 457. Murrindal production figures were compiled under these Limestone, which is used for agriculture, flux, Mining Divisions. The boundaries of Historic lime and road base is extracted by Amcor Ltd Mining Divisions covering BAIRNSDALE are GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 27

Table 4 Gold production from goldfields within BAIRNSDALE

Hardrock Alluvial Total Goldfield Production Production (kg) (kg) (kg)

Boggy Creek Historic Subdivision 1033 1284 2317 Bullumwaal goldfield 656 15 671 Yahoo Creek goldfield 9 0 9 unlocated 368 1269 1637 Crooked River Historic Division 1524 511 2035 Cobbannah goldfield 24 0 24 Dargo goldfield 177 220 337 Dargo High Plains goldfield 204 65 269 Grant goldfield 702 0 702 unlocated 417 226 643 Mitchell River Historic Subdivision 448 875 1323 Deptford goldfield 80 0 80 Store Creek goldfield 18 0 18 Tara goldfield 38 0 38 unlocated 312 875 1187 Omeo goldfield 886 0 886 Swifts Creek goldfield 4203 1769 5972 Haunted Stream and Shady Creek goldfield 1026 78 2004 other 70 0 70 Grand Total 9180 4517 13 697

Gold production for mines within the Gladstone Creek goldfield is not reported, and gold production for the Swifts Creek goldfield includes production from mines within the New Rush Creek goldfield. shown in Figure 3. The relative proportions of mines that operated between 1892 and 1897 gold taken from primary and placer deposits is will be understated. shown in Figure 7. Detailed production information for all mines is Gold statistics include production to 30 June included in the BAIRNSDALE Mine Database, 1994, and probably understate the amount of which accompanies this report. gold produced before 1867. Sources used in calculating gold production for BAIRNSDALE 3.3 Precious metal vein deposits are listed in Table 5. Since 1859, records of gold production have been published in Mines Precious metal vein deposits include all gold- Department monthly, quarterly, and annual silver vein deposits except those with reports. BAIRNSDALE production was first demonstrated epithermal characteristics. reported in 1867, even though significant These deposits are the source of all gold alluvial production occurred prior to this date. production within BAIRNSDALE. Deposits are Official statistics are considered to be more recorded only within the Harrietville-Dargo and reliable for later years when large scale mining Benambra provinces. Mineralisation is dominated the industry. distinctive in these two provinces, and to a lesser extent between goldfields within these Production statistics for individual mines were provinces. Gold within the Harrietville-Dargo not reported during the Depression years from province occurs with low sulphide quartz veins. 1892 to 1897. Cumulative statistics for whole In contrast, auriferous quartz veins within the divisions were used to calculate total production Benambra province - particularly the Omeo during this period. Total production figures for Metamorphic Complex, typically have high 28 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

component in predominantly metamorphic transporting fluids. High sulphide and base metal mineralisation in the Benambra province probably represent a greater magmatic component in transporting fluids. The source of gold is problematic.

Auriferous quartz veins occupy reverse strike faults, bedding planes and tension gashes (O'Shea et al., 1994). The orientation of these depositional sites is commonly controlled by regional structures. Trends of precious metal veins and major regional structures are shown in Figure 8. Ore shoots are commonly controlled by the intersection of veins with:

· carbonaceous beds; and · deviations in bedding or cleavage orientation related to refolding.

Wall (1987) recognised a relationship between vein style and host rock competency, with more competent sandstones tending to host stockwork veins whilst less competent slates tend to host narrow well defined veins.

In the absence of detailed ore genesis studies, it is difficult to date and classify most precious metal veins with certainty.

Within the Dargo-Harrietville gold province, most mineralisation occurs within northwest trending fissures cross cutting Ordovician Hotham Group. This trend is parallel to the axis of the Quidongan Deformation - and suggests a Middle Silurian mineralising event. Other forms of gold mineralisation suggest more than one episode of gold generation. Figure 5 Auriferous veins occur within the Early Primary, alluvial and total goldfield production. Devonian Dargo Granodiorite and Castleburn Mitchell R. - Mitchell River Historic Mining Division which Tonalite as well as adjacent, hornfelsed country includes the Tara, Deptford and Store Creek goldfields. rock. Within the Gladstone Creek goldfield, Boggy Ck. - Boggy Creek Historic Mining Subdivision which auriferous veins are hosted by Upper Devonian includes the Bullumwaal and Yahoo Creek goldfields. Moroka Glen Formation. Crooked R. - Crooked River Historic Mining Division which includes the Cobbannah, Dargo, Grant and Upper Dargo Auriferous and argentiferous veins within the goldfields. Benambra gold province largely trend north- south. This is the same trend as the sulphide and base metal values (Ramsay & Tabberabberan Deformation axis elsewhere, Willman, 1988). and suggests a shallow (hence brittle) Middle Devonian mineralising event. Alternatively, Little is known about the hydrothermal fluids this trend may be related to dilatant riedel responsible for precious metal vein shears developed in response to dextral strike mineralisation within BAIRNSDALE. O'Shea slip movement on the Ensay and Kiewa faults et al. (1994) suggested low sulphide gold during the Upper Silurian Bindian Orogeny. mineralisation in the Harrietville-Dargo Both of these models are consistent with province is consistent with a minor magmatic GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 29

Figure 6 Annual primary and alluvial goldfield production. Mitchell R. - Mitchell River Historic Mining Division which includes the Tara, Deptford and Store Creek goldfields. Boggy Ck. - Boggy Creek Historic Mining Subdivision which includes the Bullumwaal and Yahoo Creek goldfields. Crooked R. - Crooked River Historic Mining Division which includes the Cobbannah, Dargo, Grant and Upper Dargo goldfields. Omeo - Omeo Historic Mining Division which includes the Omeo, Swifts Creek, and New Rush Creek goldfields. Alluvial production prior to 1886 is not reported. 30 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Table 5 Sources used in calculating gold production within BAIRNSDALE

Period Principal Source Comment

Jan. 1867-Sep. 1891 Quarterly Reports of the Mining Surveyors BAIRNSDALE and Registrars production not reported prior to 1867. 1891-1896 Annual Report to the Secretary of Mines Hard rock and alluvial production for Historic Mining Divisions only. Jul. 1897-Jun. 1898 The Goldfields of Victoria Sep. 1898-Dec. 1901 The Goldfields of Victoria 1902-Jun. 1993 Annual Reports of the Mines Department (and various subsequent namesakes)

All sources are Victorian Government reports.

Mines within the province in BAIRNSDALE have produced 4040 kg of gold. Major primary producers are listed in Table 6.

The province is characterised by fissure controlled, low sulphide, auriferous quartz veins hosted by Ordovician sedimentary rocks (Ramsay & Willman, 1988). Gold is largely non refractory, and is occasionally associated with minor pyrite, arsenopyrite, and galena. Mineralisation at Bullumwaal is an exception - significant sulphides, and in some instances elevated cobalt and nickel, are associated with Figure 7 auriferous veins - suggesting a mafic to Source of gold production. ultramafic source of metal at depth (O'Shea et al., 1994). mineralised quartz veins truncating granites and Middle Silurian metamorphic isograds in Auriferous quartz veins occupy reverse strike Ordovician turbidites. Auriferous veins within faults, bedding planes and tension gashes the Yahoo Creek and Haunted Stream and (O'Shea et al., 1994). Mineralisation within the Shady Creek goldfields within the Dargo - Grant, Dargo (in part), Dargo High Plains, Harrietville gold province which are close to the Bullumwaal, Store Creek and Deptford Kiewa Fault, have similar trends to veins goldfields trends northwest which is parallel to within the Benambra gold province. the Kiewa Fault - and the deformation axis of the Quidongan Orogeny (Fig. 8). Veins close to Harrietville-Dargo gold province the Kiewa Fault, within the Yahoo Creek and Haunted Stream goldfields, mostly trend north- The Harrietville-Dargo gold province coincides south. This trend is consistent with the trend with the Tabberabbera Zone, which is a of veins within the Benambra gold province, structurally defined corridor extending from the and probably reflects a similar structural Mount Wellington fault zone in the west, to the control on mineralisation to that seen within Kiewa Fault in the east (Fergusson, 1988). The this province. Auriferous veins are also hosted province roughly corresponds with the Howqua by Early Devonian granite within the Dargo Basement Terrain of White and Chappell (Dunn, 1907) and Cobbannah goldfields, and (1988). Late Devonian sandstone in the Gladstone Creek goldfield (Murray, 1895; Kenny, 1938). GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 31

Table 6 Major primary gold producers within goldfields of the Dargo-Harrietville gold province

Mine Goldfield Production Average Grade (kg) (g/t)

Beehive Mine Bullumwaal 331 17 Sons of Freedom Reef Bullumwaal 94 19 Christmas Bullumwaal 54 17 Defiance Bullumwaal 48 76 Budgee Budgee Reef Cobbannah 24 24 Whitehorse Reef Cobbannah 1 7 Exhibition Dargo 59 31 Perseverance Dargo 46 27 Evening Star Dargo High Plains 91 23 Hope Reef Dargo High Plains 57 55 Deptford Proprietary Mine Deptford 34 49 Success Reef Deptford 25 31 Good Hope Grant 540 43 Mountaineer Reef Grant 32 24 Rob Roy Haunted Stream 55 31 Hans Haunted Stream 52 11 Tambo Reef Store Creek 16 10 Aunum Mine Store Creek 1 19 Great Scott Mine Yahoo Creek 5 18 Gift Mine Yahoo Creek 2 90

Weston (1992) noted most mineralisation lies vein styles reflecting host rock competency. east of the Wonnangatta Line within the The end members of this spectrum are: Ordovician Hotham Group. · slate hosted - veins are typically narrow and Brief descriptions of individual goldfields, and have sharp boundaries; and major producers follow. · sandstone hosted - typically irregular stockwork veining up to 7 m in width. Bullumwaal and Store Creek goldfields Gold bearing silicified and sericitised siltstone Auriferous veins at Bulumwaal are and sandstone units with small quartz veinlets predominantly fault controlled and trend drilled by CRA Exploration at German Creek - northwest and northeast. Veins which trend Store Creek (Cuffley, 1988), and gold bearing northeast are controlled by shear link slates and sandstones described by Fairweather structures between northwest trending faults (1980) between Clifton Creek and the (Cuffley, 1988). Wentworth River are probably examples of sandstone hosted mineralisation. Veins are lenticular, and commonly 100 to 200 m in length. They are steeply dipping, and Gold is associated with Ca-Fe-Mn alteration, commonly associated with refolded bedding or hydrothermal sericite, chlorite and sulphides in cleavage. Wall (1988) identified a spectrum of veins and host rocks (Wall, 1988). Significant pyrite, plus variably arsenopyrite, galena, 32 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Figure 8 Gold vein orientations, Bairnsdale 1:250 000 map area.

chalcopyrite and cobaltiferrous manganese are Dargo goldfield associated with mineralisation. Auriferous quartz veins mined within the The Beehive mine is the largest producer Dargo goldfield are hosted by the Dargo within the goldfield. Ore from this mine varied Granodiorite and enveloping hornfels. Veins in grade between 9 and 80 g/t, averaging 17 g/t worked by the Comet, Jorgensons, Two Cs and gold. Ore from the four highest producers Trail of the Serpent mines occur within the within the goldfield had average grades of granodiorite, and are characterised by galena between 16 and 19 g/t gold. and calcite selvedges (O'Shea et al., 1994). These veins trend northeast, which is Cobbannah goldfield perpendicular to the regional trend (Fig. 8).

Auriferous quartz veins occur at the contact of The Exhibition Reef occurs within hornfels the Castleburn Tonalite and hornfels close to close to the contact of the Dargo Granodiorite Mount Budgee Budgee. The Budgee Budgee (Anon., 1947). The Exhibition was the largest mine worked mineralisation associated with producer in the goldfield, and mined ore quartz veins and surrounding alteration zones averaging 31 g/t gold. Gold occurs in quartz in hornfels. Mineralisation is associated with veins and surrounding alteration zones. This minor pyrite and chalcopyrite (Dunn, 1890). gold is in part refractory; pyrite tailings Drainage and soil geochemistry (EL 703) analysed in 1887 grading 2300 g/t gold (O'Shea indicate anomalous gold within this granite. et al., 1994). Several other mines, including the Little Exhibition and Perseverance, were also developed on quartz veins hosted by hornfels adjacent to the Dargo Granodiorite. These GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 33

mines typically averaged in excess of 20 g/t 2 km strike to depths up to 150 m. Steeply gold. northeast dipping ore shoots commonly exceed 2.5 m thickness. Grades of shoots are typically The Dargo Granodiorite has a distinctive high, varying between 12 and 241 g/t gold signature in aeromagnetic data. Data show up (Murray, 1896). Graphitic material is to three magnetic kernels surrounding a associated with mineralisation in several magnetic core, indicating multiple intrusive shoots. events. Gold mineralisation occurs between two of these kernels. Gladstone Creek goldfield

Dargo High Plains goldfield Rare gold bearing quartz veins are hosted by Upper Devonian sandstone of the Moroka Glen Auriferous veins in the Dargo High Plains Formation. Gold is associated with pyrite, trend northwest, and are coincident with chalcopyrite and calcite. Murray (1895) stated northwest trending lineaments interpreted that several hundred ounces of coarse gold was from aerial photographs by Cozens (1985). The mined from Boyces Find (Kenny, 1938); Evening Star mine is the largest producer in although there is no official record of this the goldfield, and had an average grade of 23 production, or production from other mines g/t gold. Other significant producers averaged with in the goldfield. very high grades including 55 g/t at the Hope mine and 258 g/t at the Homeward Bound mine. Grant goldfield Despite these grades, mines were commonly abandoned at relatively shallow depths. Auriferous quartz veins within the Grant Development of these mines may have been goldfield occur in Hotham Group turbiditic uneconomic because of: sediments and undifferentiated dykes. The Good Hope mine was the largest producer in · increased costs associated with deep mining the Grant goldfield. It was mined to a depth of - including mine infrastructure, and treating 263 m, and averaged over 43 g/t gold. The mine sulphidic ore; and was developed on a set of sub-parallel, fault · high costs associated with the remoteness of controlled auriferous quartz veins. the goldfield. Mineralisation is associated with trace pyrite, arsenopyrite, galena, chalcopyrite, and This is probably true for mines in many of the sphalerite (O'Shea et al., 1994). Shoots within remote goldfields of BAIRNSDALE, including veins pitch toward the east (Dunn, 1907). The the Grant, Haunted Stream and Shady Creek, Jolly Sailors and Lone Hand mines were Dargo and Cobbannah goldfields. developed on auriferous quartz veins controlled by faults at the margin of a 0.6 m wide dyke Argillic, sericitic, and chloritic alteration, plus (Anon., 1947). The Vulcan Reef, worked by the elevated arsenic and copper values are Union and Dorritt mine, is also adjacent to a associated with some auriferous veins within dyke (O'Shea, 1994). the goldfield (Hochwimmer, 1988). Cozens (1985) reported chalcopyrite, galena and Many mines within the Grant goldfield sphalerite occurring with gold at the Mammoth produced only moderate amounts of gold mine. despite very high grades; typically greater than 20 g/t. These mines generally did not exceed Deptford goldfield 40 m in depth.

Auriferous quartz veins mined within the Haunted Stream and Shady Creek goldfield Deptford goldfield are fault controlled and trend NW - parallel to the Kiewa Fault. The Haunted Stream goldfield straddles the Detailed reports on three contiguous mines, the Kiewa Fault which divides the Harrietville - New Enterprise, Deptford Proprietary, and Dargo and Benambra gold provinces. Gold is Donnelly Brothers (Murray, 1896; Easton, hosted by quartz veins with relatively few 1936) indicate vein sets can be mineralised over sulphides. Unlike mines of the Benambra gold kilometres of strike. The Tubal Cain, Success, province, there are no reports of high sulphides and Duke are parallel veins spanning 56 m retarding the recovery of gold. (true width) in the New Enterprise Mine. Numerous diorite dykes are reported in close These veins have been selectively mined over a proximity to the mineralised veins. Quartz 34 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

veins of Haunted Stream were typically of low Benambra gold province grade, but were wide and in soft, easily worked stone (Fairweather, 1975). Gold was generally Within BAIRNSDALE, the Benambra gold restricted to these veins and stockworks, but province coincides with the Omeo and Buchan values also occurred in the host sediments. structural zones which lie between the Kiewa Larger mines were either multiple shoots from Fault in the west and the Yalmy Fault in the a single vein, or multiple veins aligned close east, and are separated by the Indi Fault together (O'Shea et al., 1994). Veins trend (Fergusson, 1988). These zones correspond to north and northwest. The mineralised zone the Wagga and Kosciusko basement terranes of follows the Kiewa Fault which trends White and Chappell (1988). northwest. Within BAIRNSDALE, the Benambra gold The Rob Roy and Hans reefs were the largest province covers the Omeo, Swifts Creek, New producers in the Haunted Stream and Shady Rush Creek and Tara goldfields. Mines within Creek goldfield. The Rob Roy Reef dips these goldfields have produced 5127 kg of gold between 52° and 64° towards 210°, and was and an unknown quantity of silver. Major worked along strike by several mines (Murray, primary gold producers are listed in Table 7. 1887). Deposits are characterised by auriferous and The Hans Reef was discovered in 1884 and is a argentiferous quartz veins with high sulphide complex of auriferous veins of highly variable contents and base metal values (Ramsay & length and width, ranging from a few Willman, 1988). These veins trend north-south. centimetres to over a metre wide. The Hans Protore gold is largely refractory and commonly Reef dipped between 80° and 90° towards associated with pyrite, chalcopyrite, between 030° and 040° (Murray, 1887). The arsenopyrite, galena, sphalerite and pyrrhotite. mine was the deepest on the field at 110 m, and The majority of deposits within the Benambra the vein was up to 61 m long and 3 m wide. gold province lie within a narrow zone from The nearby Magazine shaft, on a vein which Cassilis to Bethanga, over 100 km north was also worked by the Hans mine, had a (Ramsay & Willman, 1988). similarly steep dip, but dipped towards 315°. It was about 18 m long and over 4 m wide Omeo, Swifts Creek and New Rush Creek (Whitelaw, 1899). goldfields

Yahoo Creek goldfield Gold mineralisation over Omeo, Swifts Creek and New Rush Creek goldfields occurs in Mined veins within the Yahoo Creek goldfield boudinaged quartz veins hosted by rocks of the trend north-south. Detailed reports on the Omeo Metamorphic Complex and Hotham Fizzle Reef, which hosts several historic high Group, and within granite (Mann, 1996). Veins grade shoots, indicate the quartz vein is fault are generally controlled by north trending controlled (Easton, 1937; Hawke, 1909; fissures, and are typically narrow. Whiting, 1956). One of these shoots worked by the Dreadnought Mine - 0.6 m thick, 34 m long, Gold is associated with unusually high levels of and open at 76 m depth, returned grades sulphide. Gold is largely refractory, and occurs between 32 and 128 g/t gold. Chlorite and with pyrite, sphalerite, galena and arsenopyrite graphite are associated with this (Rosales 1897). This led to the abandonment of mineralisation. Most mines worked parallel many mines once the free gold occurring in the veins within a 200 m wide, 1.5 km long north- upper, oxidised zone had been extracted. Even south fault corridor. in the oxidised zone, high sulphide levels reduced gold recovery. In the early 1900s, Auriferous veins were first worked from 1888 to several plants designed to recover gold from early 1890, and again from 1898 until World sulphide were introduced to the goldfields War I (Whiting, 1956). Mining has been (Fairweather, 1975) which facilitated a boom in attempted at various times from 1930 to the mine production. present. Reported production is small which is surprising given shaft depths in excess of 70 m. Average grades vary from high - 17 g/t, to very high - 143 g/t. GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 35

Table 7 Major primary gold producers within goldfields of the Benambra gold province

Mine Goldfield Production Average (kg) Grade (g/t)

Samaritan Omeo 21 53 Surprise Reef Omeo 20 104 Cassilis Swifts Creek 2188 30 Perseverance Swifts Creek 131 10 Warden Swifts Creek 119 69 King Cassilis Swifts Creek 88 16 Grassmere Swifts Creek 54 107 Monarch of Tara Tara 5 148 Micawber Tara 1 47

Figure 9 Cassilis mine, c.1910. Photo, Minerals & Petroleum Victoria collection.

The Cassilis gold mine, which was discovered in than 320 m. The Ceresa, Crisps, Blacksmith, 1858 (Christie, 1993) is BAIRNSDALE’s largest Snake and New veins lie close to the Cassilis gold producer (Fig. 9). The mine comprised vein, and dip 70° towards between 041° and twelve levels, which vary in length between 088°. Veins are characterised by quartz veins 130 m and 300 m (MacLennan, 1987). The containing gold and sulphide, localised by Cassilis vein dips at 70° towards between 095° fractures and shears. Host rocks are and 115°, and has a strike length of greater interbedded psammite and lesser pelite of the 36 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Omeo Metamorphic Complex (MacLennan, chalcopyrite within quartz veins and adjacent 1987). Quartz veins are from 0.01 to 0.5 m sandstone (Waterfield, 1991; Colliver, 1993). wide, and pinch and swell along strike. Gold is associated with elevated copper, bismuth, selenium and tellurium values. Cassilis ore was highly refractory, and contained arsenopyrite, pyrite, sphalerite, Major mines were the Tara Queen, Micawber, galena, antimony sulphide, magnesium and Little Cash Box, Surprise and Orbost. Gold was aluminium silicates, silver, and some copper. also taken from narrow veins in the Lady Torr Production at the Cassilis mine was first Creek area (VandenBerg, et al., 1996). First reported in 1898. Production peaked in 1906; record of gold production is from 1904, from the before declining sharply in 1910. Tara Queen and Micawber mines . Mines continued to produce until 1920. From 1906, High grade silver commonly occurs with combined gold production is reported for the auriferous quartz veins (Dunn, 1912). Despite goldfield, and contributions from individual this, it was not extracted until 1911 when G. W. mines is not known. Forsyth discovered a series of particularly rich silver veins. Techniques for recovering The Tara Queen mine was developed on a 1 m refractory gold introduced in the early 1900s wide quartz vein. This vein trended 012° and also allowed the recovery of silver. was traced over 40 m. Reported production from two shallow shafts graded 24.1 g/t Forsyth's argentiferous quartz veins trend (VandenBerg, et al., 1996). The Micawber and north-south and are hosted by granitic gneiss Little Cashbox mines were developed on and mica schist of the Omeo Metamorphic parallel narrow quartz veins separated by 90 m. Complex (Dunn, 1912, Easton, 1923). At least High grade gold was recovered from the veins four of these veins were developed by the Auro and Pinnak Sandstone adjacent to the veins. Argentum (Silver King ) and Auro Argentum Extended (Comstock) mines. Silver probably The Orbost mine and workings along Lady Torr occurred as argentite. Veins ranged from 0.08 Creek were developed on steeply dipping, to 0.60 m thick and cropped out over at least northeast trending zones of brecciated, silicified 180 m along strike (Dunn, 1912). The total and ferruginous Pinnak Sandstone. Drilling at width of the band containing the veins was the Orbost mine intersected significant pyrite about 180 m. and chalcopyrite associated with gold in this zone (EL 3245; Brookes & Boyle, 1996). Best The Silver King No. 1 vein was accessed by intersection was 11.1 m @ 0.51 g/t gold, 0.46% open cut (3.7 m deep) and adit (37 m long). The copper from 100.9 m; including 1.5 m @ 1.82 g/t vein was sinuous, and not sharply defined. It gold, 0.79% copper. Copper is also present was traced for about 24 m, dipping steeply along Lady Torr Creek; with Dunn (1907) towards 115° (Easton, 1923). The first sample reporting native copper in a 21 m deep shaft. of ore from this vein graded 29.4 kg/t silver. This is the deepest reported shaft in the Despite 35 t of ore being produced by the goldfield. Victoria River Coal and Shale Co., and the mine appearing profitable, work was discontinued These Tara goldfield deposits have not been sometime in the 1920s (Fairweather, 1983). studied in detail and may be related to nearby ?epithermal gold and base metal mineralisation Tara goldfield hosted by Snowy River Volcanics (see Chapter 3.5). There is a strong spatial association The Tara goldfield covers quartz-gold veins in between these two styles of mineralisation. Ordovician Pinnak Sandstone north of Nowa Nowa. Pinnak Sandstone is bounded to the 3.4 Lower Devonian volcanic east and west by Snowy River Volcanics, and is interpreted to be controlled by normal faulting hosted metal deposits in the Kanni Horst. Mineralisation is controlled by subvertical shear zones which Vein, disseminated and bedded mineralisation broadly trend north, parallel to normal faults of occurs in the Lower Devonian Snowy River the Kanni Horst. In outcrop, mineralised zones Volcanics and Mount Elizabeth Caldera are characterised by siliceous breccia and Complex. gossan. Mineralisation is characterised by free and refractory gold, plus pyrite and GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 37

Zones of low temperature auriferous and Pyramid Mountain and Eel prospects argentiferous quartz veining accompanied by silicification, and clay-sericite-chlorite The Pyramid Mountain and Eel prospects are alteration and brecciation of host Snowy River hosted by a thin sequence of undifferentiated Volcanics occur north of Buchan (Orth et al., Snowy River Volcanics underlain by Silurian 1995). These characteristics are indicative of Yalmy Group. Mapping and airborne magnetic epithermal mineralisation. Mineralisation data indicate these rocks are shallowly occurs within early and late units of the Snowy underlain by the I Type Rodger River Granite. River Volcanics suggesting multiple, or a single In outcrop, this rock is porphyritic, and has late Lower Devonian mineralising event contact relationships consistent with a late associated with volcanism. Major occurrences Silurian emplacement. Similar intrusives at are the Pyramid Mountain, Eel, W-Tree Creek, the margin of the Buchan Rift host currently Halls Peninsula prospects and Glen Shiel Silver uneconomic porphyry copper deposits. While mine. Descriptions of these occurrences given timing relationships between the Rodger River below are taken from Orth et al. (1995) and Granite and Snowy River Volcanics preclude Brookes and Boyle (1996). the granite as the primary source of metal proved at epithermal prospects, spatial Indications of similar mineralisation are relationships and granite pedigree suggest reported from the Tara goldfield, Nowa Nowa, remobilisation of porphyry copper Kanni Creek and Mount Elizabeth Caldera mineralisation associated with the Rodger Complex. Descriptions of these occurrences River Granite into the overlying Snowy River given below are taken from VandenBerg et al. Volcanics. The Rodger River (Preussag) lead- (1996) and Simpson et al. (1996). Additional zinc prospect also lies within this area, and may work is required to determine the exact genesis have a similar origin. of these occurrences. Significant widths of low grade gold Volcaniclastics of the Fairy Sandstone and mineralisation occur in altered and brecciated Spring Creek Member commonly contain acid volcanic rocks at the Pyramid Mountain detrital base metal sulphide grains of prospect. The prospect has been investigated exhalative origin. This mineralisation is of low under ELs 1203 and 1204. Altered and grade, and exploration companies have had no brecciated rocks crop out over a 300 m by 30 to success in locating the source of the 80 m zone which trends 300° and is steeply mineralisation. Targets include massive dipping. Alteration is characterised by sericite - sulphides or stockwork mineralisation which chlorite-clay alteration overprinted by low may be associated with volcanic centres or temperature quartz. Results from drilling small vents and fumaroles. In most instances, downgrade the potential for economic bulk, low host rock facies indicate water depths grade resources, but leave scope for high grade compatible with these styles of mineralisation. bonanza style mineralisation. Best Major prospects and occurrences are the Shaws intersections from three diamond holes drilled Gully prospect, lead occurrence by BHP were 103.8 m @ 0.49 g/t and 8 m @ 1.38 and Blue Bullocks Creek prospect. Descriptions g/t gold (Brookes & Boyle, 1996). of these occurrences given below are taken from Orth et al. (1995). Low grade stratiform galena- Widespread quartz veining with potassic and sphalerite mineralisation was also intersected sericitic alteration and minor pyrite at the Eel in drilling of the Johnson Mudstone at the prospect was investigated by WMC under ELs Flukes Knob prospect (EL 1228). 1240 and 1241. Two drill holes designed to test anomalies in transient electro-magnetic and IP Massive iron and manganese (barite) deposits data intersected strongly silicified zones with with elevated copper, lead, zinc and silver also up to 10% pyrite and clay. Selective sampling occur at this stratigraphic level at the Oxide of core indicated low gold (less than 2 g/t) and mine and at Iron Mask. The genesis of this base metal grades (Orth et al., 1995). WMC mineralisation is uncertain, but probably considered elevated tellurium indicative of represent an element in the spectrum of epithermal mineralisation. mineralisation styles which range between carbonate hosted and volcanic hosted exhalative. Descriptions of these deposits given below are taken from VandenBerg et al. (1996). 38 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

W-Tree Creek Dunn (1907) reported that a 10 tonne parcel of hand picked ore graded 900 g/t silver and 7 g/t The W-Tree Creek prospect has been gold. Recent testing under ELs 50, 552, 1203 investigated under ELs 564, 1203 and 1659 and 1659 has not been able to replicate this (Brookes & Boyle, 1996); and covers scattered result (Brookes & Boyle, 1996). quartz veins which outcrop over a large area. Veins have gold values up to 8 g/t, and are Tara goldfield associated with widespread pyrite-sericite - kaolinite alteration. Two main zones of Zones of auriferous stockwork quartz veining mineralisation were identified by exploration - are hosted by altered and brecciated Jellung the Discovery Fault and Eastern Vein. The Ignimbrite, silicic lava, and other Discovery Fault trends north-south and cuts undifferentiated units of the Snowy River Raymond Falls Lava and Fairy Sandstone. In Volcanics. The Tara Crown, Monarch, and outcrop, this fault consists of a 2 m wide zone of Dominion mines of the Tara goldfield were chalcedony, ferruginous breccia and fine comb developed on this mineralisation. Deposits quartz, and is associated with widespread occur close to normal faults of the Kanni Horst. pyrite-sericite-kaolin alteration. A fluid Large jasper and ferruginous alteration zones inclusion in gold bearing Discovery Fault are mapped where the Kanni Horst pinches out quartz had a salinity of 14.3 wt% NaCl, and in the north (VandenBerg et al., 1996), and may indicated a formation temperature of 135°C. represent a prospective dilatational zone. Northeast of the W-Tree Creek Prospect, low level gold anomalies were identified by The Dominion mine was developed on a Preussag at Camp Creek South. No drilling has massive auriferous quartz vein which crops out been undertaken at either prospect to test over 90 m, and can be traced over 1100 m. The mineralisation at depth. vein dips steeply east and trends northeast, and is hosted by undifferentiated volcanic and Halls Peninsula volcaniclastic rocks. Gold occurs with chalcopyrite, pyrite, galena and silver. This The Halls Peninsula prospect has been mineralisation is reported to have averaged 47 investigated under ELs 50 and 536, and covers g/t gold and 252 g/t silver. A detailed stockwork veined sericite-chlorite altered, and description of the Dominion mine is given in silicified Bally Hooley Ignimbrite. One drill Cochrane (1982). hole testing this alteration zone intersected quartz veins which assayed up to 1.35% copper The Monarch (Monarch of Tara) mine was and 52 g/t silver (Brookes & Boyle, 1996). developed on stockwork quartz veining which Pyrite and chalcopyrite occur in quartz veins broadly trends north-south, and is hosted by which also have elevated lead, zinc, bismuth silicic lava. Veins are auriferous and also carry and gold values. Later rock chip sampling significant pyrite, plumbojarosite and barite showed quartz veined rocks in a 1500 m long (Gregory & Kerr, 1989). Mineralisation was zone have an average gold value of 0.4 g/t. worked over a length of 80 m, and to a depth of Similar mineralisation was delineated on the 10 m. Drilling by ICI-Newmont (EL 512) failed opposite side of the Snowy River by Preussag to intersect similar mineralisation at depth. under EL 1203 (Orth et al., 1995). Waterfield and Aravanis (1992) mapped an inner zone of pervasive sericite-kaolinite Glen Shiel silver mine alteration, and an outer zone of strong silicification coincident with mineralisation. The Glen Shiel argentiferous vein was first Average ore grades were 148 g/t gold. Elevated reported in Anon. (1894). Small pits and copper, lead, zinc and silver values occur with shallow shafts are aligned along a 0.5 to 3.0 m gold. wide quartz vein hosted by Gelantipy Ignimbrite and Glen Shiel Ignimbrite. Similar The Tara Crown (Armistice) mine was veins are reported in the neighbouring area. developed on intensely altered and brecciated Lattice textured vein quartz on Glen Shiel mine Jellung Ignimbrite with massive to stringer dumps suggests hydrothermal boiling indicative style quartz veining. This style of of epithermal mineralisation. Quartz contains mineralisation occurs in several areas, and has up to 5% disseminated pyrite with minor pink been mined in at least three of these. Veins are barite, specular haematite, chalcopyrite, and subvertical and broadly trend northeast. traces of galena and either argentite or silver. Pyrite, chalcopyrite, argentiferous galena, GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 39

arsenopyrite and calcite are recorded from Shaws Gully prospect auriferous quartz veins. Cochrane (1982) described strong alteration, including kaolinite Detrital sphalerite and galena occurs within a and disseminated pyrite, accompanying complex volcanic-sedimentary unit within the mineralisation. Mined ore was extremely high Fairy Sandstone. This unit is between 20 and grade. Best assays from sampling by Easton 40 m thick and crops out over a strike length of (1959) were 4.4% copper, 4.6% lead and 190 g/t 5 km from the Buchan-Basin road in the south silver. Drill testing by Preussag (EL 1203) to the Shaws Gully prospect in the north (Orth showed gold was concentrated in narrow zones, et al., 1995). Jennings and Preussag (EL 1203) and probably upgraded by supergene processes. showed the unit had elevated lead and zinc values over its entire length. Highest values Nowa Nowa were recorded from the Shaws Gully prospect where coincident zinc and lead soil anomalies Possible epithermal alteration and corresponded to an exhalative chert-barite lens. mineralisation crops out near Nowa Nowa. The Two drill holes designed to test for an contact between the Yalmy Group and Snowy exhalative source of detrital sphalerite and River Volcanics is exposed in Boggy Creek galena intersected mostly background zinc and north of Nowa Nowa. It is marked by an area lead, plus a thin sulphidic breccia band. of advanced argillic alteration closely associated with a late cross cutting fault. Alteration is New Guinea lead occurrence well developed in both quartzite and ignimbrite along this structure. In quartzite, alteration is Detrital galena and chalcopyrite grains also characterised by fine grained silica with occur in volcaniclastics of the Spring Creek disseminated pyrite, minor chalcopyrite, Member of the Buchan Caves Limestone at pyrophyllite and haematite. A similar New Guinea. This occurrence received cursory assemblage occurs in the ignimbrite on the investigation by Preussag (EL 1203) and north side which also contains abundant Newmont (EL 536). hydrothermal veins. The area between New Guinea and The Basin Kanni Creek contains numerous minor syn-depositional mineral occurrences hosted by volcaniclastics of Cochrane (1982) described vein and either the Fairy Sandstone or Spring Creek disseminated barite within the Rankin Road Member. Cochrane (1982) describes these Ignimbrite at Kanni Creek. Barite is associated occurrences and summarises exploration with massive limonitic bands, and minor pyrite, programs testing the area. No massive magnetite, specular haematite, and mineralisation has been found as yet despite chalcopyrite. the presence of weakly mineralised black pyritic shales, zones of iron, barite and manganese rich Mount Elizabeth Caldera Complex volcaniclastics, and quartz stockworks. Orth et al. (1996) suggested that this was unlikely Recent mapping of the Mount Elizabeth given the small exposure of prospective Caldera Complex by Simpson et al. (1996) has stratigraphy is largely non-marine. identified a number of alteration zones close to the margin of the volcanic pile. Alteration is Blue Bullock Creek prospect characterised by silicification and disseminated pyrite with patchy chlorite and haematite. Siliceous ash deposits interbedded with other Numerous ring and radial fractures volcaniclastics and shale of the Spring Creek surrounding the Mount Elizabeth Caldera have Member, outcropping in Blue Bullock Creek, also been identified (Simpson et al., 1996), and contain galena and sphalerite, together with may be favourable sites for epithermal narrow zones of abundant pyrite. Mineralised mineralisation. rock samples collected by Newmont (EL 536) returned average values of about 0.2% lead and 0.6% zinc (Orth et al., 1995). 40 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Table 8 Major alluvial gold producers within goldfields of BAIRNSDALE

Mine Goldfield Production (kg)

Bullumwaal Gold Dredging Bullumwaal 15 Dargo Gold Dredging Dargo 22 Whites Claim Dargo High Plains 64 Crooked River Dredging Grant 71 Hinnomunjie Gold Dredging Omeo 1031 Harrington Dredging Omeo 345 Tongio Gold Dredging Swifts Creek 332 Omeo Gold Dredging Swifts Creek 10

Oxide mine Two vertical shafts, 30 and 22 m deep, plus several drives (Marlow, 1988) indicate The Oxide mine is comprised of several narrow significant mining, although no record of massive manganese oxide lenses in kaolinised production is available. Murray (1896) reported and haematitic Jellung Ignimbrite (Cochrane, that massive mineralisation yielded between 1975). The deposit lies along a fault separating 10.7 and 67.3 g/t gold. Recent testing has also Jellung Ignimbrite and Buchan Group indicated elevated copper, lead, zinc and silver. Limestone (Marlow, 1988). 3.5 Placer gold deposits Manganese oxide was mined from an open cut and shaft. The McRae brothers mined red Recorded gold production from placer deposits ochre from an adit driven below the open cut within BAIRNSDALE is 4517 kg, or one third of (Cochrane (1975). Drilling by ICI-Newmont the total recorded BAIRNSDALE gold under EL 512 gave a best intersection of 5.8 m production. Howitt (1886) reported that @ 0.9% zinc, 7 g/t silver and 0.17 g/t gold from alluvial placer deposits within the Omeo, Swifts pervasively kaolinite and ferromanganese Creek and New Rush Creek goldfields were altered rock (Brookes & Boyle, 1996). almost exhausted by 1879 after 25 years of mining. Given that systematic recording of Iron Mask production from alluvial placer deposits commenced after this date, in 1886, reported The Iron Mask deposit is comprised of massive production is probably significantly fine grained haematite, limonite and understated. manganese oxide. Massive early mineralisation is cut by stockwork barite and quartz-pyrite Major alluvial gold producers within veins (VandenBerg, et al., 1996). The deposit BAIRNSDALE are listed in Table 8. trends east, and crops out over 100 m. Drilling and costeaning show that massive Production is from placer deposits hosted by mineralisation is "underlain by a coarse Cainozoic alluvium. In most instances, the andesite breccia" and dolostone (Alkemade, primary source of this gold has been shown to 1980). Both of these host rocks are deeply be precious metal veins within alluvium weathered. Contact relationships between the catchments. deposit and andesite are unclear, but disseminated, blebby and banded pyrite-galena- In addition to Cainozoic alluvium, there is sphalerite-chalcopyrite reported by Adams potential for placer deposits in conglomerates (1982) in dolostone suggest a which include large amounts of primary gold gradational/conformable contact between host material. These include conglomerates of massive mineralisation and dolostone. Results the Moroka Glen Formation, the Mount Tambo of exploration under ELs 512 and 1203 are Group and basal conglomerates of the Snowy summarised in Brookes and Boyle (1996). River Volcanics. Conglomerates of the Moroka GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 41

Glen Formation may be a source of gold for alluvial gold production for the Omeo, Swifts Cainozoic auriferous placer deposits at Creek and New Rush Creek goldfields is Gladstone Creek. significantly understated. In contrast to primary gold production which virtually ceased Omeo, Swifts Creek and New Rush Creek prior to World War I, alluvial production goldfields continued until the 1920s (Fig. 6).

Within the Omeo, Swifts Creek and New Rush Dargo High Plains goldfield Creek goldfields gold occurs within Recent alluvium and shallow leads, which are Significant placer gold deposits occur in Recent generally close together. Alluvial workings are alluvium and high terrace remnants of Tertiary concentrated about primary gold deposits. alluvial gravel. Recent alluvial deposits were Howitt (1879) reported that alluvial mining worked in and adjacent the Cobungra River within the Swifts Creek goldfield concentrated north of Mount Battery, and Brandy Creek. on Swifts Creek between the junctions with Tertiary deposits including deep leads, were Eureka Creek and the Tambo River; in Sheep also worked at Brandy Creek, and with less Station Gully; and along most of Rileys Creek. success at 25 Mile and 30 Mile creeks. From Apart from this report, very little information is 1884, deposits at Cobungra River, Brandy and available on alluvium mining prior to 1886. Murphys creeks were worked by hydraulic sluicing. The most important alluvial prospects within the Omeo goldfield were the Oriental Claims, Deep lead placer gold deposits are hosted by near Omeo. Millin (1983) reported 42 000 oz of high terrace remnants of Tertiary gravel gold were produced from these claims, largely overlain by an Older Volcanic basalt flow in the by hydraulic sluicing. Unconsolidated Upper Dargo High Plains goldfield. Gravel is exposed Tertiary alluvium up to 45 m thick, overlie on steep slopes where basalt is dissected by micaceous schist bedrock adjacent to modern drainage. The continuity of gravel is Livingstone Creek. The alluvium is masked by scree, and it is unclear whether characterised by poorly sorted quartzose gravel is confined to palaeochannels or is sediments ranging from boulders to clays, with relatively continuous (Canavan, 1988). The rounding and sorting increasing and grain size distribution of deposits is consistent with a decreasing towards the east. These sediments north-south trending palaeochannel. Whites are, for the most part, auriferous throughout, Claim, in the headwaters of Brandy Creek, with occasional 'false bottoms' of whitish selectively worked Tertiary gravel between gravelly wash. Millin (1983) considered that 1878 and 1883. Selective mining was replaced the other alluvial deposits near the township, by sluicing in 1884 to exploit low grade gold in for which a further 16,000 oz of gold production the gravel. Operations ceased in 1894 because was reported, had similar characteristics to this of the expense of treating cemented gravel deposit. The average reported grade for the and/or difficulty tracing the auriferous lead. Oriental Claims was 0.41 g/m3 (after 20-25% (O'Shea et al., 1994). loss during sluicing). The alluvium deposits cover about 100 ha, of which area the Oriental Grant, Dargo and Cobbannah goldfields Claims area may account for about 20%. Activity was halted in 1904 by the Sludge Worked placer deposits occur in Recent Abatement Board because of tailings alluvium in and adjacent to Good Luck Creek, into Livingstone Creek (Millin, 1983). and the Crooked, Dargo and Wentworth rivers. These were mostly selectively mined. Small Millin (1983) reported a deep lead overlain by scale dredging was undertaken on the Dargo basalt south of the Oriental Claims - no other and Crooked Rivers between 1906 and 1912. references to this lead were found in the The Crooked River Dredging Co. operated on literature. the Crooked River between 1907 and 1911. Total gold produced was in excess of 91.2 kg, Fifteen operators working alluvium after 1886 with an average yield of 0.21 g/bcm. have been identified from the literature, although undoubtedly many more were active, especially during the latter half of the 19th century. Given this and the limited official recording of alluvial production, reported 42 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

granite (Whitelaw, 1895) and epithermal (O'Shea et al., 1994) source for primary gold. These sources have not been proven. Gold values from quartz veins in the Mount Taylor Granite are low, however dykes on Prospect Creek are weakly altered and contain trace sulphides (Wall, 1987).

Tara goldfield

Small placer gold deposits occur in Recent alluvium in and adjacent the Loongelaat and Creamy creeks (Anon, 1897). North of Buchan, outside the Tara goldfield, small placer gold deposits in Recent alluvium are reported from drainages near the summit of Gil Groggin, and a creek draining Campbells Knob (VandenBerg et al., 1996), although no official production is recorded for these areas.

3.6 Silurian volcanic associated massive sulphide (VAMS) deposits

Figure 10 Mahony (1925) reported numerous base metal Exploration drilling at Benambra by WMC, c.1975. Photo, and silver shows identified by prospectors Minerals & Petroleum Victoria collection. within the Cowombat Rift; but it was not until after the discovery of the Woodlawn volcanic Haunted Stream and Shady Creek goldfield hosted massive sulphide deposit in NSW that the rift was investigated for similar deposits. Small placer gold deposits in Recent alluvium This work focused on the sequence of Silurian occur in and adjacent to the Tambo River, marine volcanics and sediments within the Haunted Stream, Shady Creek, Monkey Creek, Limestone Creek Graben. Lankys (Lankies) Creek, Ramrod Creek, Stuarts (Stewarts) Creek, Carrs Flat and Dead The Wilga copper-zinc-silver volcanic associated Horse Creek. These were mostly selectively massive sulphide (VAMS) deposit was mined. Sluicing of the banks of the Tambo discovered within the Limestone Creek Graben River was undertaken from 1873 but was short in the late 1970s (Fig. 10). Details of lived. exploration and discovery of the Wilga deposit are given in Brookes and Boyle (1996). Mining Bullumwaal, Deptford, Store Creek and Yahoo commenced in late 1992 and concluded in mid Creek goldfields 1996. Prior to mining, Wilga had proven reserves of 0.64 Mt at 9.45% copper, 0.09% lead Significant placer gold deposits occur in Recent and 2.39% zinc, with probable silver and gold alluvium in and adjacent to the Nicholson grading 38 and 0.16 g/t respectively. Up to the River, the Prospect (Boggy), Yahoo, Store, and end of the 1996 financial year, a total of 0.95 Mt Clifton creeks and their tributaries. Whitelaw of ore had been mined, and 0.94 Mt of ore reported "the coarsest gold in Gippsland" in treated for 213 325 t of copper concentrate, 46 alluvium at Store Creek (Whitelaw, 1895). 299 t of zinc concentrate, and in excess of 10 These deposits produced large amounts of gold 136 kg of silver (Table 3). prior to the 1900s, when the focus of alluvial mining shifted to the Omeo and Swifts Creek The geology of the Wilga deposit is summarised goldfields (Fig. 6). in Allen and Barr (1990). Wilga is an ellipsoidal lens, consisting predominantly of The distribution of placer deposits, plus massive pyrite-sphalerite-chalcopyrite, with morphology and fineness of gold in deposits chalcopyrite rich stringer zones at the north south of Bullumwaal has been used to suggest a and west margins. Both styles of GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 43

mineralisation have a pyrite alteration commonly located on regional structures. At envelope. The massive sulphide lens extends the Dogwood prospect, hypogene mineralisation 240 m down dip, and 300 m along strike, and is is upgraded at the intersection of these, and up to 37 m thick. It is subconformable with conjugate structures (Maher, 1994). Protore host Middle-Upper Silurian Gibsons Folly copper grades are typically low. Pyrite and Formation, which consists of interbedded subordinate chalcopyrite occur as volcanics, pyroclastics and volcaniclastics. This disseminations, joint coatings and in quartz formation is underlain by massive rhyolite of veins in granodiorite and host Ordovician the Thorkidaan Volcanics (Oppy et al., 1995) turbidites. Molybdenite occurs in quartz veins in most deposits. Host rocks are altered and Host sequences to the deposits are complexly fractured. faulted, resulting in repetition of sequences in a series of northeast trending belts. Faulting Cochrane (1982) attributed low copper grades to post dates emplacement of the deposits. root zone exposures of deposits. Colliver (pers. comm.) considered localisation of hypogene Allen (1987) proposed that mineralisation mineralisation in structures, and limited occurred by sea-floor, passive volcanogenic contact metamorphism about the Kaerwut hydrothermal processes within the centre of a Trondhjemite at the Dogwood prospect deep basin, in conjunction with ambient inconsistent with Cochrane's interpretation, sedimentation derived from the basin margins. and indicative of upper levels of a porphyry In 1990, Allen and Barr (1990) reclassified the system. A supergene chalcocite blanket was deposit as volcanic associated massive sulphide delineated by CRA Exploration in 1993 and - conceding that there is "no diagnostic evidence 1994 at Dogwood (EL 3012). While this that the deposit is exhalative". mineralisation is currently uneconomic, its recognition indicates new potential for A second, currently uneconomic massive porphyry copper deposits in BAIRNSDALE. sulphide deposit - Currawong, lies north of Additionally, its characterisation provides a Wilga outside BAIRNSDALE. Mineralisation vector to undiscovered acid leached porphyry lies near the base of the Gibsons Folly copper deposits. Formation, and is considered to have a similar origin to Wilga. The deposit has measured, Potential for gold associated with porphyry indicated, and inferred resources of 8.84 Mt @ copper deposits in BAIRNSDALE is indicated 1.9% copper, 0.7% lead, 4% zinc, 38 g/t silver by recently discovered porphyry copper-gold and 0.8 g/t gold (Wilkinson, 1995). mineralisation in the Lachlan Fold Belt of NSW. Wyborn et al. (1987) recognised an 3.7 Porphyry copper deposits association between these deposits and intrusives of the Boggy Plains Supersuite. Porphyry copper deposits are characterised by Although the Supersuite does not crop out in disseminated and stockwork copper BAIRNSDALE, associated deposits mineralisation associated with high level demonstrate the potential for gold in porphyry plutons (Evans, 1987). Numerous uneconomic copper deposits of the Lachlan Fold Belt. copper prospects with porphyry type characteristics were investigated by exploration The gold potential of BAIRNSDALE deposits is programs from 1968 to the present. Cochrane largely untested. Exploration programs (1982) listed five main prospects - Double Bull typically did not analyse soil samples and drill Creek, Sunday Creek, Mount Buck, Stringer core for gold, and stream sediment samples Knob, Tiger Creek, and three other possible analysed for gold do not adequately test porphyry copper occurrences - Campbells Knob, deposits. Maher (1994) reported low order gold Mount Elizabeth and . An anomalies in soil geochemistry data, and one additional prospect, Dogwood was discovered in significant intersection, 2 m @ 7.94 g/t gold, the 1980s. These prospects were identified by from RC-percussion drilling at the Dogwood follow up of anomalous copper (- molybdenum) prospect. Alluvial gold production is reported values in stream sediment data. Details of all from the Campbells Knob lead-zinc field, which prospects are given in Brookes and Boyle is interpreted to be a peripheral base metal halo (1996). about a porphyry copper deposit. Mineralisation is associated with high level oxidised I-type Silurian-Devonian intrusives, Mineralisation is associated with oxidised largely of granodiorite composition. These are plutons of the Bega Basement Terrane - Double 44 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Bull Creek, Sunday Creek, Stringer Knob and within quartz veins hosted by fractured Mount Buck prospects; and Kosciusko sandstone and granodiorite. The granodiorite is Basement Terrane - Tiger Creek and Dogwood chlorite-sericite altered. Eleven diamond holes, prospects, Campbells Knob, Mount Elizabeth totalling 2012 m, targeted polarisable IP zones and Mount Bulla Bulla (White & Chappell, within copper anomalies in soil (EL 86). Nine 1988). holes delineated an approximate resource of 2 Mt with 0.3% copper at the contact of the Mineralisation associated with plutons of the sandstone and granodiorite (Cochrane, 1982). Bega Basement Terrane lie along northeast Large areas with anomalous copper values in trending magnetic linears within, or defined by soil are untested by drilling, and may have the plutons of the Bette Bolong Group and potential for economic mineralisation given: Orbost Tonalite. These prospects were identified by regional stream sediment · in an acid leaching environment, copper ore geochemistry programs undertaken in the late zones may correspond to areas of copper 1960s. Aeromagnetic data and recent geological depletion in soils; and mapping indicate intrusives have shallow · for porphyry copper deposits, highest contacts with Ordovician Pinnak Sandstone, chargeable IP responses commonly reflect a and are currently being deroofed. Summaries pyrite zone separate from the main copper of geology and exploration history for deposits ore zone. are given in Cochrane (1982), VandenBerg et al. (1996) and Brookes and Boyle (1996). Results The Stringers Knob prospect also covers a large of geochemical soil and stream sediment area with anomalous copper in soil. Unlike the surveys are included in the BAIRNSDALE GIS Double Bull Creek prospect, IP data failed to data set. indicate significant polarisable zones, and as a consequence the prospect has not been drill The Bete Belong Group is associated with a tested. suite of narrow late altered dykes of uncertain composition. A number of these dykes have Sunday Creek prospect been mapped along the Old Bonang Highway around the Eleven Bob Granodiorite and Mineralisation at the Sunday Creek prospect is around the Feltis Farm Tonalite along Mount hosted by altered Feltis Farm Tonalite, which is Watt Track (VandenBerg et al., 1996). They locally capped by Pinnak Sandstone roof also occur east of BAIRNSDALE (Hendrickx et pendants. Exploration diamond drilling al., 1996) where they are associated with intersected sericite, secondary biotite and K- anomalous but patchy gold mineralisation. feldspar alteration at shallow levels, plus Those along the Old Bonang Highway are significant pyrite. Best protore intersection strongly altered and assays show anomalous from this drilling was 21.34 m @ 0.20% copper copper, zinc, and arsenic values (VandenBerg et (EL 86). Copper is upgraded by supergene al., 1996). enrichment in hole SC302. This hole intersected 27.44 m @ 0.30% copper as Double Bull Creek and Stringer Knob diagenite from the base of weathering. Drilling prospects targeted copper anomalies in soil geochemistry data, and geophysical anomalies. A 2000 sq m Mineralisation at the Double Bull Creek and molybdenum (plus copper) anomaly in soil is Stringer Knob prospects occurs at the contact of untested by drilling. By analogy with the the Bette Bolong-Double Bull Granodiorite and Dogwood prospect, this anomaly may represent Ordovician Pinnak Sandstone. Interpretation the centre of the hydrothermal system. If this of airborne magnetic data by Sands (1995) is the case, relatively low copper values may indicated large areas of Pinnak Sandstone reflect acid leaching and supergene enrichment. underlain by granodiorite, including the host Details of drilling and soil geochemistry are rocks to the Double Bull Creek and Stringer summarised in Cochrane (1982) and Brookes Knob mineralisation. This roof pendant bisects and Boyle (1996). the granodiorite and is coincident with a northeast trending low in airborne magnetic Booths Fancy copper mine is located 1.5 km data. north of the Sunday Creek prospect at the contact of diorite intrusives of the Feltis Farm At the Double Bull Creek prospect, chalcopyrite Tonalite and hornfelsed Pinnak Sandstone. and molybdenite occur as disseminations and Dunn (1909) reported on the mine which GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 45

consists of a shallow shaft, and an adit driven is the dominant sulphide, and averages 0.5% in 15 m along a quartz vein containing mineralised zones. Galena and sphalerite are chalcopyrite, pyrite and lesser galena. Mullock subordinate. Sulphides are present as sampling undertaken by BHP under EL 1633 disseminations, and within quartz veins. returned maximum assays of 1.9% copper and Cochrane (1982) reported high copper, lead, 7.8 g/t gold. The relationship between zinc, silver and molybdenum grades for some mineralisation at the Sunday Creek prospect veins. High grade gold, up to 225 g/t, was also and Booths Fancy copper mine is unclear. reported from quartz veins by Ferguson (1899).

Mount Buck prospect Apart from scattered shallow pits, only alluvial gold mining on Musk Creek draining Campbells Results from exploration programs covering the Knob is recorded within the field. Cochrane Mount Buck prospect indicate weak porphyry (1982) noted potential for bulk tonnage, low copper mineralisation. This work is grade lead-zinc-gold deposits in extensive summarised by Cochrane (1982). altered zones. This target is untested by Mineralisation is related to the northeast modern exploration. trending Orbost Tonalite, and occurs in fractured tonalite and resistant hornfels. Three Mount Bulla Bulla diamond drill holes showed minor chalcopyrite, sphalerite and molybdenite hosted in vein Cochrane (1982) considered stream sediment quartz (EL 86 & 460). Pyrite occurs in veins geochemistry covering the Mount Bulla Bulla and as disseminations. Holes targeted area indicative of porphyry copper polarisable zones identified by IP within copper mineralisation. Anomalous molybdenum, soil anomalies. copper and zinc values were returned from a 6 sq km area covering Ordovician rocks underlain Tiger Creek prospect by the Amboyne Granodiorite. Some box worked iron oxide bearing vein quartz was Cochrane (1982) reported several copper noted in cursory anomaly follow up (EL 92). occurrences in the Nunniong Pluton. The most significant of these was at the Tiger Creek Dogwood prospect prospect where best copper intersection from diamond drilling was 49 m @ 0.23% copper Mineralisation at the Dogwood prospect lies (EL 83). Tiger Creek was the first of several within the Kiewa Fault corridor. Hypogene porphyry copper prospects identified in stockwork vein hosted and disseminated BAIRNSDALE by regional stream sediment copper-molybdenum mineralisation is hosted by geochemistry programs. Mineralisation is the recessive epi-Silurian I-type magnetic associated with sericite and chlorite alteration, Kaerwut Trondhjemite and apophyses, and silicification and development of epidote, resistant silicified crackle brecciated Ordovician leucoxene, carbonates and albite. Significant turbidites. Protore grades commonly exceed pyrite, between 1 and 10%, occurs in the 0.3% copper as chalcopyrite, and high grade vicinity of mineralisation. Cochrane (1982) also zones are localised by northeast trending described upgrading of copper between 30 and conjugate faults. A magnetite destructive 45 m depth, which may represent supergene ?overprint masks regional magnetic features enrichment of protore mineralisation. Other over a 2 km radius about the Trondhjemite copper stream sediment anomalies and copper (Maher, 1994). occurrences within the Nunniong Pluton are Fern Tree Creek, Gap Creek, Scorpion Creek, A supergene chalcocite blanket overlying Red Steer, Snake Creek and Blackfellow Creek porphyry copper-molybdenum mineralisation south of Tiger Creek. was delineated by CRA Exploration under EL Campbells Knob lead-zinc field 3012 at the Dogwood prospect (Maher, 1994). Best drill intersection at the Dogwood prospect The Campbells Knob lead-zinc field is centred was 24.40m @ 0.77% Cu including 13.25m @ on the Campbells Knob Granodiorite. Cochrane 1.10% Cu as chalcocite about high grade (1982) suggested the field may be the hypogene mineralisation related to an intensely peripheral lead-zinc zone of a porphyry style sericite-quartz altered medium grained biotite copper deposit. Mineralisation is associated ?tonalite sill emplaced along a northeast with small fractured zones within sericite, trending fault. Grade and thickness of the chlorite, kaolinite altered granodiorite. Pyrite chalcocite blanket decrease significantly away 46 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

from the intrusive (Maher, 1994). Results of silver, lacking large alteration zones. Major exploration are summarised in Brookes and occurrences are the Accommodation Creek Boyle (1996). copper mine and the Deddick silver-lead field, which consists of many small workings. The pallid rocks and significant iron-oxide after Deposits occur on, or within a ring dyke sulphide at Dogwood are indicative of leaching interpreted from aeromagnetic data (Twyford, by acidic ground water. Acid leaching makes 1996). This dyke probably fills a concentric mapping most types of alteration difficult. Best fault in a collapsed Lower Devonian caldera. indicators of hypogene mineralisation are Despite this concentric faulting, mineralisation intensity of fracturing and quartz veining, and appears to be controlled by northwest trending surface geochemistry - particularly indicators fissures, and temporally associated with relatively immobile in an oxidising acid leached magnetic Lower Devonian dykes which also environment. occupy these fissures. This northwest trend is parallel to the Buchan Rift. Mineralisation is Erosion has outstripped supergene processes hosted by Silurian Yalmy Group and Amboyne away from the resistant silicified aureole. Most Granodiorite basement, and is not reported in significant chalcocite intersections were at an overlying caldera volcanics - the White Monkey RL of about 250m AHD. Fresh sulphides were Subgroup. intersected at depths of less than 10m in the recessive Kaerwut Trondhjemite which has an It is difficult to discriminate between some base RL of less than 180 m AHD (Maher, 1994). and precious metal vein deposits and porphyry Incision by creeks through supergene enriched copper deposits. The Campbells Knob lead-zinc mineralisation give the Dogwood prospect a field is similar to the Deddick lead-zinc field, significant copper stream sediment signature. but has been classified as a porphyry copper Surface-leached ore bodies in recessive - deposit. In this instance, disseminated weathering host rock (eg. altered granite) will mineralisation in extensive altered zones, plus probably lack this signature (Maher, 1995). significant copper and molybdenum grades The Dogwood prospect also has a significant suggest the Campbells Knob lead-zinc field is a molybdenum signature in stream sediment peripheral lead-zinc zone of a porphyry copper geochemistry. Other good geochemical deposit (Cochrane, 1982). pathfinders in this oxidising acid leaching regime are Pb Cd Se Bi Ba W. Deddick silver-lead field

Mount Elizabeth The Deddick silver-lead field comprises over eighty argentiferous galena veins. The field The Mount Elizabeth Caldera Complex lies was discovered in the early 1870s, and first northwest of Dogwood along the trend of the mined in 1896. Recorded production for Kiewa Fault. Recent mapping of the caldera by Deddick is 20 t of lead ore in 1898. Mine Simpson et al. (1996) has identified a number of development in the field suggests this value is alteration zones close to the margin of the significantly higher. Most production ceased by volcanic pile, including silicification and 1900 because of the high cost of transporting disseminated pyrite with patchy chloritic and ore. The history of the Deddick field is haematitic alteration. Numerous ring and summarised in Orth et al. (1995). Details of radial fractures surrounding the Mount mine geology below are taken from this source. Elizabeth Caldera have also been identified (Simpson et al., 1996). These may be potential Massive argentiferous galena veins with sites for late stage porphyry intrusions and accessory barite, sphalerite and pyrite occupy related mineralised zones. Elevated copper- fractures in the Amboyne Granodiorite. molybdenum values in stream sediment Sericitisation and silicification are locally geochemistry data between the Dogwood developed in fracture zones about veins. Fine prospect and Mount Elizabeth suggest grained spessartite dykes also occupy fractures, repetition of mineralisation seen at Dogwood and are cross cut by veins. Fractures trend along the Kiewa Fault. northwest and are parallel to the Turnback Fault which bounds the field in the northeast. 3.8 Base metal vein deposits This is the same orientation as faults bounding the Buchan Rift. Disseminated galena in This style of mineralisation includes base metal porphyritic dykes which are interpreted to be vein deposits, commonly with subordinate coeval with the Snowy River Volcanics suggests GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 47

an Early Devonian age for Deddick member of Buckley (1982) (Porter, 1973). The mineralisation. Iguana Creek Mudstone is a member of the Upper Devonian Snowy Plains Formation - Jenkins (1899) recorded dimensions of the Avon River Group which is exposed in the Avon largest massive galena vein within the field. and Mitchell River Basins within The Princess vein was 0.2 to 0.6 m wide, and BAIRNSDALE. Outcrop of the Iguana Creek about 18 m long. Chalcopyrite, sphalerite and Mudstone is confined to the synclinal axis at pyrite increased with depth in some veins, and Iguana Creek, Freestone Creek and Bleak Hill - may be indicative of vertical mineral zoning. In and covers a total area of 40 sq km. Elevated addition to the more common minerals, uranium and thorium values in new arsenopyrite, gold, calcite and fluorite are radiometric data correspond to this member reported from some veins. Some mineralised (Slater, 1996). shears are coincident with magnetic linears in the Amboyne Granodiorite. Workings at Freestone Creek were developed on chalcopyrite veins within a 0.3 m thick grey Accommodation Creek copper mine siltstone over 50 m. Chalcopyrite and malachite occur over a 3 m vertical interval The Accommodation Creek copper mine has a within in a similar unit at Iguana Creek. recorded production of 3676 t of copper ore. Protore copper grades are generally less than The earliest reference to the deposit was by 0.1%, with a maximum of 0.59% (Cochrane, Fergusson (1899), although Baragwanath 1982). Production is not reported. (1937) stated that the occurrence had been known for over 60 years. Gippsland Minerals 3.10Carbonate hosted metal NL mined 3024 t of copper ore between 1969 and 1970 before closure of the mine in 1971 deposits following a fall in the copper price, and increase in operating costs. A summary of the history of Basal dolostones of the Buchan Caves mining at Accommodation Creek is given in Limestone host several base metal deposits. Orth et al., 1995. Details of mine geology below Mining of these deposits commenced in 1869, are taken from this source. and continued intermittently until 1928. Major mines were the Hume Park lead, Pyramids Chalcopyrite bearing veins with accessory lead, Back Creek lead-silver, Neils Creek lead- quartz, lesser barite and minor calcite occupy copper and Spring Creek copper-lead. Reported two sets of shears. Shears trend 325° within combined production from these mines is 796 t contact metamorphosed Yalmy Group quartzite. of lead ore (Cochrane, 1982). Silver was This orientation is parallel to basin bounding produced as a by-product from smelting, faults of the Buchan Rift, however shears pre although production is not recorded. Ore also date deposition of the White Monkey Subgroup contained significant sphalerite. of the Snowy River Volcanics. Mineralisation is coincident with a ring dyke interpreted from Detailed investigation of six deposits by Arne et aeromagnetic data. This dyke probably fills a al. (1994) showed mineralisation has concentric fault in a collapsed Lower Devonian similarities with the epigenetic zones of Irish caldera. Intersections of shears and this base metal deposits. They are stratabound, and concentric fault may be favourable sites for show varying mineralisation styles from mineralisation. syndiagenetic (mineralisation in bedding planes and in cavities) to epigenetic (mineralisation in At least six separate ore shoots have been cross cutting fractures and low angle minor mined. These were between 0.4 and 1.3 m faults). There are also geochemical similarities wide, and grade between 1.2 and 4% copper. between the two provinces, both show Lower grade shoots in excess of 14 m wide are enrichment in iron and silver, and occur in very known. Drilling undertaken by Gippsland pure dolomitised carbonate (Buckley et al., Minerals NL proved extensions to narrow ore 1994). shoots 60 m below the lowest mine level. Although sulphur isotope values are consistent with volcanic exhalative mineralisation, low 3.9 Red bed copper deposits fluid temperatures, and limestone facies indicative of relatively shallow water depths, Copper has been identified in reduced zones of the oxidised, red bed Iguana Creek Mudstone 48 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

suggest direct precipitation from volcanic fluids deposits. Mineralisation occurs in low angle is unlikely (Arne et al., 1994). and bedded faults, and perpendicular fractures in some bedded horizons within massive Remobilisation of carbonate hosted dolomite (Orth et al., 1995). Exploration by Rio mineralisation probably occurred during de Janeiro Mines (EL 50) delineated two lead- Tabberabberan Deformation when rocks were zinc soil anomalies with peak values near gently folded. Competency differences between worked deposits. Despite strong induced carbonates and underlying volcanics resulted in polarisation anomalies down dip of these the development of fractures and bedding plane deposits, drilling failed to intersect significant slip in the basal portion of the carbonate which depth extensions to known mineralisation. hosts lead-zinc-silver mineralisation (Buckley et al., 1994). Back Creek lead-silver mine

A generalised paragenesis of deposits is given The Back Creek lead-silver mine was probably in Arne et al. (1994). Briefly, this is: the states largest lead producer (Cochrane, 1982). Argentiferous galena, sphalerite, pyrite ®galena ±sphalerite ±pyrite ®dolomite chalcopyrite and silver (plus rare stibnite) occur ±barite ®calcite ±fluorite ±dolomite. in veins, lenses along bedding planes, disseminations and cavity fillings in the basal Primary chalcopyrite and silver intergrown part of the Buchan Caves Limestone. This with galena accompany these minerals. mineralisation is concentrated in the eastern limb of a north plunging syncline. Veins and Several stratiform iron oxide deposits in the disseminations also occur in underlying Snowy Buchan Caves Limestone probably represent River Volcanics (VandenBerg et al., 1996). weathered pyrite rich carbonate hosted deposits. Major deposits are the McRaes Results from diamond drilling by the Mines limonite quarry, Gilbert Road ironstone, Cocks Department, Rio De Janeiro Mines and limonite deposit and the Good Hope silver mine. Pickands Mather (ELs 50 & 124) failed to Elevated copper, lead, zinc, silver and barium indicate a significant resource, leading occur with these deposits (Buckley et al., 1994). Cochrane (1982) to downgrade the prospectivity of the area. Occasional good intersections from A detailed history of mining is given in this drilling however, provide scope for Cochrane (1982), Orth et al. (1995) and undiscovered mineralisation. In particular, VandenBerg et al. (1996). Details of modern Hole 12 which intersected 7.62 m of 3.7% lead, exploration are presented in Brookes and Boyle 2.6% zinc and 51 g/t silver, is untested along (1996). Descriptions of major mines given strike (Cochrane, 1982). below are taken from these sources. Neils Creek lead-copper mine Hume Park lead mine Neils Creek lead-copper mine was prospected in The Hume Park lead mine was developed on 1872. Drilling by Preussag (EL 1403) showed galena-sphalerite mineralisation within a small similar mineralisation to other carbonate outlier of Buchan Caves Limestone, hosted base metal deposits in the area within conformably underlain by Snowy River the basal dolostone of the Buchan Caves Volcanics. The western margin of the outlier is Limestone. This mineralisation lies at the faulted by splays of the East Buchan Thrust. boundary of the dolostone and underlying Parts of the deposit are clearly fault related Amberley Park Volcaniclastic Member. A (Orth et al., 1995). This mineralisation (iron discontinuous siliceous ironstone bed also oxide, pyrite, galena and sphalerite) occurs as a occurs in the dolostone at this location. This cement in a 2.5 m wide fault breccia. Howitt work is summarised in Cochrane (1982) and (1878) also described bedded and disseminated Brookes and Boyle (1996). mineralisation in a 1 to 2 m wide massive dolomite unit. Spring Creek copper-lead mine

Pyramids lead mine Cochrane (1982) and Peers (1885) provide details of the Spring Creek copper-lead mine. The Pyramids lead mine comprises several Copper mineralisation was discovered in late workings developed on small galena-sphalerite 1860 in an area now covered by the Buchan GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 49

Caves Reserve. A shaft and adit were Newmont (EL 512) and Preussag (EL 564). Soil developed on the mineralisation, and 100 t of sampling indicated an untested lead-zinc copper ore was extracted before the mine closed anomaly 200 m south of the deposit (Brookes & in 1888 due to flooding. Boyle, 1996).

"Copper ore, traces of gold, silver, and other low Good Hope silver mine value minerals" were reported from a 1.8 m wide zone in the adit (Peers, 1885). The Good Hope (Tallatoorook) silver mine was a Mineralisation occurs at the base of the Buchan prospecting shaft developed in 1892 on massive Caves Limestone, or within the underlying limonite. Limonite crops out discontinuously Spring Creek Member. over 2.3 km and is coincident with the Carson Creek Fault which separates Buchan Caves McRaes limonite quarry Limestone and Holloways Formation in the west, and Fairy Sandstone in the east. The McRaes limonite quarry is one of a number Mineralisation is clearly fault controlled. of stratiform massive limonite lenses within the Buchan Caves Limestone. These deposits are The prospecting shaft is 56 m deep, and has a collectively called the McRaes limonite horizon drive near the bottom which extended 25 m to (O'Shea, 1980). The deposit is 100 m wide, the east. Murray (1893) described rock exposed 1.4 km long, and trends north-south. Drilling in the crosscut as decomposed feldspathic by Preussag (EL 1203) designed to intersect the material with minor limestone, clay, and deposit below the base of weathering, ferruginous and manganiferous veins. Rosales intersected colloform pyrite lining cavities in (1898) reported that the body was 20 m wide limestone, and fine pyrite disseminations. and dipped 65° to the east. Small amounts of Minor sphalerite and galena veins cut colloform galena, chalcopyrite, pyrite, haematite and pyrite (Arne et al., 1994). Sampling by ICI- quartz were also reported. A detailed Newmont (EL 512) also indicated minor galena, description of this mine is given in Cochrane plus silver (Cochrane, 1975). (1982).

Mines department drilling defined a resource of 3.11Nowa Nowa ironstones 6.8 Mt containing 32% iron (Bowen, 1970). Cochrane (1982) reported up to 10% manganese Significant iron deposits in Victoria are oxide accompanying the limonite. concentrated in the Buchan Rift. The highest grade deposits are the magnetite-haematite Gilbert Road ironstone bodies north of Nowa Nowa. These deposits have a resource exceeding 6 Mt at 51.5% iron Although the deposit is fault bounded, Jennings (Mitchell Cotts Projects, 1988). Several drill and Preussag (EL 564) concluded that it intersections have indicated potential for gold- occupies the same stratigraphic position within copper resources associated with the magnetite - the Buchan Caves Limestone as the McRaes hematite bodies. This target is relatively limonite deposit. Limonite, which characterises untested. the deposit at surface, crops out over 100 m in a cutting along Gilbert Road. Drilling by ICI- Deposits are hosted by faulted Tomato Creek Newmont (EL 512) shows limonite is oxidised Ignimbrite, Kanni Ignimbrite and Nowa Nowa pyrite within limestone. Elevated zinc-silver Conglomerate of the Snowy River Volcanics, (lead-gold) values are associated with pyrite and unnamed ?allochthonous Silurian (Cochrane, 1982). limestone megaclasts. These units are underlain at shallow depth by Ordovician Cocks limonite deposit Pinnak Sandstone. Ore bodies are characterised by massive magnetite-haematite This deposit is located 2.7 km northeast of the with lesser chlorite, pyrite, quartz and Gilbert Road ironstone, and is similar in most chalcopyrite. Magnetite is late and replaces respects. Limonite derived from oxidation of specular haematite (Moore, pers. comm.). pyrite bands in limestone occurs in a lens 450 m Haematite occurs as stringers in the Snowy long and 32 m wide (Talent, 1961). The body River Volcanics and Silurian rocks. does not crop out, and these dimensions were confirmed by ground magnetic and soil The ore bodies are major anomalies in geochemistry surveys undertaken by ICI- aeromagnetic data. The data indicate bodies 50 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

are short, narrow and steeply dipping. All high sample of this ore graded 62.1% Fe2O3. Lenses order anomalies have been tested by drilling. are 200 m and 30 m long, and 10 m and 5 m wide respectively; and have fault contacts with Bell (1959) proposed that the ore bodies Nowa Nowa Conglomerate (VandenBerg et al., represent metasomatic deposits related to 1996). intrusions. This is unlikely, given that high temperature alteration minerals do not occur in Five Mile the deposits or adjacent rocks. Ore bodies are more likely to be lower temperature The Five Mile iron ore deposit crops out over a metasomatic deposits localised by faults and length of 50 m and has a maximum width of 4 impermeable horizons such as the overlying m. Mines Department drilling designed to test Tomato Creek and Nowa Nowa ignimbrites. anomalies in BMR aeromagnetic data Alternatively, Marlow (1989) proposed deposits delineated two ore bodies. These are tabular formed by precipitation of iron ore in dilatant and steeply dipping, and have total mineable zones from hydrothermal fluids. reserves of 4.69 Mt with 52% iron and 0.5 Mt with 52.6% iron (Mitchell Cotts Projects, 1988). Magnetite replacing haematite suggests The massive magnetite-haematite-chlorite decreasing f O2 of ore forming fluids. Similar bodies occur at the faulted contact between changes in fluid chemistry were described by Tomato Creek Ignimbrite, limestone and Large (1975) for the Juno deposit, Tenant Pinnak Sandstone (Moore, pers. comm.; Bell, Creek. The Juno Mine was developed on gold, 1959). bismuth and copper mineralisation hosted in one of several transgressive magnetite-chlorite Mines Department drilling indicated potential pipes. Large (1975) proposed that ironstone for copper and gold rich zones within the ore and mineralisation formed essentially body. Best copper intersection reported by Bell contemporaneously in response to (1959) from routine core analysis was 21.5 m at metasomatism unrelated to intrusions. The 0.59% from 70 m in borehole 11. Gold assays of chlorite, gold and copper are considered to be 11 composite samples were not published. Best late, and also related to low f O2 fluids. The result was 6.1 m at 4.9 g/t from 70.1 m in mineralisation is zoned, with an inner core of borehole 8. This corresponded to a zone of gold grading outwards to bismuth and copper. elevated copper. The gangue is also zoned, with an inner core of magnetite-chlorite grading outwards to Six Mile magnetite-hydromuscovite and then to dolomite ± magnetite ± haematite. Other deposits in the The Six Mile iron ore deposit was intersected in Tennant Creek area show a similar pattern. Mines Department drilling designed to test anomalies in BMR aeromagnetic data. Bell Descriptions of the four main deposits given (1959) reported a 24.4 m intersection of massive below are largely taken from VandenBerg et al. iron ore overlain by the Kanni Ignimbrite. (1996). These deposits were delineated by drilling first reported in Bell (1959), which also Seven Mile reported several smaller magnetite occurrences. A fifth significant deposit - Three Mile, The Seven Mile iron ore deposit is exposed in a corresponds to an aeromagnetic anomaly bulk sampling pit, and was first delineated by hidden by Tertiary sediment. This deposit is Mines Department drilling designed to test described in reports for ELs 1202, 1203 and anomalies in BMR aeromagnetic data (Bell, 3035 (Brookes & Boyle, 1996). 1959). The ore body consists of massive magnetite-haematite with quartz-jasper, pyrite Two Mile and specular haematite filled vughs and veins. Review of early work by Mitchell Cotts Projects The Two Mile iron ore deposit, also known as (1988) indicated a total mineable reserve of 0.93 the No. 3 Cut, crops out on the west flank of Mt with 48.9% Iron. Gregory and Kerr (1989) Mount Nowa Nowa. Nott (1980) calculated a reported an outcropping auriferous gossan at reserve of between 11 000 and 50 000 t of iron the eastern contact of the ore body with ore in two lenses. Lenses consist of massive weathered ignimbrite. specular haematite, with lesser magnetite, limonite, jasper, quartz, and rare pyrite 3.12 Granite hosted tin deposits (VandenBerg et al., 1996). A 300 tonne bulk GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 51

Alluvial tin (plus minor gold) workings on large megaclasts in the Cowombat Siltstone. several creeks east of Bruthen - including Falls The largest of these megaclasts on Creek, were reported by Herman (1899). BAIRNSDALE occurs near Old Hut Creek. Catchments of these creeks include the Upper Analysed samples contain up to 97 % CaCO3 Devonian Colquhoun Granite. Testing of this (McHaffie & Buckley, 1995). granite was undertaken by Preussag (EL 703). Soil sampling indicated spotty weak tin The Lower Devonian Buchan Group which mineralisation, with values up to 205 ppm, crops out in the Buchan Rift and Bindi Graben within the granite. No detailed work has been is a major Palaeozoic limestone resource. It undertaken to determine the controls on this consists of three formations, the Buchan Caves mineralisation. Limestone, Taravale Marlstone and Murrindal Limestone. 3.13 Wolframite vein deposits In the Buchan Rift and Bindi Graben the Wolframite was mined at the Fainting Range Buchan Caves Limestone consists of almost mine in BAIRNSDALE until about 1945. The pure limestone and dolomitic limestone 180– mine was discovered before 1920, and produced 210 m thick (Teichert & Talent, 1958). The an unknown quantity of tungsten (Thomas & limestone is mostly mid-grey to black Crohn, 1951). The mine consisted of three open calcarenite and calcilutite. Pure dolomite and cut/adit workings developed on four quartz dolomitic limestone occur at the base of the veins. Mineralised veins are controlled by formation. This formation is of considerable faults in locally altered schists, and dip between economic importance because of its relatively 64° and 70° in several directions. high purity of limestone and the extent of its outcrop.

3.14 Brown coal deposits The Murrindal Limestone occurs only in the Buchan Rift. It is pale to dark grey limestone There is no record of coal mining within with interbedded mudstone with a maximum BAIRNSDALE. Exploration by BHP Minerals thickness of 250 m. It is divided into two Ltd (ELs 984, 985, 987, 988 & 1049) and Shell members: the McLarty Member comprising Australia (ELs 1026 & 1027) in the northern dark grey, well bedded limestone and the paler, part of the Gippsland Basin intersected only coral rich Rocky Camp Member. thin, relatively impure brown coal seams which are currently uneconomic. This work is Hard crystalline limestone was quarried for use detailed in Brookes and Boyle (1996). as dimension stone in the late 1800s and early 3.15 Non metallics 1900s, from Camerons and Heaths quarries at Buchan South and at Rocky Camp 5 km north Limestone of Buchan. Limestone from Camerons quarry has also been used in paper manufacture. The Limestone is a sedimentary rock consisting of Rocky Camp Limestone is currently quarried by greater than 50% combined calcite and AMCOR under WA 197 for production of dolomite, with calcite predominating. It is used quicklime, flux, stockfeed, paper manufacture for construction purposes such as cement and agricultural purposes. Some limestone manufacture, road making, agriculture (to south and east of Buchan has been crushed and correct soil acidity), lime manufacture, fillers, used as agricultural lime (McHaffie & Buckley, and paper, glass and steel making. 1995).

Limestone deposits of Silurian, Devonian and The calcarenite of the Buchan Caves Limestone Tertiary age are well represented in and Rocky Camp Member of the Murrindal BAIRNSDALE. These have been described by Limestone has the greatest potential for Inan et al. (1992) and McHaffie and Buckley industrial use, as it is relatively free of (1995) and readers are referred to these reports insolubles, muddy intercalations, sand and for more detailed descriptions. carbonaceous material (McHaffie & Buckley, 1995). Silurian limestone occurs in the Limestone Creek Graben northeast of Bindi, as well as The Gippsland Limestone forms part of the being reported in drill core near Nowa Nowa. Seaspray Group. It is a thick sheet of bryozoal In the Limestone Creek Graben it occurs as marl and limestone representing the middle 52 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

portion of the marine Tertiary sequence in common garnet and cordierite set in a finer Gippsland. It reaches a maximum thickness of grained groundmass. The granite is covered in 500 m onshore and extends over 3900 km2 of part by Tertiary sediments. . Between Lindenow and Orbost the formation is divided into the Wuk The Orbost Trondhjemite has been quarried Wuk Marl and Bairnsdale Limestone Member. and used as the base course of the now The Bairnsdale Limestone is the most demolished Commonwealth Bank (Collins important of the two. It is typically yellow– Street) built in in 1923. It has a orange, soft, porous and fossiliferous. It is greenish grey colour, is medium grained and currently quarried by R Herman P/L, P. Nelson quite mafic containing numerous xenoliths up and G. Tucker under WAs 260, 357 and 457 for to 0.5 m in size. aggregate and agriculture purposes (McHaffie & Buckley, 1995). Pyrophyllite

Dimension Stone Pyrophyllite is a soft, whitish hydrated aluminosilicate which has numerous industrial Dimension stone is natural stone that is cut to uses. Its characteristics in response to heating specific dimensions for use in building, make it extremely useful in numerous construction and monumental industries. The applications (McHaffie & Buckley, 1995). Some major stones used are marble, limestone, especially white grades of pyrophyllite are used granite, gneiss, basalt, sandstone and slate. as fillers, and pyrophyllite is also used as an Potential sources of dimension stone on insecticide carrier. BAIRNSDALE include: Pyrophyllite occurs in acid volcanics which have · Silurian marble at Bindi; been hydrothermally or metasomatically · Devonian marble at Buchan (Rocky Camp) altered, as an alteration product of feldspars in and Buchan South (Camerons and Heaths); acid volcanic rocks. Pyrophyllite is recorded · Granite at Colquhoun; from the Wilga deposit, and Pyramid Mountain · Granite at Mount Taylor; and and Blue Spur prospects. Although not · Granite at Orbost. recorded, pyrophyllite may also occur in the alteration zones around the Armistice, Monarch Silurian marble at Bindi features an attractive of Tara and New Guinea mines, and the Glen strong fabric accentuated by shades of cream, Shiel, Nowa Nowa and W-Tree Creek prospects. pink and grey. The marble is locally highly jointed in places which may limit its Pyrophyllite at Wilga was first noted by Allen marketability. (1987). The size of this resource is unknown. Allen and Barr (1990) describe a quartz-sericite Marbles from Buchan are represented in the alteration zone around the upper and lateral foyers of many buildings constructed from last margins of the deposit which may be century to the late 1940s. The marble colours prospective for pyrophyllite. range from black to pale grey with some yellow veined varieties. The area has high potential to Barite yield grey marbles for dimension stone. Barite is used mostly as an additive to drilling The Colquhoun Granite has been used for muds for the petroleum industry and also as a monumental purposes. The stone is uniform in pigment, filler and extender and in the texture and composition, fine grained with a manufacture of barium chemicals and glass pink to red colour and has been described in (McHaffie & Buckley, 1995). detail by McInerny (1929). The granite is poorly exposed with large portions covered by Most of Victoria’s known barite deposits occur Tertiary sediments. It has a reasonable on BAIRNSDALE and all these are associated potential for a dimension stone resource with the Snowy River Volcanics. The major depending on the amount of overburden and deposits are at Gelantipy (Glen Shiel) and land use status. Buchan South (Bally Hooley Hill, Kanni Creek and Iron Mask). Orth et al. (1995) reported 70 t The Mount Taylor Granite is medium grey, of ore was quarried from Glen Shiel in 1937. strongly porphyritic with large crystals of K- The deposits occur as vein and cavity fillings felspar, plagioclase, and quartz with less and as fine disseminations in altered volcanic GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 53

and sedimentary rocks. These deposits are Caves Limestone. Very pure dolomite several discussed in detail in Chapter 3.4. metres in thickness pass upward into normal limestones. Sporadic dolomitisation occurs at The potential for discovering a major barite higher levels of the formation, and also in the deposit in BAIRNSDALE is low. Unproven overlying Murrindal Limestone. Detailed extensions of known deposits in the Snowy descriptions of this resource are given in Talent River Volcanics remain the most prospective (1961), Teichert and Talent (1958) and Duyker sites for further barite prospects. (1993).

Talc Feldspar

Talc is a soft and smooth mineral which has a McHaffie and Buckley (1995) recorded two perfect basal cleavage, is easily ground to an feldspar occurrences within BAIRNSDALE, at extremely white powder, is a good lubricator, Mount Smythe and Mount Taylor. Feldspar is and is chemically inert. It has high absorption, used in the glass and ceramics industries as a a high fusion point, low shrinkage when fired, source of alumina and alkalis. Tinguaite and and low thermal and electrical conductivity. It phonolite dykes and plugs are the source of is used in the manufacture of paint, plastics, feldspar at Mount Smythe. Tinguaites are rubber, paper, ceramics, cosmetics, animal feed, porphyritic with coarse feldspar phenocrysts. fertilisers, insecticides, and as a filler for Analysis reported by Barnes (1971) showed that roofing products (McHaffie & Buckley, 1995) after beneficiation, the rock had low iron and high alkali content - and was of potential The only significant talc occurrence in economic value (McHaffie & Buckley, 1995). BAIRNSDALE is at Bingo Munjie North, 21 km north of Omeo. Talc occurs in altered basic dykes in red granite (Bartlett & Learmonth, 1955).

Semi-precious gemstones

Three semi-precious gemstone occurrences are recorded within BAIRNSDALE (McHaffie & Buckley, 1995). Alluvial jasper from Avon River and alluvial agate, jasper and quartz from Nowa Nowa are derived from Devonian volcanics. Common (or opaque to translucent) opal occurs at W-tree/Gelantipy. Detailed information on these occurrences is given in Birch (1988 & 1989) and Birch and Henry (1993).

Dolomite

Dolomite, (or dolostone, to distinguish the rock from the mineral) is defined by McHaffie and Buckley (1995) as a sedimentary rock containing more than 50% by weight of the minerals calcite and dolomite, in which the latter predominates. End markets for dolomite includes aggregate and construction materials, agriculture, chemical and metallurgical, glassmaking, and fillers.

McHaffie and Buckley (1995) record two dolomite occurrences within BAIRNSDALE, at Tabberabbera and east of Buchan. At Buchan, large resources of dolomite occur within the basal part of the Middle Devonian Buchan 54 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Wollastonite

Wollastonite is most commonly formed by contact metamorphism or metasomatic replacement of limestone, siliceous limestone or calcareous sandstone. It is used in the manufacture of paint, plastics, ceramics and electrical insulation.

There are two minor occurrences of wollastonite on BAIRNSDALE. The first is in the metamorphic aureole of the Suggan Buggan Granodiorite about 9 km northeast of Wulgulmerang. Here Yalmy Group sediments contain interbedded carbonate turbidites and wollastonite occurs as radiating laths 0.5 mm long infilling cavities and replacing limestone clasts. The second occurrence is on the 8 km west of Wulgulmerang where wollastonite occurs similarly in contact metamorphosed gritstone of the Seldom Seen Formation.

The potential for a major wollastonite resource on BAIRNSDALE is low. The Buchan Group which is the main potential source of carbonate in the area post dates the main period of granite intrusion and carbonate horizons in the Yalmy Group appear to be limited in extent. GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 55

4 Overview of mineral Different styles of gold mineralisation were sought, including deep lead gold in the Dargo exploration area (Endeavour Oil Corp., EL 442), shear hosted gold (Quilmin Mines & Exploration, EL This section provides an overview of mineral 233 & Valley Exploration, EL 161) and dyke exploration undertaken within BAIRNSDALE hosted gold (Transouth Mining, EL 243). since the Exploration Licence reporting system was introduced in 1965. A detailed summary of The majority of ELs focusing on gold were open file exploration programs is given in granted in the 1980s. During the early 1980s Brookes and Boyle (1996). This report gives Palaw Pty Ltd (EL 968) explored for gold within details of work programs conducted under each auriferous quartz veins and Wattle Valley EL including: Estate Pty Ltd explored for gold in old workings and streams. The (EL 696) · geological mapping; explored for alluvial gold along Livingstone · geochemical sampling procedure; Creek. During the mid-late 1980s Freeport · anomalous results from soil, drainage and Australia Minerals NL (EL 841-844), Canyon rock geochemistry; Resources (ELs 1287 & 1447), Croft (EL 1675), · drill hole locations and significant Northbridge (EL 1722) and Mumbil Mines (1660) intersections; and explored for vein stockwork and disseminated · geophysical survey specifications and gold around the Omeo and Ensay areas. results. Hardrock gold mineralisation was extensively explored for, focusing on gold of varying styles Exploration within BAIRNSDALE has been within the Ordovician sediments (Brady, EL largely directed at identifying gold, within 1656; Hochwimmer & Associates, EL 1956; areas of known mineralisation as well as Gold, EL 2413). In conjunction with adjacent to historical alluvial and hardrock hardrock gold exploration, many companies goldfields. Further interest has been focused on also explored for alluvial gold (Woods & base metal mineralisation, leading to the Associates, EL 2114; CRA Exploration, EL discovery and development of the Wilga 1443). Paringa Mining and Exploration (EL Cu/Zn/Ag mine. Exploration has been 1228) explored for residual gold in old mullock conducted in localised areas for tin, tungsten, heaps and tailings. BHP Minerals Ltd (ELs molybdenum, fluorine, heavy minerals, 1633, 1634, 1658, 1659) identified several platinum group metals and brown coal. epithermal gold deposits within the Snowy River Volcanics which were drilled but to date Since the introduction of the EL system in have failed to identify potentially economic 1965, approximately 170 ELs have been mineralisation. granted within BAIRNSDALE. Appendix 1 summarises work undertaken and expenditure Exploration in the 1980s centred largely on for each EL. EL locations are shown in areas which had been previously mined Appendix 2. however efforts were also made to discover new mineralisation. During the late 1980s and 4.1 Gold 1990s CRA Exploration Pty Ltd (ELs 1906, 1911, 2134, 2137, 2138, 3010, 3012, 3299) explored for large, auriferous hydrothermal Half of the ELs granted since 1965 have systems and acid volcanic-hosted disseminated targeted gold. In the mid-late 1960s Planet gold deposits associated with granitoid plutons Mining Company (ELs 14, 15, 16) explored over and major faults. Goldrill (EL 3017) and large areas for primary gold mineralisation. Platsearch (EL 3720) also actively explored for Around the same time Rio de Janeiro Mines (EL hardrock gold in the area. Western Mining 50) focused on mineralisation associated with Corp/CRA Exploration Pty Ltd (ELs 1662 & the Snowy River Volcanics and Buchan Caves 3245) reappraised the gold potential of areas Limestone, and Eastern Prospectors Pty Ltd that had been previously identified by Preussag (EL 95) explored for alluvial gold within the (ELs 1203 & 1204) as potential base metal Wongungarra and Crooked Rivers. prospects. Throughout the 1970s, CRA Exploration Pty Ltd (ELs 503-506) explored known areas of 4.2 Base metals and silver mineralisation for alluvial and primary gold. 56 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Exploration for base metals has occurred Australian Anglo American Prospecting Pty Ltd predominantly over the Omeo and Buchan (EL 1228) and Ticane Pty Ltd (EL 1824) also Structural Zones, encompassing a third of the focused on similar mineralisation with Freeport ELs granted over BAIRNSDALE. The first Australia Minerals Ltd (EL 1491) concentrating exploration programs were Australian on exhalative base and precious metal Geophysical Pty Ltd (EL 68) and BHP Minerals mineralisation at Flukes Knob. Ltd (EL 87) who searched for copper, lead and zinc in the late 1980s. Rio de Janeiro Mines (EL Significant exploration activity in the 1970s and 50) searched for base metal mineralisation 1980s in BAIRNSDALE has also focused on associated with the Buchan Limestone / Snowy exploration for volcanic-hosted massive River Volcanic contact as well as porphyry sulphides after the discovery of the Western copper deposits associated with granitic Mining /Macquarie Resources/Denehurst Wilga intrusions (ELs 83, 86, 115). They successfully Cu/Zn/Ag deposit in the late 1970s (ELs 1234, identified the Double Bull, Sunday Creek and 1235, 456, 537). A large program by Cultus Tiger prospects. Follow-up work by Rio de Pacific NL (EL 675) also explored for Janeiro Mines (ELs 159 & 160; Amoco Minerals, mineralisation similar to that at Wilga. EL 480) further concentrated on areas extending from the Sunday Creek and Tiger During the 1990s BHP Minerals Ltd explored prospects focusing on porphyry Cu for Irish-style Pb-Zn mineralisation within the mineralisation. BHP Minerals Ltd (EL 87) Buchan Basin (ELs 1658, 1659, 2560, 2569). explored for base metal sulphide deposits near Exploration was also conducted by BHP for Nowa Nowa whilst Gippsland Minerals NL (EL ironstone Cu-Au mineralisation in magnetic 92) explored for Pb-Zn-Ag and Cu fissure veins. ironstones at Nowa Nowa. CRA Exploration Pty Ltd (ELs 3309, 3436, 3556) further explored The majority of licences exploring for base for additional chalcocite blankets overlying metals were granted throughout the 1970s. porphyry copper systems, similar to their During the early 1970s Pickands Mather and Dogwood prospect. Co (EL 124) concentrated on base metal mineralisation and known iron ore deposits at Many prospects in the area have not been fully Nowa Nowa. During the mid 1970s Amoco Pty explored with highly anomalous stream Ltd (EL 460) further followed up previous sediment and soil samples areas not being untested Pickands Mather (EL 124) anomalies adequately tested. Many ELs were concentrating on porphyry Cu mineralisation relinquished due to company political or around Mt. Buck and Stringers Knob. financial reasons rather than on geological Dampier Mining Co. Ltd (EL 471) also explored criteria. for porphyry copper and base metal deposits around Gelantipy. ICI Australia Ltd/ Newmont 4.3 Other minerals and coal Holdings Pty Ltd (ELs 496, 500, 512, 534, 536) extensively explored for base metal Since the late 1960s, exploration within mineralisation, especially copper associated BAIRNSDALE has included exploration for with the Snowy River Volcanics and Buchan molybdenum, tin and tungsten, and brown Caves Limestone defining prospects such as coal. During the late 1970s to early 1980s, Campbells Knob as well as redrilling other Australian Anglo American Prospecting Pty Ltd areas of interest. CRA Exploration Pty Ltd (EL 695) and Seltrust Mining Co. (EL 1206) (ELs 450, 451, 964) explored for "red bed" conducted fairly extensive exploration copper mineralisation in the Upper Devonian- programs for porphyry molybdenum systems. Carboniferous sediments. Essex Minerals (EL 1082) explored for tungsten/tin mineralisation during the 1980s During the mid-late 1970s and extending into within the hypothesised extension of the the early 1980s Preussag Australia Pty Ltd Tasmanian Province. Tin and tungsten (ELs (ELs 1203, 1204) undertook an extensive 841-844, Freeport Australia; EL 2534 , Delta exploration program for base metals within the Gold NL) and molybdenum (EL 1684, Mumbil Snowy River Volcanics and lead-zinc Mines) have generally been explored for in mineralisation within the Buchan Caves conjunction with other metals. Other minor Limestone. The target was later switched to exploration programs have explored for heavy gold. The program involved extensive stream minerals (EL 322, Strahan Sands), platinum sediment and soil sampling of numerous areas group minerals (EL 1785, Helix Resources), and extensive drilling of over thirty holes. fluorine bearing minerals (EL 397, Comstock GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 57

Minerals) and uranium and vanadium (ELs covered by sparse sampling. Sparse sampling 614-616, Northern Mining Corp.). also covers the Bete Bolong Suite west of the Buchan Rift. The Grant, Dargo, Bullumwaal, During the 1980s brown coal has been explored Store Creek, Deptford and Yahoo Creek for in the eastern onshore extension of the goldfields have not been tested by this method. Gippsland Basin by BHP Minerals Ltd (ELs 984, 985, 987, 988), BHP Mining Development Many prospective areas identified by the new (EL 1049) and Shell Australia (ELs 1026,1027). airborne geophysical data and geological mapping also remain untested by modern 4.4 Soil and stream sediment exploration (see Chapter 6). geochemistry Soil sampling programs are mainly confined to the Snowy River Volcanics, Mount Elizabeth Soil and stream sediment geochemical surveys Caldera Complex and Limestone Creek Graben. are discussed briefly in this section to give a Programmes were also undertaken in some regional perspective of the distribution and type goldfields and porphyry copper prospects. of geochemical programs undertaken. Large parts of all goldfields are untested by soil sampling. Open file stream sediment and soil geochemical data reported in all relinquished EL reports have been captured digitally and are available from the Geological Survey of Victoria in the following formats:

· themes in the BAIRNSDALE GIS data set; · Explorer 3 database Ó Terra Search Pty Ltd; and · ASCII files.

The data set consists of location and assay information on in excess of 40 000 soil and 17 000 stream sediment samples collected within BAIRNSDALE.

Stream sediment sampling programs with moderate to high sample densities cover the area east of Bruthen, including the Snowy River Volcanics. West of Bruthen, small programs cover selected goldfields, with the majority of the remainder of the map area relatively untested by modern exploration.

Many stream sediment samples were not analysed for gold. Around Bullumwaal, Store Creek, Deptford and Yahoo Creek goldfields, surveys have a particularly low sample density, with sampling confined to the main mining centres.

The coverage of samples analysed for gold by bulk cyanide leach (BCL) is even more restricted. BCL analysis gives very low detection limits, and offers the best potential of detecting coarse grained gold in drainage. Samples cover Devonian volcanics with a moderate sample density. The Omeo, Swifts Creek, New Rush Creek, Haunted Stream, Cobbannah and Gladstone Creek goldfields are 58 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

5 Geophysics

Detailed airborne magnetic, radiometric and elevation data is now available for most of BAIRNSDALE. Geological interpretation of the new VIMP airborne geophysical data is presented in Sands (1995) covering the Orbost area, Slater (1996) covering the Dargo area, Haydon (1996) covering the Omeo area, and Twyford (1996) covering the Murrindal area (Fig. 1).

The intention of this section is to briefly highlight the main features on Figure 11, which shows a TMI image incorporating the new aeromagnetic data, and the location of mineral resources within BAIRNSDALE. Readers are referred to the reports listed above for a more detailed appraisal and interpretation of the geophysical data sets.

The main geological features visible in the magnetics on BAIRNSDALE are:

· Bete Belong Group of Granites (high magnetic response) · Rodger River and Mount McLeod granites (high magnetic response) · Snowy River Volcanics in the Buchan Rift (high magnetic response) · Limestone Creek Graben and Nunniong Granite (low magnetic response) · Triassic granites northeast of Omeo (high magnetic response) · The Mount Elizabeth Caldera Complex (high magnetic response) · Granites associated with the Omeo Metamorphic Complex between Omeo and Ensay (high magnetic response) · Mount Baldhead and Dargo granites (high magnetic response) · North-south trending dykes east of the Dargo Granodiorite (moderate magnetic response) · Shallow northern contacts of the Castleburn Tonalite (high magnetic response) · Tertiary basalt flows (high negative magnetic response)

Regional scale evaluation of the airborne geophysics together with new geological mapping and mineral resource and exploration geochemistry compilations have identified prospective zones which are described in Chapter 6. GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 59

6 Mineral resource indicate undiscovered repetitions of this mineralisation. potential and Many mines produced moderate amounts of prospectivity gold, and were abandoned at shallow depths despite high grades and untested potential at Significant mineral resources occur within depth. In the Benambra gold province, this was BAIRNSDALE. Mining has a 130 year history probably due to the difficulty in recovering gold in the area, and new mineral resources from highly sulphidic ore. In more remote continue to be defined by modern mineral goldfields of the Harrietville-Dargo gold exploration programs. The Cassilis gold deposit province, it is likely to reflect the high which has produced in excess of 2.2 t of gold, operating costs associated with remote was first mined in 1890. The Wilga copper- operations. Advances in gold recovery zinc-silver deposit, first mined in 1992, has technology, and improved access to remote produced approximately 45 000 t of copper, areas within BAIRNSDALE make these 21 000 t of zinc and 15 000 kg of silver. Proven previously uneconomic deposits exciting mineral resources are shown in Figures 3 and 4, development prospects. Detailed annual and described in detail in Chapter 3 and the production records and information on mine Bairnsdale Mine Database. history are provided for most mines in the BAIRNSDALE Mine Database. Regional scale evaluation of new geological and geophysical information; together with Stockwork and fine grained disseminated compilations of mineral resource, geochemistry sediment hosted mineralisation amenable to and exploration information, has identified bulk tonnage/low grade mining have been potential for new mineral resources. This recognised in the Bullumwaal and Store Creek potential is discussed in detail under goldfields (Wall, 1987; Cuffley, 1988). These mineralisation style headings. Further styles of mineralisation may be unrecognised in potential will be recognised by more detailed other BAIRNSDALE goldfields, where narrow evaluation of this information. In many high grade veins were traditionally mined instances, this would be significantly aided by detailed studies of the origin and timing of Auriferous veins of the Deptford goldfield have mineralisation. not been tested by modern exploration despite high grade ore, relatively thick reefs, and 6.1 Precious metal vein deposits repetition of veins over significant strike lengths. Very little modern exploration has been undertaken within BAIRNSDALE goldfields Linears in aeromagnetic data covering some despite significant gold production from some goldfields have the same trend as auriferous mines. In particular, the Bullumwaal, Store veins. These are interpreted to be magnetic Creek, Deptford and Yahoo Creek goldfields are dykes and faults, and may be a vector to zones covered by very low density stream sediment of fracturing and hydrothermal fluid pathways. geochemistry programs which are limited to the Within the Yahoo Creek, Bullumwaal, Deptford main mining centres only. Coverage of samples and Store Creek goldfields, auriferous veins analysed for gold by bulk cyanide leach (BCL) is correspond to a series of both broad and narrow even more restricted. The Omeo, Swifts Creek, magnetic linears. Aeromagnetic data also New Rush Creek, Haunted Stream, Cobbannah indicates a buried intrusion within the Deptford and Gladstone Creek goldfields are covered by goldfield. sparse sampling. The Grant, Dargo, Bullumwaal, Store Creek, Deptford and Yahoo Auriferous veins within the Dargo and Creek goldfields have not been tested by this Cobbannah goldfields are hosted by magnetic method. granite and hornfels. This mineralisation has probably formed separate from most Large mines within BAIRNSDALE were often mineralisation within the province, and abandoned with untested potential for indicates new gold potential for similar granites additional mineable reserves. New detailed and host rocks. The Dargo Granodiorite has a geological mapping, geophysical and recompiled distinctive signature in aeromagnetic data. geochemical data may indicate extensions to Data show up to three magnetic kernels mineralisation exploited by these mines, or surrounding a magnetic core, indicating 60 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

multiple intrusive events. Gold mineralisation are faulted against the Bendoc Group along the occurs between two of these kernels. The Gilbert and Kanni Faults. Mount Baldhead Granodiorite, east of the Dargo Granodiorite, has a similar signature. Remobilisation of metal associated with the This intrusive may also be prospective for emplacement of the Middle Silurian Crohn granite and thermal aureole hosted gold. Tonalite may have been important in the genesis of the precious and base metal deposits Granite hosted gold associated with tin has in this area. This intrusive is similar to been reported from the Colquhoun Granite, intrusives of the Bette Bolong Group which host although no detailed work has been undertaken porphyry copper mineralisation, and is to determine the controls on this prospective for this type of mineralisation. mineralisation. If controls on mineralisation within the Several mines within the Dargo goldfield also Benambra gold province can be established appear to be associated with north-south with certainty, modelling may provide a vector trending magnetic lineaments interpreted to be to undiscovered mineralisation. The most dykes. Auriferous veins in the Grant goldfield plausible model involves dilatant riedel shears correspond to a number of broad magnetic developed in response to dextral strike slip highs inferred to be deep seated intrusives. A movement on the Ensay and Kiewa faults number of mines appear to lie on northwest during the Lower Silurian Bindian Orogeny trending lineaments interpreted as dykes which acting as fluid pathways for hydrothermal crosscut the intrusives. fluids.

The main magnetic feature in the Dargo High The Swifts Creek goldfield is associated on the Plains goldfield is reversely magnetised magnetics with a number of short northwest Tertiary basalt. A number of alluvial gold trending lineaments interpreted as dykes and deposits have been mined from gravels beneath /or faults. The north-south orientation of the basalts. Comparison of the magnetics with auriferous veins in the field is weakly expressed the geology indicates a number of small in the magnetics. Exploration should focus on unmapped outliers of basalt which may hide the intersection between north-south and gold bearing gravels. Auriferous veins within northwest trending structures which may the goldfield may be associated with northwest provide favourable structural traps for trending lineaments, interpreted to be dykes. mineralisation. Several mines in the Omeo goldfield lie on northwest trending highs Precious and base metal resources in the Tara associated with mylonitised granites along the goldfield area are clustered about the toe of the Ensay Fault Zone. Kanni Horst. Mineralisation is discordant, and hosted by Pinnak Sandstone and Snowy River The Haunted Stream goldfield shows a strong Volcanics and appears most intense near the connection to northwest trending faults and margins of the horst. Modelling suggests the dykes probably associated with the Kiewa area north of this toe was a dilatant zone Fault. A number of "bulls eye" magnetic during Devonian rifting, offering good anomalies occur along the northern margin of permeability for hydrothermal fluids. Broad the goldfield. These are interpreted to be small sericitic and ferruginous zones shown on intrusions. One of these coincides with a fine mapping by VandenBerg et al. (1996) are grained, porphyritic propylitically altered coincident with this interpreted zone. Large dacitic intrusive. The alteration may be a areas within this zone are untested. Soil vector to local porphyry, epithermal or geochemistry data covering the Armistice Mine, mesothermal mineralisation. Most of the within this zone, indicate a high order gold exploration around Haunted Stream to date has anomaly open in all directions. focused on continuations of narrow quartz veins and little emphasis has been placed on other A narrow belt of graphitic black shales of the styles of mineralisation. Bendoc Group has recently been recognised in the core of the Kanni Horst (VandenBerg et al., 6.2 Lower Devonian epithermal 1996). These shales may play an important role in providing suitable geochemical sites for gold precious metal deposits deposition. The sites with the highest prospectivity are where Snowy River Volcanics GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 61

Testing of epithermal gold mineralisation related to the emplacement of a small stock at hosted by Snowy River Volcanics has delineated the end of the caldera cycle (Rytuba, 1994). several currently uneconomic bulk low grade gold resources. In light of poor early results, Recent mapping of the Mount Elizabeth several prospects remain untested and have Caldera Complex by Simpson et al. (1996) has potential for economic deposits. Tested deposits identified a number of alteration zones close to have potential for high grade zones within the margin of the volcanic pile, this includes delineated low grade zones. Airborne silicification and disseminated pyrite with radiometric data may be useful in defining patchy chloritic and haematitic alteration. alteration zones about deposits and identifying Numerous ring and radial fractures new deposits. Potential for new deposits is surrounding the Mount Elizabeth Caldera have indicated by relatively untested areas with also been identified (Simpson et al., 1996) and anomalous gold values in stream sediment these may be potential sites for epithermal sample data in the northern Snowy River precious metal stockwork vein mineralisation. Volcanics. Additionally Simpson et al. (1996) have recognised the presence of lacustrine sediments Recently recognised epithermal alteration and within the main caldera sequence. This is mineralisation occurs at the contact between considered one of the most favourable sites for Yalmy Group and Snowy River Volcanics just mineralisation, along with caldera structures north of Nowa Nowa at Boggy Creek and the Mount Elizabeth Granodiorite. (VandenBerg et al., 1996). This alteration zone Exploration programs should focus on these is untested by modern exploration. elements, rather than the caldera fill ignimbrite. Calderas The recently recognised caldera at Examples of the silicic calderas hosting base Accommodation Creek has not been geologically and precious metal deposits are numerous; mapped in any detail, and has similar potential Creede (Plumlee & Whitehouse-Veaux, 1994) for epithermal precious metal and porphyry and Summitville (Gray & Coolbaugh, 1994) in copper mineralisation. Colorado and Porco (Cunningham et al., 1994) in Bolivia are a few examples. In many 6.3 Placer gold deposits instances there is a clear genetic relationship between the caldera and ore body, however, the Tertiary Sediments process involved in caldera development produce structures that may localise A number of small areas of unmapped Tertiary mineralisation during a later unrelated event basalt are indicated by the geophysics (Slater, (Elston, 1994). Most genetically related ore 1996). These may overlie alluvial gravels which bodies form late in the caldera history and are prospective for deep lead style placer gold Elston (1994) in a recent review paper noted deposits. that ignimbrite eruptions associated with caldera collapse were more likely to disperse Mount Tambo Group metals than concentrate them in economic quantities. Favourable conditions late in the The Mount Tambo Group occupies a graben caldera history are related to magma rising south of Benambra, and consists of about 5000 along ring fractures and caldera resurgence, m of coarse grained fluvial clastics and rare producing an uplifted area within the caldera acid volcanics, folded about a tight northwest that is surrounded by a lower moat region trending syncline. The age of the group which may become the site for saline lakes. remains uncertain, it may be as old as Silurian Mixing between magmatic and meteoric waters or as young as Late Devonian. Recent can set up hydrothermal convection cells that geological mapping north of BAIRNSDALE leach and concentrate metals (Rytuba, 1994; suggests that the group is equivalent to the Elston, 1994). Both adularia-sericite and acid Wombat Creek Group. Little exploration has sulphate systems have been recognised, been undertaken in the group which may although the former is more common. The contain placer gold and possible red bed copper- distribution of gold mineralisation in the uranium deposits. Analysis of palaeocurrent Rodalquilar caldera in Spain is controlled by directions by Lew (1979) indicates sediment ring fault and radial fractures but is genetically derivation from the northwest, an area occupied by a number of goldfields, including Dart and 62 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Granite Flat and a number of base metal (eg. an important role in the discovery of new Mammoth Lode) and precious metal prospects economic deposits. (eg. Silver Flat and Silver Top). Exploration for placer style mineralisation should focus on Further exploration should be targeted towards the thick fanglomerate horizons which occur at magnetic highs associated with soil anomalies the base of the sequence. Geochemical near the contact between Gibsons Folly sampling may assist is locating small deposits, Formation and the Thorkidaan Volcanics along however due to the high degree of lithification strike from the Benambra mine. Because of the these would need to be rich in order to be structural complexity of the area these may economically extracted. Red beds occur occur at depth and may not show on the throughout the sequence and these are regional magnetics. Further detailed structural untested for copper-uranium mineralisation. mapping may assist in delineating the more prospective zones. Basal conglomerates of the Snowy River Volcanics and Avon River Group 6.5 Porphyry copper-gold The Basal Conglomerates of the Snowy River deposits Volcanics may be prospective for placer gold derived from mineralised areas surrounding the Several currently uneconomic porphyry copper Buchan Rift. Little geochemical sampling has deposits occur close to the margins of the been undertaken in these rocks. The most Buchan Rift within BAIRNSDALE. Magnetic, prospective zones are areas of high energy oxidised granites adjacent the rift are highly current flow indicated by coarse grained lag prospective for this style of mineralisation. deposits and channel conglomerates. The Moroka Glen Formation of the Avon River Potential for gold associated with these deposits Group is similarly prospective for placer gold is indicated by the discovery of porphyry deposits. copper-gold mineralisation in the Lachlan Fold Belt of NSW. BAIRNSDALE deposits are 6.4 Silurian volcanic largely untested for gold. associated massive Significant supergene mineralisation delineated sulphide (VAMS) deposits by exploration at the Dogwood prospect (Maher, 1994) in 1993-94 indicates new potential for On BAIRNSDALE this style of mineralisation porphyry copper deposits within appears to be restricted to the Limestone Creek BAIRNSDALE. Acid leached mineralisation Graben. Extensive exploration around the may lack a typical porphyry copper signature in Wilga and Currawong deposits has thus far geochemical surveys - particularly if hosts rocks failed to prove up additional resources although are recessive (eg. altered granite). Good several prospects remain to be fully tested by geochemical pathfinders in this regime are Mo drilling. However there are a number of factors Pb Cd Se Bi Ba W. which may assist in the discovery of further VAMS style deposits in the Limestone Creek Known porphyry copper deposits are covered by Graben. VAMS style mineralisation has only detailed soil and stream sediment geochemistry been delineated near the base of Gibsons Folly surveys. Samples from these surveys were Formation along the western margin of the rift, typically not analysed for gold. Stream adjacent to the Indi Fault. Both Wilga and sediment data also indicates several untested Currawong did not outcrop and soil anomalies anomalies which may correspond to developed "up dip from the deposit, on pyritic undiscovered porphyry copper mineralisation. mineralisation forming a lateral halo to the Molybdenum anomalies occur within many massive sulphide mineralisation" (Allen & Barr, broad copper anomalies indicating porphyry 1990). These deposits were defined by strong copper mineralisation. Despite being a good "bulls-eye" magnetic anomalies which were indicator of the centre of porphyry systems, confirmed by diamond drilling. Additionally particularly in acid leaching environments, the structure of the Limestone Creek Graben many anomalies remain untested. and the association it has with mineralisation remains poorly understood. An understanding Rodger River Intrusive of the structure of the graben will probably play GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 63

The Rodger River Lobe of the Snowy River where new intrusions have been mapped (ie. Volcanics comprises undifferentiated Snowy Broken Leg Tonalite, Feltis Farm Granodiorite River Volcanics and hosts a number of base and and Eleven Bob Granodiorite). precious metal prospects, including the Rodger River, Eel and Pyramid prospects. The aeromagnetic data indicates the presence Aeromagnetic data indicates that this lobe is of numerous fractures trending north-south and underlain by extensive highly magnetic I-type northeast within intrusions, and these are intrusions. In outcrop these show petrographic regarded as favourable sites for potential similarities to the Bete Belong Group of mineralisation. One of these structures runs granites, and have high potential for porphyry between the Bete Belong and Double Bull style mineralisation. In most instances, roof granodiorites which are separated by a roof zones of these deposits will be preserved. pendant of metamorphosed Pinnak Sandstone. A north-south trending fault forms the eastern While timing relationships preclude the granite boundary to the Broken Leg Tonalite at depth as a primary source of epithermal and cuts the Eleven Bob Granodiorite to the mineralisation within the Rodger River lobe, south. These two structures are largely spatial relationships suggest potential for untested and warrant further investigation in remobilisation of porphyry copper light of the new mapping. mineralisation from the intrusive bodies. A significant copper-molybdenum anomaly in Nunniong Pluton stream sediment data corresponds to the Feltis Farm Tonalite. Although copper anomalies Porphyry copper mineralisation within the have been tested at the Sunday Creek prospect Nunniong Pluton occurs within a high and Booths Fancy copper mine within and potassium phase identified in airborne adjacent to the Feltis Farm Tonalite, large radiometric data (Twyford, 1996). Northwest anomalous areas of molybdenum and copper in trending aeromagnetic linears, interpreted to stream sediment and soil remain untested. be magnetic dykes, occur within this phase - and correspond to some mineralisation. The The Bete Belong granites are associated with a relationship between these dykes and suite of narrow late altered dykes of uncertain mineralisation is uncertain. composition. A number of these dykes have been mapped along the Old Bonang Highway Bete Belong Group around the Eleven Bob Granodiorite and around the Feltis Farm Tonalite along Mount The Bete Belong Group of intrusives host Watt Track (VandenBerg et al., 1996). They several porphyry copper deposits. The also occur east of BAIRNSDALE (Hendrickx et intrusives are I-types with more mafic al., 1996) where they are associated with intrusives occurring in the eastern portion. The anomalous but patchy gold mineralisation. granites are well defined on regional magnetics Those along the Old Bonang Highway are which along with recent mapping (VandenBerg strongly altered and assays show anomalous et al., 1996 and Hendrickx et al., 1996) indicate Cu, Zn, and As values (VandenBerg et al., they have shallow contacts with the 1996). These late stage dykes represent an surrounding Pinnak Sandstone and have only important and only recently recognised target. recently been deroofed. Many intrusions contain large areas of propylitic alteration Mount Elizabeth Caldera Complex shown by the presence of epidote and chlorite and possible phyllic (sericitic?) alteration The potential for porphyry copper highlighted by areas of high potassium on mineralisation in the Mount Elizabeth Caldera radiometric images. Complex is relatively low. Most of the structural dome formed during resurgence, one Exploration for porphyry copper gold should of the favoured sites for mineralisation of this focus on the margins of the intrusion where the style has been largely removed by erosion, best geochemical anomalies occur. The more though there is potential for porphyry style mafic eastern intrusions including Broken Leg mineralisation around small apophyses and Tonalite, Feltis Farm Granodiorite and dykes associated with the Mount Elizabeth Dysentery Granodiorite (east of BAIRNSDALE) Granodiorite which have not yet been deroofed. may be more prospective. Further work should be undertaken particularly around the areas 64 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

6.6 Base metal vein deposits Arne et al. (1994) showed that mineralisation was remobilised by the Tabberabberan The Accommodation Creek copper mine lies on Deformation. Re-evaluation of work on the over a ring dyke interpreted from aeromagnetic 40 carbonate hosted base and precious metal data. This dyke is probably controlled by a occurrences should be undertaken to determine concentric fracture about a collapsed Lower whether mineralisation is primary or Devonian caldera. Repetitions of remobilised. Remobilised mineralisation may Accommodation Creek style copper be a vector to unrecognised primary mineralisation may be coincident with the ring mineralisation. IP has been effective in dyke at other locations. Mineralised veins of delineating pyrite alteration zones surrounding the Deddick lead-zinc field occupy northwest primary mineralisation. trending fractures in Amboyne Granodiorite basement of this caldera. Magnetic dykes 6.9 Tennant Creek style which are temporally related to mineralised copper-gold deposits veins also occupy these fractures. Lineaments in aeromagnetic data indicating dykes are Review of unpublished geochemical ledgers probably a good indicator of basement fractures, from Mines Department drilling of the Nowa and potential hydrothermal fluid pathways. Nowa ironstones showed significant gold The intersections of these basement fractures intersections. The Nowa Nowa ironstones have and concentric fractures may also be important characteristics which make them broadly hydrothermal fluid pathways. analogous with some Tennant Creek ironstones which host significant gold and copper Aeromagnetic data indicates fracturing in the resources. Typically, Nowa Nowa ironstones south and east of the Nunniong Pluton. Similar have not been adequately tested for this style of fracturing is present within host rocks to the mineralisation. Deddick and Campbells Knob lead-zinc fields, and indicates potential for fissure vein style Ironstones occur close to normal faults of the base and precious metal mineralisation within Buchan Rift. New aeromagnetic data indicates the Nunniong Pluton. potential for small undiscovered ironstones in the Nowa Nowa area. Ironstones may also 6.7 Red bed copper - uranium occur in the Snowy River Volcanics south of Nowa Nowa where there is no detailed Elevated uranium and thorium (a daughter geophysical coverage. While drilling and product of uranium) values in new radiometric magnetic surveys show Ironstones have small data correspond to the "fluvial upper micaceous plan areas, bodies are generally open at depth. siltstone" of the Snowy Plains Formation - Avon River Group (Porter, 1973; Buckley, 1982; Specular haematite ± barite occurs as stringers Slater, 1996). Reduced zones of this facies host in large alteration zones near Nowa Nowa in small, low grade copper deposits. These the south of the Snowy River Volcanics. characteristics make the facies prospective for Mineralisation occurs in basal units of the sandstone uranium (copper) type deposits. Snowy River Volcanics, and is probably synchronous with emplacement of the Nowa 6.8 Carbonate hosted base Nowa ironstones. Early reports of gold associated with these zones are not proven, metal deposits however this potential has not been fully tested.

Arne et al. (1994) proposed carbonate hosted The presence of these epigenetic mineral metal deposits in the Lower Devonian Buchan occurrences in basal units of the Snowy River Group Limestone are similar to Irish style Volcanics suggests the Snowy River Volcanics deposits. Geological mapping by VandenBerg et have acted as an impermeable trap for al. (1996) and Orth et al. (1995) has delineated ascending hydrothermal fluids. the basal dolostone horizon which hosts the Buchan deposits, plus several new areas of limestone. They also provide a clearer picture 6.10 Granite hosted tin deposits of the structural evolution of the Buchan Rift which is important if like the Irish deposits, the Tin and gold deposits associated with Middle Buchan deposits are localised by growth faults. Devonian granites within the Howqua Basement Terrain north of BAIRNSDALE at GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 65

Beechworth indicate potential for this style of 6.12Heavy mineral sands mineralisation within similar granites. Weak tin and gold mineralisation is known within the Potential for heavy mineral sands in Colquhoun Granite within BAIRNSDALE. Quaternary and Tertiary sediments along the Although tin values are low, controls on coastal plain of BAIRNSDALE is untested. mineralisation are not well understood. Small heavy mineral occurrences of ilmenite, Investigation of these controls may improve the with minor amounts of rutile and zircon occur likelihood of discovering significant in Quaternary beach and dune deposits east of mineralisation in the Colquhoun Granite, and BAIRNSDALE at Point Pearl, , Sarsfield and Mount Taylor granites which and Point Hicks (McHaffie & have similar compositions. The Sarsfield and Buckley, 1995). Heavy minerals, including Mount Taylor granites are untested by modern gold, may also be concentrated in ancient exploration. shorelines. Airborne radiometric data shows east-west lineaments which may represent These and similar granites are also prospective ancient shore lines. Tertiary sediments are for tungsten and molybdenum veins, plus dominated by limestone, which suggests an tungsten skarn type deposits in north unfavourable environment for heavy mineral BAIRNSDALE where host rocks are more deposits. reactive. Local sources of heavy minerals include 6.11Skarns granites and auriferous veins.

Limestone megaclasts in the Limestone Creek 6.13Industrial minerals Graben, and interbedded calcareous turbidites the Yalmy Group are potential sites for skarn Limestone horizons, sand and gravel in the mineralisation. Seaspray Group are suitable for use in agriculture and construction materials. Limestone megaclasts in the Limestone Creek Granitic rocks also provide a source for Graben have a close spatial relationship with construction materials, and are possible sources the Thorkidaan Volcanics, Silurian granites and for dimension stone. the Snowy River Volcanics. Late stage intrusives of the Thorkidaan Volcanics intrude Large resources of limestone and dolomite have the Towanga Sandstone and Cowombat been defined in the Buchan Group. Potential Siltstone both of which contain large limestone uses are outlined in Chapter 3.15. The most megaclasts. Porphyry and skarn style important of these are pure limestone of the mineralisation may occur where limestone Rocky Camp Member and dimension stone at bodies have been intruded. Undifferentiated Bindi and Buchan. Snowy River Volcanics unconformably overlie limestone near Bindi. Narrow intrusive dykes are common in the volcanics and there is 6.14Diamonds potential for skarn style mineralisation around them. Numerous pin point anomalies may represent mafic intrusions similar to those which host The extent of carbonate turbidites in the Yalmy diamonds in other parts of the world. The Group appears limited. They have thus far only potential for diamonds within BAIRNSDALE is been recognised in northeast BAIRNSDALE untested. (Orth et al., 1995). However, recent mapping in southeast BAIRNSDALE (VandenBerg et al., 6.15Buried intrusions 1996) and east of BAIRNSDALE (Hendrickx et al., 1996) indicates these may be more The aeromagnetic data has highlighted a widespread than previously thought. The number of buried intrusions. Depending on potential for skarn mineralisation in the Yalmy their depth these may prospective for porphyry Group is largely untested. The best areas for copper-gold or mesothermal and epithermal exploration are in the Yalmy Fold and Thrust precious metal mineralisation. All but one of Belt south of the Gelantipy Plateau where the these have been discussed in previous sections. group is intruded by the mafic Rodger River A circular intrusive is defined by the magnetics Granite. southwest of the Mount Elizabeth Caldera Complex (Fig. 11). It is traversed by a number 66 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

of magnetic lineaments which may be dykes or faults. Limited exploration to date has recognised elevated copper, zinc, gold, tungsten, molybdenum and arsenic values around the Lanky Tom Creek prospect which sits above the magnetic anomaly. A detailed geochemical survey is required to further define potential targets above the intrusion. Detailed mapping of the area may identify alteration zones. The limited geochemical data available indicates this is a worthwhile exploration target. GEOLOGY AND PROSPECTIVITY - BAIRNSDALE 67

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MARSDEN, M.A.H., 1988. Upper Devonian- MURRAY, R.A.F., 1887. Notes on the mining Carboniferous. In J.G. Douglas & J.A. features of the Haunted Stream goldfield. Ferguson (eds) Geology of Victoria. The Gold-fields of Victoria Reports of the Geological Society of Australia, Victorian Mining Registrars for the Quarter Ended Division, Melbourne, pp. 147-194. 30th September, 1887. Department of Mines, Victoria. MCDOUGALL, I. & WELLMAN, P., 1976. Potassium-Argon ages from some MURRAY, R.A.F., 1893. Tallatoorook Mine, Australian Mesozoic igneous rocks. Bruthen (1). Geological Survey of Journal of the Geological Society of Victoria Unpublished Report 1893/1725. Australia 23, pp. 1-9. MURRAY, R.A.F., 1895. Gold on the Upper MCHAFFIE, I.W. & BUCKLEY, R.W., 1995. Gladstone a tributary of Freestone Creek, Industrial minerals and rocks of Victoria. near Briagolong. Geological Survey of Geological Survey of Victoria Report 102. Victoria Unpublished Report 1895/3035 & 1353. MCINERNY, K., 1929. The building stones of Victoria Part II. The igneous rocks. MURRAY, R.A.F., 1896. Report on the Deptford Proceedings of the Royal Society of Goldfield. Department of Mines, Victoria, Victoria 41(2), pp. 121-159. Special Report.

MCKENZIE, D.A., NOTT, R.J. & BOLGER, P.F., NEILSON, J.L., 1964. Moroka 1:31 680 1984. Radiometric Age Determinations. geological map. Geological Survey of Geological Survey of Victoria Report 74. Victoria, Unpublished geological compilation & field map. Map file, MCLAUGHLIN, R.J.W. & TATTAM, C.M., 1976. Mapping Section, Geological Survey of Plutonic Rocks. In J.G. Douglas & J.A. Victoria. Ferguson (eds) Geology of Victoria. Geological Society of Australia Special NOTT, R.J., 1980. Geological and magnetic Publication 5, pp. 349-362. survey of the Two Mile iron ore deposit, Nowa Nowa, East Gippsland. Geological MILLIN, P., 1983. A.C.A. Howe Australia Pty. Survey of Victoria, Unpublished Report Ltd. Report on the survey and initial 1980/17. geological assessment of the Omeo Placer Gold Prospect Omeo Victoria, EL 1219. O'SHEA, P.J., 1980. Mineral potential of the Department of Natural Resources and Snowy River Volcanics and Buchan Caves Environment, Victoria, Expired Mineral Limestone. Geological Survey of Victoria Exploration Reports File. Ref No. 1324. Report 63.

MITCHELL COTTS PROJECTS, 1986. ML's 536, O'SHEA, P.J., ROONEY, S., WHITEHEAD, M., 947 and 974. Reports jointly microfilmed FINLAY, I.S. & HIEW, P., 1994. Primary June 1986. Department of Natural gold mineralisation potential in the Resources and Environment, Victoria, Tabberabbera Zone of the Lachlan fold Expired Mineral Exploration Reports File Belt, Eastern Victoria. Geological Survey (unpubl.). of Victoria Unpublished Report 1994/23.

MORAND, V.J., 1990. Low pressure regional OPPY, I.D., CAYLEY, R.A. & CALUZZI, J., 1995. metamorphism in the Omeo Metamorphic The geology and prospectivity of the Complex Victoria Australia. Journal of Tallangatta 1:250 000 sheet. Victorian Metamorphic Geology 8, pp. 1-12. Initiative for Minerals & Petroleum Report 10. Department Agriculture, MORAND, V.J. & GRAY, D.R., 1991. Major fault Energy and Minerals. zones related to the Omeo Metamorphic Complex, northeastern Victoria. ORTH, K., VANDENBERG, A.H.M., NOTT, R.J. & Australian Journal of Earth Sciences 38, SIMONS, B.A., 1995. Murrindal 1:100, 000 pp. 203-221. map geological report. Geological Survey Reports 100. 72 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

PARINGA MINING & EXPLORATION CO, 1988. 1994 airborne survey. Victorian Reports jointly microfilmed under EL Initiative for Minerals and Petroleum 1288. Department of Natural Resources Report 9. Department of Agriculture, and Environment, Victoria, Expired Energy and Minerals. Mineral Exploration Reports File (unpubl.). SHERREN, G.I., 1979. Geology of the Dellicknora Valley region, East PEERS, J.G., 1885. Report on the Alleged Gippsland. Bsc (Hons) thesis, Discovery of a Payable Gold-field at Black Department of Geology, La Trobe Watch Creek. The Goldfields of Victoria, University, Melbourne (unpubl.). Reports of the Mining Registrars for the Quarter Ended 30th June 1885. SIMPSON, C.J., SIMS, J. & ORANSKAIA, A.N., Department of Mines, Victoria, pp. 70-71. 1996. The geology and prospectivity of the Mt. Elizabeth area, Eastern PORTER, T.M., 1973. CRA Exploration Pty Ltd. Highlands VIMP area. Victorian EL 451, Mitchell River, eastern Victoria, Initiative for Minerals and Petroleum final report. Department of Natural Report 19. Department of Natural Resources and Environment, Victoria, Resources and Environment. Expired Mineral Exploration Reports File (unpubl.). SLATER, K.R., 1996. An appraisal of new airborne geophysical data over the Dargo PUMLEE, G.S. & WHITEHOUSE-VEAUX, P.H., region, Victoria. Victorian Initiative for 1994. Mineralogy, paragenesis and Minerals and Petroleum Report 32. mineral zoning of the Bulldog mountain Department of Natural Resources and vein system Creede district, Colorado. Environment. Economic Geology 89, pp. 1883-1905. STIRLING, J., 1887. Appendix B. Report on the RAMSAY, W.R.H. & WILLMAN, C.E., 1988. Gold. alleged discovery of auriferous quartz at In J.G. Douglas & J.A. Ferguson (eds) Nowa Nowa. The Goldfields of Victoria. Geology of Victoria. Geological Society of Reports of the Mining Registrars for the Australia, Victorian Division, Melbourne, Quarter Ended 31st December 1887. pp. 454-481. Department of Mines, Victoria, pp. 72-74.

RICHARDS, J.R. & SINGLETON, O.P., 1981. TALENT, J.A., 1956. Devonian brachiopods and Palaeozoic Victoria, Australia: igneous pelecypods of the Buchan Caves rocks ages and their interpretation. Limestone Victoria. Proceedings of the Journal of the Geological Society of Royal Society of Victoria 68, pp. 1-56. Australia 28, pp. 395-421. TALENT, J.A., 1961. Dolomite bores, Parish of RINGWOOD, A.E., 1995. The geology of the Buchan. Geological Survey of Victoria Snowy River district, east Gippsland. Unpublished Report 1961/53. Proceedings of the Royal Society of Victoria 67, pp. 67-74. TALENT, J.A., 1963. The Buchan Caves. Geological Survey of Victoria ROSALES, H., 1897. Report on Mount Wills as a Unpublished Report 1963/35. gold-field and tin-field respectively, and also on the Tongio West gold-field. TALENT, J.A., 1964. Cobberas. 1 mile to 1 inch Department of Mines, Victoria, Special geological map. Department of Mines, Report. Victoria.

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Appendix 1

Bairnsdale 1:250 000 map area: Summary of Exploration Licences Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 14 Planet Mining Co. Pty Ltd Au 12/07/65 07/08/69 $320,0001 ü ü ü ü ü EL 15 Planet Mining Co. Pty Ltd Au 12/07/65 07/08/69 > $32,862 ü ü ü ü ü EL 16 Planet Mining Co. Pty Ltd Au 12/07/65 07/08/69 n/a ü ü EL 50 Rio de Janeiro Mines Pty Ltd Cu, Pb, Zn 06/06/66 16/06/71 n/a ü ü ü ü ü EL 68 Australian Geophysical Pty Ltd Cu, Pb, Zn 14/11/66 10/07/68 n/a ü ü ü ü EL 83 Rio de Janeiro Mines Pty Ltd Au, Cu, Pb, Zn, W 27/11/67 27/09/71 n/a ü ü ü ü ü EL 86 Rio de Janeiro Mines Pty Ltd Cu, Pb, Zn 27/11/67 27/09/71 n/a ü ü ü ü ü EL 87 BHP Minerals Ltd Cu, Pb, Zn 04/03/68 29/04/68 n/a ü ü ü EL 92 Gippsland Minerals NL Cu, Pb, Zn 30/09/68 22/03/72 $90,735 ü ü ü EL 95 Eastern Prospectors Pty Ltd Au 02/09/68 03/06/70 n/a ü EL 115 Rio de Janeiro Mines Pty Ltd Cu, Pb, Zn 30/01/69 20/10/71 n/a ü ü EL 124 Pickands Mather & Co Cu 08/09/69 13/10/71 n/a ü ü ü EL 156 Gippsland Minerals NL Cu 19/01/70 29/03/72 n/a ü ü ü EL 160 Pickands Mather & Co Cu 24/08/70 17/02/70 n/a ü EL 161 Valley Explorations Au 01/04/70 31/03/71 $1,525 ü ü ü EL 233 Quilmin Mines & Exploration NL Au 10/02/71 07/04/76 $135,165 ü ü ü ü ü EL 243 Transouth Mining Pty Ltd Au 02/11/70 26/04/72 n/a ü ü ü EL 322 Strahan Sands Pty Ltd Heavy Minerals 12/07/71 09/02/72 n/a ü ü EL 325 Comstock Minerals Ltd Cu, Zn, Mo 22/03/71 24/03/71 n/a ü ü EL 356 Coopers Creek Mining & Exploration NL Cu 12/07/71 18/10/72 n/a ü ü EL 397 Comalco Ltd Fl 08/09/72 13/09/72 $21,183 ü ü ü EL 442 Endeavour Oil Company NL Au 13/10/72 11/04/73 $1,795 ü ü EL 450 CRA Exploration Pty Ltd Cu 20/10/72 30/05/73 $12,027 ü ü EL 451 CRA Exploration Pty Ltd Cu 20/10/72 30/05/73 $2,894 ü ü

1 Figure reported together with EL 233 Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 456 Western Mining Corporation Ltd Cu, Pb, Zn 27/10/72 26/10/82 see EL 1236 ü ü ü ü ü ü EL 460 Amoco Minerals Australia Pty Ltd Cu 15/12/73 28/08/74 $66,694 ü ü ü ü ü EL 471 Dampier Mining Co Ltd Cu 13/07/73 10/07/74 $2,157 ü ü ü EL 480 Amoco Minerals Australia Pty Ltd Cu 29/06/73 23/01/74 $3,260 ü ü EL 496 ICI Australia Ltd /Newmont Cu, Pb, Zn 05/10/73 05/02/75 $45,7402 ü ü ü EL 500 ICI Australia Ltd /Newmont Cu, Pb, Zn 28/09/73 05/02/75 see EL 496 ü ü EL 503 CRA Exploration Pty Ltd Au 14/09/73 28/08/74 n/a ü ü ü EL 504 CRA Exploration Pty Ltd Au 14/09/73 28/08/74 n/a ü ü ü EL 505 CRA Exploration Pty Ltd Au, As 12/10/73 20/02/74 $1,493 ü ü EL 506 CRA Exploration Pty Ltd Au, As 12/10/73 20/02/74 $2,386 ü EL 512 Newmont Holdings Pty Ltd Cu, Pb, Zn 06/03/74 22/01/75 see EL 496 ü ü ü ü EL 521 Newmont Holdings Pty Ltd Cu, Pb, Zn, Ba 24/05/74 05/02/74 see EL 496 ü ü EL 534 CRA Exploration Pty Ltd Pb, Zn 04/10/74 11/06/75 $8,422 ü ü ü EL 536 ICI Australia Ltd /Newmont Cu, Pb, Zn, Ba ? 1975 n/a ü ü EL 537 Western Mining Corporation Ltd Cu, Pb, Zn 13/12/74 26/10/82 see EL 1236 ü ü ü ü ü ü EL 552 Preussag Australia Pty Ltd Cu Pb Zn 29/05/75 28/05/83 see EL 1466 ü ü ü ü ü EL 559 Planet Mining Co Pty Ltd Au 14/08/75 01/07/76 n/a ü ü ü EL 564 Preussag Australia Pty Ltd Cu Pb Zn 22/03/76 27/05/81 see EL 1466 ü ü ü ü ü EL 570 Western Mining Corporation Ltd Cu Pb Zn 08/04/76 07/04/82 see EL 1236 ü ü ü ü ü ü EL 572 Preussag Australia Pty Ltd Cu Pb Zn 14/01/76 17/03/82 see EL 1466 ü ü ü ü ü EL 596 Western Mining Corporation & BP Cu, Pb, Zn, Au 24/01/77 23/01/83 see EL 1241 ü ü ü ü ü ü Mining Development Pty Ltd EL 597 Western Mining Corporation & BP Cu, Pb, Zn, Au 24/01/77 23/01/83 see EL 1241 ü ü ü ü ü ü Mining Development Pty Ltd EL 614 Northern Mining Corporation U, V 17/11/77 11/04/79 $12,6383 ü

2 Figure reported together with ELs 500, 512, 512, 521, 536 3 Figure reported together with ELs 612, 613, 615, 616, 617 Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 615 Northern Mining Corporation U, V 17/11/77 11/04/79 see EL 614 ü EL 616 Northern Mining Corporation U, V 17/11/77 11/04/79 see EL 614 ü EL 668 Asarco Australia Pty Ltd Cu, Pb, Zn 06/09/78 28/02/79 $9,289 ü ü EL 671 Australian Anglo American Prospecting Cu, Pb, Zn 24/08/78 23/08/82 see EL 1228 Pty Ltd EL 675 Cultus Pacific NL Cu, Pb, Zn 26/10/78 25/10/82 $120,920 ü ü ü ü EL 684 Preussag Australia Pty Ltd Cu, Pb, Zn 02/05/79 01/05/82 see EL 1466 ü ü ü ü ü EL 695 Australian Anglo American Prospecting Mo 15/02/79 30/06/82 $222,447 ü ü ü Pty Ltd EL 696 Shire Of Omeo Au, Ag 15/08/79 8/08/82 $87, 997 ü ü ü ü ü EL 697 Preussag Australia Pty Ltd Cu, Pb, Zn 02/05/79 01/05/82 see EL 1466 ü ü ü ü ü EL 703 Preussag Australia Pty Ltd Cu, Pb, Zn 09/08/79 16/03/81 see EL 1466 ü ü ü ü ü EL 705 Preussag Australia Pty Ltd Cu, Pb, Zn 09/08/79 08/08/82 see EL 1466 ü ü ü ü ü EL 754 Maver.G Au 20/02/80 25/02/81 n/a ü ü ü EL 764 Australian Anglo American Prospecting Au, Cu, Pb, Zn 04/12/81 09/02/83 $40,635 ü ü Pty Ltd EL 766 Preussag Australia Pty Ltd Fe 13/03/80 12/03/83 see EL 1466 ü ü ü ü ü EL 772 Wattle Valley Estate Pty Ltd Au 20/11/80 08/12/82 >$12,000 ü ü EL 841 Freeport Australia Minerals Ltd Au, Ag (Sn, W, Cu) 21/08/80 11/06/82 $172,5254 ü ü ü ü EL 842 Freeport Australia Minerals Ltd Au, Ag (Sn, W, Cu) 15/08/80 10/02/83 see EL 841 ü ü ü ü EL 843 Freeport Australia Minerals Ltd Au, Ag (Sn, W, Cu) 15/08/80 10/02/83 see EL 841 ü ü ü ü EL 844 Freeport Australia Minerals Ltd Au, Ag (Sn, W, Cu) 21/08/80 10/02/83 see EL 841 ü ü ü ü EL 964 CRA Exploration Pty Ltd Cu, Au 26/10/81 17/03/83 n/a ü ü EL 968 Palaw Pty Ltd Au 06/07/81 14/10/82 $5,774 ü ü EL 984 BHP Minerals Ltd Brown Coal 17/09/81 28/10/82 $17,273 ü ü EL 985 BHP Minerals Ltd Brown Coal 17/09/81 28/10/82 $23,785 ü ü

4 Figure reported together with ELs 842, 843, 844. Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 987 BHP Minerals Ltd Brown Coal 17/09/81 20/12/82 $54,719 ü ü ü EL 988 BHP Minerals Ltd Brown Coal 17/09/81 28/10/82 $38,234 ü ü ü EL 1026 Shell Australia Pty Ltd Brown Coal 09/11/81 19/05/83 $157,678 ü ü ü ü EL 1027 Shell Australia Pty Ltd Brown Coal 09/11/81 24/12/82 $23,794 ü ü ü ü EL 1049 BP Mining Development Pty Ltd Brown Coal 23/10/81 05/10/82 $106,215 ü ü ü ü EL 1082 Essex Pty Ltd Au 23/10/81 15/09/82 $169,753 ü ü ü ü ü ü EL 1203 Preussag Australia Pty Ltd Au 16/09/82 15/09/85 see EL 1466 ü ü ü ü ü EL 1204 Preussag Australia Pty Ltd Cu, Pb, Zn, Au 16/09/82 15/09/85 see EL 1466 ü ü ü ü ü EL 1206 Seltrust Mining Corporation Pty Ltd Mo 31/03/83 15/08/83 $1,565 ü ü ü EL 1228 Australian Anglo American Prospecting Cu, Pb, Zn, 05/10/82 08/09/83 $1,067,129 ü ü ü ü ü Pty Ltd EL 1234 Western Mining Corporation Ltd Cu, Pb, Zn 16/09/82 15/09/88 see EL 1236 ü ü ü ü ü ü EL 1235 Macquarie Resources Pty Ltd Cu, Pb, Zn 16/09/82 15/09/88 see EL 1236 ü ü ü ü ü ü EL 1236 Western Mining Corporation Ltd & Cu, Pb, Zn 16/09/82 15/09/88 ³ $13 Million 5 ü ü ü ü ü ü Macquarie Resources Pty Ltd EL 1240 Western Mining Corporation & BP Cu, Pb, Zn, Au 06/01/84 19/07/85 see EL 1241 ü ü ü ü ü ü Mining Development Pty Ltd EL 1241 Western Mining Corporation & BP Cu, Pb, Zn, Au 06/01/84 19/07/85 $1,028,7546 ü ü ü ü ü ü Mining Development Pty Ltd EL 1274 Barry Luxton & Co. Pty Ltd Au 16/05/83 15/05/85 $27,490 ü ü ü EL 1287 Canyon Resources Pty Ltd Au 5/07/83 5/07/85 n/a ü ü ü EL 1288 Paringa Mining And Exploration Au 17/03/83 16/03/88 $152,190 ü ü EL 1302 Plagolmin Au, VMS 5/07/83 5/07/85 n/a ü ü ü EL 1433 CRA Exploration Pty Ltd Au 29/10/84 25/02/86 n/a ü ü ü EL 1447 Canyon Resources Pty Ltd Au 12/04/85 11/04/87 $10,664 ü ü EL 1455 Samedan Oil Corporation Cu, Pb, Zn 29/10/84 25/02/86 $22,408 ü ü ü

5 Figure reported together with ELs 456, 537, 570, 1234, 1235 6 Figure reported together with ELs 1240, 596, 597 Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 1491 Freeport of Australia Inc. Cu Pb Zn Au 08/03/85 25/06/86 $5,753 ü ü EL 1466 Preussag Australia Pty Ltd Cu., Pb, Zn, Au 29/10/84 09/09/85 $2,269,0267 ü ü ü ü ü EL 1514 Freeport Australia Minerals Ltd Au, Ag, Cu, Pb, Zn 2/08/85 25/06/86 $6,673 ü ü ü EL 1633 BHP Minerals Ltd Au 23/10/86 28/06/89 $81,383 ü ü ü EL 1634 BHP Minerals Ltd Au 15/08/86 14/08/88 $59,386 ü ü EL 1656 Brady.J/Noble Resources NL Au 17/11/86 16/11/89 $50,493 ü ü ü EL 1658 BHP Minerals Pty Ltd Au, Pb, Zn 13/05/87 13/05/91 $666,419 ü ü ü ü EL 1659 BHP Minerals Pty Ltd Au 13/05/87 20/04/89 $97,902 ü ü ü ü EL 1660 Mumbil Mines NL Au 3/11/86 2/11/88 $4,149 ü ü ü EL 1662 Western Mining Corporation Au 06/05/87 01/12/90 see EL 3245 ü EL 1667 Krummei, G.K Au 29/09/87 29/08/88 n/a ü ü ü EL 1675 Croft, T.F / Noble Resources NL Au 18/06/87 18/06/91 $38,216 ü ü ü ü EL 1684 Mumbil Mines NL Au, W, Mo 14/01/87 13/01/89 n/a ü ü ü ü EL 1722 Northbridge Gold Resource Pty Ltd Au 16/10/87 15/10/88 n/a ü ü ü ü EL 1785 Helix Resources Ltd Au, Pt, Pd 03/07/87 02/07/88 $22,613 ü ü EL 1824 Ticane Pty Ltd Au 01/03/88 28/06/89 $20,595 ü ü EL 1906 CRA Exploration Pty Ltd Au 01/03/88 28/06/89 $23,039 ü ü EL 1911 CRA Exploration Pty Ltd Au 17/11/89 18/09/91 $31,994 ü ü EL 1956 Hochwimmer & Associates Au 28/12/87 27/12/88 $12,250 ü ü ü EL 2114 Peter Woods & Associates Au 27/04/88 24/06/90 $30,793 ü ü EL 2134 CRA Exploration Pty Ltd Au 13/07/89 13/07/91 $17,284 ü ü EL 2136 CRA Exploration Pty Ltd Au 15/08/89 15/08/92 see EL 3299 ü ü ü ü ü EL 2137 CRA Exploration Pty Ltd Au 25/05/88 25/09/91 $61,430 ü ü EL 2138 CRA Exploration Pty Ltd Au 21/09/90 21/09/92 $74,354 ü ü EL 2244 CRA Exploration Pty Ltd Au 16/12/88 16/12/92 see EL 3010 ü ü ü

7 Figure reported together with ELs 552, 564, 572, 684, 697, 703, 705, 1203, 1204 Holder Primary Exploration Grant Expiry Expenditure Mapping Gnd. Air Geochem. Lit. Drill Target date date geoph. geoh. survey

EL 2263 CRA Exploration Pty Ltd Au, Cu 15/11/88 16/12/94 see EL 3012 ü ü ü ü ü ü EL 2264 CRA Exploration Pty Ltd Au 05/04/89 05/04/91 $113,847 ü ü EL 2410 Goldrill Pty Ltd Au 1/12/89 1991? see EL 3017 ü ü EL 2413 Bendigo Gold Associates Pty Ltd Au 11/08/89 21/12/89 $2,578 ü EL 2441 Tasrock Resources Pty Ltd Au 29/09/89 23.3.95 see EL 3023 ü ü EL 2534 Delta Gold NL Cu, W 12/09/90 14/02/92 $7,266 ü ü ü EL 2560 BHP Minerals Ltd Pb, Zn 24/05/90 14/08/91 $77,360 ü ü ü EL 2568 BHP Minerals Ltd Au, Cu, Pb 05/07/90 14/08/91 $12,250 ü ü EL 2569 BHP Minerals Ltd Pb, Zn 05/07/90 14/08/91 $10,141 ü EL 3010 CRA Exploration Pty Ltd Au 16/12/88 16/12/92 $362,1018 ü ü ü EL 3012 CRA Exploration Pty Ltd Au, Cu 15/11/88 16/12/94 n/a ü ü ü ü ü ü EL 3017 Goldrill Pty Ltd Au 1/12/89 1991? $95,6299 ü ü EL 3023 Tasrock Resources Pty Ltd Au 29/09/89 23.3.95 $116,83110 ü ü EL 3035 Hardrock Exploration Pty Ltd Au, Cu, Pb, Zn 05/11/86 04/11/94 $473,386 ü ü ü ü ü EL 3245 CRA Exploration Pty Ltd Au 01/12/90 06/05/93 $1,252,35511 ü EL 3299 CRA Exploration Pty Ltd Au 15/08/89 15/08/92 $291,68812 ü ü ü ü ü EL 3309 CRA Exploration Pty Ltd Au 27/08/92 27/08/95 $97,712 ü ü ü ü ü ü EL 3436 CRA Exploration Pty Ltd Au 29/06/93 29/06/95 $11,596 ü ü ü EL 3556 CRA Exploration Pty Ltd Au, Cu 24/03/94 24/03/96 n/a ü ü EL 3720 Platsearch NL Au 28/02/95 29/11/95 $34,246 ü ü

8 Figure reported together with EL 2244 9 Figure reported together with EL 2410 10 Figure reported together with EL 2441 11 Figure reported together with EL 1662 12 Figure reported together with EL 2136 82 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Appendix 2

Bairnsdale 1:250 000 map area: Location of expired Exploration Licences

Legend:

Sheet 1: ELs 14, 15, 16, 68, 87 Sheet 2: EL 95 Sheet 3: ELs 50, 83, 86, 115, 124, 160, 161, 325 Sheet 4: ELs 92, 156, 243, 322, 356, 397 Sheet 5: ELs 442, 450, 451 Sheet 6: ELs 460, 480, 471, 503, 504, 505, 506 Sheet 7: ELs 233, 496, 500, 512, 521, 534, 559, 614, 615, 616, 668 Sheet 8: ELs 456, 537, 564, 572, 671, 675, 684, 695, 696, 697, 703, 705, 754, 772, 968, 984, 985, 987, 988, 1027, 1049, 1082 Sheet 9: ELs 552, 596, 597, 764, 766, 842, 843, 844, 964, 1026, 1206, 1228 Sheet 10: ELs 1203, 1204, 1240, 1241, 1274, 1287, 1302, 1443 Sheet 11: ELs 1234, 1235, 1288, 1455, 1447, 1514, 1634, 1660, 1667, 1722, 1785, 1956 Sheet 12: ELs 1633, 1656, 1659, 1684, 1824, 1906, 2413 Sheet 13: ELs 1658, 1675, 1911, 2134, 2137, 2114, 2264, 2560, 2568, 2569 Sheet 14: ELs 2138, 2534, 3010 (ex EL 2244), 3017 (ex EL 2410), 3012 (ex EL 2263), 3035, 3245 (ex EL 1662), 3299 (ex EL 2136) Sheet 15: ELs 3023 (ex (EL 2441), 3309, 3436, 3556, 3720

98 GEOLOGY AND PROSPECTIVITY - BAIRNSDALE

Victorian Initiative for 13 BUSH, M.D., CAYLEY, R.A. and ROONEY, S., 1995. The geology and Minerals and Petroleum prospectivity of the Glenelg region, (VIMP) report series North West VIMP area. 14 SLATER, K.R., 1995. An appraisal of 1 BUCKLEY, R.W., BUSH, M.D., new airborne geophysical data over the O'SHEA, P.J., WHITEHEAD, M. and Glenelg region, North West VIMP area, VANDENBERG, A.H.M. 1994. The Victoria. geology and prospectivity of the Orbost 15 RYAN, S.M., KNIGHT, L.A. and Survey area. PARKER, G.J., 1995. The stratigraphy 2 VANDENBERG, A.H.M., WILLMAN, and structure of the Tyrendarra C., HENDRICKX, M., BUSH, M.D. and Embayment, Otway Basin, Victoria. SANDS, B.C. 1995. The geology and 16 KNIGHT, L.A., McDONALD, P.A., prospectivity of the 1993 Mount FRANKEL, E. and MOORE, D.H., 1995. Wellington Airborne survey area. A preliminary appraisal of the pre- 3 HOLDGATE, G., 1995. The exploration Tertiary infrabasins beneath the potential of the Permian Numurkah Murray Basin, Northwestern Victoria. Trough and Ovens Graben, Victoria. 17 PERINCEK, D., SIMONS, B.A., 4 BUSH, M.D., CAYLEY, R.A., ROONEY, PETTIFER, G.R. and GUNATILLAKE, R., SLATER, K. and WHITEHEAD K., 1995. Seismic interpretation of the M.L., 1995. The geology and onshore Western Otway Basin, Victoria. prospectivity of the southern margin of 18 LAVIN, C.J. and NAIM, H.M., 1995. the Murray Basin. The structure, stratigraphy and 5 ROONEY, R., 1995. Mineral petroleum potential of the Portland exploration history of the North West Trough, Otway Basin, Victoria. VIMP area. 19 SIMPSON, C.J., SIMS, J.P. and 6 WILLOCKS, A.J., 1995. An appraisal of ORANSKAIA, A., 1995. The geology the new airborne surveys over the North and prospectivity of the Mt Elizabeth West VIMP area. area, Eastern Highlands VIMP area. 7 WHITEHEAD, M.L., 1995. Geological 20 ORANSKAIA, A., 1995. A geological interpretation of geophysical data over interpretation of geophysical data over the Dunolly 1:100 000 sheet. the Mallacoota 1:250 000 sheet, Eastern Highlands VIMP area. 8 VANDENBERG, A.H.M., CALUZZI, J., WILLOCKS, A.J. and O'SHEA, P.J., 21 SARMA, S., 1995. Seismic 1995. The geology and prospectivity of interpretation of the offshore Otway the Mallacoota 1:250 000 sheet, Eastern Basin, Victoria. Highlands VIMP area. 22 MEHIN, K., and LINK, A.G., 1995. 9 SANDS, B.C., 1995. A geological Early Cretaceous source rocks of the interpretation of the geophysical data Victorian onshore Otway Basin. from the Orbost 1994 airborne survey. 23 PARKER, G.J., 1995. Early Cretaceous 10 OPPY, I.D., CAYLEY, R.A. and stratigraphy along the northern margin CALUZZI, J., 1995. The geology and of the Otway Basin, Victoria. prospectivity of the Tallangatta 24 MOORE, D.H., 1996. A geological 1:250 000 sheet. interpretation of the geophysical data of 11 CALUZZI, J., 1995. Mineral exploration the Horsham 1:250 000 map sheet area. history of the Tallangatta 1:250 000 25 VANDENBERG, A.H.M., HENDRICKX, sheet. M.A., WILLMAN, C.E., MAGART, 12 SIMONS, B.A., 1995. An appraisal of A.P.M., ORANSKAIA, A.N., ROONEY, new airborne geophysical data over the S. and WHITE, A.J.R.,1996. The Tallangatta 1:250 000 map area, geology and prospectivity of the Orbost Victoria. 1:100 000 map area, eastern Victoria. GEOLOGICAL SURVEY - PUBLICATIONS 99

26 HENDRICKX, M.A., WILLMAN, C.E., MAGART, A.P.M., ROONEY, S., VANDENBERG, A.H.M., ORANSKAIA, A. and WHITE, A.J.R. The geology and prospectivity of the Murrungowar 1:100 000 map area, eastern Victoria. 27 BOYLE, R. J., 1996. Mineral exploration history of the Omeo 1:100 000 map area. 28 HAYDON, S.J., 1996. An appraisal of airborne geophysical data from the 1995 Omeo survey, Victoria. 29 MAHER, S., 1996. Mineral resources of the Dunolly 1:100 000 map area. 30 CHIUPKA, J.W., 1996. Hydrocarbon Play Fairways of the Onshore Gippsland Basin, Victoria. 31 MEHIN, K., and LINK, A.G., 1996. Early Cretaceous source rock evaluation for oil and gas exploration, Victorian Otway Basin. 32 SLATER, K.R., 1996. An appraisal of new airborne geophysical data over the Dargo region, Victoria. 33 McDONALD, P.A., 1996. An appraisal of new airborne geophysical data over the region, northeastern Victoria. 34 TWYFORD, R., 1996. An appraisal of airborne geophysical data from the Murrindal survey, Victoria. 35 HUTCHINSON, D.F., 1996. Mineral exploration history of the Dunolly 1:100 000 map area. 36 BROOKES, D.J. and BOYLE, R.J., 1996. Mineral exploration history of the Bairnsdale 1:250 000 map area. 37 MAHER, S., HENDRICKX, M.A., BOYLE, R.J. and BROOKES, D.J., 1996. Geology and prospectivity of the Bairnsdale 1:250 000 map sheet area. 38 McDONALD, P.A. and WHITEHEAD M.L., 1996. Geological interpretation of geophysical data over the Ararat 1:100 000 map sheet. 39 MOORE D.H. 1996. A geological interpretation of the geophysical data of the Ouyen 1:250 000 map sheet area.