Tambo North – EL007484


The tenement area has received very little historic mining or contemporary exploration, especially in the last 20 years.  The exploration will be very grass-roots consisting initially of historic research, field mapping, petrology, regional geochemical, geophysical and remote sensing surveying.  Exploration will primarily and initially focus on the areas described below.  A key target area and mineralisation style will be associated with the Tambo Crossing Granodiorite/Tonalite (Fig. 2, refer discussion below).  Field mapping, petrological and geochemical alteration studies will be initially important in the area.  To the north, exploration along the Ensay Shear Zone will initially seek near-surface mineralisation not previously identified.  This will include Deep Penetrating Geochemistry (CPG) and geophysics as warranted.  Follow-up drilling of targets, either RC or diamond drilling, will be conducted as warranted when targets are delineated.  Details of the likely activities are discussed below.


Nature of office based activities

The office based program proposed for the EL application area is expected to comprise:

  • Review of open file exploration literature, historic mine and prospect production records.
  • Review and appraisal of publicly available government geophysical surveys including gravity, radiometrics and magnetics.
  • Mapping of structural features such as faulting and linear fracture lines with utilisation of satellite imagery and airborne magnetic images to interpret significant geological structures, and;
  • Use surrounding data to evaluate the geology within the application area.


Nature of on-ground activities

  • Stream sediment geochemistry to assist to define drainage provinces of interest.
  • Test the applicability of soil / auger sampling, including application of modern DPG soil analysis techniques (such as ionic leach) which can detect pathfinder elements which have migrated from shallow depths.  This will be in conjunction with regional conventional soil sampling and portable XRF (pXRF) soil geochemistry.
  • Ground reconnaissance mapping and rock chip sampling across sub-cropping areas and mine dumps where possible.  Rock chip samples will be integral for petrological and alteration studies of the Tambo Crossing Granodiorite/Tonalite, and;
  • Ground geophysics, most likely magnetics, gravity or induced polarisation.


Nature of sub-surface activities


  • Drill testing using applicable methods relative to target depth and location. It is proposed that RC and diamond core drilling would be the prominent techniques used to test for primary gold mineralisation in the basement.
  • Petrological and geochemical examination of drill core samples, primarily to seek relevant mineral assemblages and alteration styles to represent intrusion-related mineralisation.



The ELA covers an extension of the Cassilis goldfield that includes the historic mining locality of Boucher Town.  However, there is very little gold production and few mine sites away from the portion of the goldfield within the ELA area (Fig. 1).  Regardless, the tenement covers geological features that are likely mineral hosts (refer geological rationale below) and initial exploration will focus on these.  These features include the Ensay Shear Zone and the Tambo Crossing Granodiorite/Tonalite (Fig 3).  Previous mapping by company geologist, Rodney Boucher, has identified intrusion-related target areas in the northern portion of the Tambo Crossing Granodiorite (Boucher, 1990), this will be an initial focus.  Geochemical surveying will commence on the Ensay Shear Zone, initially in the southern portion of the tenement.



The exploration within the Boucher Town ELA will primarily seek:

  • Orogenic reef gold
  • Intrusion-related gold

However, exploration will additionally seek evidence for differing mineralisation styles where relevant.

Orogenic reef gold occurs to the west of the tenement at the Cassilis-Brookville and Stirling/Haunted Stream goldfields (Willman et. al., 1999).  The likelihood that such a system remaining undiscovered at surface is very low given the significant mining history throughout the district.  However, the significant regional faults that pass through the tenements provide significant structure and potential to host or provide structural reactivation of nearby structures to host auriferous orogenic reefs.  High sulphide systems, such as Cassilis, may provide a significant proxy mineral halo surrounding reef deposits to be more readily detectible than analogous reefs in central Victoria.

The Tambo Crossing Granodiorite/Tonalite (with roof pendants) and nearby intrusive and extrusive bodies show a highly variable, high-level intrusive/extrusive system conducive of intrusion-related gold mineralisation.  While mining related to target type has not occurred, the rocks are highly prospective and poorly explored (Simpson et. al., 1996).  Some intrusion-related signatures were identified in petrological examination of the Tambo Crossing Granodiorite/Tonalite (Boucher, 1990) that warrants follow-up investigation.



Basement to the ELA’s is Ordovician Pinnak Sandstone deep marine turbidites and medium to high grade metamorphic equivalents north of the Ensay Shear zone.  Multiple deformation events and movement of the major shear zones and accompanying structures occurred during the Benambran, Bindian and Tabberabberan orogenies, all named after nearby localities.  High-level intrusive and extrusive rocks emplaced/erupted during the Devonian.  Some Cenozoic alluvials cover small areas withing the tenement.  More extensive cover occurs in the Gippsland Basin to the south (Fig. 2).

The geology of the goldfields and surrounding areas (Willman et. al.,1999; Simpson et. al., 1996) define highly prospective environments for economic mineral deposits.  Previous mapping and gold prospecting by company geologist, Rod Boucher, supports these findings.  The Tambo Crossing granodiorite is part of a series of high level intrusives/extrusives with variable and favourable geology and alteration.  Alluvial gold prospected in some creeks by Rod Boucher reveals potential, previously unrecognised sources of gold within the tenement area.  Orogenic reef gold occurs in surrounding goldfields and there is the potential for similar deposits at shallow depths within the tenement area associated with the same structures, the Ensay and Cassilis shear zones (Fig. 2).



The proposed exploration program will be dictated by the nature and tenor of targets as they are discovered.  A proposed program is listed in Table 1:


Year Description of Activity
Year 1 Landowner access agreements.  Literature review.  Magnetic/gravity/satellite imagery interpretations.  Field mapping.  Geochemistry: DPG, conventional soil & pXRF sampling.
Year 2 Landowner access agreements.  Field mapping & petrology.  Geochemistry: DPG, conventional soil & pXRF sampling.  Geophysics if warranted.  Preparation for RC/diamond drilling if targets are generated
Year 3 Landowner access agreements.  Field mapping & petrology.  Geochemistry & infill geochemistry: DPG, conventional soil & pXRF sampling.  Geophysics if warranted.  RC/diamond drilling if targets are generated, petrology of drill samples
Year 4 Landowner access agreements.  Field mapping.  Infill geochemistry: DPG, conventional soil or pXRF sampling as warranted.  RC/diamond drilling if targets are generated
Year 5 Infill geochemistry: DPG, conventional soil or pXRF sampling as warranted.  Geophysics if warranted.  RC/diamond drilling if targets are generated

Table 1.  Proposed exploration program