Aeris Resources holds an exploration tenement package covering in excess of 1,800km2 over the prospective Tritton region, made up of six granted exploration and three mining leases.

 

Geology

The geology of the deposits at the Tritton Copper Operations are described as Besshi style Volcanic Massive Sulphides (VMS). They are exhalative deposits of banded sulphide lenses with predominate pyrite, lesser chalcopyrite, sphalerite and trace gold.

Importantly, these VMS deposits are characteristically found in clusters. This is the experience at the Tritton Copper Operations where stacked sheet lenses are typical in the stratigraphic sequence. Deposit size varies widely from more than 20 million tonnes in the main Tritton deposit to smaller lenses of less than 1 million tonnes. Typical geometry is tabular lenses with moderate dip (30o to 50o) and short strike of lengths from <50m to 300m. The length of the lenses can be significant, with the main Tritton deposit extending for at least 1500m down dip. Copper grades range from 1.0 to 3.0%. Zinc grades are not of economic interest and typically in the range 0.2 to 0.5%. The deposits also contain gold content that frequently return payable value in the concentrate.

Exploration

In July 2016 the Aeris Board approved a two year, $7.5 million strategic greenfields exploration program, focusing on discovering “Tritton” sized orebodies (+10Mt). 

The first stages of this strategic greenfields exploration program involves using high power electromagnetic (EM) geophysics technology.  This has involved using moving loop EM technology (MLTEM) which is able to “see” 400m-500m below surface, compared to the 200m depth of the equipment previously used on the tenement package, and airborne EM survey (VTEM-Max survey), which is able to cover large areas but not “see” as deep. 

The MLTEM program commenced in December 2016 and was 50% completed by the end of the FY17.  Results to date from the MLTEM survey have detected three new bedrock EM conductors (anomalies), including two which are within 5km of the Tritton processing infrastructure, whilst also detecting the sulphide rich component of the Kurrajong prospect.  Importantly the modelled EM conductors at Kurrajong extend below 500m, providing confidence the technique is successful in detecting conductive bodies to depths significantly greater than EM methods used extensively throughout the mid to late 1990s. 

The airborne EM survey was completed in the March 2017 quarter on the northern and southern extremities of the Tritton tenement package, with the latest results also identifying numerous new anomalies, which now require further investigation. 

Whilst it is early stages in our revitalised greenfields exploration program and more work is required, we are highly encouraged by the results to date and we hope to build on this success in the coming year.

 

 

 

Tritton region showing Aeris Resources Tritton  tenement package and prospective corridors for copper mineralised systems.  The planned MLTEM geophysical survey coverage is highlighted by shaded orange regions and completed survey areas by shaded magenta regions.  

 

Bedrock EM conductors (Kurrajong Corridor)

Finalised MLTEM results over the Kurrajong complex is constrained to the north east corner of the survey area.  The survey has detected two EM conductors, the already known Kurrajong Prospect and the McPhersons geochemical anomaly (McPhersons EM Anomaly).

Plan view of the north east corner of the Kurrajong complex showing MLTEM results (CH25 B field Z component) overlain on a magnetic 2VD image (black and white image).  Anomalous copper surface geochem contours are also displayed.

The Kurrajong Prospect is defined by a broad surface geochemical anomaly and associated historical workings. An initial shallow RC drill program completed in 1997, targeting oxide mineralisation in the vicinity of the historical workings, returned sporadic zones of elevated copper mineralisation (+1.0% Cu) within broader low grade copper haloes. A second phase of drilling over the prospective area was completed between May 2012 to March 2013 and utilised down hole EM technology to assist with vectoring toward mineralisation.  The drill program targeted down plunge extensions of the previous shallow copper mineralisation. A majority of drill holes intersected a series of stacked sulphide lenses defined by massive/banded pyrite +/- chalcopyrite and in places, stringer pyrite with lesser chalcopyrite (see Figure 5). The mineralised system has been traced from drill intercepts over 500m along strike and down plunge. The modeled EM conductor plates from the current MLTEM survey correlate with the higher grade massive/semi massive sulphide core which is defined from a limited number of drill holes in the table. 

Preliminary models defining the dimensions, orientation and depth below surface for the Kurrajong and McPhersons EM conductors has been completed.  The Kurrajong EM conductive response is interpreted to represent two stacked moderate strength conductors (1500 to 2000 siemens) positioned approximately 400m below surface with dimensions in the range of 125m (strike) x 150m (depth).  The modeled plates correlate favourably with the higher grade sections of the known deposit based on current drill hole information. Both modeled plates are orientated parallel to the regional geology.Greater Hermidale is part of the Tritton Complex and is located south of the Tritton mine. Aircore drilling, targeting magnetic and geochemical anomalies, intersected anomalous copper mineralisation at Greater Hermidale. The anomalies occur adjacent to magnetic anomalies in close proximity to local scale mafic units, which are comparable to the mineralised setting at the Avoca Tank deposit.

 

Drill Hole Table

HOLE ID

FROM (m)

TO (m)

LENGTH (m)

CU GRADE (%)

TKJD007

567.0

571.0

4.0

2.46

TKJD008

572.0

578.0

6.0

3.92

TKJD012

603.0

613.0

10.0

2.43

Drill hole intersections through massive/semi massive mineralisation at the Kurrajong prospect which broadly correlates with the modelled bedrock EM conductors from the current MLTEM survey.

 

Long section view of the interpreted Kurrajong mineralised envelope showing location, thickness and copper grade from drill hole intersections through the sulphide deposit.The results are very encouraging and further work is planned to unlock the potential of the Greater Hermidale project.

 

Recent surface mapping within the Kurrajong complex confirms the broad stratigraphic units identified at Kurrajong trend toward the McPhersons EM Anomaly. Both the Kurrajong Prospect and the McPhersons EM Anomaly are located within or adjacent to basic – intermediate volcanic units which manifest as magnetic highs.  The McPhersons bedrock EM conductor is of similar size and conductance to the Kurrajong modeled plates.

Preliminary modeling of the McPhersons EM response defined a moderate strength conductive plate (1000 to 2000 siemens) with dimensions in the range of 200m (strike) x 150m (depth) from 350m to 400m below surface.

A fixed loop EM (FLEM) survey will be completed over each EM conductor to refine the modeled plate spatial location and dimensions further to assist with prospect ranking and drill targeting. Modeled EM plate parameters (size/signal strength) will be considered in conjunction with the geological setting (stratigraphy/proximity to magnetic embayments) and surface geochemistry results. EM anomalies positioned higher on the prospectivity ranking will be prioritised for follow up exploration work including a first pass drill program.  

 

Bedrock EM conductors (Tritton Corridor)

MLTEM results to date within the Tritton corridor are centralised around Tritton, extending 9km south and 5km north of Tritton.  Two EM conductors have been identified.  The Raven EM Anomaly is located 2.5km north of Tritton and is interpreted to occur within the same stratigraphic package hosting the Tritton deposit.  The Marlin EM Anomaly is located 3.5km south of Tritton within the extensive Greater Hermidale geochemical anomaly which extends periodically over a 5km strike length.  A number of small highly conductive cover units occur throughout the area shown as magenta/red shaded regions.

Preliminary modelling has been completed on both the Raven and Marlin EM conductors to define their spatial location and dimensions.  The Raven conductive model is defined as a large 500m (strike) x 100m (depth) plate from 350m to 400m below surface. The plate is orientated parallel to the regional trend and dipping steeply to the west.  The Marlin EM response is defined by a 300m (strike) x 300m (depth) plate located approximately 200m below surface.  The interpreted orientation is striking north-east which is oblique to the interpreted regional trend (north-south). 

 

A fixed loop EM (FLEM) survey will be completed over each EM conductor to refine the modeled plate spatial location and dimensions further to assist with prospect ranking and drill targeting. Modeled EM plate parameters (size/signal strength) will be considered in conjunction with the geological setting (stratigraphy/proximity to magnetic embayments) and surface geochemistry results. EM anomalies positioned higher on the prospectivity ranking will be prioritised for follow up exploration work including detailed a first pass drill program.  

 

Airborne EM Survey

During the March 2017 quarter a helicopter-borne EM geophysical survey (VTEM-Max survey), covering 977 line kilometres, was also conducted across the northern and southern extremities of the Tritton tenement package. The VTEM-Max survey was flown on 200m line spacings over three discrete areas within the Tritton tenement package.  Each area is interpreted to represent along strike extensions from known stratigraphic corridors hosting the current Mineral Resource/advanced deposits within the Tritton and Kurrajong corridors.  The intent of the survey was to identify conductive bedrock conductors within 300m from surface.

The results from the VTEM-Max survey were finalised during the current quarter with multiple EM anomalies being identified, which require follow up work to assess their prospectivity.  A majority of the EM anomalies have been detected toward the northern end of the tenement package, which is interpreted to represent the northern extension of the Tritton stratigraphic corridor.  Further work is required to verify whether the anomalies may represent a conductive sulphide body, however at this early stage it indicates there is considerable prospectivity within this portion of the tenement, which historically has not been explored as extensively.

 

Plan view showing MLTEM results within the Tritton corridor (CH23 B field Z component). The Raven EM conductor is located north of Tritton while the Marlin EM conductor is located south of Tritton within the Greater Hermidale geochemical anomaly.

 

 
 
Plan view showing 2017 VTEM-Max geophysical survey results over the Tritton tenement package
 
 

Regional geology compilation

In conjunction with the focused MLTEM survey within the known stratigraphic corridors, work is being undertaken to understand the geological architecture further afield.  During the quarter a regional mapping and historical data compilation program commenced, focusing on the structural and lithological features within the interpreted extensions of the Tritton and Kurrajong corridors. Copper deposits discovered within the tenement package to date are localised within the Tritton and Kurrajong stratigraphic corridors.  The projection of each corridor is understood through the central portion of the tenement, however beyond this their location is not well understood, predominately from poor outcrop/increased cover and paleao-channels masking bedrock trends from magnetic imagery.  Importantly this area covers approximately 50% of the current tenement package.

The intent is to identify and trace the outcropping lithological units within the favourable horizons along strike to identify and project the prospective corridors and provide a more detailed understanding of the structural framework. 

 

Surface outcrop exposures are limited to a series of resistant quartzite/chert units within the Kurrajong extensions and a regionally continuous sandstone unit within the Tritton corridor, referred to as the Budgery Sandstone.  The Budgery sandstone unit is a significant marker unit which has been traced intermittently throughout the known corridor from Budgery through to Murrawombie.  The unit represents a correlatable marker horizon from which the inferred stratigraphic position of the known deposits can be made.  The regional mapping will result in a more detailed geological interpretation, which will be used in conjunction with historical data (geophysics, surface geochem and geological interpretations) to refine prospective areas for follow up work, including the anomalies identified from the VTEM-Max survey.