Yarram Park Project
The Yarram Park Project is located adjacent to the southern Grampians National Park in western Victoria, approximately 250 km to the west of Melbourne. The tenement is located to the north west of the regional town of Glenthompson.
The exploration target for Yarram Park is porphyry related copper-gold mineralisation associated with a potential extension of the Mt Stavely Volcanic Complex beneath Quaternary alluvium. Work by the Geological Survey of Victoria has identified the Stavely Belt as a ‘fertile’ Andean-style magmatic arc system.
The Yarram Park Project lies within the Grampians – Stavely Zone of the eastern Delamerian Orogen and hosts several belts of calc-alkaline volcanics including the Cambrian calc-alkaline Mount Stavely Belt and the Bunnagul Belt. The Mount Stavely Volcanic Complex has been correlated with the Cambrian Mount Read Volcanic Belt of western Tasmania on the basis of similarities in the age of volcanism and intrusion chemistry.
The Mount Stavely Belt / Bunnagul Belt lies approximately 15-20 km west of the east-dipping Moyston Fault, a regionally important fault that marks the eastern terrane boundary of the Delamerian Orogen and the western margin of the Stawell Zone in the Lachlan Orogen. The western margin of the Stawell Zone is characterised in many places by Cambrian volcanic rocks of tholeiitic and boninitic affiliation typical of the volcanic rocks exposed elsewhere in the Lachlan Orogen. These volcanic rocks and associated marine sedimentary rocks have been metamorphosed to form the Moornambool Metamorphic Complex.
Cambrian volcanic rocks of the Grampians / Stavely Zone were deformed during the Delamerian Orogeny and intruded by post-tectonic Late Cambrian granites. By contrast, the Cambrian to Ordovician volcano-sedimentary sequence of the Stawell Zone was deformed during the late Ordovician to early Silurian Benambran Orogeny and intruded by late Silurian to early Devonian post-tectonic granites.
Toora West Copper – Gold Porphyry Prospect
At the Toora West prospect, a coincident gravity low with peripheral and central magnetic anomalies was interpreted to indicate the presence of a buried intrusion. This gravity / magnetic anomaly was traversed with two lines of IP spaced 400 metres apart in August 2015. Two anomalous chargeability responses on each of the two IP lines appear to coincide with the flanks of the hypothesised intrusion. In November 2016, a three line IP survey, which was co- funded by the Victorian Government TARGET minerals exploration initiative, was conducted prior to the diamond drilling programme. The IP survey closed the line spacing to 200 metres which significantly improved the constraints along strike and also permitted 3D inversion modelling allowing for improved drill targeting.
The maiden 2-hole diamond drilling programme completed at Toora West in early 2017 was undertaken with co-funding assistance from the Victorian Government’s TARGET exploration initiative.
The prospect area is completely overlain by younger Tertiary transported cover and the targeting was directed by interpretation of magnetic, gravity and IP geophysical data. The two drill holes successfully confirmed the existence of a ‘blind’ intrusive complex consistent with a porphyry copper-gold environment.
Petrographic description of the intrusive units intersected in the drilling indicates that, texturally and compositionally, they are typical of those found in some low-K calc-alkaline porphyry copper-gold systems.
Further, the petrographic description of the intrusive and metamorphic units describes a widespread weak-to-moderate early and hot potassic alteration, expressed as biotite and K-spar alteration of mafic minerals and K-spar alteration of plagioclase feldspars. Also noted is a later moderate propylitic alteration overprint expressed as a chlorite alteration of mafic minerals.
These observations are consistent with the initial diamond drill holes having been drilled in a location potentially peripheral to a mineralised copper ± gold porphyry source.
Subsequent to the diamond drilling campaign, Stavely Minerals expanded the 2016 IP geophysical programme by extending existing lines to the south-west and with two additional 400 metre spaced lines to the south. Using this additional IP data, Stavely Minerals’ geophysical consultants, Newexco Services Pty Ltd, have identified a very large and very strong IP chargeability anomaly with the 50mV/V anomaly being some 500 metres in diameter and the 20mV/V anomaly being in excess of 1 km in diameter in an NW/SE orientation.
There is strong potential that this chargeability anomaly may be caused by disseminated sulphides associated with copper-gold mineralisation. This is now considered a Priority 1 drill target for the Company, which is being prepared for drill testing in early 2018.