Legend Mining Limited (ASX:LEG) has completed the processing phase of the data from the 3D seismic survey over a +24 sq. km area at the Octagonal prospect within the Rockford Project, Fraser Range, Western Australia.
HiSeis field teams carried out the survey data collection in November 2022. Processing has now been completed, with incorporation of existing data sets and further interpretation underway.
The Legend technical team is extremely pleased to see the detail of the Octagonal seismic cube which shows a strong correlation with geophysical models and structural interpretations from previous drill data,” Managing Director, Mark Wilson, said.
“In addition, the cube gives new information below and outside of existing drilling, all of which will assist in the ranking of holes for the diamond drill programme at Octagonal scheduled for commencement in May 2023.”
HiSeis was engaged by Legend to conduct a 3D seismic survey at the highly prospective Octagonal prospect within the Rockford Project, Fraser Range, WA.
The aim of the survey was to define the architecture of the Octagonal Intrusive Complex (OIC) in relation to the stratigraphic package, to a depth of investigation of a minimum 1500m below surface.
The confidence to conduct this +$1M survey was based on the results Legend has generated from the drilling of seismic targets at the Mawson deposit in 2022.
HiSeis has now completed the data processing phase of the 3D seismic survey data for the Octagonal prospect with time and depth modelling resulting in the delivery of the final 3D cube.
The results highlight the excellent correlation between the seismic dataset and the existing structural interpretation. The newly acquired 3D seismic data supports the exploration model that the OIC continues at depth below drilling completed to date. 3D seismic reflectors clearly map the eastern and western sidewall contacts of the OIC, confirmed by diamond drilling, and importantly the basal contact.
The limited RC and diamond drilling completed to date has intersected multiple intervals of massive, semi- massive, net textured, stringer and disseminated pyrrhotite-pentlandite-chalcopyrite sulphides associated with the mafic/ultramafic intrusives of the OIC.
This mineralisation demonstrates all the characteristics of a fertile magmatic Ni-Cu sulphide system, akin to the known deposits of Nova-Bollinger, Silver Knight, and Mawson in the Albany-Fraser Belt. Significantly, Octagonal sits within the same structural corridor that host the Nova-Bollinger and Silver Knight intrusions and Ni-Cu-Co deposits.
The previously completed pole-dipole IP surveys highlight a Ni-Cu sulphide mineralised corridor along the eastern contact of OIC, confirmed by multiple drill intercepts. Depth of IP penetration is approximately 600m below surface, rendering drill targeting blind below this level.
A deep penetrating AMT survey completed across the OIC was completed to aid in identifying potential sulphide mineralisation below IP and surface EM limits. The resultant AMT models identified a large conductive feature along strike from, and coincidental with, the chargeable IP features and associated Ni-Cu sulphide drill intercepts. Independent, coincidental datasets give strong encouragement for sulphide mineralisation to continue at depth below levels of current drill testing. The 3D seismic data will drive drill targeting below existing drilling levels.
Legend, in conjunction with HiSeis, is continuing to conduct the intensive process of interrogation, including incorporation of existing geophysical, geological, geochemical, and structural datasets. The modelling to date has already identified multiple new drill targets. The geological team is currently ranking new diamond drilling targets for a May start to the 2023 field season at Octagonal.
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