Taking the Plunge – The Core Orientation Tool

Observations in the field provide the basis for all downstream interpretation. As such, Rox geologists have been utilising various field logging and data interpretation techniques as a key to unlock the answers to the Youanmi Gold System.

One of these logging practices is using the Core Orientation Tool, or “Rocket Launcher” on both contemporary and historical diamond core to help recognise structural patterns with context.

An unassuming yet powerful tool, the Rocket Launcher re-orientates diamond core so that it is set up in-situ – positioned in the same orientation as it was when it was in the ground. This allows geologists to take strike and dip measurements on core in the same way that they can be taken on outcropping during traditional geological mapping.

While resulting structural measurements are the same as taking alphas/betas with a kenometer, the significance of setting up core in a Rocket Launcher is that it provides field geologists with real-time context – for example relationships between observed structures are being measured and taken into wider geological consideration as the core is being logged.

Displaying structures in a useful visual medium, such as a stereonet, further strengthens the contextual importance of the data being recorded, as transformations such as pole-to-planes and structural kinematics can be rapidly determined on-site during the logging process.

Early in 2021 Rox geologists were conducting a comprehensive data review on historical core at Youanmi, where they observed a recurring structural pattern in the core that appears to have been previously largely overlooked.

While taking structural measurements of historical core in the Rocket Launcher, geologists noted a pervasive lineation intersection within the Main Lode shear zone repeated at a similar orientation between drillholes.

This intersection occurs at the low-angle junction between C-S fabrics within the overall shear zone, often represented by plane of weakness structures such as boudins.

Judging the pervasive structure to be mineralogically significant, Rox geologists applied these findings to the wider geological interpretation of the Youanmi system through modelling software, resulting in a statistical correlation between the structural orientation of the intersection and gold grade. Notably, the lineation intersection appears to splay at an oblique angle to the greenstone/granite contact, and trends towards the NW with a shallow plunge in a stacked en echelon/ladder array. This interpretation formed the basis for the ‘multiple high-grade shoot’ theory at Link and provided a significant contribution to drillhole targeting for the 2021 program.

Encouraging results from the 2021 drill campaign largely confirm the presence of these high-grade shoots splaying from the greenstone/granite contact and plunging towards the NW, especially within the Link mineralised envelope. This subtle yet significant trend had been broadly overlooked from historical drilling until core was logged routinely in the Rocket Launcher, highlighting the crucial part that context plays when logging core.

Rox geologists continue to believe in the importance of context when analysing data and rely on the Core Orientation tool frequently to assist in cracking the Youanmi code.