IHC Robbins recently carried out a resource estimation for Strandline Resources Limited for its Tanga South heavy mineral sands project located in northern Tanzania (Figure 1). The Tanga South project lies within the northern Tanzanian coastal plain, comprised of Pleistocene to Recent marine sediments which are host to HM deposits. The local surface geology of the Tanga South project is dominated by pale orange and red soils overlying an undulating limestone basement.
Tanga South Deposits
There are a total of six individual deposits that form part of the Tanga South resources, each with their own distinct geology and mineralogy, such as limestone shelves and channel morphology. Due to these factors the estimation process was conducted in a staged approach whereby each deposit was interpreted individually. This was done to accurately identify variations in mineral assemblage based on the correlating depositional environments associated with each of the mineral deposits.
Geological interpretations were supplied by Strandline and IHC Robbins prepared digitised strings and wireframes based on those interpretations. The interpretations were prepared coincidently with the selection of the mineral assemblage composites which allowed for detailed mapping of mineralogical domains across the deposits. This will be used to select deposit domains for further metallurgical testwork. A rigorous QA/QC assessment and validation of the drill hole and assay data, in association with a comprehensive geostatistical analysis were also undertaken in preparation for the development of the Mineral Resource estimates.
Mineral Resource Estimation
Construction of the geological grade models was based on a combination of coding model cells in drill holes below open wireframes surfaces, including topography and basement and inside closed wireframes defined by the strandline domains. This approach was followed for each deposit with a variance in model parameters and constraints based on geological features such as changes in dip and mineralisation trend across the tenement. The modelling was undertaken in Datamine Studio RM utilising the dynamic anisotropy/ellipse function which allowed for a more representative grade interpolation of assay grades both locally and in the direction of grade trends.
IHC Robbins has extensive experience within the mineral sands industry across a broad range of applications such as geological, metallurgical, engineering and project services. The ability for IHC Robbins to utilise and integrate its services in a way that delivers a comprehensive geological understanding backed up by rigorous metallurgical test work allows for a high degree of confidence in their JORC 2012 resource estimation work.
The correct domaining and mineralogical determination allowed for a clear delineation of each deposit continuity, volume and grade. This clear differentiation of the higher THM portions of the deposits can then be utilised to form the basis of potential mining methods and schedules in a way that is cost effective and produces the best result for the client and project.