b'Geophysics in the SurveysNewsand is being increasingly taken up byuncertainty (at least as far as potential explorers.field responses are concerned) in the 3D model geometry.An interpreted sub-surface granite intrusion identified by preliminaryThe most recent 3D model released by modelling in the northern Rosebery-LyellMRT is of the Alberton-Mathinna gold region (described by Bombardieri andcorridor in NE Tasmania (Figures 47). Duffett in Preview 183) was subsequentlyA significant outcome of this modelling targeted by exploration drilling. Itwas gravity-derived delineation of a intersected the serpentinites predictedgranite cupola in the vicinity of the by the model but was terminated byGolden Gate mine, the most richly technical difficulties before reaching theendowed in the goldfield historically. target depth (Bombardieri et al. AGGCSubsequently the company awarded 2018, Preview 192).the exploration licence for the area have indicated that they are using the model However information obtained fromin their assessment. Further details of the new core including rock propertythe Alberton-Mathinna modelling are and Hylogger data have been usedin Preview 195. All models produced together with revised gravity data toby MRT are being made available as produce a refined model of the area.Gocad projects, viewable via Mira Improved uncertainty characterisationGeosciences free Geoscience Analyst is a feature of the new model. Thesoftware.example west-east section depicted in Figure3a-b indicates the distributionMRTs 3D geophysical modelling is of model physical properties betweenunderpinned by a database of rock and within geological units in onephysical properties that continues to of the thousands of models deemedexpand steadily, in response to the need acceptable in the ensemble. Zones offor better constraints. A strategic approach low contrast tend to be where voxelsopportunistically targeting drill core in fail to meet the threshold of retainingareas and stratigraphic units hitherto poorly the same geological unit membershipcharacterised has enabled significantly in at least 99% of acceptable models.improved petrophysical definition of These voxels, coloured black in FigureTasmanias geological constituents with aFigure 4.Alberton-Mathinna geology. Known 3c, thus indicate regions of greaterminimal commitment of resources. Theregold occurrences indicated by yellow circles.Figure 3.Density (a, t/m3), magnetic susceptibility (b, SI) and geological units (c) present in at least 99% of acceptable models on representative west-east section of northern Rosebery-Lyell model.23 PREVIEW AUGUST 2019'