Efficient regional scale 3D potential field geophysical modelling to redefine the geometry of granite bodies beneath prospective, geologically complex, northwest Tasmania

Insights and Lessons from 3D Geological and Geophysical Modeling of Mineralized Terranes in Tasmania

“…No direct geological indications of this intrusion have yet been identified, nor are they necessarily expected (its depth being no less than 3 km); thus, its age is undetermined but possibly Neoproterozoic or Devonian. Another negative gravity residual in the southern sector of the model was tentatively interpreted as a southward extension of subsurface Cambrian granite [15]; however, its non-magnetic character marks it as dissimilar from the dominant Cambrian granitoid phases. An isolated intrusion of Devonian granite is another possibility.…”

“…An entirely concealed granite intrusion was also inferred beneath the eastern Rocky Cape Group on the basis of an 8 mGal residual gravity low [15] (p. 23). No direct geological indications of this intrusion have yet been identified, nor are they necessarily expected (its depth being no less than 3 km); thus, its age is undetermined but possibly Neoproterozoic or Devonian.…”

“…Initial unit bulk physical rock properties and allowed ranges for susceptibility and density for all Western and Eastern Terrane models are illustrated in Tables 1-4. These were sourced from values adopted from the literature [10,15,33,41] and MRT's publicly available physical rock property database, henceforth referred to collectively as "existing values". [10,33,45,50] and MRT's publicly available physical rock property database, 2 denotes GeoModeller TM -informed sensitivity statistics for mean susceptibility (SI × 10 −3 ) from an ensemble of acceptable models, 3 denotes lithology and susceptibility for typical Mt Lyndsay skarn material sourced from MRT's publicly available physical rock property database.…”

“…Carbonates become slightly more common approaching the bottom of DDH TCGA-01, with magnesite being the dominant species identified both by HyLogger TM (Figure 18) The potential modeling [15] resulted in a number of improvements to the 3D geological understanding of the region. Combined gravity and magnetic signatures indicate the Housetop Granite as relatively thin (≤5 km thickness), with a mafic-ultramafic complex near its base at a depth of ~3-6 km, similar to the model of [61].…”

“…Figure 1 illustrates the Western Terrane model localities, which include the Rosebery Region 3D model and its derivatives, (i.e., Rosebery-Lyell, Rosebery-Pieman 3D models). These models have stimulated both exploration (e.g., gravity surveys and drilling) and research efforts in the form of Honors and PhD projects, (e.g., [15]). Eastern Terrane models (Figure 2) were constructed to cover the major orogenic gold and zoned Zn, Sn, and Cu deposits of Northeast Tasmania.…”