Just a bit more info for everyone on Mt unicorn, there is plenty more information on it if anyone is interested in goggling about it.
Abstract
The Unicorn Mo porphyry discovery occurs within a regionally jogged rift environment in NE Victoria (Figure 1). To date geological, geochemical, petrological, tectonic, CSAMT & 3DIP geophysics work and nine diamond holes within an outcropping mineralised silica cap and rhyolitic porphyry centred on a very large Mo surface soil and rock chip anomaly have demonstrated Unicorns Climax-Type parentage and its hybrid metallogenic Cu and Ag additions attributed to near arc and suture setting in NE Victoria. Unicorn mineralisation comprises molybdenite-quartz stockworks, zoned as stacked arches resembling inverted bowls, emplaced by growth or pulses of siliceous rhyolitic porphyry stocks. This work, combined with field visits to Colorado’s archetypical Climax-Types, the giant Climax and Urad–Henderson deposits, reveal Unicorn has some analogies with Urad-Henderson. In particular similar palaeo-depth and structure to Urad occurs within a confined vent, with possibilities of a Henderson like lateral expansion and depth target. Dart Mining NL has just released its maiden JORC estimate of 105M tonne Indicated + Inferred resource at 0.07% molybdenum equivalent, including initial 29M tonne Indicated Resource at 0.09% molybdenum equivalent from surface to a depth of 250m. Significantly, this only looks at a small portion of a potentially larger system, with deeper drilling up to 575m already confirming presence of high grade molybdenite (Figures 2). Additional potentials exist in Mo bearing apron breccia and aplite and a potential cluster to Unicorn exists beneath a 1km wide Bi-Te-As-Ag-Au anomaly, centred 1km east of the Unicorn Mo anomaly centre (Figure 3). A bridge of low order Pb-Ag-Cu-Au anomalism connecting with Unicorn is suggestive of structural and magmatic connectivity. In the Climax-type Mo deposits, extension tectonics and very deep structures control mineralisation, sourcing Mo laden high silica magma, by interaction of mantle and a sialic build, melts ascend and differentiate into highly volatile peraluminous rhyolitic magma, highest levels of several or more kilometres ascending through convection, apices controlling the highly characteristic plume geometry of the Climax-type stocks. The convective model of Shinohara and others (1995) explains not only the large volatile and metal flux seen in porphyry Mo, but also the Climax-type structural and textural features, described in detail by Carten, (1998) and others, and outlined here for Unicorn. Conduit width positively affects convection speed; Henderson’s most heavily mineralised intrusive centres are the Henderson-Primos and Seriate cupola centres that are also the widest. Given Unicorn’s drilling, CSAMT and 3DIP geophysical evidence of a host package complex that trumpets outward with depth, this may be a positive sign for a Henderson like depth expansion for Unicorn. Unicorn’s structure, petrography, texture, mineral grain size, alteration and composition are consistent with high palaeo-level deposition, similar to Urad, as is the Urad complex outcrop footprint. Unicorn’s dome complex of high silica zones, rhyolitic porphyry, hornfelds, breccia aprons and dykes has an outer 30 ppm Mo contour around 0.65 Sq Km. This is similar to the Climax and Henderson complex footprint, consistent with hypogene leakages to surface from an expanding host package at depth. Very wide base metals shells, well away from the central SLC’s and hornfelds zone influence, over 3km for bismuth and tellurium, is supportive of considerable anorogenic energy capable of underplating Unicorn, as has Henderson under Urad. The tellurium-silica system has stability fields around 250oC and 550oC, suggesting at times considerable heat penetrate distal polygonal ring fractures, remote from central SLC influence. Despite high initial heat in the SLC, as evidenced by both magmatic and hydrothermal Mo associated veining, including Unidirectional Solidification Textures and high temperature Mo-Quartz-feldspar veining, rapid cooling as evidenced by adularia in the SLC, confirmed by SEM, is consistent with shallow depths emplacement at Unicorn Ridge level, it is suggested around 1km. Combined, these features support a lateral Climax-type host expansion under plating Unicorn, comprising a major depth target (Figure 6). Discover the world's research
Australian Institute of Geoscientists
AIG NEWS
Quarterly Newsletter • No 107 • February 2012
INSIDE THIS AIG NEWS:
AIG
Introduction
The Unicorn Mo-Cu-Ag porphyry in northeast Victoria is the first Climax-type Mo discovery in
Australia and heralds a newly emerging molybdenite province within the SE Lachlan Fold
Belt,(LFB), with some spatial analogies to the Urad Climax-type Mo deposit at Red Mountain,
Colorado. Exploring basal sections of Unicorn may reveal analogies to basal areas of Urad,
where indications of remanent high Mo grades exist, now largely destroyed by the Red Mountain
Porphyry from eruptive processes.
Unicorn differs from the typical Climax-type, which only features molybdenum, in that it is a
metallogenic hybrid with significant copper, and attributed to its near arc and suture tectonic
Figure 1: Tectonics
Cont. Overleaf
DTM Price at posting:
1.2¢ Sentiment: Buy Disclosure: Held
