If anyone was doubting the prospectivity of Estelle, this will probably put that well and truly to bed.
The announcement today included a quite signifcant reference, being a 2014 Masters Thesis containing a very detailed scientific study of the Estelle Property for a Masters Thesis.
It's very unusual for an explorer to have such a detailed resource and is perhaps one reason (in addition to historic data and their own field work) that Nova management are very bullish on the gold prospects for Nova Minerals.
Note the project comparisons in the slide, which are both examples of Reduced Intrusion Gold Projects
https://core.ac.uk/download/pdf/62883760.pdf
ORE CHARACTERIZATION OF THE ESTELLE PROPERTY IN THE SOUTH-CENTRAL ALASKA RANGE
By
Ember M. Flagg
Bachelor of Science in Geoscience University of Iowa
2011
A thesis submitted in partial fulfillment of the requirements for the Master of Science - Geoscience
Department of Geoscience College of Sciences The Graduate College
University of Nevada, Las Vegas May 2014
Extract from Abstract:
The Estelle Property, located 170 km northwest of Anchorage, Alaska in the South Central Alaska Range, has been the focus of recent exploration activity for gold. Geological and geochemical investigations indicate that gold is spatially associated with felsic end-members of a series of zoned, Late Cretaceous intrusions that were emplaced into the Kahiltna terrane. A detailed study of outcrop and drill core samples was conducted to characterize host rock lithologies, intrusion compositions, and four main vein types including their mineralogy as well as their associated alteration mineral assemblages that are restricted to narrow selvages adjacent to veins. This study was also conducted to determine if the geology is consistent with a proposed reduced intrusion- related gold system (RIRGS) model.
Examination of core samples indicated felsic lithologies associated with gold vary from a biotite granite/granodiorite at the Oxide Prospect to a quartz monzonite at the Shoeshine and Shadow Prospects to a quartz monzodiorite at the Discovery Prospect. Examination of vein assemblages and cross-cutting relationships, using transmitted and reflected light petrography as well as scanning electron microscope and electron probe microanalyses, identified minerals associated with gold mineralization and determined the relative timing of mineral and vein formation.
The study including field trips to the property was sponsored by Millrock Resources who carried out the exploration on the property from 2008 to 2014.
NB - Millrock Resources and Teck Resources allowed the claims lapse in 2015, but still had significant exploration plans for the property ( Teck Resources who were funding the exploration had been bleeding cash in their main business and significantly slashed their worldwide exploration budgets ). My full analysis of background on that here.
The material the study contains will be a useful aid in exploration targeting, prioritising and planning.
The study included analysis of drill core and sample from key prospects at the Estelle and identified four main vein types, with Types II and III being gold-bearing (brief descriptions are from the thesis by Flagg):
- Type I Veins - a quartz-only vein that commonly has sinuous contacts with the host rock
- Type II Veins - planar quartz-sulfide-albite+gold veins
- Type III Veins - planar quartz-sulfide-chlorite±ankerite±gold veins that are locally sheeted (Figure 12A). The sheeted nature of these veins means they occur as parallel sets of veins which results in their commonly being more abundant than other vein types.
- Type IV Veins - are calcite-only veins (Figure 13A) that are typically branching in nature, fine- to coarsely-crystalline, and iron-oxide stained.
In the research Flagg examined the spatial relationships between the vein types by studying cross-cutting relationships. The study notes:
- Type 3 veins appear to host most of the gold mineralisation at the Estelle Property; and
- The most significant gold mineralization occurs as inclusions of gold, bismuth, and tellurium within arsenopyrite that are inferred to be exsolution products from the replacement of loellingite and pyrrhotite by arsenopyrite.
This is undoubtedly important and significant research that will aid exploration efforts, essentially giving Nova Minerals a guide that aids further exploring of the property.
I won't go into much more detail here. The thesis is incredibly technical, however it contains this description of the Oxide Prospect (which is the focus of current exploration efforts by Nova):
Oxide Prospect
The primary lithology in the Oxide core based on drill core samples is a fine to medium (<1-6 mm) grained biotite granite/granodiorite with variable titanium-bearing hornblende (1-3%). The mineralogy consists dominantly of feldspar (50-60%) plus quartz (20-30%) and biotite (5-10%) (Figure 6A). Plagioclase crystals are typically 1-6 mm, euhedral to subhedral, and commonly twinned (albite and Carlsbad). Orthoclase crystals are 1-6 mm in size, euhedral to subhedral, and are difficult to distinguish from plagioclase in hand-sample as the crystals are white in appearance. Quartz crystals occur as <1-3 mm, euhedral quartz-eyes. Biotite crystals are black where unaltered and occur as ≤1 mm euhedral crystals that commonly form in ≤ 5 mm clots (Figure 6B). Hornblende, where present in Oxide samples, composes ≤ 3% of the whole-rock lithology, is 1-2 mm in size, and is euhedral to subhedral. Accessory minerals include apatite, zircon, and rutile. Pyrite and arsenopyrite are disseminated everywhere throughout the groundmass and occur as fracture-coatings.
Two intrusive units cut the Oxide granite: black lamprophyre dikes (Figure 6C) and grey aplite dikelets (Figure 6D). The aplite dikelets are commonly wavy in appearance, 0.5-1.5 cm in width, and are composed of very fine-grained quartz and feldspar. The lamprophyre dikes typically have a width of 5-10 ft. in core and are composed of black, fine-grained biotite with disseminated pyrite and <1 mm calcite blebs.
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