Androit Resources Inc - Exploring and Developing Gold, Silver and Antimony Projects in Italy.

Geology / Mineral Prospectivity

General Outline

Italy displays a complex geological and tectonic setting due to its central position in the Mediterranean Basin, which is affected by the converging and lateral movements between the European and African continental plates.

Its northern border is occupied by the metamorphic belt of the Alps, extending from Liguria to Austria and Slovenia-Croatia-Serbia to the NE and E, where it connects to the major Alpine-Himalayan orogenic system.

In the Ligurian area, the Alpine belt is connected to the Apennine chain, which forms the backbone of the Italian peninsula. The Apennines are part of the evolution of the Alpine orogeny in the Mediterranean area and represent the link between the Alps and the North-African belts (Maghrebides, outcropping in northern Sicily). The Apennine belt is made up of a complex system of nappe structures, with NE to ESE-verging frontal thrusts outlining a festoon-like pattern. Two main phases are responsible for the evolution of the belt:

the first, syn-orogenic phase is marked by a compressive tectonic regime, which formed the Apennine nappes from the Tertiary until the mid-upper Miocene. During the Oligocene, a change of tectonic polarity occurred, resulting in active southward and eastward Apennine-verging deformation superimposed on the initial northward Alpine-verging phase. Folding styles consist of irregular anticlines and synclines with arched NW-SE trending axes. These have eastward overturns, involving mainly ophiolite-bearing flyschoid Allochtonous Complex, that overrides a partly autochtonous terrane made up of a Paleozoic basement and a marine-pelagic sedimentary sequence (Verrucano). Detachments, slidings, shearing and doubling of lithological series at various levels occur and are favoured by evaporitic horizons present in the Apennine sequence.

The second, post-orogenic phase begins in the upper Miocene and reaches its climax during the lower Pliocene. It develops through tensional tectonics with block-faulting, bringing about a series of sub-parallel horst-graben structures trending NW-SE (called Apennine) to N-S and affecting the whole Thyrrenian seaboard of the Apennines. This extension gradually shifted towards the East, preserving the same principal directions. The NE-SW (called Anti-Apennine) trending structures also play a significant regional role, as they limit the longitudinal extension of the Plio-Pleistocene ridges and basins. These extensional structures relate to an upper Pliocene uplift (known as the Etruscan Swell). This uplift occurs between the Apennine chain and the Thyrrenian coast in Southern Tuscany and Latium, and is characterized by a general crustal thinning and a high heath flow. Crustal structures with anomalous transitional levels (at a depth of less than 20 km), characterized by alternate crustal and mantle material have been detected by geophysical studies.

The tectono-stratigraphic evolution of the Appenines, as described hereabove, resulted in Tuscany in a stack of east-vergent thrust slices composed of Triassic through early Tertiary formations. The Calcare Cavernoso, a largely dolomitic sequence that includes basal anhydrite beds, is typically in thrust contact with predominantly siliciclastic units, the Verrucano below and the Macigno and Ligurian flysch above (Fig. 2).

Magmatism

Since the Palaeogene, Italy has been affected by a number of volcanic episodes of varying intensity and duration. The nature of this volcanism is a function of the tectonic evolution and its consequences on the tectono-stratigraphic assemblages of the Tuscany region are fundamental to the gold mineralisation models that are the objectives of this joint venture.

The peri-Thyrrenian regions underwent widespread and strong magmatism along a belt extending for about 900 km. Volcanism is still active in Southern Italy, in the Aeolian Island Arc, in the abyssal part of the Thyrrenian basin and in Sicily.

Another important volcanic episode occurred in the western part of the Venetian area (Colli Euganei, north-eastern Italy) during the Palaeogene up to the lower Neogene. It is confined to an area characterized by block-faulting tectonics and may be related to a tensional phase. A present high heath flow anomaly marks most of the Tertiary and Quaternary volcanic areas of Italy and is pointed out by the widespread late-stage hydrothermal activity.

Three major processes controlled the development of the peri-Thyrrenian volcanism during the Tertiary and the Quaternary:

The last two episodes are strictly connected and are largely responsible for the nature of this volcanism. On the basis of geological, structural, geochemical and isotopic data, the volcanic products may be classified into four main groups:

The last two episodes are strictly connected and are largely responsible for the nature of this volcanism. On the basis of geological, structural, geochemical and isotopic data, the volcanic products may be classified into four main groups:

Mineralization Control

As a result of the geological evolution of the area gold mineralization was controlled by a combination of tectonic and magmatic events:

Mineralogical Association

Irrespective of whether the gold mineralization is hosted by thrust or high-angle faults, its associated alteration and overall style are very similar. The gold is mainly confined to jasperoid developed by pervasive silicification of Cavernoso dolomite. The jasperoid is commonly intergrown with acicular crystal aggregates of stibnite or its pseudomorphous supergene oxidation product, stibiconite. Pyrite or derivative limonite are also present, but generally in relatively minor amounts. Crystalline barite may line open cavities in the jasperoid.

Coarsely banded, crystalline quartz veins and veinlets, in places stained by manganese oxide, commonly accompany the jasperoid.

The siliciclastic units alongside auriferous jasperoid are altered in places, but appear to have acted mainly as aquitards during the gold mineralization event. This is particularly the case where the siliciclastic units cap mineralized thrusts. Where alteration is observed in the siliciclastic rocks, it generally comprises partial silicification, although alunite and kaolinite replaced the phyllite in the immediate footwall of a high-angle normal fault in the Alunite quarry at Frassine .

Gold Mineralization

The jasperoid-hosted gold mineralization in the Tuscany province is closely related to anomalous concentrations of antimony (as stibnite), arsenic and mercury. Such mineralization, hosted exclusively by carbonate rocks, may be assigned to the sedimentary rock-hosted gold category.

The general features, mineralogy and element association of the gold mineralization suggest (R. Sillitoe, 2006) that it took place in the epithermal environment, say at paleodepths of < 1 km, somewhat shallower that most sedimentary rock-hosted gold deposits elsewhere. The epithermal affiliation is difficult to specify further. Complexity is introduced by the recognition of hydrothermal alunite, defining advanced argillic alteration, in the Alunite quarry at Frassine and the minor hydrothermal adularia at Pietricci and crustiform vein quartz near one of the Pietratonda rhyolite plugs when it is recalled that advanced argillic alteration characterises the high-sulphidation environment and adularia and crustiform quartz the low-sulphidation environment. If both high- and low-sulphidation epithermal mineralization indeed exists in the Tuscany province, inter-relationships remain to be addressed. It is suspected that the rhyolite plugs

north of Pietratonda, dated at 1.2 Ma (Pleistocene), are broadly contemporaneous with the gold mineralization event and, in all likelihood, derived from the same magmatic source as the gold-mineralizing fluid. Furthermore, the rhyolite may be considered as a subvolcanic equivalent of the similarly aged Larderello pluton that underlies the currently exploited geothermal system of the same name in the northwestern part of the gold province. If this can be confirmed, it implies that the Tuscany gold province may be a distal manifestation of the early Plio-Pleistocene stages of the Larderello geothermal system. Furthermore, it is tempting to propose that the base-metal mineralization, occurring in the area, represents an even earlier and/or deeper product of the same intrusion centred geothermal system (R. Sillitoe, 2006).

Gold Potential

The widespread distribution of jasperoid-hosted gold prospects in Tuscany augurs well for the existence of economic gold concentrations, which may be localised by Cavernoso limestone within and immediately alongside both shallowly dipping thrusts and high-angle normal faults. It should be emphasized that the gold-bearing, high-angle fault at Fogari is >8km in defined (intermittently outcropping) length and the gold-bearing thrusts at Pietricci and Frassine crop out discontinuously over areas of at least 1 km²: sizes that are entirely adequate to host an economic gold deposit. Although these structures are known from rock-chip sampling and, in the case of Pietricci and Frassine, reconnaissance drilling to be consistently gold bearing, more work is needed to determine whether or not a gold deposit exists.

The general features, mineralogy and element association of the gold mineralization suggest (R. Sillitoe, 2006) that it took place in the epithermal environment, say at paleodepths of < 1 km, somewhat shallower that most sedimentary rock-hosted gold deposits elsewhere. The epithermal affiliation is difficult to specify further. Complexity is introduced by the recognition of hydrothermal alunite, defining advanced argillic alteration, in the Alunite quarry at Frassine and the minor hydrothermal adularia at Pietricci and crustiform vein quartz near one of the Pietratonda rhyolite plugs when it is recalled that advanced argillic alteration characterises the high-sulphidation environment and adularia and crustiform quartz the low-sulphidation environment. If both high- and low-sulphidation epithermal mineralization indeed exists in the Tuscany province, inter-relationships remain to be addressed. It is suspected that the rhyolite plugs

In principle, first-order upflow conduits (high-angle faults) connected to thrusts that were efficiently sealed by siliciclastic aquitards should have the highest chance of developing ore-grade gold concentrations. High-angle faults that transect Cavernoso, as envisaged at depth in the case of Fogari (Fig. 4), provide particularly intriguing targets. The existence of disseminated gold concentrations in carbonate rocks beyond jasperoid bodies is, by analogy with the deposits in Nevada and elsewhere (e.g. Guizou, China), a possibility, although to date it has not been observed. The ongoing work programmed in Tuscany needs to be focused on the already known gold prospects, in particular Pietricci, Frassine, Fogari and the northern part of Pietratonda (Poggio Carpinelle, currently under application).

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