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BANANGHILIG (B1) GOLD DEPOSIT
The Tambis Project, containing the Bananghilig (B1) Gold Deposit as shown on Figure 1, is operated under a Mining Agreement with Philex Gold Philippines Inc. over Mineral Production Sharing Agreement (“MPSA”) 344-2010-XIII which covers 6,262 hectares.
The area has been known as an alluvial gold producing area since Spanish times. The first modern exploration pre-Medusa group was conducted in the 1970s followed by further work in the 1990s. The Company commenced a concerted effort in July 2010.
Figure 1: Tenement location map
showing the mines and prospects.
Figure 2: Bananghilig area interpreted geology showing the position of the B2 discovery beneath limestone cover and relative to the Banaghilig deposit
In July 2010, new regional and detailed mapping and drilling programmes were commenced with the aim of validating the existing resource and extending it to approximately 1,000,000 ounces. This new resource would form the basis for a feasibility study for a new production centre.
On 28 August 2012, Cube Consulting Pty Ltd estimated a new estimate resource for the deposit based on all available drilling as at 31 July 2012 including 74,522 metres of new drilling in 235 holes.
Regional Geology Setting
The Tambis regional geology is centred around the Tambis intrusive-breccia complex which typifies a structurally complex, intermediate-sulphidation, epithermal gold, breccia-type system, including disseminated gold overprinting the host Tertiary-age igneous package which had been emplaced into an andesitic volcanic basement. The fertile igneous suite comprises a multi-phase calc-alkaline, high level, sub-volcanic intrusive package cut by extensive bodies of phreatomagmatic diatremes and hydrothermal breccias.
Laboratory studies including fluid inclusions have indicated that the Tambis area is only shallowly eroded with an estimated 500 to 950 metres of material stripped from the original surface.
The Tambis intrusive-breccia complex is overlain by younger marine limestones and basal mudstones to the south and the east. The extent of the complex below this younger cover is yet to be determined.
BANANGHILIG DEPOSIT DESCRIPTION AND MINERALISATION
Figure 2 shows location of the Bananghilig Deposit and the B2 Discovery area.
Deposit Geology and Mineralisation
The B1 Deposit (Figure 2) is located predominately within diatreme breccias which measure at least 1,000 metres west to east and still open to the south beneath the younger sediments, and also around the diatreme margins and in the country rocks along structural corridors. The B2 Discovery area mineralisation is hosted entirely within the diatreme breccias as shown in Figure 4 .
The diatreme breccias contain unsorted fragments of the andesitic basement as well as fragments of the later intrusive rocks predating the diatreme events in a matrix of comminuted rock flour and magmatic crystals. Fragment sizes range from granule-sized to building-sized mega-blocks which have been torn off the walls of the diatreme during the multi-episodal explosive activity. The explosive activity also fractured the mega-blocks and wall rocks, preparing them for subsequent mineralisation deposition.
After the diatreme formation, several events of hydraulic fracturing, hydrothermal and fault brecciation, rock alteration, quartz veining and precious- and base-metal mineralisation occurred. Based on mineral associations and fluid inclusion results, the main gold deposition event appears to have occurred following multiple hydrothermal fracturing along the margins of, and within the diatreme complex. High gold concentrations appear to be associated with elevated Ag and base metals.
The gold mineralisation style (+Ag ±Zn ±Cu ±Pb) is classified as an intermediate sulphidation epithermal system. In and immediately adjacent to the diatreme, the gold mineralisation generally occurs in hydrothermal breccia vein-like zones, in fractures and/or breccia in-fill in milled/fluidised muddy matrix breccia bodies and coarsely brecciated/fractured andesitic-dacitic wallrock. It should be noted that the vein zones shown on Figure 2 that are in the area of the younger sediments are projected from below the limestone contact.
Breccia veins in the deposit exhibit epithermal mineral growth textures and in particular are related to retrograde boiling of the mineralizing fluids. Major hydrothermal breccia veins are sub-vertical to steeply dipping, averaging one metre thick, and form anastomosing pinch-and-swell patterns up to several hundred meters along strike. They are commonly offset in many places by post-mineralisation faults. Down dip continuity of breccia vein mineralisation has been demonstrated to persist down to 500 meters from surface. The breccia veins generally form a northeast-trending sub-parallel array with minor north-south and east-west trends.
Widespread silica-illite-pyrite hydrothermal alteration affects the volcanic wallrocks, the various breccia bodies and the hypabyssal intrusives associated with them. The pervasive near-surface argillic alteration haloes grade laterally and vertically at depth into chloritic and propylitic alteration assemblages.
Detailed drilling results for the B1 Deposit and the B2 Discovery area are contained in numerous announcements including those dated 12 September 2011, 17 January 2012, 28 August 2012, 21 November 2012, 07 January 2013, 02 April 2013, 08 July 2013, 08 August 2013 and December 2013 Quarterly Report and the 2014 March, June and September Quarterly reports.
Drilling was completed in July 2014.
Bananghilig Scoping and Pre-feasibility Study¹
On 09 April 2013, the Company published the results of a first pass Scoping Study1 of the Bananghilig Gold Deposit. The Scoping Study was carried out and reported under the guidelines of the JORC Code 2004, therefore the results of the Scoping Study do not now necessarily comply with the requirements of the JORC Code 2012 and will not be reported henceforth.
1 The Scoping Study referred to in the announcement dated 09 April 2013 was based on low-level technical and economic assessments of Indicated and Inferred Mineral Resources, as defined under the guidelines of JORC Code 2004, and is insufficient to support estimation of Ore Reserves or to provide assurance of an economic development case at this stage, or to provide certainty that the conclusions of the Scoping Study will be realised.
Feasibility Study activities were initiated on the completion of the Scoping Study involving sterilisation and geotechnical drilling programmes which were completed in early October 2013.
A decision was made towards the end of the September 2013 quarter to temporarily suspend the feasibility study following the new mineralisation being encountered at the new B2 Discovery area, as well as due to the depressed gold price and commissioning of the new Co-O milling circuit.
B2 Discovery Area
On 02 April 2013, the results of a sterilisation drilling were announced showing widespread gold mineralisation located to the southeast of the main B1 Deposit. Subsequent drilling has identified mineralisation similar to Bananghilig which may potentially be extensions to the B1 Deposit.