The Halilağa property is located in the south-central portion of the Biga Peninsula in Western Turkey, a lithologically and structurally complex region with a long history of industrial mineral (clay, quartz, coal, dimension stone), gold and base metal mining.
The basement rocks of the Biga Peninsula consist of Paleozoic metamorphic rocks and Mesozoic accretionary mélange consisting of eclogitic, clastic and carbonate rocks. Intrusive rocks ranging from granite to quartz diorite cut these basement rocks, which are in turn overlain by calc-alkaline and alkaline Oligocene-Miocene volcanic and related sedimentary rocks ranging in age from 42-23 Ma. The Miocene volcanic suite includes andesite, latite, dacite, rhyodacite flow dome facies and volcaniclastic sequences (including ignimbrites), and is the primary host for epithermal gold and silver mineralization within the Biga Peninsula. This sequence is intruded by co-magmatic quartz diorite to quartz monzonite bodies, giving rise to associated Cu-Au porphyry and skarn mineralization.
The Halilağa property is transected by major structures which relate to, or are part of, the North Anatolian Fault System. The general architecture of the faults is controlled by ENE-WSW transtension. Local transpressional faulting has been interpreted for the Kestane area, leading to the local exhumation of the Kestane porphyry and older stratigraphy related to a series of ENE-trending horsts and grabens. The overlying Upper Miocene-Lower Pliocene volcanic succession is restricted to the grabens.
All post-basement volcano-sedimentary sequences show a clear tilt to the NW, N or NE by up to 35 degrees which is more pronounced in the vicinity of major structures. Tilting of the rocks could be due to movement related to the North Anatolian Fault System.
The Halilağa property is underlain by a sequence of Oligocene-Miocene volcano-sedimentary rocks. The local basement to this sequence consists of schist and carbonate rocks which outcrop in the southeast portion of the property in the Bakirlik Tepe area. The Miocene andesites within the sequence are interpreted to be volcanic to sub-volcanic, with overlying and intercalated tuff units; the latter are now present only as silicified erosional remnants at higher elevations.
A polyphase batholith intrudes the basement rocks, generating areas of widespread metasomatism and skarn alteration. The various phases of the batholith have not been studied in any detail, but it is thought to average granodiorite in composition. One phase of this batholith, the 28 Ma Kestane porphyry is the primary host for mineralization, and has been studied in more detail. Petrographic data suggest that it averages quartz monzonite in composition, with an overall crowded porphyry texture, with dominantly feldspar and hornblende phenocrysts in a fine-grained matrix. Some difference of opinion exists between various researchers studying the Kestane porphyry, with some ascribing most of the mineralization to a single phase and others noting up to three phases with varying Cu-Au endowments. The mineralization is cut by barren andesite dykes.
Alteration and Mineralization
The Halilağa alteration system covers a large (4 km x 2 km) area. Deposit types (porphyry, high sulphidation epithermal, and skarn) in and near the Halilağa property are the varied products of magmatic-hydrothermal processes related to structurally-controlled high level porphyry intrusions.
The Central Zone of the Cu-Au mineralized Kestane porphyry is affected by strong potassic alteration (K-feldspar, biotite and magnetite) with the highest gold and copper grades associated with early biotite, abundant magnetite (5-8%), chalcopyrite and quartz veining. Chalcopyrite, in some cases accompanied by trace amounts of pyrite, is the dominant sulphide in the potassic-altered zone. Outcrops and drill core are characterized by dense stockwork veining of at least four generations, including early, semiductile quartz veins (“A” veins), quartz veins with axial sulphides and magnetite (“B” veins), veins composed dominantly of pyrite with sericitized margins (“D” veins) and late anhydrite/gypsum and calcite veins. In outcrop, quartz veins dominantly strike northwest and dip steeply to the northeast.
Potassic-altered rocks are variably overprinted by weaker phyllic alteration, consisting of pervasive sericite, pyrite, quartz and chalcopyrite, which is at least partially magnetite destructive. Argillic alteration overprints the potassic alteration locally, although it appears to be restricted mainly to near-surface areas, the result of supergene processes. Other evidence of weathering and acid leaching in surficial areas includes the presence of limonite and oxidized boxworks within D veins.
The Central Zone is characterized by an exposed 0 to 20-metre-thick leached zone with elevated gold values, low copper values and clay alteration, followed by a 20 to 40-metre-thick supergene copper enriched zone consisting of up 1 to 2% copper as covellite, digenite and minor chalcocite, followed by a hypogene copper zone of chalcopyrite-pyrite ± magnetite at shallow depths. Chalcopyrite mineralization gives way to relatively barren pyrrhotite ± magnetite at greater depths. One puzzling aspect of the Kestane porphyry is the apparent lack of a central chalcopyrite-bornite zone characteristic of most other classic, zoned porphyry systems. This suggests the possibility that drilling to date has tested the marginal portions of a porphyry system, with the core area yet to be discovered.
Drilling to date in the Central Zone of the Kestane Porphyry has intersected copper-gold porphyry mineralization over a strike length of 1,200 metres, a width of 750 metres, and average thicknesses of 200 to 400 metres. The northern portion of the mineralized zone has been offset down to the north on a moderately to steeply north-dipping fault zone, such that it is now covered by up to 200 metres of post-mineral volcanic and sedimentary rock. Additional faults within the mineralized zone are likely, based on abrupt juxtapositions of alteration types.
A broad area of sericite alteration with oxidized pyrite veins is located a few kms to the southeast of Halilağa, perhaps representing the phyllic zone of another porphyry system, or the continuation of the existing one.
Kunk high sulphidation epithermal system
At Kunk Tepe, one kms south-southeast of the Central Zone, east-northeast- and east-southeast-trending ridges are capped by extensive areas of silicified volcanic rock. These “lithocaps” consist of massive to vuggy quartz depending on host rock, alunite and iron oxides ranging from hematite to limonite. The silicified rocks are flanked and underlain by strongly limonitic to pyritic breccias and argillic to advanced argillic altered volcanic rocks, which are the host for high sulphidation gold mineralization. Limited drilling has returned up to 0.3 ppm gold. The close proximity to and higher elevation of Kunk Tepe relative to the Central Zone suggests a genetic link.
Skarn Cu Mineralization
At Bakirlik Tepe, four kms ESE of the Central Zone, garnet-wollastinate-magnetite-epidote skarn is hosted in carbonaceous limestone near the contact with a quartz monzonite intrusion. Other areas are affected by widespread hornfelsing. Copper is in the form of chalcopyrite and associated weathering products. Limited drilling has returned short intervals of copper and gold mineralization.
Moira Smith, Ph.D., P.Geo., Chief Geologist, Pilot Gold, is the Company's designated Qualified Person within the meaning of NI 43-101 and has reviewed and validated that the information contained herein is accurate.