Figure 3. Silvia Project rock chip copper geochemistry on airborne magnetics (analytic signal)
Silvia Northwest target
At Silvia Northwest, three areas of outcropping copper mineralization occur along a northeast-southwest trend encompassing a broad area of approximately 3.0 km by 1.0 km, each area referred to as Areas A, B, and C respectively (see Figure 4). Copper mineralization is associated with skarn alteration of Upper Cretaceous Jumasha Formation limestone and various intrusive and sub-volcanic rocks including diorite and dacitic porphyry. Coincident magnetic anomalies are interpreted to reflect the underlying intrusive rocks and, possibly, magnetite or pyrrhotite associated with the mineralization. Results of previous exploration can be summarised as follows:
At Area A, copper-bearing skarn mineralization occurs over a surface area of approximately 0.4 km by 0.2 km associated with altered dacitic porphyry. The skarn consists mostly of garnet and pyroxene accompanied by chlorite, biotite, quartz and magnetite. Sulphide minerals include chalcopyrite, pyrite, pyrrhotite, chalcocite and rare bornite. Copper oxide (malachite) is common. Copper values from 13 rock chip samples of skarn and altered porphyry at Area A range from 0.02% to 1.90% Cu; gold values range from <0.005 to 0.93 g/t Au; and zinc values range from 0.003 to 3.85% Zn. Extensive outcrops of white and grey marble are interpreted to form a halo around and above a buried skarn.
At Area B, skarn alteration outcrops sporadically over an area of approximately 0.7 km by 0.7 km associated with quartz diorite and porphyritic andesite dikes. Extensive areas of white and grey marble surround the intrusive and skarn rocks. Fine grained hornfels alteration interpreted to be caused by thermal metamorphism is associated with silty limestone of the younger Celendin Formation in the axis of a synclinal fold. Copper values from 28 rock chip samples of skarn at Target B range from 0.02% to 1.09% Cu; gold values range from <0.005 to 0.63 g/t Au; and zinc values range from <0.01 to 0.54% Zn.
At Area C, copper-bearing skarn occurs in sporadic outcrops over a surface area of approximately 0.5 km by 0.3 km together with outcrops of diorite and dacitic porphyry. Garnet skarn has been mapped around the contact of dacitic porphyry surrounded by a wide area of white and grey marble. Copper values from 13 rock chip samples from outcrop of skarn at Target C range from <0.01% to 1.10% Cu; Gold values range from <0.005 to 3.55 g/t Au; Zinc values range from <0.01 to 3.55% Zn.
(A) Photos of skarn outcrops at Area A: (B) copper minerals at surface at Area A.
Silvia South target
At Silvia South, skarn alteration is exposed in numerous sporadic outcrops along a northeast-southwest trend within an area of approximately 3.7 km x 0.8 km associated with outcropping diorite and monzodiorite porphyry. Garnet and pyroxene skarns are associated with minor sulphides (pyrite, chalcopyrite) and sporadic malachite.
A previous explorer’s geochemical data includes 23 samples of skarn outcrops at Silvia South with copper values ranging from <0.01 to 1.37% Cu; gold values range from <0.005 to 0.28 g/t Au; and zinc values range from 0.03 to 0.06% Zn.