Lithocap Structure-controlled feeder zone Lithology-controlled ...

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Mankayan district, Philippines Mohong Hill quartz-alunite lithocap Lepanto fault Looking NNW Most ore (~70%) in root zone of lithocap, in Lepanto fault or its splay branches Dickite ± kaolinite Lepanto fault Quartz-alunite Dickite ± kaolinite Hedenquist et al., 1998; Chang et al., 2011 Hedenquist et al., 1998; Chang et al., 2011
1.41 Ma 1.35 Ma 1.42 Ma FSE – Lepanto alteration: Coupled potassic and quartz-alunite (lithocap), later phyllic overprint Early alteration: AA: Quartz – alunite – pyrite ± pyrophyllite ± diaspore ± dickite ± kaolinite lithocap Locally silicic: Vuggy quartz – pyrite Later mineralization + silicification ! Pyrite ! Pyrite, enargite, luzonite ! Tennantite, chalcopyrite, sphalerite, galena, tellurides, selenides, native Au Hedenquist et al., 1998 Gonzalez, 1959; Tejada, 1989; Claveria, 1997, 1998, 2001 Early convecting magma, rapid crystallization = High rate of fluid advection, fluid rises rapidly with little cooling, and intersects its solvus High-temperature, ductile conditions at shallow depth Brine forms deep potassic zone, vapor separates from brine and discharges through ductile zone: part of vapor condenses near the surface to acidic liquid, creating lithocap Shinohara & Hedenquist, 1997
Page 1 and 2: Zhaoshan Chang, Noel White, Jeffrey
Page 3: 50 ppb Au X Small workings Breccias
Page 7 and 8: - Related to Na content Chang et al
Page 9 and 10: Weak smectite + pyrite, illite-smec
Page 11 and 12: Geologic setting of intermediate- (
Page 13 and 14: OR, perched, barren lithocap, margi
Page 15 and 16: 15.4-14.5 Ma 14.5-14.4 Ma Colquijir
Page 17 and 18: Dante Loayza and Jorge Barreda (Aru

Lithocap Structure-controlled feeder zone Lithology-controlled ...

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