THE RELATIONSHIP BETWEEN INTRUSION AND ALTERATION AT THE CHUQUICAMATA PORPHYRY COPPER SYSTEM, CHILE
The potassic alteration affecting the Este Porphyry is the result of a late hydrous phase of the same magma rather than an overprinting by a separate intrusion. The lack of Ca-bearing silicate minerals in the potassic zone resulted from high halogen contents that preferentially partition Ca into the melt and fluid phase. The Banco Porphyry is unaffected by the potassic Ca-leaching event giving a firm relative age of intrusion.
The Qser, formed from a reduced and highly acidic fluid of magmatic-meteoric origin, overprints the potassically altered Este Porphyry and the Banco Porphyry.
Petrography, geochemistry, and geochronology indicate the FIC is unrelated to the juxtaposed CIC. However, the FIC may have shared a common source, thus explaining their similarities.