Resolving different fluid pulses in hydrothermal veins from Los Pelambres porphyry copper by quartz cathodoluminescence and fluid inclusions

Abstract

Porphyry copper deposits are characterized by superposition of multiple mineralization events. This result in veins containing multiple populations of fluid inclusions (Rose, 1970; Moore and Nash, 1974) trapped during different hydrothermal pulses. Where multiple fluid inclusion populations are superimposed, it is difficult to decipher the chronologic sequence of fluid trapping, resulting in a fluid history that is equivocal (Bodnar, 2003, Goldstein, 2003).

In this study we combine the use of scanning electron microscope-cathodoluminescence (SEM-CL) of quartz and fluid inclusion petrography and microthermometry to constrain the temporal relationship among fluid inclusions trapped in quartz veins from the Los Pelambres, Porphyry copper deposit, Chile. Based on these results, we can decipher the physical and chemical history of hydrothermal vein formation. The goal of this study is to discriminate the various events of fluid inclusions entrapment at the finest possible level, minimizing the mistakes originated from ambiguous classification due to particular petrographic relationships of fluid inclusions present in a given sample.