High Temperature Fluid Inclusions in Quartz-Anhydrite-Sulfide Veins from the Giant Grasberg Porphyry Cu-Au Deposit, West Papua

Date & time

12.30–1.30pm 17 March 2017

Location

Ringwood Room, J4, RSES

Speakers

Terry Mernagh (RSES)

Contacts

 Michael Anenburg
 0451 406 232

The Grasberg Igneous Complex (GIC) is host to one of the largest copper and gold porphyry-type ore deposits in the world. Previous fluid inclusion studies of Grasberg have reported homogenisation temperatures up to 700 ⁰C (the limit of the heating stage). However, in this study, quartz-hosted fluid inclusions from deep in the Grasberg System have been identified that partially homogenise by vapour disappearance at high temperatures (up to 1300°C), well above the hottest measured fumaroles. These inclusions contain 20 – 40 vol.% vapour, three or more transparent crystals and one or two dark  to opaque solid phases and less than 10 vol.% water. Are these inclusions with low water contents salt melts? Are the very high temperatures related to magmatic processes or do they represent post-entrapment modification of the inclusions? These scenarios and others will be discussed in this presentation.

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