Skarn-porphyry transition: an example from the Antamina skarn, Peru

Chang, Z., Mrozek, S.A., Meinert, L.D., and Windle, S. (2015) Skarn-porphyry transition: an example from the Antamina skarn, Peru. In: Proceedings of PACRIM 2015. pp. 409-413. From: PACRIM 2015 Congress, 18-21 March 2015, Hong Kong, China.

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Abstract

It is important to understand skarn-porphyry transitions in order to use exposed skarns to look for associated and potentially larger porphyries. For such purposes, a good start is to understand the transition between porphyry and skarn in known deposits. In this contribution, we report the transition at Antamina, Peru, where skarns occur in and around a Miocene complex comprised of more than seven porphyritic intrusions. There are three types of skarn-porphyry relationships. The earliest intrusive phase, PlA, contains both endoskarn and porphyry-style quartz veins with secondary biotite halos. The porphyry quartz veins and endoskarns formed at the same time. Locally, the intrusion contains only endoskarn without porphyry quartz veins and is surrounded by exoskarns in carbonate wall rocks. In the third scenario, later porphyry (P2) intruding into PlA porphyry and skarns related to PlA contains abundant granular quartz veins and secondary biotite alteration but does not have significant endoskarn. The granular quartz veins also extend into earlier P1A skarns. The scarcity of endoskarn associated with P2 is related to the supply of Ca. The earliest PIA intrusion intruded into carbonates that supplied abundant Ca, therefore both endoskarns and exoskarns formed. In contrast, where the wall rocks of the later P2 intrusion are PlA or skarn related to PlA, there was little free Ca, therefore only porphyry-style quartz veins formed.

Item ID: 38253
Item Type: Conference Item (Research - E1)
ISBN: 978-1-925100-25-9
Date Deposited: 16 Jun 2015 04:05
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040307 Ore Deposit Petrology @ 100%
SEO Codes: 84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840102 Copper Ore Exploration @ 70%
84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840108 Zinc Ore Exploration @ 30%
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