Arizona Geological Society
2023 Speaker Series
Tuesday, 2 May 2023 | 5:30 - 8:00 PM
Location: Hexagon Mining Division Office
40 East Congress Street, Suite 150, Tucson, Arizona 85701
Parking: On the street or parking garage (Old Pueblo Parking)
Social Hour with Sandwiches from Beyond Bread (5:30-6:30 PM) Presentation (6:35 PM)
For those unable to attend, remote broadcast begins at 6:35 PM. No registration or fee to attend remotely.
Streaming URL forthcoming soon.
The Arizona Geological Society thanks
May 2023 Meeting Sponsor: Rio Tinto Group
The Arizona Geological Society also thanks Hexagon for generously providing the venue and drinks
Microsoft Teams meeting
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Meeting ID: 356 313 246 47
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Lithospheric Controls on the Formation of Porphyry Copper Deposits: What could possibly go wrong?
Dr. Hervé Rezeau
Lundin Family Endowed Chair in Economic Geology, Department of Geosciences, University of Arizona
Abstract: Porphyry copper deposits (PCDs) formed in the upper continental crust represent rare short-lived events within the protracted evolution of volcanic arc systems. PCDs are the primary world’s copper resources and provide a substantial source of gold and molybdenite – all of them considered as critical elements. Despite their economic importance, the trans-crustal geologic processes that carry these elements and culminate in their economic enrichment remain unclear. Based on a global compilation of available Cu concentrations of arc volcanic rocks, I will discuss processes that control the evolution of melt Cu concentrations during magmatic differentiation, and ultimately demonstrate the crucial role of the initial melt water content in arc magmas to form PCDs. While melt Cu concentrations are of secondary importance, I will still argue that it may play an important role to modulate the size of PCDs.
Based on a case study focused on the Meghri-Ordubad pluton in southern Armenia, I will use a comprehensive zircon U-Pb and molybdenite Re-Os geochronological dataset to show that long-lived magmatism is a pre-requisite to build up fertile magmatic-hydrothermal systems. I will combine these data with field observations and mineral chemistry to argue that the presence of appropriate structures focusing ore-bearing fluid flow over time is a key parameter to form large PCDs. Overall, these complementary multi-scale approaches will highlight a series of parameters that influence the journey of copper enrichment from the mantle to the upper continental crust.
Bio: Dr. Hervé Rezeau is an assistant professor and the Lundin Family endowed Chair in Economic Geology at the department of Geosciences, University of Arizona. Dr. Rezeau obtained his master and PhD degrees at the University of Geneva, Switzerland. Then, Dr. Rezeau carried on his scientific journey from 2018 to 2021 as a post-doctoral fellow at the Massachusetts Institute of Technology in Cambridge, USA.
As an economic geologist and igneous petrologist, Dr. Rezeau investigates the relationships between arc magmatism and ore deposits to unravel petrological processes that dictate the ore-forming potential of magmas. Over the years, Dr. Rezeau developed a strong interest in the petrogenesis of arc magmas and the evolution of volatiles (H2O, S) and chalcophile elements during melt differentiation in the lithosphere.
His current research themes are 1. the evolution of sulfur and chalcophile elements in arc magmas, 2. the timing, characteristics, and genesis of porphyry-epithermal Cu (Mo-Au) systems, and 3. the magmatic and metallogenic evolution of the Central Tethyan belt. Dr. Rezeau uses a multidisciplinary approach that includes fieldwork, petrography, fluid/melt inclusions, rock and mineral geochemistry and geochronology.
Hexagon Mining Division Office - 40 East Congress Street,
Suite 150, Tucson, Arizona 85701
