"LINKING COUNTERTOPS TO ORE DEPOSITS" by ERIK SCHOONOVER ‘21

Rising demand for key metals has placed increased focus on discovering new deposits in Earth's
crust. Resources, such as Fe, Cu, and the rare earth elements, are fundamental for infrastructure,
energy systems, and national security. Generating deposits large enough to be economically viable
requires efficient crustal processes that mobilize and concentrate these metals of interest.

Investigating the mechanisms of ore-forming processes is important, particularly, for developing new
exploration targets and reducing the economic costs associated with ore discovery and
characterization. Crustal ore deposits provide a partial view of these processes because they are the
final product of multistage, complex processes. Deposits are often overprinted by successive
mineralization events, strongly modified by post-emplacement alteration, and their source rocks are
rarely preserved or exposed. As a result, the physical and chemical mechanisms of ore formation are
difficult to observe directly. 

Bridging this gap in deposit formation requires shifting focus from the mineralized deposits to
the magmatic environments that generate them. Two major deposit types that supply strategic and
critical elements are iron oxide-apatite (IOA) and iron oxide-copper-gold (IOCG) deposits. These
deposits are exemplar models for metal concentration and mobilization from arc magmas. Competing
models for these deposits suggest either that enrichment occurs through separation of an Fe-rich
immiscible melt or through Cl-rich fluid flux that sequester metals from a crystal-rich magma.
Therefore, without source context, the interactions and relative roles of fluid, melt, and magmatic
rocks during metal concentration remains unresolved. 

In this talk, I will present new observations from granites (the “Countertop”) in Yosemite
National Park that look strikingly similar to IOA deposits (the “Ore Deposit”).  This will include
demonstrating how I integrate field observations, novel analytical methods, and geochemical
modeling to test hypotheses about how ores may be forming from within some of the most common
and mundane rocks in the continental crust.

Biography: Erik Schoonover graduated from Hope College in 2021 with degrees
in Chemistry and Geology. He currently serves as the laser ablation mass
spectrometry lab manager after recently defending his PhD advised by Jesse
Reimink (Hope College ’09) at Penn State. His work focuses on how granitic
magmas form and how their chemistry evolves throughout Earth’s history. This
work primarily leverages the geochemical history recorded by accessory minerals
and accessed with novel analytical and statistical methods. He will be starting as
a Peter Buck Postdoctoral Fellow at the Smithsonian National Museum of Natural
History in Washington D.C. this fall.