The Economic Petrology research lab has the overarching theme of using petrological techniques to investigate the interactions of fluids with rocks during ore formation and during ‘normal’ magmatic processes. Our ongoing research projects include:
Lights Creek Stock - Moonlight Deposit
The Lights Creek Stock in northern California is a pre-Sierra Nevadan composite pluton comprising a range of compositions from hornblende gabbro to granite. Hosted by this pluton are three Iron Oxide-Copper-Gold (IOCG) deposits, two of which (Superior and Engels) have been historically mined. The third (Moonlight) has very limited surface exposure but has been extensively explored through drilling. The Economic Petrology team is working to understand the geologic history of this pluton and its associated mineral deposits through investigations of the granitoid and gabbro, as well as to characterize the three copper deposits using drillcore samples.
Support for this project has been provided by a new Petrology and Geochemistry NSF grant 2240250 (to HA in summer 2023), funding, data and samples from US Copper Corp (formerly Crown Mining Corp.), a GSA graduate student research grant (to AL in spring 2019), two CSC2 grants (to MV and MA in summer 2019), a CSU SARC grant (to AL in spring 2019) and departmental funding (to AL, MV, MA, MP, and AB).
Petrology of rocks hosting Carlin Deposits
Carlin deposits in Nevada represent one of the world’s most significant sources of gold. These deposits are primarily operated by Nevada Gold Mines, which is a joint venture between Barrick and Newmont mining companies. Having been characterized by different teams working for different companies, there is still some uncertainty in classification of some of the host rocks for the deposits, and in how they correlate to one another. The Economic Petrology Lab are working with Nevada Gold Mines to characterize some of the downhole geology for one of the drillholes located between two major ore deposits, to try and correlate units hosting the two deposits through petrography and geochemistry.
Support for this project has been provided by Nevada Gold Mines.
Bald Rock Pluton
The Bald Rock Pluton is part of the northern Sierra Nevada, now located partly under Lake Oroville. This pluton was mapped in detail by R. Compton back in the early 1950s, before the Oroville dam was constructed and before the theory of Plate Tectonics was widely accepted. The history of the pluton has never been reinterpreted. The Economic Petrology lab are investigating the origin of the zoning (tonalite -> granodiorite -> trondhjemite from rim to core) and the detailed variation in the texture of the pluton.
Support for this project has been provided by an Award for Research and Scholarly Creativity (to HMA in Spring 2019). Much of the samples and data for this project were collected by petrology classes in the spring semesters of 2017, 2018, 2019, 2020 and 2022.
