Porphyry copper (-gold-molybdenum) deposits are major producers of these metals and are actively explored for globally. Given this global distribution, these deposit-types offer a massive range of interest for a broad section of the exploration community, including students through seasoned professionals. Many of the geologic characteristics of porphyry deposits have been understood for several decades and have driven their exploration and mining. However, more recent work has shed light on the differences between the two types of porphyry deposits: those that are emplaced at shallower crustal levels versus those emplaced at deeper levels. Many overarching geologic characteristics are similar between both families of porphyry deposits; other characteristics vary and pose challenges and opportunities for exploration. This course will aim to explore these differences and how to leverage a greater understanding of them to develop a more complete geologic picture and exploration approach.

The similarities, differences, challenges, and opportunities presented by these two porphyry types will be discussed, beginning with the basics of petrologic processes that form porphyry magmas, and continuing with emplacement, hydrothermal alteration, and veining. There will be a special emphasis on how to identify and map some of these geologic features for exploration and mining purposes and how shallow and deep porphyries should be explored for differently. The first part of the course will cover the broader geologic understanding of porphyries, and the second part will dive deeper into hydrothermal alteration, veining, and exploration implications.

Top takeaways:
-Deep porphyry deposits are Cu-Mo rich (early halo type), whereas shallow porphyry deposits are Cu-Au rich (A-vein type).
-Different exploration approaches and why they matter.
-Shallow deposits have multiple generations of porphyry dikes and the early porphyries host the best Cu-Au grades.
-Deep deposits have fewer porphyry dikes, and wall-rock composition controls the Cu grade.
-Shallow deposits are rich in quartz A veins, while deep deposits are rich in early halo alteration selvages.
-Properly identifying and mapping vein and alteration types remains one of the most valuable exploration tools and if done properly can provide a much more solid base for exploration success.