This project found that the chemical and textural characteristics of zircon minerals in granite rocks that typically host porphyry copper deposits can help identify rocks that formed under 'copper-friendly' (fertile) conditions.
Geoscience BC co-hosted an online webinar with MDRU – Mineral Deposit Research Unit on October 21, 2020 to discuss a series of research projects that show the potential to identify buried porphyry deposits from till or bedrock samples near the surface in British Columbia.
Finding additional copper deposits is important to BC’s economy and to meeting forecast increases in global demand.
Zircon is a mineral often found in rocks that host copper porphyry deposits. Zircons are some of the oldest and toughest minerals found on earth. Often referred to as ‘time capsules’ these minerals lock in information about the conditions that existed during their formation and are tough enough to survive high temperatures (such as within a magma) and in surface sediments, carried for miles by rivers and rain.
The trace elements found in zircon mineral grains can provide information on the magma before it solidified into rock, as well as the age of the rock. Internal textures and zoning within the zircon grains can also give clues to the environment of the rock’s formation and ore-forming processes, thereby helping mineral explorers determine if a rock formed under potentially ‘copper-friendly’ conditions.
This project fits under Geoscience BC’s Strategic Objective of Advancing Science & Innovative Geoscience Technologies and our goal to:
Specifically, the goal of this project was to develop an exploration toolkit to evaluate porphyry fertility in BC plutons by:
These objectives were accomplished using field, mineralogical and geochemical techniques on fertile and barren plutons.
Recent studies show that zircon provides a useful tool to evaluate a pluton’s fertility or ability to generate porphyry copper deposits. This study can help to determine if a rock formed under potentially ‘copper-friendly’ conditions.
Samples were collected from batholiths in BC’s South Central and North Central Regions that host porphyry copper deposits, including:
The researchers analyzed 1,021 zircon grains from 42 rock samples. They found that zircon mineral grains from porphyry-fertile batholiths in BC have characteristics that record distinct chemical and physical properties and indicate increased potential to host porphyry copper deposits.
The researchers identified key features of zircon that indicate porphyry-fertile plutons in BC. They contain zircons with: