Geodynamic evolution of felsic magmatism in the Yellowknife greenstone belt, N.W.T., Canada: evidence for Archean magmatism in a volatile-saturated environment

The Yellowknife greenstone belt in the Archean Slave province, N.W.T., Canada, hosts multiple generations of porphyry dikes and plutons, including feldspar–quartz porphyry (FQP), quartz porphyry (QZP), and aplitic dikes, along with the regional Ryan Lake Pluton (RLP), Defeat Suite, and Duckfish granites. Chondrite-normalized REE patterns differentiate three aplite groups and their genetically related parental plutons. The RLP and aplite-1(a) dikes have smooth REE profiles that decrease from LREE to HREE, shared by FQP and QZP dikes. The Defeat Suite granite and aplite-1(b) dikes display flatter REE patterns with a strong negative Eu anomaly. Duckfish granite and aplite-2 dikes share concave-up REE patterns with weak positive Ce (up to Ce/Ce * = 3.1) and strong negative Eu anomalies. These geochemical distinctions link subvolcanic intrusions with source plutons. Aplite dikes were further characterized by petrogenetic models, establishing four stages of dike emplacement during pluton crystallization. Progressive stages of emplacement show increasing differentiation (e.g., decreasing Al 2 O 3 , MgO, TiO 2 , Eu/Eu * ). Evidence of volatile saturation was observed macroscopically as cm-scale quartz cores and quartz pods. Further study of volatile evolution and its relationship to mineralization (e.g., timing, volatile composition) is warranted.