The rare element Little Nahanni Pegmatite Group, NWT : studies of emplacement, and magmatic evolution from geochemical and Li isotopic evidence ...

• Main Author: Barnes, Elspeth M.
• Format: Text
• Language: English
• Published: University of British Columbia 2010
• Subjects: Mackenzie mountains
• Online Access: https://dx.doi.org/10.14288/1.0052534; https://doi.library.ubc.ca/10.14288/1.0052534

Rare element pegmatites represent some of the last stages of igneous differentiation and are influential in element redistribution in the upper crust, leading to significant enrichment/depletion of various trace elements. Research into the processes that form these intrusions increases our understanding of the geochemical evolution of silicate earth and improves the potential for successful pegmatite exploration. This study focussed on the dikes comprising the rare element Little Nahanni Pegmatite Group (LNPG), Mackenzie Mountains, northern Canadian Cordillera. These peraluminous dikes have high concentrations of several rare elements, e.g., Li (up to 14,000 ppm), Cs (up to 500 ppm), Ta (up to 190 ppm), and Rb (up to 7,500 ppm). Orientation of the dikes was influenced during emplacement (2-3 kbar, ~400-500 °C) at ~90 Ma (apatite, U-Pb) by pre-existing foliation in the strongly deformed, stratified host rock of the Fork anticlinorium (axial planar cleavage and bedding). Differences in ⁴⁰Ar/³⁹Ar dates on ...