Using zircon in mafic migmatites to disentangle complex high-grade gneiss terrains – Terrane spotting in the Lewisian complex, NW Scotland

The zircon record of complex high-grade gneiss terrains is key to interpreting their tectonothermal evolution. Typically, such studies focus on zircon-rich, felsic rocks, which commonly have a complicated (partial melting, inheritance, partial dissolution, and reprecipitation) record. Here we show that metamorphosed mafic rocks retained melts (i.e. in situ leucosomes) provide the evolution crustal blocks simpler easier interpret. We apply our method Archaean gneisses iconic Lewisian NW Scotland use it test proposed terrane model based largely geochronology. Our work focusses migmatites central region, where identified long-established metamorphic age clusters ca. 2.75 Ga 2.5 Ga, as well 2.85 protolith ages. A finding these ages are recognised across both putative region previously different histories. oldest (inherited) similar those within other outside region. Thus, all likely share common pre-metamorphic history, questioning validity for complex. demonstrate lithologies powerful tool identifying stages polyphase complexes typify Earth’s earliest rock records offer additional context assessing geodynamic