Ms. Marissa Hindemith, a former MSc student of my colleague Dr. Aphrodite Indares (co-author on the paper), and I recently published a new paper entitled: “Hydrothermally altered volcanic rocks metamorphosed at granulite-facies conditions: an example from the Grenville Province” in the Canadian Journal of Earth Sciences. The paper studied 1.2 Ga rocks from the Manicouagan area of the central Grenville Province shows preservation of primary field relationships, potential relict volcanic textures, and geochemical and mineral chemical variations indicative of original submarine hydrothermal alteration, despite being metamorphosed to granulite facies. The work illustrates that aluminous nodules and sillimanite seams in tehse rocks are reflective of metamorphosed hydrothermal alteration assemblages. In addition, garnetites within these assemblages have Mn-rich garnets, Zn-rich spinels, and whole rock geochemical trends including Fe-Mg-Mn-enrichment and alkali depletions typical of mild argillic alteration found in less metamorphosed submarine altered rocks. The work illustrates that even though rocks can be metamorphosed to high grade they often preserve a chemical record of hydrothermal alteration and that rocks with such signatures in the Grenville Province may be potential volcanogenic massive sulfide (VMS) targets.
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