OCGC Seminar - ON THE INFLUENCE OF THE PERVASIVE EMPLACEMENT OF ANATECTIC MAGMAS AS INJECTION COMPLEX IN THE CONTINENTAL CRUST

   

Dr. Samuel Morfin
University of Ottawa 

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Thursday, October 22nd, 2015
11:30 a.m.  

233 Advanced Research Complex (ARC) 
University of Ottawa 

 

Abstract

Crustal differentiation occurs through the ascent of anatectic magma from its lower crustal source. Studies from granulite terranes show that magma migrates through a pervasive network of narrow veins. Modeling of this mechanism and field work indicates that a considerable part of the mobile magma accumulates at the depth of the solidus and forms an injection complex there. The Archean Superior Province provides a rare opportunity to observe different crustal levels and to assess the distribution of anatectic magma in the crust.

Our work in the Opinaca Subprovince during my PhD identified an injection complex recording lower granulite facies thus although regional scale partial melting occurred there, the deep middle crust is actually an accumulation zone for pervasively injected anatectic magma.

Contrary to the widely accepted model that anatectic magma leaves its source and accumulates in plutons at the brittle/ductile transition, our results indicate that a considerable fraction remain at depth in the continental crust. Thus, we argue that the total production of anatectic granite in the crust may be underestimated and its balance may require adjustments. Changes in the distribution of granite throughout the crust imply changes of fundamental crustal parameters such as chemical differentiation or heat and water distribution.