MICROSTRUCTURAL AND METAMORPHIC ANALYSIS OF THE MALTON GNEISS DOME, SOUTHERN CANADIAN CORDILLERA
Kabazi, Hana Najed 1986-
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The Malton Gneiss Dome is located in the Southern Canadian Cordillera, at the northern most tip of the Shuswap Metamorphic Core Complex (SMCC). It is one of four domes within the SMCC, and is located closest to the foreland. Although deformation fabrics within the SMCC are dominated by E-W/NE-SW verging deformation fabrics, deformation fabrics within the Malton Gneiss Dome show top-NW sense of shear, parallel to the orogenic front. One possible explanation for this difference is the tectonically forced orogen parallel flow model, where foreland directed flow of low-viscosity mid-lower crust encounters a barrier, either thermal or structural, forcing it to flow laterally/parallel to the orogen. This model predicts that orogen parallel fabrics are synchronous with peak metamorphic conditions, during the late-Cretaceous to early-Cenozoic. Peak metamorphic conditions were investigated though quantitative thermobarometry and the relationship between deformation and metamorphism assessed through quartz deformation fabrics. My results show all samples analyzed have experienced amphibolite facies pressure and temperature conditions, with ranges of 600- 775 OC and 400-900 MPa. These conditions are similar to the other domes within the complex. Petrofabric analysis confirmed the orogen parallel movement within the dome coincided with peak metamorphic conditions, indicated by both syn-kinematic garnet and feldspar porphyroblasts which record peak metamorphic conditions.