Integrated interpretation of the Blake River Group using geophysical data from metal earth's Rouyn-Noranda transect, Quebec

Abstract

The study of crustal structure in Precambrian greenstone belts is crucial for understanding of mineral deposits and their genesis. This thesis takes on an integrated interpretation of geophysical data for Metal Earth’s Rouyn-Noranda transect as part of a large collaborative research. Regional scale seismic reflection, magnetotelluric and gravity data as well as magnetic and surface geology maps are used to conduct the study. The seismic reflection data was enhanced by the application of the curvelet enhancement method and seismic attributes for to improve interpretation ability. Two sets of density models were used, namely, constrained and unconstrained models. A 2-D conjugate gradient inversion of Magnetotelluric data was done after the phase tensor and skew angle were analyzed to determine dimensionality and directionality. The data was interpreted together in the form of integrated interpretation in order to understand the structure and architecture of the crust along the transect. The seismic data is characterized by poorly reflective upper crust, strongly reflective mid crust, exhibiting complex reflection structure sub-horizontal reflections truncated by gently dipping reflections. The lower crust is characterized by sub-parallel reflections with weak continuity. The magnetotelluric model is characterized by a resistive upper crust with conductive pathways penetrating through the resistive bodies; and a conductive mid-to-lower crust. Integration of the data reveals a good correlation between the data sets and the upper crustal conductive conduits correlate directly with surface geology map structures a well as lineations from the magnetic map. The highly reflective mid crust correlates with the conductive feature in the mid crust in which the correlation is attributed to partial melts in the mid-crust. The density models also show a good correlation with the seismic data and were used to constrain the depths and dimensions of plutonic rocks along the transect.