Project: Geological setting, structural geology and timing of deformation at the Gibraltar Cu-Mo Mine: controls on mineralization.
The Gibraltar Cu-Mo porphyry deposit is located 65 km northwest of Williams Lake and 45 km southeast of Quesnel and is hosted in the Late Triassic Granite Mountain batholith. The Gibraltar Cu-Mo mine is one of several mineralized systems currently being investigated as part of the Geological Survey of Canada’s Intrusion Related Ore Systems TGI4 Program. The main ore zone on the mine property, hosted within the Mine Series Phase tonalite, is structurally dismembered by several deformation events. Questions still exist regarding the relationship between mineralization and the earliest deformation.
My research is aimed towards unravelling the geometry, kinematics and timing of the deformation events that have affected ore distribution and to determine if mineralization was synkinematic with the earliest deformation event. Maps have been constructed at 1:2000 scales, of bench walls located within four of the 4 open pits, including the Granite operational pit. Documented structural geology at the mine scale, along with micro-structural analysis of oriented and non-oriented thin sections will allow for a better understanding of the fault kinematics and geometry, and allow the placement of constraints on temperature.
Geochronology is of paramount importance to determine the absolute ages of deformation. A suite of illite samples from which we will obtain Ar-Ar cooling ages on different fault zones, high strain zones, S1 foliation and illite which crystallized with late-phase Mo-mineralization. Along with an Ar-Ar (hornblende) cooling age and U-Pb (zircon) geochronology (TIMS) for a more accurate crystallization age on the Mine phase tonalite, geochronology will be interpreted with field observations and microstructural analyses of the textural relationship between deformation, veining, and mineralization. Short wave infrared spectroscopy coupled with x-ray diffraction analyses of outcrop and drill core samples will allow evaluation of fault zones, veins and alteration zonation for any similarities or differences between clay and chlorite minerals.
Ultimately, a 3-D structural geological model of a select area that will exemplify the structural geometry of a portion of the mine will be constructed. This model, in conjunction with the age constraints and microstructural analyses findings will be placed into a regional tectonic framework.