Geoscience BC’s QUEST survey area in central British Columbia has a large amount of regional geophysical and geochemical data available to the exploration industry; however, despite the wealth of data, the bedrock geology remains poorly constrained, especially in the extensive areas covered by glacial drift in the Prince George area. The area is generally prospective for porphyry Cu-Au mineralization beneath covering glacial drift. Previous attempts to integrate geophysical, geochemical and geological information to constrain the geology beneath cover (Logan et al., 2010) provided results that were heavily biased toward interpolation between known outcrops and failed to take into consideration much of the geophysical and geochemical evidence. This study is focused on the interpretation of magnetic and gravity data and provides a fresh look at the structural architecture and the bedrock geology in the QUEST area and can be used as a base layer for exploration for Porphyry style deposits in this highly prospective area. See project deliverables for illustrations.

La incorporación sistemática de aspectos estructurales al mapeo e interpretación de data geológica, geoquímica y geofísica en diferentes escalas es pieza fundamental para la selección del terreno a explorar y, últimamente, para la generación exitosa de blancos de exploración. El presente curso entrega una mirada a la evolución tectónica y metalogénica desde Colombia a Patagonia con énfasis en depósitos tipo pórfido y epitermal de las franjas de Domeyko y Maricunga. A escala local, se exponen las principales señales geoquímicas relacionadas al control estructural, zonación de alteración hidrotermal y dispersión de elementos geoquímicos en torno a depósitos de tipo pórfido cuprífero. Adicionalmente, el curso incorpora técnicas de interpretación geológica y estructural para data magnética basada en la habilidad de reconocer, delinear y entender diversos estilos y tipos de falla y fractura. El curso está dirigido a exploradores que desean profundizar en una mirada estructural que integra conceptos tectónicos, metalogénicos, geoquímicos y geofísicos para la vectorización de depósitos minerales.

Regional-scale magnetite-destructive structures transecting the allochthonous to parautochthonous Intermontane terranes of western Yukon are characterized by northwest-trending and steeply north-east dipping fault systems, whereas eastern Alaska is dominated by a series of northeast-trending and sub-vertical faults. At a local scale, geological, structural and geophysical data support the role of these structures in focusing of orogenic style and magmatic-related mineralization under contractional and strike-slip tectonics, respectively. Orogenic gold mineralization in the Klondike and White Gold districts is closely linked to contractional deformation and to cooling of upper plate rocks in the Middle to Late Jurassic, following accretion and amalgamation of the Intermontane terranes to the Laurentian margin. Orogenic gold mineralization associated with this event formed in a variety of structural settings, including orogen-parallel thrust surfaces, breccias and veins in orogen-perpendicular to oblique transfer faults, and dilational veins hosted in fold-related shear and tensional fractures. This phase of Jurassic northeast-southwest directed contraction was followed by northwest-southeast extension by Early to mid-Cretaceous time and to transtension in the Late Cretaceous. In the Yukon’s Dawson Range, mid-Cretaceous epizonal orogenic gold mineralization (Coffee Gold Au system) and early Late Cretaceous porphyry Cu-Au(-Ag-Mo) systems (e.g., Casino, Nucleus, Revenue, Cash) are structurally related to the northwest-trending, dextral strike-slip Big Creek fault, which represents a branch of the Teslin-Thibert-Kutcho fault system of southern Yukon and northern British Columbia. By the latest Cretaceous, defomation is dominated by northeast-trending sinistral strike-slip magnetite-destructive faults (e.g., Pb-Ag veins of the Sixtymile and Fortymile districts of far western Yukon and eastern Alaska). We interpret fault bends, fault relay zones and fault tips, as well as lower-order structures, to favour the formation of mid- to Late Cretaceous magmatic-related mineralization.