|Title||IOCG potential in northern Canada: Lessons from the Great Bear magmatic zone|
Montreuil, J F; Potter, E; Hayward, N; Enkin, R; McMartin, I; Davis, W; Normandeau, P X; Acosta-Gongora, P; de Toni, A; Jackson, V; Ootes, L|
|Source||PDAC, Prospector and Developer Association, abstracts; 2013 p. 3-5|
|Alt Series||Earth Sciences Sector, Contribution Series 20130033|
|Publisher||Prospector and Developer Association|
|Meeting||Prospector and Developer Association Annual Convention; Toronto; CA; March 3 - 5, 2013|
|NTS||86E; 86L; 86K; 86C; 86D; 86F|
|Area||Great Bear Magmatic Zone|
|Subjects||general geology; economic geology; iron oxides; contact metasomatic deposits; hydrothermal alteration; alteration; mineralization; exploration; albitites; uranium deposits|
|Program||GEM: Geo-mapping for Energy and
Minerals, Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)|
|Abstract||Space-time evolution of alteration within the 1866-1870 Ma iron-oxide alkali-altered (IOAA) metasomatic systems of the Great Bear magmatic zone highlights a systemic coupling and decoupling of elements
and metals at regional to local scale that frames the development of iron oxide copper-gold (IOCG) and derived/affiliated deposit types. Collectively, these systems also give a detailed picture of the realm of base, precious, high technology/green
and nuclear energy metals that IOAA systems may host (e.g., iron oxide-apatite, base metal-poor specialized metal, magnetite- to hematite-group IOCG and multiple-metal albitite-hosted uranium deposits).|
The extreme redistribution of elements
across prevailing physico-chemical gradients produced a series of metasomatic facies with diagnostic composition and mineral assemblages unified under their key chemical elements and temperature of formation (e.g., Na, Ca-Fe, HT K-Fe, LT K-Fe).
Framed within a unidirectional alteration vector-to-deposit model, each facies can also be permuted or repeated to adapt to the transition, juxtaposition, superimposition and cyclical build-up of alteration that result from faulting, brecciation,
differential exhumation and magma emplacement. The model also presents predictive exploration capabilities on the basis that incoming and outgoing fluids and metals can be inferred to account for alteration observed and to reflect on what components
of the system remain to be found. Building on the model, new discrimination diagrams and geochemical alteration profiling provide further insights on the fertility of IOAA systems. At regional scales, IOAA systems can be rapidly targeted through new
geophysical potential field techniques integrating gravity and aeromagnetic data with rock physical properties, or by till geochemistry using pathfinder and alteration-related elements multivariate signatures of glacial sediments. In addition, the
abundance and distinctiveness (chemical, physical) of a selection of minerals derived from IOCG systems show potential as indicator minerals for exploration in glaciated terrain.
The case examples, methods, maps and up-coming databases supplied by
the Geomapping for Energy and Minerals (GEM) program expand exploration tools for IOAA systems in the Great Bear magmatic zone and within any terrane or mineral camp where metasomatic alteration and mineralization have not been fully re-examined
using modern IOCG exploration criteria. In addition, the alteration vector-to-deposit model represents a means to unify exploration programs in areas where formerly disparate deposit types now fall under IOAA systems. The improved efficiency in
exploring for the spectrum of resources of IOAA systems is required to drive resource discoveries essential for our 21st century needs.
|Summary||(Plain Language Summary, not published)|
This abstract presents a new ore deposit model that frames the evolution of iron oxide-rich hydrothermal systems in terms of space, time and metal
associations for the Great Bear region, a Precambrian volcanic belt in the NWT. Extremely hot fluids accumulated below volcanoes and interacted intensely with the rocks they have percolated through. Element and metals contents in the fluids evolved
significantly from heat sources to surface and metals were forced to precipitate incrementally potentially leading to an extraordinary range of iron oxide copper-gold (IOCG) and derived deposits. The model presents predictive exploration capabilities
and a means to unify exploration programs in areas where formerly disparate deposit types now fall under iron-oxide alkali-altered mineralizing systems. The improved efficiency in exploring for the spectrum of resources of iron oxide alkali-altered
hydrothermal systems is required to drive resource discoveries essential for our 21st century needs.