|Title||Identifying new vectors to hidden porphyry-style mineralisation|
|Author||Rogers, N; Plouffe, A; Chapman, J; McClenaghan, M B; Kellet, D; Anderson, R A; Rice, J M|
|Source||Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 37, 2014 p. 235|
|Links||Online - En ligne (PDF 8.75 MB)|
|Alt Series||Earth Sciences Sector, Contribution Series 20130602|
|Meeting||GAC-MAC Joint annual meeting; Fredericton, NB; CA; May 2014|
|Subjects||structural geology; porphyry deposits; mineral deposits; tungsten; molybdenum; tin; mineralization; structural interpretations; Triassic; Jurassic|
Geoscience Initiative (TGI-4), Intrusion/Porphyry Ore Systems|
|Abstract||Intrusion related (e.g., porphyry) deposits are the most important sources for Cu, Mo, W and Sn, along with Au, Ag, and PGEs. Porphyry deposits are large, low- to medium-grade deposits in which
mineralisation is hosted within and immediately surrounding distinctive intrusive phases within larger intrusive complexes that commonly have prolonged emplacement histories. To develop more effective exploration criteria to identify and evaluate
deeply buried and/or hidden fertile intrusive mineralizing systems, studies into Cu-Mo/Au and W-Mo-Sn systems are aimed at answering the following questions: i) Are there distinctive proximal and distal footprints for each deposit type that will
allow identification of, and vectoring towards hidden economic deposits?; ii) Is there evidence of fertility within the root system of intrusions, i.e. what are the triggering conditions and indicators of an hydrothermal-magmatic system of size and
duration sufficient to develop a large porphyry deposit? To help answer these questions studies are being undertaken at sites associated with the Triassic-Jurassic porphyry deposits of the British Columbia interior and for the array of mineralised
Canadian Appalachian Siluro-Devonian intrusions, for which the fundamental geoscience knowledge is often lacking.|
A common problem facing Cordilleran and Appalachian exploration is how to detect intrusion-related mineralization through the
extensive glacial sediment cover. Consequently, research activities are focussing at identifying key geochemical and mineral indicators in till near known mineralization and their detrital dispersal down-ice. Indicators are being developed for the
detection of mineralization, but also the alteration halos and vein systems associated with mineralization, which represent much larger exploration targets than the actual economic orebody itself. Once identified in till, these indicators can be
traced to their bedrock source using reconstructed ice movement vectors.
Structural relationships indicate that Sn - W - Mo mineralised intrusive systems can form due to extension associated with far removed non-orthogonal accretion. Deposits
within these bodies form along fluid pathways such as the intersection of high-angle syntectonic breaks.
Mineral potential can also be resolved through trace element fingerprinting. Subtle compositional changes in commonly occurring minerals
(i.e., biotite) and fluid inclusions provide evidence of chemical variations related to magma fertility and vectors to mineralisation.