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The Jasper Property, southwest Vancouver Island, contains
several showings of Cu, Pb, Zn, Ag, and Au; however, the origin
and style of mineralization is not well understood. Based on the
nature of mineralization, two different deposit models have been
hypothesized: Noranda/Kuroko volcanogenic massive sulphide
(VMS) or Cu-Mo-Au Porphyry The goal of this research project
is to determine whether or not the Jasper Property hosts a VMS
deposit. This will be determined by analyzing the geology and
geochemistry of Jasper Property drill core. Geological and
geochemical predictions are as follows:
Veins containing Cu, Pb, Zn, Ag, or Au[6]
Submarine volcanic rocks: rhyolite, dacite, andesite, basalt
Enriched Cu-Zn relative to Pb
Geochem signatures of mafic boninite, LOTI, MORB rocks
M-affinities on Nb/Y discriminant diagram
.
The Jasper Property is underlain by a variety of lower-Jurassic
Bonanza Group volcanic rocks .
Felsic to mafic volcanics formed in an island arc environment
Bedrock exposure is due to convergent plate tectonics; the
exotic Wrangellia Terrane collided with N. America ~100 Ma
Economic mineralization is associated with alteration zones
VMS deposits originate at submarine plate boundaries
Seawater flows down joints towards igneous intrusions
Due to hydrothermal processes, sulphide minerals become
incorporated in seawater and travel back to seafloor
Sulphide minerals precipitate at 'black smoker' sites and
accumulate in lens-shaped deposits on the seafloor
Bimodal-mafic VMS deposits are associated with subduction
Vancouver Island hosts VMS in Sicker Group volcanics
Observations:
Jacques Houle and Nitinat Minerals Corporation provided three
drill cores from the Jasper Property. Drill core observations led to
the identification of four different rock units. See figures below.
Bedrock Units:
Unit A: Grey-green lapilli tuff
50% ash, %50 lapilli; most lapilli fragments occur as 2mm-5mm
quartz crystals; suspected hornblende crystals (5%); alteration
evidenced by bleaching, anastomosing calcite veins, and very
fine-grained disseminated pyrite (<5%); 4.5 cm thick galena vein
Unit C: Feldspar-phyric andesitic basalt
50% groundmass, 50% phenocrysts; grey-green aphanitic
groundmass with abundant feldspar phenocrysts: 25% K-feldspar
and 20% plagioclase; suspected hornblende (4%); alteration
associated with calcite veins (1mm-30mm thick) and
disseminated sulphide minerals: pyrite (<1%), galena (<1%).
Unit D: Overprinting alteration of A-E contact
Light green matrix with lapilli and dark rounded nodules; variable
quartz-sericite, chlorite, and red alteration; fine disseminated
pyrite(<1%); anastomosing veins; bleaching; brittle zones
Unit E: Red lapilli-tuff
50%ash, 50% lapilli; lapilli fragments (2mm-50mm); deep red
matrix; epidotization; minor calcite veins associated with pyrite
Expectations & Discussion:
If the Jasper Property hosts VMS, we should see the following:
Ore associated with the felsic or intermediate volcanic rocks?[6]
Mineralization is present, but ore is not economic.
Veins containing Cu, Pb, Zn, Ag, or Au?[6]
One 4.5 cm thick Pb vein found in grey-green lapilli-tuff.
1. British Columbia Geological Survey (BCGS). 2014. BCGS Geoscience Map http://www.mapplace.ca, Ministry of Energy,
Mines, and Petroleum Resources. Retrieved January 25th, 2014
2. Flower, K. 2013. British Columbia Geological Survey (BCGS) MINFILE Record Summary - MINFILE No. 092C 088.
3. Franklin JM. Gibson HL. Galley AG. Jonasson IR. 2005. Volcanogenic Massive Sulfide Deposits. In: Hedenquist JW.
Thompson JFH. Goldfarb RJ. Richards JP (editors). Economic Geology 100th Anniversary Volume. Littleton, CO. Society of
Economic Geologists. p 523-560.
4. Gibson HL. Galley AG. Jonasson IR. 2005. Volcanogenic Massive Sulfide Deposits. In: Hedenquist JW. Thompson JFH.
Goldfarb RJ. Richards JP (editors). Economic Geology 100th Anniversary Volume. Littleton, CO. Society of Economic
Geologists. p 523-560.
5. Houle, J. 2012. 2011 Assessment Report for Prospecting, Trenching Geochemistry, Geology, and Diamond Drilling May 2011
– March 2012 on the Jasper Property.
6. Höy T. 1991. Volcanogenic Massive Sulphide Deposits in British Columbia. In: W.J. McMillan (Coordinator). Ore Deposits,
Tectonics and Metallogeny in the Canadian Cordillera. British Columbia Ministry of Energy, Mines and Petroleum Resources.
Paper 1991-4. p 89-123.
7. Nasmith HW, Yorath CJ. 2001. The Geology of Southern Vancouver Island. Victoria (BC): Orca Book Publishers. 172 p.
8. Nelson, J., and Colpron, M., 2007, Tectonics and Metallogeny of the British Columbia, Yukon and Alaskan Cordillera, 1.8 Ga
to the present, in Goodfellow, W.D., ed., Mineral Deposits of Canada: A Synthesis of Major Deposit-Types, District Metallogeny,
the Evolution of Geological Provinces, and Exploration Methods: Geological Association of Canada, Mineral Deposits Division,
Special Publication No. 5, p. 755-791.
9. Piercy, S.J. 2010. An overview of petrochemistry in the regional exploration for volcanogenic massive sulphide (VMS)
deposits. Geochemistry: Exploration, Environment, Analysis. Vol 10, pp. 1-18.
10. Stevens R. 2010. Mineral Exploration and Mining Essentials. Port Coquitlam, BC: Pakawau GeoManagement. Chapter 3,
Mineral Deposits; p 70-74.
Predictions Y/N Comments
Veins containing Cu, Pb, Zn, Ag, Au Y Core contains one significant galena (PbS) vein
Submarine volcanic rocks:
rhyolite, dacite, andesite, basalt Y Core contains intermediate tuffs and andesitic basalt,
but alteration may complicate rock classification
Ore found in felsic to intermediate rocks ? Interesting mineralization, but no major ore
Enriched Cu-Zn relative to Pb Y Evidence of a juvenile environment, consistent
with a bimodal mafic VMS model
Geochemical signatures of mafic boninite,
LOTI, or MORB rocks ? No boninite signature; may explain lack of
mineralization; likely island arc tholeiite
M-affinities on Nb/Y discriminant diagram Y Supports, but does not prove, VMS
mineralization; ore is possible, not evident
Many thanks to Jacques Houle and Nitinat Mining Corporation for
providing drill core and geochemical data. Further thanks to our
instructor, Sandra Johnstone.
Geological and geochemical findings support a potential VMS
deposit at the Jasper Property, but hard evidence is lacking. The
scope of this research is limited due to a lack of core samples,
geochemical information, and geologic mapping. Further sampling,
geochemical analysis, and property mapping are recommended.
Samples were analyzed by Inspectorate Mining and Exploration
Service using inductively coupled plasma mass spectrometry
(ICP-MS) and atomic absorption spectroscopy.
...
Image from Google Earth
Spider Diagram: The pattern of
enrichment or depletion of
certain elements in the local
rock units is similar to those of
back-arc basin basalt (BABB)
and island arc tholeiites (IAT).
Al2O3/TiO2 vs. Nb/Y: Data
points straddle the boundary
between mid-ocean ridge basalt
(MORB) and boninite/low Ti
tholeiitic (LOTI)-associated
VMS. Al2O3/ TiO2 is too low for
rocks to be considered boninitic.
Nb vs. Y: Rhyolites with M-type
affinities are most likely to host
VMS mineralization. Drill core
data plot within the M-type field.
Zr vs. Y: Drill core plots within
the tholeiitic field. This disagrees
with Bonanza Grp. descriptions
indicating calc-alkalic rocks[5].
Although these plots are better suited for rhyolite analysis, mafic,
intermediate, and felsic rock samples should display geochemical
signatures similar to rhyolites[5].
0
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V (
pp
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Nb (ppm)
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(p
pm
) Nb (ppm)
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Zr (
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Nb (ppm)
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Nb
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pm
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Y (ppm)
Within-plate
(A-type)
M-type
Volcanic arc
(I-type)
Ocean ridge
(OR-type)
Syncollisional
(S-type)
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Zr
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Calc-alkalic
Tholeiitic
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Th
Nb
La
Ce Pr
Nd
Sm Zr
Hf
Eu Ti
Gd
Tb
Dy Y Er
Yb
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ck/P
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e M
an
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Element 0
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0 0.5 1 1.5 2
Al 2
O3/T
iO2
Nb/Y
MORB Associated
Boninite and LOTI Associated
