THE COLORBACK AND HILLTOP PROPERTIES Carlin

Transcription

THE COLORBACK AND HILLTOP PROPERTIES Carlin
THE COLORBACK AND HILLTOP
PROPERTIES
Carlin-style Systems in the Battle
Mountain-Eureka Trend
Nevada
January 2015
Kiska Metals Corporation
#575-510 Burrard Street
Vancouver, BC V6C 3A8
(604) 669-6660
www.kiskametals.com
The content of this report has been reviewed and approved by Dr. Michael Roberts, Ph.D., P.
Geo., V.P. Exploration of Kiska Metals. Dr. Roberts is a Qualified Person as defined under the
terms of National Instrument 43-101.
The Colorback and Hilltop properties are early stage exploration properties and do not contain
any mineral resource estimates as defined by National Instrument 43-101 Standards of
Disclosure for Mineral Projects. The potential quantities and grades disclosed herein relating to
targets on the Colorback and Hilltop properties are conceptual in nature and there has been
insufficient exploration to define a mineral resource for these targets. It is uncertain if further
exploration will result in these targets being delineated as a mineral resource.
Disclaimer: In this document, we make statements about historical fact and future events. Statements about future
events are “forward-looking” and may prove inaccurate, as the future could differ materially from our current
expectations. Forward-looking statements are subject to much risk and uncertainties, including those described in our
public filings with securities regulatory authorities in the United States and Canada, which we urge you to read.
Except as required by law, we do not intend to update any of these forward-looking statements.
OPPORTUNITY
The Colorback and Hilltop prospects offer both excellent Carlin-style and porphyry
intrusive-related gold potential within the prolific Battle Mountain-Eureka Trend,
Nevada. Important attributes to these properties include:
Rare Nevada opportunity to acquire a property position on an established and
prolific gold trend with excellent exploration indicators including gold in drill
holes that remains virtually untested.
Near surface resource potential as supported by strongly anomalous gold in
surface samples, trenches and by significant gold-bearing drill intercepts at the
Discovery Zone.
Two primary exploration targets exist on the property:
1. Shallow, structurally hosted - intrusive related Au mineralization in
“Upper Plate” rocks akin to the Battle Mountain Au-Ag-Cu porphyry skarn
and sedimentary hosted gold deposits of Copper Canyon, Fortitude and
Phoenix;
2. Deep Carlin-Style mineralization along the Roberts Mountain Thrust as
interpreted through geological and geophysical reconstruction
Excellent infrastructure potential with easy site access via road and nearby
power.
PROPERTY TITLE
Geoinformatics Alaska Exploration Inc. (GXL), a wholly owned subsidiary of Kiska Metals,
holds a 100% interest in two claim blocks in the Bullion Mining District, Nevada (Figure
1). The Colorback block of 120 claims (2150 acres) consists of 7 adjacent groups in the
Mud Springs Gulch area and the Hilltop block of 82 claims (1640 acres) in 3 groups in the
Bateman Canyon Creek area (Figure 2). The claims are held under the Bureau of Land
Management (BLM) as lode mining claims and are renewed annually. Annual
maintenance fees are USD$28,280 ($140/claim) paid to the BLM and USD$2,121
($10.50/claim) paid to Lander County. Placer claims are held in the Colorback area by a
separate party.
Kiska recently entered into an exploration agreement with Baker Hughes Oilfield
Operations, Inc. (Baker Hughes) for the Hilltop property. Under the agreement, Baker
Hughes has the right to explore for barite minerals on the company’s 82 unpatented
lode mining claims, but this does not inhibit exploration by Kiska for metallic minerals
including gold. Baker Hughes drill sample splits are to be available for precious metals
analysis.
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LOCATION, ACCESS AND GEOGRAPHY
The Colorback and Hilltop properties are located in central Nevada’s Lander County on
the west slope of the Shoshone Mountains (Figure 1). The Colorback claims are 35 km
southeast of Battle Mountain and the Hilltop claims lie 10 km to the northwest of
Colorback (Figure 2).
Figure 1 - Property Location Map for Hilltop and Colorback Properties
A good network of roads provides access to both claim blocks. For example, the
Colorback property is reached by driving 48 kilometers east of Battle Mountain on
Interstate 80, then 32 km south on paved Hwy 306 to the small town of Crescent Valley.
About 3 km south of Crescent Valley a 6 km long gravel road heads west to the
Colorback claims. A high voltage power line passes within 6 km of the Colorback
property and services the large mines nearby. Skilled mining and exploration manpower
is available in the area.
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Figure 2 - Claim block location map for Colorback and Hilltop Properties
The climate is very arid high desert at 1,800 m elevation with warm summers and cold
winters. Nearby mining operations work year-round. Vegetation is sparse sage on the
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hills and sporadic pinion pine. Most land in the area is used for cattle grazing. The few
creeks in the area are spring-fed but most creek beds are dry.
EXPLORATION HISTORY
Nevada Bureau of Mines Bulletin 88 documents barite, turquoise and placer gold
production from the Colorback area with references to lode gold-style mineralization
(Master, 2007). Turquoise was discovered in 1938 and two small mines had limited
production; one of the mines is 240 m up-slope from GXL’s Discovery Zone. Barite was
produced from the district starting in 1954. Barite production and exploration continued
into the early 1980s.
Placer gold was discovered in Mud Springs Gulch during 1907 and minor production was
recorded from the Old Tenabo and Pastime placers, south and east of the Colorback
property, respectively. The Pastime also produced from vein (lode) gold located on the
east side of the property. The occurrence was verified by GXL sampling in 2006 and
contained 0.18 opt (5.64 g/t) gold in silicified cherty argillite and quartzite.
In 2006, GXL conducted a seismic survey consisting of three lines on Colorback and two
lines on the Hilltop property. This survey was carried out in 2006 in an attempt to
detect the depth position of the Roberts Mountain Thrust and thereby the region of
Carlin-style gold potential. Several breaks were outlined in the seismic data that are
interpreted to represent the Thrust.
At Colorback, GXL drilled 4 core holes totaling 833 m and one 123 m trench in 2006.
This work targeted the Discovery Zone and the Myers Hill area. The drill holes were
positioned to cross cut mineralized faults in the Upper Plate rocks to test the extent and
viability of breccias and fracture-controlled mineralization.
Numerous small pits and historic trenches are present and follow presumed mineralized
WNW structures. Historical exploration drill pads are also located around these
workings in both the Discovery Zone and Myers Hill areas. Kiska is not aware of any
geologic or geochemical records associated with this historical work.
Exploration undertaken on the Hilltop property by Geoinformatics in 2006 consisted of
mapping, rock sampling and the seismic survey. The early stage exploration at Hilltop
was undertaken in conjunction with similar work elsewhere in the area and although
Colorback received follow up drilling, nothing further was done on Hilltop by GXL.
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REGIONAL GEOLOGY
The Colorback and Hilltop prospects occur in the center of the prolific Battle Mountain –
Eureka Trend. The Battle Mountain – Eureka Trend is defined by a 56 km long trend of
mineralization containing the multi-million ounce sedimentary hosted gold deposits at
Cortez and Pipeline approximately 13 -20 km southeast of the Colorback Property and
the Battle Mountain gold-silver-copper porphyry skarn and sedimentary hosted gold
deposits of Copper Canyon, Fortitude and Phoenix.
The Phoenix Project is
approximately 33 km WNW of the Colorback Property. Barrick Gold Corporation
(“Barrick”) owns the Hilltop gold deposit (not to be confused with Kiska’s Hilltop claim
block) that is approximately 6 km WNW of the Colorback property (Master, 2007).
Numerous small gold and silver occurrences are present between the large resource
areas and define a WNW trend as being rather continuous in mineralization on a
regional scale.
The rocks exposed in the region are primarily chert, quartzite, siltstone and argillite of
the Devonian Age Slaven Formation and the Ordovician Age Valmy Formation (Figure 3).
These rocks are part of the “western facies” eugeosynclinal deep water sedimentation
sequence (Stewart and Carlson, 1978). Stratabound sedimentary hosted barite lenses
were deposited during rift-related sedimentation within the middle of the Slaven
sequence. Numerous barite lenses are exposed in open pits and prospects (Figure 3)
associated with the chert - siltstone - argillite sedimentation of the Slaven chert. Granitic
intrusions of unknown age trend in a WNW direction from Crescent Valley through the
Bullion, Hilltop and Lewis Districts, across the Shoshone Range to the Reese River Valley.
The Valmy quartzite occurs overlying the Slaven chert and is interpreted to have been
thrust over the Slaven Chert during late Devonian – Early Mississippian time of the
Antler Orogeny (Stewart and McKee, 1977). There are windows of Slaven chert exposed
through quartzite in fold crests and along fault boundaries where erosion has exposed
Slaven chert and Elder sandstone, primarily in valley areas. These thrust faults are part
of an imbricate thrust sequence in the Upper Plate western facies clastic sequence that
was thrust over the “eastern facies” carbonate sequence hosting the Silurian Age
Roberts Mountain Formation limestone and Devonian Age Wenban limestone. The
Upper Plate clastic sequence hosts Barrick Gold Corporation’s nearby Hilltop gold
deposit and the Colorback gold occurrences.
The Silurian Age Elder sandstone, Roberts Mountain Formation limestone and Devonian
Age Wenban limestone outcrops where erosion of uplifted, folded and faulted upper
plate rocks locally expose Lower Plate carbonate stratigraphy in the western Shoshone
Range and they also outcrop at Cortez. The Roberts Mountains thrust is identified as the
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thrust separating the two stratigraphic packages. The Wenban and Roberts Mountain
limestones are the known hosts for the major productive mines and economic resources
in the Cortez District containing Pipeline, Pipeline South, Cortez, Cortez Hills and the
Pediment deposits.
PROPERTY GEOLOGY
Project scale geological mapping identified a window of Slaven chert and siltstone
exposed through overlying Valmy quartzite and chert (Figure 3). The window of Slaven
chert is fault bound by thrust and high angle faults at the contact with the Valmy
quartzite and chert. The shape of the window is elongate in a WNW and NW direction
which follows two prominent fault directions mapped on the property. The thrust
faulting and overlying Valmy quartzite are crosscut by the WNW and NW directed faults
(Figure 3).
A north-south elongate intrusion of an Eocene-age equigranluar granite/granodiorite
occurs on the western boundary of the property and is interpreted to have intruded
along a fault (Master, 2007). Smaller intrusive granitic plugs and porphyritic felsic dikes
(34.8 m.y., McKee and Silberman, 1970) occur in numerous locations on the property
and tend to follow the WNW and NW trending fault zones suggesting that this structural
orientation controlled emplacement.
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Figure 3 - Regional and project scale geologic map of Colorback and Hilltop.
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ALTERATION AND MINERALIZATION
Sediments in contact with the dikes and granitic intrusives display varying degrees of
hornfelsed metamorphism where cherts are recrystallized and bleached and argillites
contain biotite. Felsic dikes and granitic intrusives are altered to white argillized rock
with relict porphyry textures. The dikes and contact sediments contain minor veining
and associated copper oxides after chalcopyrite
Overall gold mineralization coincides with northwest trending breccias and occurs in
strongly oxidized fractures and silicified breccias in Slaven Chert containing goethite,
limonite and hematite +/- jarosite. Turquoise and black copper oxides also occur in the
Discovery Zone and Myers Hill Areas. Silver mineralization occurs in close association
with gold in the Discovery and Myers Hill Zones.
The Discovery Zone is an iron-stained breccia zone measuring approximately 300 m long
and approximately 100 m wide at widest location (Master, 2007) and is oriented in NW
direction and abuts a mineralized high-angle, WNW-trending, fault/shear zone. The
breccia and fracture trend appears to extend approximately 1000 meters to the
northwest and approximately 1000 meters to the southeast (Master, 2007).
The Myers Hill area is also hosted in silicified, goethitic fractures and shears, but where
the Discovery Zone mineralization is hosted in the Slaven Chert and shows a strong
preference to WNW oriented structures, Myers Hill is hosted within the Valmy Quartzite
and mineralization is present along all structural directions (WNW and N-NE).
Barite mineralization occurs primarily as bedded sedimentary type deposits in siltstone
and chert on both the Colorback and Hilltop blocks. Vein barite also occurs in chert near
the contact with granitic intrusions along the west side of the property.
SURFACE GEOCHEMISTRY
Data exist for 270 rock samples collected at Colorback and Hilltop; 214 were taken at
Colorback (inclusive of the Discovery Zone and Myers Hill) and 56 were collected at
Hilltop. Figure 4 shows gold in rock samples for the Colorback and Hilltop properties.
Gold values at Colorback tend to be highest adjacent to steep WNW trending faults and
breccias in the Discovery Zone and on-trend from the Discovery Zone in WNW and SE
directions.
The highest grade samples within the Myers Hill area also tend to occur along the
primary WNW-NW structural trend, however several fault and fracture orientations at
Myers Hill tend to carry significant gold mineralization.
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Additional higher grade samples (> 0.30 ppm) occur outside the Discovery Zone and
Myers Hill areas and are similarly associated with fracture zones and silicified breccias.
Additional work focusing on further definition of the occurrence and continuity of the
structures and breccias throughout the property via mapping and surface sampling is
recommended to facilitate placement of future Upper Plate drill targets.
Figure 4 - Surface geochemistry for gold (ppm) for Colorback and Hilltop. Samples 0.30 ppm and above
are indicated in red. Note the clustering of higher grade samples around the WNW-trending high-angle
fault zones around the Discovery Zone.
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Figure 5 shows copper in the rock samples. Like gold, copper grades tend to be highest
around WNW-oriented fracture and breccia zones in the Discovery Zone area. However,
copper grades appear to be lower in the Myers Hill area than the Discovery Zone,
possibly reflecting the difference in host rock (Valmy) versus the Discovery Zone
(Slaven).
Figure 5 - Surface geochemistry for Cu (ppm) for Colorback and Hilltop.
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GEOPHYSICS
In 2006, Geoinformatics
conducted a total of 16.4 km
and 12.7 km of seismic
reflection
survey
over
Colorback
and
Hilltop,
respectively. The primary
objective of this study was
to map the depth to
carbonate units underlying
the
Roberts
Mountain
Thrust that could potentially
host Lower Plate Carlin-style
gold mineralization (Zapata
Engineering, 2006). Three
lines were conducted over
the Colorback area and two
lines were acquired over
Hilltop (Figure 6).
Figures 7 and 8 show the
interpretation of Colorback
seismic lines 1 and 2,
Figure 6 - Location of seismic reflection surveys. These surveys were respectively
and
the
intended to identify the location and depth of the Roberts Mountain
interpreted depth of the
Thrust so that deeper Carlin-Style targets could be outlined below
Roberts Mountain Thrust.
the near-surface mineralization.
The interpretations for Hilltop are similar in appearance and function and are not
presented here for brevity. At Colorback, the Thrust is interpreted to dip shallowly
toward the west. While at Hilltop, the Thrust appears to dip southward.
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Approximate location of
Roberts Mountain Thrust
Figure 7 - Interpreted section of Seismic line 1 showing the inferred location of the Roberts Mountain
Thrust (base of orange unit).
Approximate location of
Roberts Mountain Thrust
Figure 8 - Interpreted section of seismic line 2 showing the inferred location of the Roberts Mountain
Thrust (base of orange unit).
The seismic surveys show that the Roberts Mountain thrust and the Lower Plate
carbonate units are located at a depth of approximately 1000 to 2000 feet below
surface. Carlin-Style deposit potential lies at and below this depth (Zapata Engineering,
2006).
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EXPLORATION DRILLING AND TRENCHING
Prior to core drilling, GXL conducted trenching (CBT_1) to better understand the surficial
continuity and confirm direction of the Discovery Zone breccia and associated
structures. The trench results confirmed the association of gold and copper
mineralization with WNW trending structural zones and were subsequently used to
locate the core holes.
A total of four core holes were drilled in 2006 to test the extension and mineralization of
the mapped surficial breccias and mineralized fault zones at the Discovery Zone and
Myers Hill. Three holes (CB06_01, CB06_02, and CB06_04) were drilled in the Discovery
Zone (Figure 9) and one hole (CB06_03) was drilled at Myers Hill.
All three Discovery Zone holes encountered intervals of moderate to intense
silicification with corresponding goethite, limonite and jarosite mineralization that
typically carried the highest gold grades. Sulfides are present as fracture coatings and
veinlets in the more intensely silicified breccias and typically contain pyrite and
chalcopyrite that display varying degrees of oxidation. Notable copper (>300 ppm)
coincides with gold in zones of heavy weathering, but is typically present in wider
intervals than gold suggesting remobilization of copper during subsequent oxidation.
Drilling at Myers Hill (CB06_03, Figure 10) intersected one zone of intense brecciation
and silicification that contained abundant sulfides (pyrite/chalcopyrite) weathering to
goethite and limonite. Gold and copper grades were highest in this zone. The
distribution of copper in CB06_03 displayed the same spread distribution as that
exhibited in the Discovery Zone holes.
The core drilling results correspond well with the surface geochemistry and trench
mineralization and show that mineralization at the Discovery Zone continues vertically
to a depth of approximately 170 m and remains open at depth.
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Figure 9 - Plan view of 2006 core holes and surface trench (CBT_1) in the Discovery Zone. Drilling and trenching
was located to test the mineralization within breccias and along high angle faults in the Upper Plate siliclastic
rocks.
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Figure 10 - Plan view of 2006 core hole at Myers Hill. Drilling was located to test the mineralization within breccias
and along high angle faults in the Upper Plate siliclastic rocks.
DISCUSSION AND CONCLUSIONS
The Colorback and Hilltop properties represent excellent greenfield exploration
opportunities in an actively mined, prolific, and established gold belt within a stable
political jurisdiction.
Colorback and Hilltop display similarities to Barrick’s Hilltop deposit nearby, which is
approximately 6.7 km west-northwest of the project boundary. This prospect is
described by Barrick (Bergen, et al, 2012) to consist of the following:
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“49 holes for 19,000 ft of drilling at Hilltop and have outlined a body of
epithermal, intrusive-related gold mineralization with a preliminary
potential of 1.0 million to 1.5 million ounces of gold. There is still potential
to expand this target as it remains open in several directions. The next
steps are to complete fill-in drilling for Barrick Gold Corporation – Cortez
Joint Venture Operations grade continuity, metallurgical test-work for
recovery process options and extension drilling to expand the
mineralization. The objective is to establish a reportable Mineral Resource
at Hilltop.” (NB: The reference quoted here is not to be confused with
Kiska’s Hilltop property, which does not contain any mineral resource
estimates as defined by National Instrument 43-101 Standards of
Disclosure for Mineral Projects. Furthermore the above statement does
not imply that there is a Mineral Resource on Barrick’s Hilltop prospect as
defined by the CIM Definition Standards).
Barrick’s Hilltop prospect is characterized as an epithermal, intrusive-related Au deposit
with minor Cu hosted within the Valmy Chert. The numerous granitic and granite
porphyry dikes mapped on Colorback suggests that the mineralization in the Upper
Plate units may be similar to that observed at Barrick’s Hilltop.
Figure 10. Conceptual SW-NE cross-section through the core of the Colorback property indicating the potential for
near-surface Upper Plate Au mineralization and deeper Cortez-Pipeline-style Lower Plate Au mineralization
below an interpreted Roberts Mountain thrust.
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The intrusive relationship whether genetic or spatial at Colorback has commonalities
with the Battle Mountain Camp and Hilltop Deposit that contain intrusion related
deposits including copper-gold porphyries, skarns and the so-called distal disseminated
style of deposits. Colorback rock geochemistry shows a variable pattern but a general
intrusive character marked by anomalous copper-lead-bismuth-tellurium and a high
silver to gold ratio, which further supports Colorback as an intrusion-related gold-copper
occurrence at surface (Figure 10). The near-surface gold-mineralization at Colorback
may also be symptomatic of a larger Cortez-like system that may have preferentially
developed in Lower Plate carbonates. Based on the seismic data, this may be a viable
conceptual target to test with deeper drilling.
RECOMMENDATIONS
Based on the current status of the project, the following exploration activities are
recommended:
Colorback
Soil sample orientation surveys, and if results are positive, complete extensive
soil sample surveys of the claim group to detect new zones and better define the
extents and trends of known zones of mineralization.
Additional shallow trenching and drill targeting of breccia and fault targets to
help define potential surface resources as well as identify deeper targets in the
southern extension area of the Discovery Zone and Myers Hill Area.
Additional drilling targeting deeper Lower Plate mineralization.
Hilltop
Surficial soil and rock sampling combined with project scale geologic mapping to
identify favorable areas for trenching and drilling.
Drill shallow and deeper holes (below Roberts Mountain Thrust as indicated on
the seismic survey results) to define upper and lower plate mineralization.
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REFERENCES
Bergen, R.D., Gareau, M.B, and Altman, K.A., 2012, Technical Report on the Cortez Joint Venture
Operations, Lander and Eureka Counties, State of Nevada, U.S.A, NI 43-101 Report, 231 pages.
Master, T.D., 2007, Technical Report on Colorback Gold Project, 72 Pages. Unpublished, Internal
Report.
Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and
Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and
distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386).
Stewart, John H. et. al. Geology and Mineral Deposits of Lander County, Nevada. Nevada Bureau
of Mines and Geology, Bulletin 88. 1977, 106 pages.
Zapata Engineering, 2006, Seismic Reflection Surveys in the Colorback and Hilltop Prospects,
Northern Shoshone Mountains, Nevada, 17 pages., Internal Report.
TECHNICAL INFORMATION
The technical information in this document has been reviewed and approved by Dr. Michael
Roberts, P.Geo., Vice President, Exploration of Kiska Metals Corporation, a Qualified Person as
defined by National Instrument 43-101. The technical information pertaining to Kiska’s
Colorback and Hilltop properties have been compiled from “Master, T.D., 2007, Technical Report
on Colorback Gold Project, unpublished, internal report” by T.D. Master, CPG. Data verification,
sampling programs, and Quality Assurance and Quality Control programs used in the collection
and compilation of the field data and drilling data are detailed in this document and are deemed
to be accurate and adequate to support targeting efforts and guide exploration strategies.
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