South Grass Valley Project - March 2020 Drilling Update https://www.nevadaexploration.com/news/2020/south-grass-valley-project---march-2020-drilling-update
March 31, 2020
Nevada Exploration Inc. (“NGE” or the “Company”) (TSX-V: NGE; OTCQB: NVDEF) is pleased to provide an update regarding its reverse-circulation (“RC”) drilling program at its South Grass Valley Carlin-type gold project (the “Project”). Since beginning the program in January 2020, the Company has completed the first of its two planned drilling cycles at all four of its initial targets, and has begun the second cycle of drilling at its Golden Gorge and Freddie targets. NGE is pleased to share that early results have significantly improved the resolution of the Company’s geologic model at this covered, district-scale Carlin-type mineral system, and have focused the Company’s efforts at each of its target areas.
Specifically, the Company reports that:
At Water Canyon, NGE has completed first-cycle drilling – initial assays show highly-anomalous Carlin-type gold deposit (“CTGD”) pathfinder geochemistry, and once the Company has received all assays it will begin detailed logging of the sample chips;
At Golden Gorge, NGE has attempted two second-cycle drill holes, both of which successfully encountered lower plate, though the RC drill rig could not reach target depths at either location;
At Waterfall, NGE has received all assays for the first-cycle drill holes – in general, gold and pathfinders are lower than at Golden Gorge and Freddie;
At Freddie, based on results of first-cycle drilling, NGE has begun second-cycle drilling to sample thicker sections of the targeted lithologic units; however, similar to at Golden Gorge, the RC drill rig is performing below expectations in terms of its penetration rate; and
At East Golden Gorge, NGE believes that the target area may represent a common, deeper feeder system to the shallower mineralization seen up dip (to the west) at Golden Gorge and Freddie, and the Company expects to incorporate advancing Eastern Golden Gorge into its next phase of drilling.
Discussing the program, Wade Hodges, NGE CEO: “As we shared in our last update, the first cycle of drilling accomplished its objectives in terms of improving the resolution of our geologic model across each target area, as well as refining the larger geologic context across this otherwise-covered, district-scale project. Driven by this improved resolution, we’re seeing that the first holes of our second cycle of drilling are intersecting the predicted geologic units; however, the RC drill rig is not reliably completing holes down to the depths needed to test our targets.
“There is growing evidence that the intensity of mineralization increases towards the eastern edges of the Golden Gorge and Freddie target areas, where the favourable stratigraphic units dip deeper. With this in mind, now that we’ve been able to use the first-cycle RC drill holes to cost-effectively focus our targets, we’re now winding down the RC drilling program and looking at transitioning back to core drilling, in order to more confidently reach the depths needed to test what we believe have become even more compelling targets.
“In the coming weeks, once we’ve received all data from the RC drilling and incorporated it into our geologic model, we look forward to providing a substantive update on each target area, and lay out a detailed plan for our next phase of drilling, which we expect to consist of a number of highly-focused, deeper core holes.”
WATER CANYON TARGET
Water Canyon is located at the intersection of a NNW lineament, a NW fault fabric, and a NE fault, to the east of an historic adit and trench workings exposed in outcrop. The target is supported by elevated mercury and arsenic in soils, as well as gold, antimony, and arsenic in groundwater. The concepts to be tested at Water Canyon are that of typical Carlin-type mineralization in Roberts Mountains Formation units below upper-plate cap rocks, as well as that of potentially higher-grade mineralization in hornfelsed lower-plate carbonates emplaced along a series of SE-plunging folds and structural trap sites.
RC Drilling Program Objectives
NGE’s objectives for its planned program are to test for evidence of ponding, mineralized Carlin-type hydrothermal fluids in low-angle trap sites sitting beneath the upper-plate cap rocks, as well as for gold and related pathfinders within hornfelsed host rocks close to the Grass Valley Stock.
During March, NGE completed its first cycle of drilling at Water Canyon, which consisted of two drill holes, the first located at the southwestern edge of the target (SGVR013), and the second located at the eastern edge of the target (SGVR014). In total, the Company has now completed 580 metres of RC drilling at Water Canyon, and has received complete assay results from its first hole, SGVR013.
First-Cycle Drill Holes
SGVR013 encountered bedrock at 20 metres, which based on preliminary logging consisted of alternating units of lower-plate Roberts Mountain Formation and granite, down to the bottom of the hole at 270 metres. NGE has now received assays for the entire hole, and will soon begin detailed logging of the sample chips. Of note, the assays show highly-anomalous CTGD pathfinder geochemistry, with arsenic up to 554 ppm, antimony up to 20.8 ppm, and thallium up to 1.5 ppm.
SGVR014 hit bedrock at 188 metres, in this case a mudflow unit sitting immediately on top of lower plate, comprised of a mudstone that began at 218 metres that transitioned into limestone at 278 metres until the bottom of the hole at 311 metres. Once full assay results for the hole are available, NGE will begin detailed logging.
NGE expects to provide a detailed update for Water Canyon once it has completed the detailed logging and incorporated the data into its geologic model.
Golden Gorge is located to the east of the Grass Valley Stock, where NGE’s earlier core drilling confirmed the presence of anomalous gold and CTGD pathfinders within silicified and marbled breccias along the intrusive margin surrounding the Grass Valley Stock. The target is supported by the coincident alignment of the highest gold-in-groundwater concentrations seen at the Project, which closely map the interface between the lower-plate bedrock units and the intrusive. The concepts to be tested at Golden Gorge are that of high-grade, oxide gold mineralization within the hornfelsed lower plate, as well as potential additional gold mineralization in breccia units.
RC Drilling Program Objectives
NGE’s objectives for its planned program are to establish the extent of and test for mineralization within the hornfels aureole on the east flank of the intrusive, as well as to test the western extension of the intensely-altered breccia units seen in the earlier drilling.
As described in the Company’s February 2020 update (https://www.nevadaexploration.com/news/south-grass-valley-project---february-2020-drilling-update
), NGE has completed its first cycle of drilling at Golden Gorge, consisting of five relatively shallow holes along the western edge of the target, for a total of 900 metres. The majority of the first-cycle drill holes were located too close to the intrusive to test for mineralization. NGE has now received the remaining assays for holes SGVR008, SGV011, and SGVR012 (all of which encountered granite), and as expected there is little evidence for mineralization within the granite, as also seen in hole SGVR005.
These holes did, however, help to constrain the relative location of the intrusive margin, placing it further to the east. Of the first-cycle drill holes, only SGVR006 was located far enough away from the granite to intersect the projected favourable host units surrounding the intrusive margin, though the hole did not go deep enough to test the desired stratigraphy.
During March, driven by its updated geologic model and improved understanding of the location of the intrusive margin, NGE began its second cycle of drilling towards the eastern edge of the target, with the goal of sampling thicker sections of lower plate along the intrusive-margin, contact-aureole interface.
Second-Cycle Drill Holes
SGVR015 was located between NGE’s earlier core holes SGVC001, which had encountered granite, and SGVC005, which had encountered highly-anomalous CTGD pathfinder geochemistry associated with intensely-altered breccia units. Preliminary logging is still in progress, though NGE can confirm that SGVR0015 encountered lower-plate bedrock at 146 metres until the bottom of the hole at 311 metres, where the hole was terminated due to extremely slow penetration in densely silicified, hard, and broken bedrock.
SGVR016 was located approximately 250 metres ESE of SGVR006, with the goal of testing a deeper and thicker section of the altered and geochemically-anomalous lower-plate units seen in SGVR006. SGVR016 hit lower-plate bedrock at 67 metres, consisting of a non-calcareous mudstone. At 229 metres, the hole began to encounter silicification and decalcification, until the hole was stopped at 256 metres, again due to slow penetration in hard and broken bedrock.
With the RC drill rig at the Project not able to reach the planned target depths in either SGVR015 or SGVR016, these holes did not test the target concept at Golden Gorge. To continue to advance Golden Gorge, NGE is now looking at transitioning back to core drilling in order to reach the depths needed to test this very important area of the Project.
Waterfall is located within lower-plate bedrock in close proximity to the Grass Valley Stock, at the projected intersection of high-angle NW and NE-trending faults. The target is supported by evidence that some component of the high concentration of gold in groundwater centred over Golden Gorge could possibly have originated from the Waterfall area, as well as by a discrete zone of elevated arsenic in soil across the western part of the target. The concept to test at Waterfall is that of fracture-controlled mineralization within hornfelsed lower-plate.
RC Drilling Program Objectives
NGE’s objectives for its planned program are to: (1) define the interface between the lower-plate and the Grass Valley Stock in this area, and (2) test this geologic setting for evidence of mineralization.
As described in the Company’s February 2020 update, NGE has completed its first cycle of drilling at Waterfall, consisting of a NE-SW fence of three drill holes (SGVR004, SGVR009, and SGVR010) along the northwestern edge of the target, for a total of 966 metres. The first-cycle drill holes confirmed the presence of a thick section of the projected favourable carbonate host rocks above large areas of the Grass Valley Stock, which achieved this first objective of the program in confirming the target’s exploration concept.
During March, NGE received the remaining assays for SGVR009 and SGVR010. The results show that the hard siliceous mudstone and chert units in these holes contain similar anomalous CTGD pathfinder geochemistry to that seen in SGVR004, with SGVR009 containing gold up to 20 ppb, arsenic up to 129 ppm, and antimony up to 9.8 ppm, and SGVR010 containing gold up to 22 ppb, arsenic up to 287 ppm, and antimony up to 13.0 ppm. Based on a preliminary review, while anomalous, the gold and pathfinder concentrations at Waterfall appear lower and less consistent compared to those seen at Golden Gorge and at Freddie.
Now that all assays have been received, the Company is updating its geologic model at Waterfall, and expects to provide a detailed update once complete.
Freddie is centred northeast of Goodwin Butte, where initial drilling defined large zones of sulphide-bearing, silicified breccias within silty carbonate units that show evidence of low-angle thrust faulting. These favourable host units sit below a shale cap rock at the intersection of high-angle NNW and NE district-scale faults along an antiformal fold hinge, which together represent a characteristic combination of host rocks and mineral controls for CTGD mineralization. The target is supported by elevated gold and related pathfinders within the silicified breccias, as well as by strong geochemistry anomalies in soils and groundwater. The concept to be tested at Freddie is that of oxidized, silicified breccia-hosted gold mineralization, analogous to the mineralization at Goldrush.
RC Drilling Program Objectives
NGE’s objectives for its planned program are to: (1) determine the extent and controls of the silicification, and (2) test the up-plunge extensions of the pathfinder-bearing breccias seen in the earlier drilling for higher-grade mineralization.
As described in the Company’s February 2020 update, NGE has completed its first cycle of drilling at Freddie, consisting of four drill holes located in the southwestern portion of the target, for a total of 1,800 metres. All of the first-cycle drill holes encountered at least the top of the targeted favourable lithologies as well as alteration features seen in NGE’s earlier drilling, and together have established that the Carlin-type hydrothermal-system at the Project extends another kilometre to the WNW, which achieved the first objective of the program. Of the first-cycle drill holes, only SGVR002, the northwesternmost hole, was completed deep enough to test the full thickness of the targeted lithologies, and in general, the assay results for SGVR002 show a decrease in gold and pathfinder budgets relative to those seen in holes to the east, suggesting that the direction of hydrothermal fluid flow was from the east.
Based on the first-cycle drill results, NGE has selected second-cycle drilling locations, eastwards from SGVR002, to sample thicker sections of the now-confirmed up-plunge extension of the favourable lithologies seen in the earlier core drilling, which is the remaining second objective of the program, and during March, NGE began its second cycle of drilling.
Second-Cycle Drill Holes
SGVR017 is currently in progress, and is located approximately 400 metres SE of SGVR001, and approximately 600 metres, ENE of SGVR007. This hole was started with the goal of continuing considerably deeper than SGVR007, which encountered significant alteration and pathfinder geochemistry, but was stopped at only 238 metres. SGVR017 hit bedrock at 59 metres, consisting of a volcanic unit sitting on top of the lower plate, which began at 73 metres, made up of alternating limestone and chert. SGVR017 is presently at 116 metres and proceeding slowly in challenging hard and broken bedrock conditions.
Similar to at Golden Gorge, now that the first-cycle RC drill holes at Freddie have helped to focus the target, NGE is looking at transitioning back to core drilling to reach the targeted favourable lithologies at the depths projected by the earlier core holes.
EAST GOLDEN GORGE
As described in the Company’s February 2020 update, NGE engaged Mira Geoscience to prepare a constrained inversion model of the major geologic units at the Project by integrating data from NGE’s air magnetic, gravity, and core drilling programs. Based on the results of the inversion model, NGE believes that the linear, NNW-oriented, air magnetic feature located east of Golden Gorge and Freddie may represent a structurally-controlled trough or canyon-like topographic feature within the prospective Paleozoic units that has been filled with a magnetic mudflow unit, marking a regional-scale, high-angle structural feature. These types of major high-angle structural features represent critical, deep-seated fluid pathways at Nevada’s major CTGD camps, such as the Post-Gen fault, which cuts through the northern Carlin trend. Given its potentially important role in the larger South Grass Valley district, NGE believes East Golden Gorge is an important area of focus at the Project.
During March, NGE incorporated the latest drilling results to update its geologic model, which continues to suggest that the favourable lithologic units seen at Golden Gorge and Freddie dip downwards to the east, towards the East Golden Gorge lineament. The target concept at East Golden Gorge is the projected intersection of these favourable host units with a major, district-scale structure. First-cycle drilling at Freddie has provided evidence that the source direction of the mineralized hydrothermal fluid flow at the district is likely from the east at depth, which supports the concept that the fluids would have likely also passed through the Eastern Golden Gorge target area.
NGE believes that Eastern Golden Gorge may represent a common, deeper mineralized root or feeder system to the shallower mineralization seen up dip at Golden Gorge and Freddie, and expects that following this mineralization deeper at both targets, towards where they meet the Eastern Golden Gorge area, will be an important component of the Company’s next phase of drilling.
About the South Grass Valley Project
The Project is located approximately 50 kilometres south-southwest of the Cortez complex operated by Nevada Gold Mines (Barrick Gold Corp. and Newmont Mining Corp. joint venture) and Barrick Gold Corp.’s latest Fourmile discovery. As described in detail in the Company’s January 7, 2020, news release (https://www.nevadaexploration.com/news/2020/nevada-exploration-commences-2020-drilling-program-at-south-grass-valley-carlin-type-gold-project
), NGE is presently completing a follow-up RC drilling program to achieve specific objectives at four target areas at the Project (Water Canyon, Golden Gorge, Waterfall, and Freddie), as well as developing an exploration plan for a fifth target (East Golden Gorge).
As NGE continues to advance the Project, per NI 43-101, 2.3(2), the Company must remind its stakeholders that the Project remains an exploration target for which the potential quantity and grade of any mineral resource is still conceptual in nature. There has been insufficient exploration to define a mineral resource, and it is uncertain if further exploration will result in the target being delineated as a mineral resource.
About Nevada Exploration Inc.
With mature, exposed, search spaces seeing falling discovery rates, NGE believes the future of exploration is under cover.
The Company has spent 15 years developing and integrating new hydrogeochemistry (groundwater chemistry) and low-cost drilling technology to build an industry-leading, geochemistry-focused, under-cover toolkit specifically to explore for large new Carlin-type gold deposits (“CTGDs”) in the more than 50% of Nevada where the bedrock is hidden beneath post-mineral cover. Nevada’s exposed terrains have produced more than 200 Moz of gold, and experts agree there is likely another +200 Moz waiting to be discovered under cover in Nevada.
NGE has completed the world’s largest hydrogeochemistry exploration program, focused on north-central Nevada, and is now advancing a portfolio of three district-scale projects in the heart of the Cortez (Battle Mountain-Eureka) Trend.
NGE’s most advanced project is South Grass Valley, located south of Nevada Gold Mines’ Cortez Complex. In 2019, NGE completed an initial program of 10 wide-spaced core holes across the project, and based on the Company’s resulting geologic model, NGE believes it has discovered a mineral system at South Grass Valley with the architecture and scale to support multiple Carlin-type gold deposits (CTGDs), and the potential to host an entire new district. NGE’s widespread groundwater, soil, and core sample geochemistry coverage has provided the data to prioritize specific targets for the Company’s next stages of exploration. NGE believes South Grass Valley is one of the most exciting new district-scale, Carlin-type projects in Nevada.
For more information, the Company’s latest videos are available at: https://www.nevadaexploration.com/investors/media/
For further information, please contact:
Nevada Exploration Inc.
Telephone: +1 (604) 601 2006