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EM surveys over Green Giant graphite property in Madagascar

Posted by on Tuesday, 24 February, 2015
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by Alexander Prikhodko, 24 Feb., 2015

Graphite mineralization has a high electrical conductivity, which makes it an excellent target for electromagnetic (EM) methods.

Energizer Resources Inc. and it’s predecessors have conducted several airborne and ground electromagnetic  surveys over different areas of Green Giant graphite property in Madagascar (province of Toliara). Different EM technologies have been used in accordance with their progress.

Geological position and characteristics of the property:

Regional position – Ampanihy Shear Zone, NS foliation of rocks;

-Vertical to sub-vertical nature;

-The area is underlain by supracrustal and plutonic rocks deformed with N-NE trending structures;

-Graphitic zones consist of multi-folded graphitic strata;

-Graphitic schist and gneiss with vanadium mineralization.

 Geologic map (magnetic field interpretation)

Green_Giant_quick_Mag

 

AEM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AEM surveys covering with different technologies is in the picture above.

The basic AEM surveys results which demonstrate a potential of the territory and effectiveness of the applied methods are below.

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DIGHEM survey

Inverted (EMflow, Encom) DIGHEM data. Conductivity 3D voxel, sections and a map.

(conductors in red, resistors blue colors)

DIGHEMConVoxel

 

 

 

 

 

 

 

 

 

 

 

 

 

sections

 

condmap

 

 

 

 

 

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VTEM survey

Time-domain EM TAU parameter calculated with sliding window algorithm picks up the most conductive part of the geoelectrical section on each station-sounding.

TAU

 

 

 

 

 

 

 

 

 

 

 

 

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The resistivity-depth imaging (RDI) of EM time-domain data is a base of depth positioning of conductors potential for graphite mineralization and the first approximation of their geometry and dimensions.

rdisections

 

 

 

 

 

 

 

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3D apparent resistivity distribution with <1 Ohm-m clipping areas:

RDIvoxel

 


Fresh insights on magnetic field from Geosoft

Posted by on Friday, 20 February, 2015

 

 

Virginia Heffernan: “Magnetization Vector Inversion (MVI) is a modern technique which is gaining acceptance as an effective tool for subsurface exploration in areas where magnetization does not necessarily run parallel to the earth’s magnetic field, a more common scenario than geoscientists have traditionally appreciated.”

– See more at: Earth Explorer

 


2014 issued patents by Assignee Geotech Airborne Limited

Posted by on Tuesday, 27 January, 2015
Patent number: 8878538
Abstract: An airborne geophysical surveying system comprising a receiver coil assembly for towing by an aircraft, the receiver assembly including a receiver coil for sensing changes in a magnetic field component of a magnetic field, and a receiver coil orientation sensing system for sensing orientation changes of the receiver coil. A controller receives signals representing the sensed changes in the magnetic field component from the receiver coil and the sensed orientation changes from the receiver coil orientation sensing system and corrects the sensed changes in the magnetic field component to provide a signal that is corrected for noise caused by changing orientation of the receiver coil in a static geomagnetic field.
Filed: November 26, 2010
Issued: November 4, 2014

Bucking coil and B-field measurement system and apparatus for time domain electromagnetic measurements

Patent number: 8786286
Abstract: According to one example embodiment is a time domain electromagnetic (TDEM) geophysical survey system for producing a B-field measurement, comprising: a transmitter coil; a bucking coil positioned in a substantially concentric and coplanar orientation relative to the transmitter coil; a receiver coil positioned in a substantially concentric and coplanar orientation relative to the bucking coil; an electrical current source connected to the transmitter coil and bucking coil for applying a periodic current thereto; and a data collection system configured to receive a magnetic field time-derivative signal dB/dt from the receiver coil and integrate the magnetic field time-derivative signal dB/dt to generate, a magnetic B-field measurement, the transmitter coil, bucking coil and receiver coil being positioned relative to each other such that, at the location of the receiver coil, a magnetic field generated by the bucking coil has a cancelling effect on a primary magnetic field generated by the transmitter coil.
Filed: August 28, 2009
Issued: July 22, 2014

Airborne time domain electromagnetic transmitter coil system and appratus

Patent number: 8766640
Abstract: A tow assembly for an airborne electromagnetic surveying system, including: a transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having rotating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the rotating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly being attached to the circumference of the transmitter coil frame at spaced apart locations.
Filed: May 23, 2011
Issued: July 1, 2014

Airborne electromagnetic transmitter coil system

Patent number: 8674701
Abstract: A tow assembly for an airborne electromagnetic surveying system including a semi-rigid transmitter coil frame supporting a transmitter coil, the transmitter coil frame being formed from a plurality of serially connected frame sections forming a loop, the transmitter coil frame having articulating joints at a plurality of locations about a circumference thereof enabling the transmitter coil frame to at least partially bend at the articulating joints; and a suspension assembly for towing the transmitter coil frame behind an aircraft, the suspension assembly comprising a plurality of ropes and attached to the circumference of the transmitter coil frame at spaced apart locations.
Filed: February 25, 2009
Issued: March 18, 2014

IP survey in Dominican Republic on Tireo Gold Trend

Posted by on Wednesday, 21 January, 2015

Precipitate Gold Corp. announces results from its recently completed Phase 2 induced polarization (“IP”) geophysical survey at the Ginger Ridge Zone within the Company’s Juan de Herrera project in the Dominican Republic.

The second phase of IP geophysical surveying at Ginger Ridge consisted of a total of 7.5 line kilometers primarily focused on four parallel grid lines (at 200 metre intervals) which extend 800 metres (“m”) northwest from the northern limit of the initial IP survey (Line 10), and 850 metres north of the Company’s highlight discovery drill hole 5 (“Hole 5″). Line 10 and Hole 5 represent a target signature of coincidental high chargeability readings with the discovery of 98.1 m of massive and semi-massive sulphide carrying multiple intervals of elevated gold mineralization (including 13.4 grams per tonne (“g/t”) gold over 5.0 m within 4.5 g/t gold over 18.0 m). The goal of the Phase 2 geophysical survey was to test for the continuation, and possible increase in strength, of the chargeability anomaly to the north as a means of delineating possible follow up drill targets. Highlights from the latest geophysical surveying include:

  • Extending chargeability anomaly by an additional 850 m northward on-strike from the discovery Hole 5;
  • Discovery of the strongest and widest chargeability readings to date in newly surveyed lines 6 and 8, which extend the anomaly to the northwest (readings up to 13.5 mV/V on Line 8); and
  • Delineating over 1 kilometre of continuous strike length of a strong chargeability readings largely coincident with the surface multi-element geochemical anomaly, warranting systematic follow up drill testing

See accompanying IP maps and figures and the Company’s website for additional compilation illustrations.

Jeffrey Wilson, Company President & CEO stated, “We are very pleased with the follow up Phase 2 Ginger Ridge IP survey results, as they extend the main gold target chargeability anomaly an additional 850 m north from our discovery Hole 5. This new northwestward extension provides us with more than one kilometre of on-strike gold exploration potential with similar signature characteristics to those encountered in Hole 5. It’s additionally encouraging that the gold target chargeability anomaly increases in strength between lines 12 and 6, which may indicate higher sulphide content and increased potential for gold bearing mineralization. We are excited that the results of this survey have provided a significant target area for follow up drilling and the potential for expansion of this exciting new gold zone.”

Ginger Ridge IP geophysical surveying now covers an area measuring approximately 1.6 kilometres by 1.0 kilometre “km”), blanketing much of the zone’s multi-element surface geochemical anomaly that marks anomalous mineralization in Tireo volcanic rocks. Field crews have reported numerous visual observations of variably mineralized surface exposures roughly coincident with the chargeability high, extending from line 2 to line 14; a distance measuring about 1.2 km.

From line 2 to 18, the main high chargeability anomaly is more than 1.6 km long, with elevated chargeability readings starting at bedrock surface on lines 6, 8, 10 and 12 (up to 13.5mV/V on line 8). Readings on the north and south survey lines project the chargeability anomaly deeper to the northwest and also to the southeast, each with a reduced relative strength of up to 4.5 to 5.5 mV/V. A petrophysical study carried out on select Hole 5 drill core indicates that massive and disseminated pyrite samples have chargeability responses of 84 and 27 mV/V, respectively.

Together, the resistivity and chargeability readings appear to map mineralization, major rock types and structures well. On the western side of the survey area, a possible regionally mapped thrust fault is inferred to dip vertically to steeply to the northeast, marking a possible structural contact between limestone rocks and the overlying gold enriched Tireo volcanic lithologies.

The two phases of induced polarization/resistivity surveys (April & December 2014) used a 10 kW generator Time Domain IP system using the Elrec Pro 10 channel receiver with a receiver dipole spacing of 50 metres, which provided quality subsurface resolution for each 2D section schlumberger-style array. The survey was conducted by Insight Geophysics Inc. of Oakville Ontario.

Michael Moore, VP Exploration of the Company and Qualified Person for purposes of National Instrument 43-101 has reviewed the technical information in this news release.


Magnetic and IP surveys over the high grade gold mineralization in Wawa

Posted by on Tuesday, 20 January, 2015

Red Pine Exploration Inc. completed drilling of 6 exploration holes on the Surluga Gold Deposit during the December 2014 field program to better define mineralization and alteration mineralogy on the property. A ground magnetic survey and an initial induced polarization geophysical survey were also completed over the known gold mineralization.

The Company believes that the drill results combined with a comprehensive examination of the geology, geophysics, geochemistry, alteration mineralogy and structural geology at Surluga are likely to uncover several new priority gold targets. The first three holes have been logged, sampled and submitted for assaying. The Company has mobilized its geoscientists who will be on site this week to complete logging and sampling core from the remaining three drill holes.

Quartz veins and altered rock have been intersected in each of the drill holes, and gold in the form of flakes visible with the naked eye (VG)* has so far been observed in three holes**;

  • SD14-02 between 119.5 – 121.5 metres (m) within a zone of altered quartz from 117m to 134m (not true width)
  • SD14-03 between 247.8 – 248.8m and 268.5-269.65m within a zone of altered quartz from 241m to 277m (not true width)
  • SD14-06 VG rich intersection occurred around 321m within a zone of altered quartz from 288m to 324m (not true width)

*Although VG is considered positive the Company cautions it has not received assay results for these intersections at the time of this press release.

**Logging and sampling of SD14-04, SD14-05 and SD14-06 will be completed shortly.

Quentin Yarie, President and Chief Operating Officer commented, “These results validate our hypothesis that high-grade shoots of gold mineralization are prevalent at Surluga. Potential high gold grades present new opportunities and we will target these high-grade areas for resource delineation.”

Red Pine Begins Revised Resource Assessment

The recent technical report by Watts, Griffis and McQuat, dated October 15, 2012 (Inferred resource of 1,072,335 ounces at 1.49 grams per tonne gold), describes the geology, the gold exploration, and the mineral resource estimation work undertaken by previous owners. The recent exploration work completed by Red Pine warrants the preparation of a new mineral resource technical report and the Company has retained SRK Consulting (Canada) Inc. (SRK) and Ronacher McKenzie Geoscience to complete this evaluation.

Wawa Gold Project Highlights

  • Located in Wawa, Ontario, an area of significant historical and current gold exploration (since 1890’s) and production (1902 to 1991);
  • 172 patented and leased and unpatented mining claims within the McMurray Township, a total of 2,426 hectares;
  • 182 claim units on crown land, a total of 2,912 hectares;
  • Property hosted eight past producing mines with historic production of over 120,000 ounces (Watts, Griffis and McQuat, NI 43-101 technical report dated October 15, 2012 );
  • Inferred resource of 1,072,335 ounces at 1.49 grams per tonne gold contained in 22.355 million tonnes, open along strike and at depth;
  • Proximity to established regional infrastructure (roads, rail, regional airport, high voltage power lines, water).
  • Assumption agreement in place with Augustine Ventures (CSE: WAW) and Citabar

Magnetic and VLF survey on the silica project in Quebec

Posted by on Tuesday, 20 January, 2015

Rogue Resources Inc.  announces that it continues to advance the Lac de la Grosse Femelle Property (the “Femelle Project”), located approximately 95 km northeast of Québec City, and adjacent to the Mine Sitec silica mine, in operation for the past 50 years.

Airborne Heli-MAG geophysics surveys were flown over the Femelle Project on December 7, 2014, consisting of 316.5 line km of north-northwest oriented flight lines spaced at 100 m. The helicopter-borne radio-magnetometric geophysics survey was conducted by Geophysics GPR International Inc. The objective of this first phase exploration program of airborne geophysics was to better define the widths, attitudes and strike length of the east-northeast trending quartzites. A follow-up airborne VLF (very low frequency) geophysical survey to further define the quartzite units will be undertaken within the next several weeks and upon compilation will form the basis of conducting surface exploration.

http://file.marketwire.com/release/Hlb_Mag_Femelle%20Silica%20ROGUE.pdf

Following the compilation of the VLF airborne data, and when ground conditions permit, line cutting, surface geological mapping and sampling of the quartzites at surface and at depths of 6 m to 12 m will commence. The work at surface is expected to begin in early May with a priority to define the high purity silica zones along the quartzites of the “G” quartzite unit as well as localizing the quartzites of the “D” quartzite unit. Results from surface mapping and sampling will be used to guide the upcoming drill program on the quartzites as well as for identifying new quartzite targets.

The airborne Heli-Mag survey produced total field magnetic and vertical gradient geophysics maps of the area. The samples collected in the quartzite unit “G” by Geologica Groupe-Conseil Inc., of Val d’Or, Québec, (press release December 16, 2014), occur on the southern margin of the lower magnetic expression. The samples assaying 99% or better in silica are associated with lower magnetic expressions and define widths of approximately 125 m, strike lengths of over 1 km and illustrates that the quartzites dip to the northwest. The quartzite unit “D” located 690 m southeast of the quartzite “G” unit also flanks the north side of the magnetic anomaly and extends east-northeast a strike length of over 1 km.

http://media3.marketwire.com/docs/Regional-Geology-ROGUE.jpg

http://media3.marketwire.com/docs/Location_of_Samples_ROGUE.jpg

Ongoing discussions with a number of producing and past producing silica mine operators and owners has begun as well as sourcing potential buyers for silica. The Company continues its community consultations in the region with the various local groups (MRC de Charlevoix, MRC de Charlevoix Est, MRNQ in La Malbaie, the Mairie de St.Urbain, and Zec des Martes).


Inversion electromagnetic survey data in web app

Posted by on Monday, 22 December, 2014

TDEM geomodel is an online software designed for editing, inversion, and interpretation of transient electromagnetic (TDEM) data. It outputs resistivity cross sections and maps which can be superposed on Google maps.

Here is an example of  ground TEM data on-line inversion:

 


In the news – Geotech technologies in Kazakhstan and Russia

Posted by on Tuesday, 2 December, 2014

In the National TV News (Kazakhstan)

 

In the local (Yakutia) Russian TV news:


Geology For Investors about an airborne EM technology for exploration

Posted by on Monday, 1 December, 2014

Hunting for Giants: An Introduction to ZTEM Surveys in Mineral Exploration
By: Kylie Williams in Exploration Methods

ZTEM

 

 

 

 

 

 

 

 

Overview

It may just look like an enormous, flying spider web towed behind a helicopter, but the ZTEM airborne geophysical survey system has the potential to identify giant porphyry copper deposits and features of other large ore deposits up to 2000 meters below the surface.
Z‐Tipper Axis Electromagnetic (ZTEM) is an airborne electromagnetic survey system which detects anomalies in the earth’s natural magnetic field. These disruptions are caused by zones of rock that conduct or resist electrical current more than the surrounding rock, like ore deposits. The proprietary technology belongs to Canadian company, Geotech, who have flown over 250,000 line-kilometres with ZTEM in under 4 years.

History

Geotech Ltd. is a Canadian airborne geophysical survey company that began operations in 1982. The company developed the now well-known VTEM (the versatile time-domain electromagnetic) system in 2002.
The helicopter version of the airborne Z‐Tipper Axis Electromagnetic (ZTEM) system was introduced into commercial service by Geotech in 2006-2007, and the less-expensive fixed-wing (FW ZTEM) system was introduced in 2010-11.

How ZTEM works

ZTEM specifications 300×225 Hunting for Giants: An Introduction to ZTEM Surveys in Mineral Exploration exploration methods ZTEM vtem uranium kimberlite exploration Geotech electromagnetism copper porphyry airborne geophysics
Flying spider web: the airborne loop of the ZTEM system (Geotech)
ZTEM is a type of electromagnetic (EM) survey to measure variations in the electrical properties of rocks.
EM surveys try to identify bodies of rock that conduct electricity well, like massive sulfide bodies of copper or nickel ore, or rocks that resist carrying current more than their surrounds, like the silicic alteration found in the core of porphyry deposits.
ZTEM surveys are different to other commercial EM systems because they measure variations in naturally-occurring EM fields rather than introducing an EM field into the ground and measuring the responding field, like VTEM.
Instead, ZTEM measures variations in the naturally-occurring or passive magnetic fields produced by thunderstorms around the world. This magnetic field is planar – constant in all directions – but areas of highly conductive or very resistive rock will cause measurable disruptions.
ZTEM surveys are designed to map resistivity contrasts to great depths, exceeding 1-2km, making ZTEM well-suited to finding porphyry-hosted and structurally-controlled exploration targets at depth.

What does a ZTEM survey look like?

The ZTEM system is transportable, able to be packed into small units which can be shipped around the world. There are two key pieces of equipment to the system, an airborne loop and ground receivers.
The airborne loops can be towed behind a helicopter or a fixed wing aircraft. The loop itself is a little over 7m across and looks a little like a giant, red-rimmed spider web. It is towed behind the aircraft at a height of around 100m above the ground to measure the vertical component of the magnetic field.
A 75-90m cable attaches the loop to the aircraft. The cable separates the loop from the vibrations of the aircraft and transmits the collected information back to the receivers in the plane or helicopter.
On the ground, base stations are set up in the survey area to measure variations in the horizontal magnetic fields.
GPS receivers are used on the coil in the air and also on the ground to keep track of the orientation of each of the parts, with respect to each other and the earth’s magnetic field.

A few Geotech case studies

Copper-porphyry, Alaska, USA
ZTEM was tested over a section of the world-class Pebble calc-alkalic copper-gold molybdenum porphyry deposit located in the Bristol Bay region of southwest Alaska in 2010. Some of the richest parts of the Pebble deposit are buried under up to 600 m of volcanic and sedimentary cover.
With careful processing, ZTEM was able to identify several of the distinctive alteration haloes found around the porphyry deposits, with more detail at depth than other systems.
ztem pebble Hunting for Giants: An Introduction to ZTEM Surveys in Mineral Exploration exploration methods ZTEM vtem uranium kimberlite exploration Geotech electromagnetism copper porphyry airborne geophysics
2D Resistivity cross-section over Pebble porphyry deposit in Alaska (Geotech)
Uranium deposits, Athabasca Basin, Canada
ZTEM tests were flown over unconformity-type uranium deposits in northern Saskatchewan, Canada, in 2008. The results correlated with known geological features to below 500m depth, penetrating through the thick cover materials to identify defining features in the basement rocks.
Kimberlites, Northwest Territories, Canada
A ZTEM survey flown over the Drybones Kimberlite near Yellowknife in NWT, Canada, was able to differentiate between diatreme (consolidated kimberlite) and the host rock buried under 100m of conductive cover sediments.

Further reading

The best place for information about ZTEM is the Geotech website, especially the ZTEM case study page

Several ZTEM case studies have also been published in peer-reviewed journals, for example:


New Multiple and Significant Nickel Sulphide Intersections at Maniitsoq – Greenland

Posted by on Tuesday, 4 November, 2014

North American Nickel Inc.  reports assay results for multiple and significant nickel sulphide intersections at the P-013 prospect, located seventeen kilometres south of the Imiak Hill Complex (IHC) on the Company’s 100% owned Maniitsoq Nickel – Copper – Cobalt and PGM project in southwest Greenland.

Highlights include:

  • MQ-14-066 (P-013): 5.85metres of 2.07% Ni and 0.12% Cu of semi-massive sulphides within a broader zone of 11.0 metres of 1.31% Ni and 0.15% Cu.
  • MQ-14-068 (P-013): 3.4 metres of 2.07% Ni and 0.34% Cu net-textured to semi-massive sulphides within a broader zone of 15.85 metres of 0.87% Ni and 0.27% Cu.

NAN President and Interim CEO, Mark Fedikow, commented: “Drilling at the P-013 prospect in 2014 was a follow-up to the initial discovery hole drilled in 2013, and has resulted in significant and multiple nickel sulphide intersections. These results not only confirm the prospectivity of P-013 but also the larger exploration potential of the central region of the Maniitsoq project. The results validate our regional exploration strategy and the excellent work being carried out by the exploration team. I look to further assay results pending from the 2014 program.”

Results for three regional drill holes and one IHC hole are reported below and provided in Tables 1 and 2 and Figures 1 and 2. Figures may be viewed using the link provided with this release.

REGIONAL

The P-013 area is located seventeen kilometres south of the Imiak Hill Complex, in the central portion of the Maniitsoq property, and comprises several helicopter-borne electromagnetic (VTEM) anomalies occurring over a distance of approximately 500 metres. The anomalies include the P-013 Centre, P-013 SE and P-013 NW targets (see Figure 1). In 2014, three holes totalling 739 metres were completed to test the P-013 targets.

P-013 Centre

Nickel sulphide mineralization intersected at this target was discovered by a combination of ground prospecting and drill testing of a VTEM anomaly buried beneath a large boulder field. In 2013, one hole (MQ-13-032) was drilled to test a 200m long northeast trending VTEM anomaly, and intersected a thick section of norite and leucogabbro containing several intervals of nickel sulphide mineralization (News Release November 21, 2013). The best intersection graded 0.44% Ni and 0.20% Cu over 6.51 metres including 2.35% Ni and 1.21% Cu over 0.73 metres. Borehole electromagnetic (BHEM) surveys detected moderate to high conductance off-hole anomalies associated with the mineralized intervals, suggesting the presence of stronger mineralization nearby.

In 2014, two holes (MQ-14-066 and MQ-14-068) totalling 597 metres were completed to follow-up the 2013 results. Both holes intersected mineralized norite as outlined in more detail below.

MQ-14-066 was drilled to test an off-hole BHEM geophysical anomaly detected from the discovery hole, MQ-13-032. MQ-14-066 was collared in orthogneiss and intersected leuconorite, norite and pyroxenite extending from 63.48 metres to the end of hole at 365 metres. A number of narrow intervals of net-textured to semi-massive sulphides were intersected between 94 and 150 metres returning values ranging from 1.55% to 2.23% Ni and 0.18% to 0.70% Cu (see Table 1). The main zone of mineralization was intersected from 157.0 to 168.0 metres and consisted of 11.0 metres of norite-hosted bleb, net-textured and semi-massive sulphides grading 1.31% Ni and 0.15% Cu, including a semi-massive sulphide interval grading 2.07% Ni and 0.12% Cu over 5.85 metres from 158.43 to 164.28 metres. A second wide zone of similar mineralization was intersected from 201.20 to 223.94 metres and graded 0.50% Ni and 0.15% Cu over 22.74 metres including 1.79% Ni and 0.31% Ni over 2.14 metres from 203.35 to 205.49 metres.

MQ-14-068 was drilled approximately 45 metres up-dip of MQ-14-066 and intersected 15.85 metres of norite-hosted bleb and net-textured sulphides grading 0.87% Ni and 0.27% Cu from 126.7 to 142.55 metres. Included within this zone was a higher grade interval of net textured to semi-massive sulphides which graded 2.07% Ni and 0.34% Cu over 3.4 metres from 130.85 to 134.25 metres. These intersections correlate well with the main sulphide zone intersected in hole MQ-14-066.

Borehole EM surveys indicate that the mineralization is correlated with a conductive trend interpreted to strike northeast-southwest, dipping steeply northwest and plunging steeply west. Additional drilling will be required to determine the extents of the P-013 mineralization, and more work will be planned for this area in 2015.

P-013 SE

MQ-14-069 was drilled to test a second VTEM anomaly (P-013 SE) located approximately 250 metres southeast of the above P-013 Centre target. A previous attempt was made in 2013 to test this target with hole MQ-13-034. Both holes intersected intervals of norite but failed to intersect the conductor. Re-modeling of the VTEM data, as well as modeling of the borehole EM survey data from hole MQ-14-069, indicates the target lies to the west of both holes. Target P-013 SE remains a high priority drill target based on positive results obtained at the nearby P-013 Centre target.

NN-VTEM

- See more at: http://www.northamericannickel.com/news/news-details/2014/North-American-Nickel-Reports-New-Multiple-and-Significant-Nickel-Sulphide-Intersections-at-Maniitsoq/default.aspx#sthash.qftRtJBB.dpuf


Airborne geophysics for La India Gold Mining District in Nicaragua

Posted by on Tuesday, 30 September, 2014

Condor Gold plc , a gold exploration company focused on delineating a large commercial reserve on its 100%-owned La India Project in Nicaragua, which hosts a CIM compliant Mineral Resource of 2.4 Million oz gold at 4.6g/t, is pleased to announce the results of a helicopter borne magnetic and radiometric survey on the entire 280 sq km La India Project.

Highlights

  • The 3,351 line kilometer helicopter borne geophysics survey resulted in high quality datasets suited for interpretation on both regional and project scales.
  • The radiometric data sets can be used as a direct tool to map vein presence.
  • The magnetics can be used as an indirect tool for target delineation by the interpretation of zones of magnetite destruction. In addition, the magnetics are of sufficient detail to make a realistic structural interpretation. 
  • The recognition of the geophysical properties associated with the known veins and extrapolation of those characteristics into other less well-mapped areas demonstrates that only a small part of La India Project has been tested by drilling.
  • Two prospective regions in the north and northeast of La India Project have been identified as having similar geophysical signatures to the main Vein Sets.

Mark Child, Chairman and CEO commented:

“The 3,351 line kilometer helicopter-borne geophysics survey covering the entire 280 sq km La India Project has confirmed that there remains considerable exploration upside for La India Project. The radiometric survey provides a powerful regional mapping tool. In particular, the potassium response has a strong correlation with areas of known gold veining. The magnetic survey helps identify fault zones, which normally hold gold mineralisation in the District. Together, the radiometric and magnetic surveys provide a targeting tool for future exploration whereby three areas have been highlighted that have a prospective radiometric and magnetic signature but relatively little drilling when correlated to the areas containing the existing gold mineral resources.”

New Sense Geophysics Limited completed a 3,521 line-kilometer helicopter-borne magnetics and radiometrics survey on behalf of the Company in May 2013. The main survey was flown on 100m spaced lines with an azimuth of 030/210 degrees with tie-lines flown at right angles to the main survey lines on 1000m line-spacing (Figure 1: http://media3.marketwire.com/docs/condor-0813-fig1.pdf). A terrain clearance of 30m was specified and largely achieved for the survey. The survey produced high quality datasets well suited for interpretation on both regional and project scales.

The heliborne geophysics data has been processed and interpreted by consultant geophysicist Buks Lubbe (BSc. Hons. Exploration Geophysics) and detailed in a report to the Company. The key points in the report are summarised here.

Radiometric Survey

The radiometric responses are robust and well-defined in the survey area. Although there are some obvious topographic-radiometric relationships, especially in the eastern portion of the survey and locally in larger drainages, the majority of the radiometric response appears to be related to the underlying geology.

The potassium response, as well as the thorium to potassium ratio, has a strong correlation with areas of known veining in the core of the La India Project. Maps of these data sets clearly show other areas within the Project area with a similar high potassium and low thorium:potassium ratio that may host undiscovered vein zones (Figure 2: http://media3.marketwire.com/docs/condor-0813-fig2.pdf).

The radiometric data also provides a powerful geological mapping tool. Ternary images, which combine the three main radiometric responses, potassium, uranium and thorium to show areas of common and exclusive radiometric signatures, are reasonably robust and can be used to define lithological units through correlation with known outcrops.

Magnetic Survey

The magnetic data has been transformed using industry-standard reduction to the pole algorithm and then processed to highlight various geological features. The traditional reduced to the pole dataset reflects the geology nearer to the surface. This, together with a dataset that has been processed to generate the first vertical derivative, which reflects changes in the magnetic signature, is very useful in mapping local geological fabrics. The displacement and/or abrupt termination of these fabrics typically maps fault zones. Deeper geological features which have longer wavelength magnetic signatures can be highlighted by using a 100m upward continued directional filter.

The magnetic data shows a general WNW to NW-striking fabric over much of the survey area (Figure 3:http://media3.marketwire.com/docs/condor-0813-fig3.pdf). The known veins are mostly parallel to these trends and are often associated with zones of disrupted magnetic signature that reflects the localised destruction of magnetite. Similar structures can be traced through less well explored parts of the Project area. The identification of disrupted signatures on these structures provides a targeting tool for future exploration.

Lithological mapping is aided by the magnetic intensity data. For example a magnetic high on the footwall side of the America vein can be correlated with a basaltic andesite unit.

A series of alternating NW-striking magnetic highs and lows evident when the 100m upward continued directional filter is applied suggests that the basement is made up from a series of parallel and sub-parallel horst/graben features. Sigmoidal patterns are possibly the result of the slight angles between the grabens, or alternatively, an indication of the presence of extensional faults.

Conclusion

Radiometric and magnetic data can be correlated to the known gold mineralized veins. The mineralized veins are associated with elevated potassium, especially where elevated relative to thorium, and with destruction of the magnetic signature, effects attributable to potassic alteration and magnetite destruction respectively by the epithermal fluids that deposited the gold mineralized veins. The identification of a similar geophysical signature elsewhere in the Project area can be used to target exploration for both the discovery of new gold mineralization and the prioritization of the many existing gold anomalies recognized in the existing rock chip sampling database.

Structural and lithological information gained from the geophysics contributes to a better understanding of the mineral deposit system at La India, which will help guide exploration strategy and targeting.

Three broad target areas have already been identified based on the geophysics. The main target is the central portion of the survey area containing the majority of known veins and hosting the current resource. See Figure 4 below. This clearly looks to be the most prospective part of the area surveyed. Here the strong and robust potassium response and wealth of magnetic features that are associated with veins suggest potential for additional vein discoveries. The structural interpretation suggests that the main vein field is located within a regional NNW striking fault corridor. Only a small portion of this prospective area has been tested by drilling where a mineral resource of 2.3M oz gold has been defined.

Two further target areas have been identified to the north and northeast of the existing gold resource in Figure 4 (http://media3.marketwire.com/docs/condor-0813-fig4.pdf), which offer excellent exploration potential. In the area to the northeast multiple gold mineralised rock chip samples have been recorded but only followed up with trenching in one locality; the Andrea Vein that was trench sampled by Condor in 2009-2010, and only drilled in one locality; ten drill holes on the Cristallito-Tatescame Prospect which hosts an inferred mineral resource of 200kt at 5.3g/t gold for 34,000 oz gold. In the area to the north, a strike continuous linear potassium high anomaly is subparallel to the main north west trending veins to the south and may be an extension to the main zone. There has been no drilling in this area.

The next step is to conduct a more detailed interpretation of the geophysical dataset, integrating the data with satellite derived high resolution topographic models and geological outcrop mapping and drilling data to produce an updated geological map. Exploration targeting will look in particular for zones of truncated and disrupted magnetics that are associated with positive potassium signatures.


Airborne EM and ground IP geophysical anomalies – the new Significant Copper-Gold System in Panama

Posted by on Tuesday, 30 September, 2014

Pershimco Resources Inc. announces that the results of its recent exploration drilling on the Idaida target have confirmed a new copper-gold system. Importantly, this newly revealed system shows both near surface and deeper mineralized feeder structures analogous to the Company’s two main targets, La Pava and Quema Deposits, the latter of whose center is located 1.3 km north-west of Idaida.

HIGHLIGHTS OF THE IDAIDA DRILLING

  • Extends high-sulphidation alteration and mineralization to depth;
  • Intercepted an oxide gold zone and an underlying sulphide copper-gold zone;
  • Intercepted new high-sulphidation “feeder” zones at depth;
  • Both upper and lower ‘feeder” zones flank and dip towards the modeled airborne and ground IP geophysical targets.

Dual Reverse Circulation/Diamond drill holes (RC/DH), PRH13316/PDH135316 (‘316′) and PRH13317/PDH135317 (‘317′) are the deepest to date on the Cerro Quema project, and provide important information on the mineralization and alteration system at Idaida as well as other exploration targets within the concession. Both drill holes (‘316 & 317′) intercepted sulphides commencing at 85 and 50 meters downhole respectively and both continued to show sulphides and alteration to their final depths. Intercepted “feeder” zone mineralization within both the upper and lower levels show similar intense alteration (acid leach – advanced argillic) and moderate to strong sulphide mineralization.

Of particular significance, the lower feeder structure intercepted by drill hole ‘317’ which returned 58m @ 0.38%Cu was enveloped within a broader intercept of 95m @ 0.25%Cu. This intercept showed elevated sulphides (>6%) and hosted within an advanced argillic alteration zone containing pyrophyllite. The dominance of the advance argillic mineral pyrophyllite indicates a higher temperature setting typically found within the ‘root zones’ of high sulphidation systems.

These “feeder” structures are on the margins of and dip towards the airborne VTEM and ground IP chargeability geophysical anomalies.

Figure 1 below shows the drill hole location plan as well as the location of the IP Chargeability target. Furthermore, a short video demonstrating the location, size and geometry of the Idaida project’s IP chargeability anomaly is accessible at http://youtu.be/m8eXp0bsHkA.

During the first half of 2013, Pershimco completed important exploration activities on two new targets outside of the La Pava and Quema-Quemita deposits. This work included:

  • Idaida and Pelona were drill tested, returning significant copper and gold intercepts;
  • 7,195 meters of drilling (RC and diamond) completed;
  • 112.5 Line Kilometers of IP geophysics completed; and,
  • Commenced regional mapping and geochemical sampling program on additional exploration targets identified by previous airborne geophysics.

The Idaida drilling results are extremely exciting in terms of the significant grades and thicknesses of copper and gold mineralization intersected near surface as well as the discovery of additional feeder structures at depth. The exploration geophysics and geological modeling undertaken by the Pershimco Team is proving to be successful as more targets are being strategically identified and developed. As we have noted previously, this deliberate multi-staged approach continues to prove to be invaluable in building on the success our project,” said Alain Bureau, President and CEO of Pershimco.


Drilling Results of Anomalous Radioactivity and Conductors (Athabasca basin)

Posted by on Thursday, 25 September, 2014

 FISSION URANIUM CORP. announces the results of 21 of its 22 regional drill hole program at its PLS (Patterson Lake South) property in Canada’s Athabasca Basin. Four new holes have discovered anomalous radioactivity on three new conductors in the PL Corridor and Far East target areas of PLS. This follows exploration hole, PLS14-255 (see NR August 11, 2014), also drilled on the Far East target area, which hit radioactivity 17km from the main PLS discovery where high-grade mineralization has been outlined along a 2.24km strike length. The remaining 17 regional holes encountered encouraging geological features but did not intersect significant radioactivity.

Another Three Holes Encounter Anomalous Results on Far East of PLS Property

  • Significant anomalous radioactivity intersected by:
    • Hole PLS14-260 (104A EM conductor)
    • Holes PLS14-262 and PLS14-284 (105A EM conductor)
  • PLS14-262 and PLS14-284 are approximately 14m and 25m respectively from hole PLS14-255 (105A EM Conductor), which recently intersected anomalous radioactivity of up to 2532 cps.
  • Holes are located near the Fission 3.0/Brades Clearwater West project, approximately 17km south east of the main PLS discovery

One Exploration Hole Hits on PL Corridor of PLS Property

  • Anomalous radioactivity intersected by:
    • Hole PLS14-252 (1B EM Conductor) has intersected anomalous radioactivity on the PL Corridor,
  • Hole is located approximately 750m east from the main discovery

Ross McElroy, President, COO, and Chief Geologist for Fission, commented,

“The regional exploration program has been a great success and we have three very clear target areas prioritized for aggressive follow up: The PL Corridor, the Far East where we recently hit anomalous radioactivity in hole PLS14-255 and the Forrest Lake Areas. With over 105 separate conductors, we have felt for some time that the prospectively of PLS goes beyond the incredible discovery we have already made. These regional drill results confirm that belief.”

 

PLS is one of the most exciting uranium discoveries made to date in Canada’s prolific Athabasca Basin, which hosts the richest producing uranium mines in the world. The discovery is driven by a highly skilled technical team and successful entrepreneurial management. After a series of corporate transactions, Fission Uranium consolidated 100% ownership of the PLS Property, which comprises 17 claims totaling 31,039 ha located on the southwest margin of the Athabasca Basin. The property is accessible by all-weather Highway 955 which continues north through the area of the UEX-AREVA Shea Creek discoveries to the past producing Cluff Lake uranium mine.

The PLS discovery is a basement hosted unconformity uranium deposit, characterized by shallow, high-grade mineralization in five separate zones trending for approximately 2.24 km in length. From west to east, these zones are; R600W, R00E, R780E, R1155E and R1620E. Up to and including the drilling from the winter 2014 program, 163 delineation holes have defined mineralization over a strike length of 1155m in the R00E and R780E zones, with 158 holes intersecting mineralization, for a 97% success hit ratio. Mineralization has exhibited high grades over exceptionally wide thicknesses, which remain wide open.

 


Unlocking Australia’s hidden mineral potential with geophysics

Posted by on Friday, 1 August, 2014

Dr Richard Blewett:

“It is becoming increasingly difficult to discover near-surface mineral resources in Australia. New and innovative products and techniques are being developed as part of the UNCOVER Initiative to help attract mineral exploration investment that has the potential to lead to the discovery of new resources.”

One of the focus regions for the UNCOVER Initiative is the Thomson Orogen: “The Thomson Orogen is a large area that lies to the north and west of the Lachlan Orogen in New South Wales, South Australia, the Northern Territory and Queensland. Much of it is under the cover of younger sedimentary basins, with some up to several kilometres thick, and it is therefore a poorly understood element of Australia’s geology.

The southern Thomson Orogen is true ‘greenfields’ country. Although the mineral potential of the region is largely unknown, the northeastern Thomson Orogen (for example Thalanga, Charters Towers) and the similar-aged Lachlan Orogen to the south are well mineralised (for example Cadia, Northparkes, Lake Cowall Cobar). In order to attract exploration investment into the southern Thomson Orogen, and also to improve the geological understanding of the area, Geoscience Australia, the Geological Survey of Queensland and the Geological Survey of New South Wales have commenced a collaborative project to collect new (and synthesise existing) pre-competitive data.

One of the first steps in this collaboration is to acquire airborne and ground geophysical data including airborne electromagnetics (AEM), gravity and magnetotelluric (MT) data. Regional AEM data has now been collected to map cover thickness and assess the geology and prospectivity of the Southern Thomson Orogen across the New South Wales-Queensland border around Hungerford and Eulo. These data will be interpreted using existing borehole stratigraphic data and a new solid geology compilation of the region developed between Geoscience Australia, the Geological Survey of Queensland and the Geological Survey of New South Wales.

 

The Geotech VTEM FullWaveForm
airborne electromagnetic acquisition
system used in the Southern Thomson
Orogen airborne electromagnetics survey.
Image credit: Geotech Airborne Limited.

 

 

 Geoscience Australia is a leading promoter of AEM surveying for regional mapping of cover thickness, under-cover basement geology and sedimentary basin architecture. Geoscience Australia flew three regional AEM surveys during the 2006-11 Onshore Energy Security Program (OESP): Paterson (Western Australia, 2007-08); Pine Creek-Kombolgie (Northern Territory, 2009); and Frome (South Australia, 2010) [1]. The surveys were primarily designed to provide reliable, fit-for-purpose pre-competitive AEM data for mapping critical features of uranium mineral systems.

Results from these surveys have now produced a new understanding of the architecture of critical mineral system elements and mineral prospectivity for a wide range of commodities of these regions and includes details on the thickness and character of the regolith, sedimentary basins and buried basement terrains. The data have since been found suitable not just for uranium, but for mapping a range of other mineral systems including gold, silver, copper, lead, zinc and potash, as well as for under-cover geological mapping and groundwater resource estimation.

The survey data are now processed using the National Computational Infrastructure (NCI) facility at the Australian National University to produce GIS-ready interpretation products and GOCADTM objects suitable for 3D modelling.

A number of 3D models are being developed to interpret the near-surface under-cover geology of cratons and mobile zones, the unconformity surfaces between these and the overlying sedimentary basins, and the architecture of those basins. These models are constructed primarily from AEM data using stratigraphic borehole control and show how AEM data can be used to map the cross-over area between surface geological mapping, stratigraphic drilling and seismic reflection mapping. These models can be used by minerals explorers to more confidently explore in areas of shallow to moderate sedimentary basin cover by providing more accurate cover thickness and depth to target information. A 3D model of basement-cover relationships and depth of cover will be developed for the southern Thomson Orogen.”


“Forgotten Truths, Myths and Sacred Cows of Potential Fields Geophysics” – Alan Reid, KEGS talk

Posted by on Tuesday, 29 July, 2014

 

 

 


Ground EM and gravity for a Ni-Cu-PGE project in Greenland

Posted by on Friday, 25 July, 2014

North American Nickel Inc. announces the completion of surface geophysical surveys and identification of electromagnetic and gravity anomalies at the Company’s 100% owned Maniitsoq nickel-copper-cobalt-PGM project in southwest Greenland.

Surface time domain electromagnetic (TDEM) and gravity surveys were initiated at the Maniitsoq project in mid-April and were completed in mid-June. The surveys were carried out by Crone Geophysics of Mississauga, Ontario and focused on two areas, the Imiak Hill Conduit Complex (IHCC) and Fossilik, where previous drilling intersected significant Ni-Cu-PGE mineralization (See Figure).

Preliminary TDEM results indicate the presence of EM anomalies correlating with both existing mineralization and also representing new geophysical targets. Preliminary gravity results indicate that gravity anomalies exist in both the Imiak and Fossilik areas and correlate with noritic intrusions identified from both surface mapping and drilling. Several of the known nickel-copper occurrences are empirically observed to occur at the margins of these gravity highs.

NAN President and Interim CEO, Mark Fedikow, commented: “The 2014 exploration program is well underway and completion of the surface geophysical surveys over the IHCC and Fossilik areas is an important component in our exploration strategy. The addition of gravity surveying this year represents a valuable new tool for exploring the Company’s large Maniitsoq property where noritic intrusions occur over a 75 km strike length. Identification and correlation of gravity highs with two of the known mineralized norite intrusions in the belt indicate that gravity will be very useful in mapping the subsurface extents of mafic and ultramafic intrusions and in helping to understand the distribution of related nickel-copper sulphide mineralization”.

TDEM surveying totaling 87 line km have been completed in the IHCC and Fossilik areas located in the central portion of the Maniitsoq property. Data interpretation and modeling are in progress and results are being used to target both follow-up drilling as well as define new targets for potential drill testing.

Gravity surveys were completed over the IHCC and, based on favorable results, an additional gravity survey was carried out over the Fossilik area. In each area, the surveys consisted of a core of gravity readings at 50m stations on 200m line intervals surrounded by more widely spaced readings typically on 500m centers. Gravity readings were taken at a total of 944 stations. The preceding comments are based on initial data modeling and inversions.

At the IHCC (see Figure 2), several gravity highs are observed to be coincident with, or flanking, the mapped and interpreted norite outcrops. Gravity inversion modeling shows one of the gravity highs to be coincident with the mineralized Spotty Hill norite intrusion. This gravity high extends south of the current Spotty drilling and also extends to the northwestward towards the Imiak North area. Another larger more complex double lobed gravity high lies in the immediate vicinity of the mineralized Imiak Hill norite intrusion. One lobe of this gravity high extends south of the Imiak Hill drilling and the other lobe lies to the NW.

GravityNAN

At the Fossilik area located 9 km southwest of the IHCC (see Figure 3); gravity surveying identified a large ~1.5 km x 2.5 km gravity high which is coincident with the Fossilik norite intrusion. Surface nickel occurrences and nickel mineralization intersected in historic drilling and past drilling by the Company are observed to lie at or near the southwestern and western margins of this gravity high.

Data interpretation and modeling are on-going but results to date indicate that gravity data will be a useful tool to aid in mapping the sub-surface extents of the target noritic intrusions, particularly as compared to the magnetic data where correlation of anomalies with norite intrusions is less consistent. Additional images of the gravity inversions may be viewed on the Company’s website.

- See more at: http://www.northamericannickel.com/news/news-details/2014/Surface-Electromagnetic-and-Gravity-Geophysical-Surveys-Completed-and-New-Anomalies-Identified-at-Maniitsoq-Nickel-Sulphide-Project-in-Greenland/default.aspx#sthash.fnhpBAK6.dpuf

To view the photo associated with this press release, please visit the following link: http://media3.marketwire.com/docs/958596a.pdf.


A set of geophysics for Iron Oxide Copper Gold deposit in Quebec

Posted by on Thursday, 17 July, 2014

Honey Badger Exploration Inc.  has completed the interpretation of the geophysical data over the Delhi Pacific copper showing on its Sagar Property. The coincident gravity, magnetic, electromagnetic (“EM”) and induced polarization (“IP”) anomaly associated with the Delhi showing are typical of those expected from an Iron Oxide Copper Gold (“IOCG”) deposit.

The IOCG model is further supported by the presence of a favourable structural setting for an IOCG deposit, namely the abundance of polymetallic showings (copper-gold-silver-cobalt) and the presence of diagnostically verified IOCG hydrothermal alteration.

At the Delhi Pacific showing, historical significant drilling intersections include 45.81 metres @ 0.51% copper and 10.7 metres @ 0.78% copper. While these intersections were not tested for silver, gold or cobalt, historic and recent grab samples* contain up to 1.8 grams per ton (“g/t”) gold, and up to 35 g/t silver.

*Grab samples are selective by nature and are unlikely to represent average grades of the deposit(s).

The selection of new drill targets is based on an interpretation of the IP/Resistivity, airborne magnetics, ground gravity and airborne EM data. In the winter of 2014 ClearView Geophysics Inc. completed a Surface Spectral IP survey over part of and extending east of the Delhi Pacific showing (Figure 1).

To view ‘Figure 1 – Surface Spectral Induced Polarization survey location lines’, please visit the following link:http://media3.marketwire.com/docs/honef10715.pdf

The interpretation indicates an anomaly associated with the historic drilling at Delhi that increases both in intensity and size east of these drill holes for more than 1.5 kilometres. The apparent resistivity data is presented in Figure 2 (red-purple indicates low resistivity and represents the target area):

Figure 2 – Resistivity Data at Delhi Pacific

The gravity data indicates that the southwest side of the magnetic high zone at Delhi Pacific coincides with a gravity low feature, whereas to the north is a gravity high. This indicates that the resistivity low/chargeability/electromagnetic target is located along a major structure that represents a favourable event for IOCG mineralization. The target area at Delhi covers more than 3 square kilometres: approximately 1.5 kilometres in strike length multiplied by an average width of 200 metres (Figure 3).

‘Figure 4 – Magnetic Inversion over Delhi Pacific’