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Factors of Modern Discoveries

Posted by on Wednesday, 8 April, 2015
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“INTEGRATING NEW TECHNOLOGY WITH HISTORICAL DATA, GEOLOGICAL INTUITION AND A LITTLE LUCK, COMPANIES ARE FINDING SUCCESS WHERE OTHERS HAVE NOT”

Mineral Exploration Strategies

Written by E&MJ News

By Steve Fiscor

“All of the discoveries were in the zone of other major discoveries, but most of them had been overlooked for one reason or another. The motivation could only be attributed to a geologically motivated hunch. New technology in the form of deep-penetrating airborne surveys allowed ground-based geophysical surveys to target undiscovered anomalies. Combining the new information with what they knew historically, exploration geologists were able to improve the drilling programs to quickly determine a resource.”

The next discoveries made with airborne geophysical technologies:

Albany Ultra-pure Graphite – VTEM survey

The Balboa Discovery at Cobre Panama – ZTEM survey

Kennady North Kimberlite Discoveries – airborne gravity gradiometer survey

PLS High Grade, High Techand Contrarian – airborne radiometric survey

Details..

 


Earth Explorer: About Insightful geophysics..

Posted by on Thursday, 2 April, 2015

by VIRGINIA HEFFERNAN on MARCH 30, 2015

The founders of Insight Geophysics have deep roots in the past, but their approach to Induced Polarization (IP) represents the future of mineral exploration: real time interpretation of data, integration of non-geophysical information with 3D inversions, and a dynamic style of surveying that allows for tweaks on a day to day basis depending on feedback from the exploration team.

See more

 


Novel technologies for greenfield exploration – GEOLOGICAL SURVEY OF FINLAND 2015

Posted by on Wednesday, 1 April, 2015

The Geological Survey of Finland (GTK) reports about new mineral exploration and mapping methods which were developed in the project ‘Novel technologies for greenfield exploration’ (NovTecEx) carried out in 2012–2014. The project was a part of the Green Mining Programme funded by Tekes. The research partners of the project were the Geological Survey of Finland and the University of Oulu. The main study areas were in the SavukoskiPelkosenniemi area and in the Lätäseno area in Finnish Lapland.

The methods include a tool for Audiomagnetotelluric (AMT) measurements, GUI developing for 2D MODELLING AND INVERSION SOFTWARE FOR AIRBORNE TIME-DOMAIN EM DATA, and description  THE EQUIVALENT SOURCE METHOD for CALCULATION OF THE DERIVED BOUGUER ANOMALY.

The report pdf


Current Issue of “Exploration Geophysics” – Airborne Electromagnetics AEM 2013

Posted by on Monday, 30 March, 2015

Exploration Geophysics
Volume 46 Number 1 2015
6th International Conference in Airborne Electromagnetics (AEM 2013)

This special issue of Exploration Geophysics comprises papers from the 6th International Conference in Airborne Electromagnetics (AEM 2013) held in South Africa, and showcases the latest ideas and advancements in the discipline of airborne electromagnetic geophysics.

Developing an efficient modelling and data presentation strategy for ATDEM system comparison and survey design
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Magdel Combrinck
pp. 3-11

A proposal to simplify the display of ATDEM responses through the concept of a three-dimensional signal:noise nomo-volume is presented. It contains the signal:noise values of all system time channels and components for various target depths and conductances integrated into a single interactive three-dimensional image.

3D-spectral CDIs: a fast alternative to 3D inversion?
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James Macnae
pp. 12-18

Spectral 3D approximations of the EM response can efficiently model vortex induction and current gathering for simple geological target geometries. This paper presents results of a spectral model fitting algorithm to automatically pick, locate and define a sulphide target from VTEM data at the Forrestania test range, Western Australia.

The analysis of ZTEM data across the Humble magnetic anomaly, Alaska
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Daniel Sattel and Ken Witherly
pp. 19-26

ZTEM data acquired across a magnetic anomaly of almost 30 000 nT were analysed for the presence of a magnetic gradient response and the effects from elevated magnetic susceptibilities. Modelling results indicate distortions in the conductivity structure recovered by 3D inversion when elevated magnetic susceptibility values are ignored during the inversion.

Regional TEMPEST survey in north-east Namibia
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Geoffrey Peters , Gregory Street , Ivor Kahimise and David Hutchins
pp. 27-35

A regional scale low-cost TEMPEST208 survey in north-east Namibia has provided a geo-electric map of the area, including an indication of Kalahari cover thickness. While there are limitations in terms of detail and depth penetration, the results will assist explorers in selecting areas of shallow cover to reduce costs.

Helicopter EM (ZTEM–VTEM) survey results over the Nuqrah copper–lead–zinc–gold SEDEX massive sulphide deposit in the Western Arabian Shield, Kingdom of Saudi Arabia
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Jean M. Legault , Carlos Izarra , Alexander Prikhodko , Shengkai Zhao and Emad M. Saadawi
pp. 36-48

Magnetic and electromagnetic (EM) results from both time-domain (VTEM and AFMAG (ZTEM) helicopter EM surveys are compared over the Nuqrah sedimentary exhalative (SEDEX) massive sulphide deposit in Saudi Arabia. The magnetic and EM data map major controlling structures but only the EM surveys are able to define the Nuqrah deposits.

MULTIPULSE – high resolution and high power in one TDEM system
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Tianyou Chen , Greg Hodges and Philip Miles
pp. 49-57

The MULTIPULSE technology airborne TEM system transmits a high power pulse and low power pulse(s) (trapezoid or square) within a half-cycle. The high power pulse ensures good depth of exploration and the low power pulse allows higher near-surface resolution and better sensitivity to weak conductors as confirmed by field results.

Geobandwidth: comparing time domain electromagnetic waveforms with a wire loop model
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Greg Hodges and Tianyou Chen
pp. 58-63

The effect of time domain EM waveform, power and receiver sampling times are effectively compared for a wide range of time constants using a wire loop conductor model. Peak time constant and equivalent frequency can be determined analytically or numerically. Arbitrary waveforms can be modelled as a sum of simple short ramps.

Not extinct yet: innovations in frequency domain HEM triggered by sea ice studies
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Andreas A. Pfaffhuber and Stefan Hendricks
pp. 64-73

Operational use of frequency domain HEM for sea ice thickness mapping was the driving force for developing new purpose-designed systems. We present improvements in decreasing noise levels by one to two orders of magnitude, and implemented control signals to eliminate system drift. Ground tests and airborne field data confirmed the achievement of these goals.

Airborne electromagnetic modelling options and their consequences in target definition
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Alan Yusen Ley-Cooper , Andrea Viezzoli , Julien Guillemoteau , Giulio Vignoli , James Macnae , Leif Cox and Tim Munday
pp. 74-84

Given the range of geological conditions under which airborne EM surveys are conducted, there is an expectation that 2D and 3D methods used to extract models of geological significance would be favoured over 1D inversion and transforms. We analyse data from the Musgrave province, South Australia, used for mineral and for hydro-geological prospecting.

Modelling an arbitrarily oriented magnetic dipole over a homogeneous half-space for a rapid topographic correction of airborne EM data
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Julien Guillemoteau , Pascal Sailhac and Mickael Behaegel
pp. 85-96

In mountainous areas, the airborne electromagnetic system can be at an angle with regard to the ground. We analyse how the data and the eddy current are affected in such a context. We also suggest a simple correction for the data and for the sensitivity function that reduces topography effects.

New developments in AEM discrete conductor modelling and inversion
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Marc A. Vallée
pp. 97-111

In the last 20 years, sphere and plate models have been integrated in parametric inversion programs which are used today for interactive interpretation of airborne electromagnetic surveys on powerful workstations. Different problems encountered in the implementation and application of these models are discussed and a case history from Abitibi, Canada, is presented.

Rapid approximate inversion of airborne TEM
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Peter K. Fullagar , Glenn A. Pears , James E. Reid and Ralf Schaa
pp. 112-117

Two algorithms have been developed to perform rapid approximate 3D inversion of airborne TEM. VPem1D performs 1D inversion at each data location above a 3D model. Interpretation of cover thickness is a natural application. VPem3D performs 3D inversion of resistive limit data. Conversion to resistive limits delivers a massive increase in speed. Both programs can operate on geological models to foster integrated interpretation.

Modelling the superparamagnetic response of AEM data
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Daniel Sattel and Paul Mutton
pp. 118-129

VTEM data flown at different system elevations across a known sulphide body and surface cover with elevated superparamagnetic (SPM) properties were analysed. The results indicate that SPM responses can be distinguished from deep conductor responses if the vertical AEM gradient is measured, with EM sensors being offset vertically by 2–40 m.

Using the in-line component for fixed-wing EM 1D inversion
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Adam Smiarowski
pp. 130-135

In conductive areas, the in-line component of an offset transmitter–receiver EM system can be more sensitive to the near-surface than the vertical component. Using estimated noise levels, this paper calculates the expected uncertainty on the inverted parameters of a bathymetry model and compares this to inversion results from field data.

Extending the range of time constants recorded by the SPECTREM AEM system
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Peter B. Leggatt
pp. 136-139

The Spectrem AEM transmitter has no off-time; secondary signals are recorded at the same time as the transmitter primary. By assuming the secondaries have decayed away by the last window, the signal value is used as an estimate of the primary. The result is underestimation of the secondary amplitudes if the target is highly conductive. This paper describes a method to compute a better estimate of the primary amplitude.


Airborne and ground geophysics for Grasset Project in Quebec

Posted by on Wednesday, 25 March, 2015

Xmet Inc. announces that it thus far completed drilling eight holes on its Grasset Project out of the ten holes originally planned. Three of these holes encompassing approximately 460 metres have been cut and sent to the lab for assays. The remaining completed holes are being cut and processed and will be sent for assays in the near future.

Xmet has also decided to expand its Grasset drill program to include two additional land based holes as a result of geophysical interpretations it has received from its VTEM survey that it completed in January 2015. The Company recently received drill permits from the Province and is currently completing the access road to reach the land based targets. Drilling for the entire program should be completed by the end of March 2015 with assay results to follow.

About Xmet’s Grasset Project

In January 2015 Xmet completed a 330 line kilometre Versatile Time Domain Electromagnetic (“VTEM”) and Magnetic Gradiometer Survey on its 100% owned Grasset Project. The survey was a follow up to its March 2012 geophysics when the Company mobilized a geophysical crew onto the property to carry out 28 line km of a gradient induced polarization survey over the interpreted trace of the Detour-Sunday Lake Deformation Zone. Results of the completed part of the survey were announced on 3 May, 2012. The survey clearly identified a favourable gold target in the survey. Phase two of ground geophysics was completed in March 2013 totalling 68 line km of gradient IP with an additional 8 line km of a detailed pole-dipole survey also covering the SLDZ.

The property has been subjected to relatively little exploration work.  A total of 14 drill holes were collared on the claims between 1959 and 1987, for a total of 1,910 m.  All of the holes were drilled from land and no holes were collared in Grasset Lake.  Few geophysical surveys were undertaken, consisting mainly of magnetic/gradiometric and electromagnetic surveys.

Two mineral occurrences have been identified on the property.  The Ingamar occurrence consisting of 0.93 g/t Au over 1.83 metres and the Harricana-Turgeon occurrence  of 0.50% Cu over 1.0 metres, both of which are located along the south shore of the lake.   In addition, on the western shore of the lake, a few hundred metres from the property boundary a showing is reported to have assayed 5.5 g/t Au in grab sample.


EM surveys over Green Giant graphite property in Madagascar

Posted by on Tuesday, 24 February, 2015

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.

____________________________________________________________________

DIGHEM survey

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

(conductors in red, resistors blue colors)

DIGHEMConVoxel

 

 

 

 

 

 

 

 

 

 

 

 

 

sections

 

condmap

 

 

 

 

 

 ________________________________________

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

 

 

 

 

 

 

 

 

 

 

 

 

__________________________________________________

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

 

 

 

 

 

 

 

___________________________________________

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.