Posts Tagged EM

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

Posted by on Monday, 30 March, 2015
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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.


Linking Porphyry Deposit Geology to Geophysics via Physical Properties

Posted by on Tuesday, 7 January, 2014

Geoscience BC Releases the Report:

Linking Porphyry Deposit Geology to Geophysics via Physical Properties: Adding Value to Geoscience BC Geophysical Data
by Dianne Mitchinson, MDRU; R.J. Enkin, GSC; and C.J.R. Hart, MDRU.

Regional geophysical surveys were flown in 2007 and 2008 as part of the QUEST and QUEST-West projects to improve geological understanding in Quaternary sediment-covered areas and thereby encourage mineral exploration. As part of the ongoing process of adding value to Geoscience BC datasets, Project 2009-001, “Integrated Geological & Geophysical Porphyry Models: Adding Value to Geoscience BC Geophysical Data (NTS 93E, 93K, 93L, 93M, 93N)” was undertaken to define relationships between geophysical datasets collected as part of these QUEST surveys and porphyry deposit geology at six known porphyry deposits. The deposits chosen for investigation include: Mount Milligan, Endako, Huckleberry, Bell, Granisle and Morrison. 
Geoscience BC Report 2013-14 presents physical rock property data from the six above-listed BC porphyry deposits, and discusses observed trends within the detailed QUEST and QUEST-West geophysical datasets and mapped geology. The resulting physical rock property data compilation has implications for improving interpretations of geophysical data from porphyry deposits. A synopsis of physical property criteria defining hydrothermally altered or mineralized rocks in BC porphyry settings is provided, which can ultimately be used for ranking similar mineral exploration targets throughout BC, thereby minimizing exploration risk.

GBC_Report2013-14a

 

 

 

 

 

 

 

 

 

 

 

Porphyry deposits surveyed during the QUEST and QUEST-West projects include Mount Milligan, Endako, Huckleberry, Bell, Granisle, and Morrison. Airborne magnetic and electromagnetic surveys (VTEM or AeroTEM) were conducted over each of these deposits. Additionally, a ZTEM (Z-axis tipper electromagnetic) survey was completed over the Mount Milligan deposit as a joint initiative between Geoscience BC and Terrane Metals Corp.

2009 : AeroTem Survey Results from the Equity Silver Mine
– Mineral Exploration Roundup Poster (pdf, 3.96MB)

Technical Article: 2009: “QUEST-West Geophysics in Central British Columbia (NTS 093E, F, G, K, L, M, N, 103I): New Regional Gravity and Helicopter-Borne Time-Domain Electromagnetic Data”
– Summary of Activities 2008, Report 2009-1 p.1-6 (pdf, 4.64MB)

 

 

 

 

 

Geophysical Surveys

 

 

Technical Article: 2007 : “Airborne electromagnetics and airborne gravity in the QUEST Project area, Williams Lake to Mackenzie, British Columbia (parts of NTS 093A, B, G, H, J, K, N, O; 094C, D)”
– Summary of Activities 2007, Report 2008-1 p.1-6 (pdf, 6.81MB)

Suggested Reference: Mitchinson, D.E., Enkin, R.J., and Hart, C.J.R. (2013): Linking Porphyry Deposit Geology to Geophysics via Physical Properties: Adding Value to Geoscience BC Geophysical Data; Geoscience BC, Report 2013-14, 116 p.

Report Components


The technical program for SAGA-AEM Joint Conferences 2013

Posted by on Friday, 26 July, 2013

SAGA 13th biennial conference – 6th to 9th October 2013
6th International Airborne EM 2013 – 10th to 11th October 2013
Skukuza Rest Camp, Kruger National Park
Mpumalanga South Africa

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SAGA 2013 Conference Technical Programme

Click here to view the preliminary version of the SAGA 2013 Conference technical programme. A pdf version of the programme is also available for for viewing or download.

AEM 2013 Conference Technical Programme

Click here to view the preliminary version of the AEM 2013 Conference technical programme.pdf version of the programme is also available for for viewing or download.

Workshops and Short Courses

The workshop/tours list will be finalised end of July. Depending on registration numbers, some workshops will be cancelled and others will go ahead. Please register soon before end of July. Final workshop programme will be updated in August. The following workshops and short courses will be available during the conference. Download Workshops and Short Courses Information Pack.


Practical Inversion for Geoscientists

Posted by on Wednesday, 10 April, 2013

A short course on the why, how, and what of geophysical inversion

Presented by the B.C. Geophysical Society

This is a 2-day workshop consisting of 1 day of lectures (April 24th) followed by a 1 day hands-on workshop (either April 25th or 26th). Delegates can register for just the lectures or both the lectures and workshop.

Registration available until April 15th at: www.bcgsonline.org

Date: April 24th – 26th 2013

Address: SFU Downtown Campus; Vancouver BC

Registration: Registration is now open!  Please fill out attached pdf form (link below) and click submit.  Registration will be complete once payment is made via Paypal link.  Delegates are asked to choose one workshop day among April 25th or 26th.

Day 1 – Introduction to inversion
– Introduction to inversion in exploration

Reasons for doing inversion
Range of inversion options: magnetics, gravity, EM, IP-resistivity, seismic
Fitting geology and data

– Background on inversion

Unconstrained/constrained
Joint and collaborative
The future of inversion

– Before inversion – forward modeling

forward modeling
petrophysics drives the story
complexity vs. adequacy

– Case studies

Potential fields
EM
IP-resistivity

Day 2 – Workshop with Case studies
Multi-disciplinary teams will use geological, geophysical and geochemical data from two deposits (Babine Lake porphyry Cu-Mo, BC and Minto Cu, YK) to develop exploration targets. Teams will present their evaluations of the data to stimulate group discussion.

Inversion results for the available geophysical surveys will be presented to demonstrate state-of-the-art technology and best practices.
Sponsors for the short course are currently being solicited. Please contact Victoria Sterritt at Victoria.Sterritt@teck.com for details. Proceeds go to the KEGS Foundation.
For those interested in more information about the short course, please email info@bcgsonline.org


The New Near-surface Resistivity Method

Posted by on Monday, 22 October, 2012

“The Leading Edge” has published in October 2012 issue the article of  Roy K. Warren, Warren Geophysical Service (Houston, TX), “Near-surface resistivity for hydrocarbon detection”. The article consists of many case studies which demonstrate the accuracy of the results.

Abstract

Roy K. Warren
Warren Geophysical Service
A new method called the “grid resistivity system” (GRS) is described which measures relative changes in subsurface resistivity using the low-frequency harmonics (either 50 or 60 Hz) generated by electric power lines. The electromagnetic waves emanate from the power grid, and some of this energy interacts with the air-Earth interface to be absorbed by the Earth. The lowest frequency penetrates to the greatest depth. The power from the grid causes current to flow in the rocks and soil. The Earth material with higher conductivity offers a path for the current to follow. The method can help locate geophysical signatures associated with the geochemical response of hydrocarbon chimney leakage. Data collection is fast and low cost. Processing results in cross sections of resistivity. Interpretation focuses on the identification of the larger conductors related to clay alteration caused by chimney leakage from a reservoir. ©2012 Society of Exploration Geophysicists

How EM Geophysics Can Help Feasibility Studies?

Posted by on Wednesday, 11 July, 2012

In this exclusive interview with Professor David Thiel, Director at the Centre for Wireless Monitoring and Applications at Griffith University, he discusses how electromagnetic geophysics can help those who are conducting a feasibility study and opens up on the real cost benefits of this technology. He also highlights some of the concerns mining companies may have when using electromagnetic geophysics. Questions we ask include:

  • How can surface-based electromagnetic geophysics help those who are conducting a feasibility study?
  • What kinds of results or information can a mining company get from ground-based electromagnetic geophysics?
  • How accurate is this form of scoping? Are there any areas users should be careful of?
  • Feasibility studies tend to be very expensive; is electromagnetic geophysics cost effective?

http://www.miningiq.com/mining/podcasts/how-electromagnetic-geophysics-can-help-feasibilit/


The Maxwell and CSIRO Workshop schedule and booking form for 2012 is now available

Posted by on Thursday, 21 June, 2012

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The 2012 Maxwell software training schedule and booking form is now available. Please see the PDF below.

Many hardware and software queries can be answered by EMIT staff over the phone. However, for more intensive personalised training, we can organise one-on-one training sessions either at your workplace or at our office in Midland. Alternatively, customised sessions for your acquisition or interpretation groups can be held at your organisation using your data.

EMIT Workshop Schedule and Booking Form 2012 (Maxwell and CSIRO)
EMIT Workshop Agenda – Maxwell
EMIT Workshop Agenda – CSIRO

Participants are encouraged to book four (4) weeks ahead to ensure their desired workshop dates. Each workshop will be confirmed only when the minimum of four (4) bookings have been received. Workshops are limited to ten (10) participants.


Graphite deposit on Madagascar with geophysics

Posted by on Tuesday, 29 May, 2012

Energizer turned its attention to graphite in November 2011, and continues to identify new graphite opportunities on its 120 kilometre-long Green Giant Project.  Through the completion of 29 diamond drill holes over 3,780 metres, 20 trenches over 1,900 metres, regional sampling with 670 prospecting samples, geological mapping of 3 areas, analysis of 3 airborne geophysical surveys, and the completion of 160.5 kilometres of ground-based electromagnetic geophysical surveying, the Company has identified over 320 kilometres of graphitic trends.


An unidentified flying object?

Posted by on Tuesday, 27 March, 2012

Helicopter surveying for company, but no one knows who

Buchans (Newfoundland, Canada) residents have been witnessing strange flying objects over their town this past month.

Last week, helicopters were seen hovering over the town, with objects suspended below – one horizontal in shape, the other a circle.

One might think it had something to do with mineral exploration, and they would be right.

But which company? Buchans Mayor Derm Corbett, who is regularly updated on mining activities in the region, said he had no idea who the mystery company or companies could be.

“The only company that I know that was doing geophysics in the Buchans area is the Buchans Minerals Corporation,” he said. “That’s the only group I’m aware of.”

But Paul Moore, the vice-president of exploration for Buchans Minerals, said it wasn’t his company, or SG Spirit Gold, the firm that it is engaging with.

He said people with Buchans Minerals have seen a surveying helicopter, but he did not know what company it was.

Another exploration firm, Messina Minerals, is active in the central region 48 kilometres southwest of Teck’s Duck Pond mine. Results the company announced on March 13, from its Main Zone project featured an estimate which includes indicated resources of 70 million pounds of zinc, 14 million pounds of lead, 8.7 million pounds of copper, 640,000 ounces silver and 7,500 ounces gold.

“I don’t know who the company could be in Buchans,” said Messina President Peter Tallman. “Messina isn’t doing geophysics.”

According to Merv Stacey, owner/operator of Red Ochre Inn in Buchans, two surveying companies are in town with the machines, including Geotech Ltd. of Aurora, Ontario, and Fugro Airborne Surveys.

Anyone familiar with geophysical surveying would guess that the objects were used for collecting data, and they would be right. They are magnetic gradiometers for taking readings where the presence of specific elements can be identified.

According to the website of Fugro Airborne Surveys, which carries out the process for a variety of mining and exploration companies, an element such as gold, which despite being highly conductive (in relation to electricity), vein type gold does not occur in sufficient concentration to be detected directly with airborne geophysics. However, the effects of the geological processes which result in gold deposition are often detectable.

Geotech Ltd of Aurora, Ontario is currently carrying out a geophysical survey over the Buchans area, said Buchans correspondent for the Advertiser, Pauline Dean.

“The magnetic gradiometer which hangs from the helicopter is approximately 1,000 lb and the largest part measures 26 metres in diameter and can take readings to a depth of 700 meters,” she said.

However, the person she spoke to from Geotech would not identify their client. Stacey said that was the same thing with the Fugro employees, who would not say the name of the company that contracted them to conduct the survey in Buchans.

Peter Tallman, the Messina president, speculated that a company may be interested in a property, but isn’t allowed to start work until the Exchange (whatever stock market they are listed on) regulation services grants regulatory approval.

Published on March 26, 2012
Sue Hickey & Terry Roberts

Abstracts from the ASEG Natural Fields EM Forum 2012 released

Posted by on Sunday, 4 March, 2012

Geoscience Australia Record 2012/04 contains abstracts from the Australian Society of Exploration Geophysics (ASEG) Natural Fields EM Forum 2012, held at the recent ASEG 2012 Conference in Brisbane.

The report is a collation of abstracts presented at the forum and reviews the current state-of-the-art use of natural EM fields in exploration applications. It also includes details of significant developments in acquisition, processing and interpretation methods in recent years, many of which have been made possible through ready access to increased computing power, both in the field and in post-acquisition processing facilities.

Principally, these applications involved aspects of ground-based MT and AMT methods, but also included airborne techniques (e.g., ZTEM) which use only natural EM fields as an energy source. The abstracts cover a wide range of applications of natural EM fields which are used in the search for minerals and energy resources and range from the development of broad-scale regional models to direct detection of drill targets.

The record is available as a free download.


Details about the history of North America’s strongest discrete gravity anomaly

Posted by on Friday, 2 March, 2012

Darnley Bay Resources announces the release, filing on SEDAR and posting on its own website of the 43-101 Technical Report prepared by Stephen Reford, P.Eng., a Qualified Person for the purposes of National Instrument 43-101 and the Company’s Chief Technical Officer. The Report details the history of North America’s strongest discrete gravity anomaly and its exploration by the Company and others over a period of 17 years.

The Anomaly has been favourably compared by the Geological Survey of Canada (the “GSC”) to other prominent gravity anomalies such as those at the prolific mining camps of Noril’sk and Sudbury Basin. The Darnley Bay Anomaly is stronger than any of these comparatives by a wide margin. The GSC discovered the Anomaly in 1969 .The Company has 100% control of its exploration and potential development subject to certain back-in and other rights of the Inuvialuit Regional Corporation on whose land it occurs.

The Report details the work undertaken by the Company to identify 41 gravity, magnetic and electromagnetic targets widely distributed over the 100 km by 80 km extent of the Anomaly, in addition to larger zones of exploration significance. It recommends an exploration and drilling strategy to fully test the base and precious metal potential of the property. In view of the size and potential significance of the Anomaly, the Company has now decided to undertake a thorough search for joint venture partners to assist in the further exploration of this unique but gigantic occurrence.

http://www.darnleybay.com/DBR_Corporate_Presentation_Feb.2012.pdf


Airborne Mag-EM results for BC Homestake Ridge Property

Posted by on Wednesday, 22 February, 2012

Bravo Gold Corp. has received final results from the 2011 airborne DIGHEM geophysical survey on its 596 square-kilometre Kinskuch project located adjacent to, and southeast of its own Homestake Ridge project in northwest British Columbia.

The survey, which used Fugro’s DighemV-DSP electromagnetic system, totaled 3,821 line-kilometres flown at a nominal 100 metre spacing, which included 364 line-kilometres of tie lines at 1,000 metre spacing, and was completed from August 1st to September 14th, 2011.

The survey coverd about 60 percent of the total project area, was completed from the company’s base of operations at Alice Arm at the southern margin of the survey block.

The goals of the survey were met, the company said, with the data allowing for the mapping and delineation of controlling gold structures, as well as the identification of areas with anomalous conductivity, which suggest the presence of sulphide mineralization.

Bravo said several zones of anomalous conductivity have been identified within key target areas throughout the project.

The Illiance River trend, which was a target of the company’s 2011 exploration efforts, showed up in the survey as both a broad magnetic low and an electro-magnetic high (conductive zone suggesting the presence of sulphides) extending over a five kilometre strike length of strongly altered volcanic stratigraphy – an important host at the nearby Homestake Ridge project.

The target in this area is high-grade silver-enriched polymetallic mineralization within a series of sub-vertical structures occurring along the altered trend. Only a 2.5 kilometre strike length of this geophysical trend was mapped and sampled by Bravo during 2011, it said.

Bravo also completed four drill holes within the Illiance River trend in 2011, three of which returned what it called “encouraging” assay results including a 2.8 metre interval averaging 318 grams per tonne (g/t) silver, 0.4g/t gold, 2.2% lead and 6.5% zinc from drill hole KN11-02; and a 3.9 metre interval averaging 268 g/t silver, 0.2g/t gold, 3.4% lead and 6.5% zinc from drill hole KN11-03.

The holes were drilled from two set-ups, 500 metres apart. Mineralization remains open at depth and to the north and south, Bravo added.

The company also said that a program of geological prospecting, sampling and ground geophysics is being recommended to further delineate the conductive zones and to identify disseminated sulphides, which could indicate anomalous silver and gold mineralization.

Follow-up exploration will be carried out within an expanded 2012 exploration program on the project, which is planned to include an “aggressive surface exploration program” and up to 10,000 metres of diamond drilling on the Illiance River trend, as well as other targets throughout the property.


Down-hole and ground EM surveys for VMS in Australia

Posted by on Saturday, 18 February, 2012

Southern Cross Goldfields Limited has identified a series of new drill targets from recently completed geophysics at its Copper Bore VMS Copper-Gold Project, located 400km NE of Perth in WA, as drilling activity for 2012 ramps up.

The new drill targets have been generated from down-hole electromagnetic (“DHEM”) and surface moving loop electromagnetic (“MLEM”) surveys completed in December and January, highlighting the potential of the Copper Bore Project to host multiple accumulations of base metal mineralisation.

Details: http://www.scross.com.au/downloads/announcements/sxg20120216.pdf

Southern Gossan

At Southern Gossan, where recent drilling has extended the previously discovered zone of VMS copper-gold mineralisation, a well defined DHEM conductor has been identified immediately below previous drill hole SGRC004D, which intersected 2.6 metres @ 3.0% Cu, 0.9g/t Au, 4.2% Zn and 19.2g/t Ag from 265m down-hole.

The Southern Gossan prospect has returned a number of shallow drill-hole results over the previous 15 years (most of which did not extend below the base of oxidation). In 2011 SXG completed three reverse circulation (RC) and three diamond drill holes.

A Long Projection of these drill holes and the results of recent down-hole EM surveys completed in January 2012 shows the current understanding of the emerging VMS-style sulphide mineralisation, which has now been defined over a strike length of approximately 130 metres and to a vertical depth of approximately 280 metres.

EM conductors from ground and down-hole surveys are evident across the Southern Gossan prospect, including a well defined conductor immediately to the south of existing drilling which extends over an estimated strike length of 800m (ASX Announcement – 15 December, 2011).

This southern conductor will be tested by drilling in Q1 of 2012.

Copper Bore VMS Horizon

Project-wide ground EM surveys were completed along the entire 10km long prospective VMS horizon extending from Copper Bore to Southern Gossan in December 2011 and January 2012, resulting in the identification of several Moving Loop Electromagnetic (MLEM) conductors. A number of these conductors are coincident with aeromagnetic and soil geochemical anomalies.

Base metal mineralisation has already been confirmed at several locations along this horizon.

Importantly, a review of historic soil geochemical surveys has also identified copper anomalism parallel to the Southern Gossan-Copper Bore horizon. These new areas of interest will be followed up with new soil geochemical surveys, mapping and potentially EM.

A number of additional targets have also been generated from the project-wide ground EM surveys and acquisition of previous and recent soil geochemistry.

Next Steps

The Company has this week commenced an initial RC and diamond drilling programme to test some of these newly identified targets along the Copper Bore trend. Further drilling will also be undertaken at Southern Gossan, which is the most advanced prospect, located at the southern end of the 10km long prospective VMS horizon.

Other key activities to be undertaken by SXG at Copper Bore include:

· completing analysis of the surface EM results across the entire 10km strike of the host horizon and particularly across two aeromagnetic bullseye anomalies on the host horizon;

· completing soil sampling along the existing prospective VMS horizon; and

· undertaking soil sampling along the potential new prospective VMS horizon.
SXG’s Managing Director, Mr Glenn Jardine, said the recent work undertaken by the Company had opened up the entire Copper Bore project area, highlighting the potential for additional base metal discoveries.

“We are currently embarking on a new focused program of drilling to follow-up some of these exciting targets and further test the mineralisation at Southern Gossan,” Mr Jardine said. “We also remain confident that the comprehensive mapping, EM and soil sampling campaign may define additional walk-up drill targets to be tested later in the year.

“This is a project which is still at a very early stage in its exploration life, and we are very much looking forward to progressing it over the coming months.”

Details: http://www.scross.com.au/downloads/announcements/sxg20120216.pdf


New discovery of sulphides at St. Stephen project

Posted by on Sunday, 29 January, 2012

St. Stephen Ni project in New Brunswick, Canada: discovered new nickel-copper sulphide zones while drill testing EM anomalies.

Continental Nickel Limited announces the assay results from its 2011 drilling program on the St. Stephen Nickel-Copper project in New Brunswick which have confirmed the discovery of new nickel-copper sulphide mineralization. Highlights include: 2.35% nickel and 1.06% copper over 5.45 metres from drill hole SSD11-013 at the new Hanson Brook target, and 0.68% nickel and 0.41% copper over 58.2 metres, including 0.85% nickel and 0.48% copper over 20.8 metres from drill hole SSD11-011 at G zone.

The Company commenced a diamond drilling program in early December to test new electromagnetic (“EM”) targets identified in the 2011 airborne EM survey and to further test nickel-copper mineralization intersected in 2010 in the St. Stephen intrusion. Five drill holes totalling 772 metres were completed in December and borehole electromagnetic surveys (“BHEM”) were also carried out in each of the holes. The drilling program was suspended on December 15th due to wet ground conditions and resumed on January 17th. Assay results are reported herein for the five completed holes (see Table I below). A location figure may be viewed using the link provided with this release.

Patricia Tirschmann, VP Exploration of Continental Nickel Limited, commented “We are very encouraged by the recent drilling results, particularly the new nickel-copper sulphide discovery at Hanson Brook and the expansion of mineralization at G zone, both located along the western side of the St. Stephen intrusion. EM geophysical surveys and drilling are proving very effective at identifying new mineralization and we look forward to both evaluating the new discoveries and to testing additional new targets. St Stephen is shaping up to be a high quality exploration project which complements our flagship Nachingwea Project in Tanzania.”

In 2010, the Company reported the discovery of new nickel-copper sulphide zones while drill testing EM anomalies at the Triple J and G targets.

Hanson Brook Target

One hole, SSD11-013, was drilled to test a new airborne EM anomaly located 350 metres northwest of SSD10-003 (G Zone). SSD11-013 intersected a zone of massive sulphides grading 2.35% nickel and 1.06% copper over 5.45 metres from 45.5 to 50.95 metres. The sulphides are hosted in metasedimentary rocks and are interpreted to be remobilized from the mafic rocks of the St. Stephen intrusion. BHEM data indicates that the conductor was intersected near its southern edge and additional drilling is planned to further test the Hanson Brook Target.

Todd Mountain Target

Two holes, SSD11-014 and SSD11-015, were drilled to test a new, >1 kilometre long airborne EM anomaly located in the south-western portion of the St. Stephen intrusion where no previous drilling has been carried out. SSD11-014 was drilled near the southern extent of the airborne EM anomaly and hole SSD11-015 was drilled near the northern extent. Both holes intersected intrusive gabbroic rocks but failed to intersect an EM conductor and did not return any significant assays. Borehole EM surveys were conducted and strong off-hole anomalies were detected in the immediate vicinity of both holes. The BHEM results indicate the presence of multiple conductors and complex geometry when compared to the airborne EM data. Additional drilling is planned to more fully test the Todd Mountain target.

http://media3.marketwire.com/docs/CNI2501map.pdf

Canadian Mining Journal


Reinterpreted historical EM data for nowadays drilling

Posted by on Sunday, 29 January, 2012

Western Troy Capital Resources has announced the assay results of holes it drilled at its MacLeod Lake Copper/Molybdenum Project in November of 2011.
Three holes were drilled on geophysical anomalies near the Main Zone. Two holes did not intersect significant mineralization, but Hole 228, drilled on an anomaly between the Main Zone and the South Zone intersected 2.14% copper and 21.32 g/t silver over an interval of 3 meters from 63 to 66 meters depth. This interval includes 1.0 meter of 5.93% copper and 50.6 g/t silver.
These widths are believed to be close to true widths due to the sub-horizontal attitude of the mineralized zone.

The map shows the location of Hole 228 relative to the Main and South Zones along with
geophysical anomalies in the area.

Hole 228 was drilled on Rocky Point to intersect a conductive zone south of the Main Zone. Past work in this area uncovered high grade, copper mineralized boulders with assays of 6 to 9 percent copper as well as mineralized outcrop in granodiorite and biotite gneisses.  The mineralized outcrop is likely the up-plunge extension of the new Rocky Point Zone.

(Pink)located approximately 450 meters down plunge from the mineralized outcrop and at the centre of  the conductive zone that appears to represent the outline of the new Rocky Point Zone.

With this new drill intercept in Hole 228, the associated mineralized boulders and outcrop, and the configuration of geophysical anomaly, it is possible that a new zone similar in size and configuration to the South Zone could be present in the Rocky Point area.  The combination of the South Zone and Rocky Point Zone could provide sufficient resources that would allow inclusion of the zones in the mineable resource at some point in the future.


Airborne EM for permafrost mapping

Posted by on Wednesday, 25 January, 2012

ANCHORAGE, Alaska — A tool used by mining companies to find mineral ores has been adapted to map frozen soils below the ground in Alaska and could be used to track the effects of global warming, according to the U.S. Geological Survey.

The agency announced Monday that an airborne survey conducted in Alaska’s Yukon River drainage collected unprecedented images of the presence and absence of permafrost down to 328 feet. The study used an electromagnetic survey tool flown beneath a helicopter.

“We really think we’ve got the story nailed down from these data,” research geophysicist Burke Minsley said by phone from the Crustal Geophysics and Geochemistry Science Center in Denver.

Minsley is lead author of the study published Friday in the journal Geophysical Research Letters (http://www.agu.org/pubs/crossref/2012/2011GL050079.shtml).

Mapping permafrost extents has been done by satellite, Minsley said.

“It’s hard to get any information at depth, and that’s what’s unique here,” he said.

Permafrost is below about 24 percent of the land area in North America. The research will be important for climate scientists looking at the thawing of permafrost as a greenhouse gas contributor, studying ecology in lake systems, or looking at the effects of thawing ground on river chemistry, Minsley said. Thawing also will bring important impacts for northern infrastructure such as buildings and roads.

The Yukon River begins in Yukon Territory, Canada, and spans Alaska from east to west.

The research team surveyed more than 116 square miles of the Yukon Flats in an area centered 140 miles northeast of Fairbanks. The area was picked in part because it’s between continuous permafrost to the north and discontinuous permafrost to the south, according to the agency.

Electromagnetic surveys have been used in mining for years, Minsley said. Scientists recently have used it to define the geometry of aquifers in Nebraska.

“What’s new about it is that it’s being used for more discrimination of more subtle features related to things like groundwater and permafrost,” Minsley said.

The tool is torpedo-shaped and about 33 feet long. In front are coils oscillating at different frequencies, Minsley said. Towed by a helicopter and flown just under 100 feet off the ground, the tool sends electromagnetic pulses into the ground and determines what’s below by measuring how well the pulse is conducted. The ground itself has conductors and resistors. Permafrost is not as conductive as solid ground.

“It induces currents in the ground. Those currents induct a signal, a magnetic field, that’s picked up by another set of coils that’s in the back of that thing that we’re towing under the helicopter,” Minsley said.

The tool collected data that showed a lack of permafrost below the Yukon River and other water bodies that don’t completely freeze in the harsh interior Alaska winter.

“That’s consistent with a lot of conceptual models that people have developed, but they haven’t really had the solid measurements that we have to see that,” Minsley said.

The mapping also showed “thermal relics” where the Yukon River had been centuries ago. As the river migrated to a new location, ground slowly refroze. The farther away from the new location, the more it had frozen in a downward slope. Minsley said it was the biggest surprise of the study.

“It was not something we expected to capture in this data set, to actually see that thermal legacy over a thousand-year history. That’s pretty rare for this kind of data,” he said.

The tool collected data over only one week in June 2010. Minsley said he spent four to five months analyzing and processing data to make images, and the research team spent many more hours interpreting the results.

Drilling boreholes to acquire the same information would have taken a much greater effort, he said.

Source: http://www.therepublic.com/view/story/ad6b2e26841f4a43b94544da1fc50b34/AK–Permafrost-Mapping/


Graphite – the growing market for geophysics

Posted by on Thursday, 5 January, 2012

Global consumption of natural graphite has increased from approximately 600,000 tonnes in 2000 to roughly 1.2 million tonnes in 2011. Demand for graphite has been increasing by approximately 5 per cent per year since 2000 due to the continuing modernization of China, India and other emerging economies, resulting in strong demand from traditional end uses such as the steel and automotive industries. Graphite also has many important new applications such as lithium-ion batteries, fuel cells, and nuclear and solar power that have the potential to create significant incremental demand growth. There is roughly 10-20 times more graphite in a lithium-ion battery than there is lithium. Demand for graphite is expected to rise as electric vehicles and lithium battery technology are adopted.

Natural graphite comes in several forms: flake, amorphous and lump. Of the 1.2 million tonnes of graphite produced annually, approximately 40 per cent is of the most desirable flake type. China, which produces about 70 per cent of the world’s graphite, is seeing production and export growth leveling, and export taxes and a licensing system have been instituted. A recent European Commission study regarding the criticality of 41 different materials to the European economy included graphite among the 14 materials high in both economic importance and supply risk (Critical Raw Materials for the EU, July 2010).

Graphite prices have been increasing in recent months and over the last couple of years prices for large flake, high purity graphite (+80 mesh, 94-97%C) have more than doubled. Other public companies developing graphite projects in Canada include Northern Graphite Corp. with its Bissett Creek project in Ontario and Focus Metals Inc. with its Lac Knife project in Quebec. High-growth, high-value graphite applications require large-flake and high-purity graphite which is the prime exploration and development target at the Quatre Milles Property.

The Quatre Milles Property is road accessible and is located approximately 175 km northwest of Montreal and 17 km due north of the village of Sainte-Veronique, Quebec. The property consists of 28 contiguous claims totaling approximately 1,600 hectares.

The property was originally staked and explored by Graphicor Resources Inc. (“Graphicor”) in the summer of 1989 based on the results of a regional helicopter-borne EM survey. The underlying geology consists of intercalated biotite gneiss, biotite feldspar gneiss, marble, quartzite and calc-silicate lithologies of the Central Metasedimentary Belt of the Grenville Province.

Graphicor completed reconnaissance mapping and prospecting as well as ground geophysics and a 26 hole diamond drill program totalling 1,625 metres. The work identified several conductive trends in the central portion of the property and at least three, relatively flat lying graphitic beds. Three surface samples were collected and analyzed returning results of 14.16% Cgf, 18.06% Cgf and 20.35% Cgf. 23 of the initial 26 drill holes intersected graphite concentrations with a highlight of 8.07% Cgf over 28.60 metres in hole Q90-9. The highest individual assay was reported in hole Q90-10 reporting 15.48% Cgf over 0.50 metres.