Posts Tagged TEM

GEOMODEL – online time-domain EM data inversion

Posted by on Tuesday, 19 May, 2015
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Significant improvements have been made since the last presentation of the webapp on ExplorationGeophysics.Info pages. Now the shareware TDEM data inversion web application (ww.geomodel.info) has easy and comfy Eng-Rus interface, the input supports six different file formats (airborne and ground systems), sounding stations position can be represented on the scalable Google Map, data is showed in a sheet, TEM off-time decay chart and calculated apparent resistivity with time or depth.

 

AppResChart

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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The software can be used with data from WalkTEM, TerraTEM, ProTEM, Geotech airborne VTEM, TEM-FAST 48HPC, Tsikl and other TEM systems. A user can suggest any new data format and provide GEOMODEL developers with corresponded information.

The inversion process is interactive (forward modeling with thickness and/or resistivity changing) or iterative (automatic iterations to get correspondence between calculated and measured decay curve).

The inversion is based on 1D algorithm with support of CSIRO Division of Exploration and Mining and Australian Mineral Institute Research Association (AMIRA), P223F project.

Inversions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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The next procedures can be done with TDEM Geomodel webapp:

-Import-export TEM data and inversions from a large number of industrial formats, including USF;

-Viewing and analysis of transient field decay curves;

-Editing individual decays or tens of decays together in a fast and easy way;

-Runing 1D inversion and compiling resistivity sections;

-Saving results in ASCII format for further processing and presentation in third-party software (Surfer, Autocad, Geosoft Oasis Montaj, etc.).

-Saving inversion results as resistivity sections and maps in different image file formats.

The next example shows  Geotech airborne VTEM  data inversion (Alberta, Canada):

 

The development team welcomes user’s comments and suggestions.


IP or not IP? (notes about IP in transient EM)

Posted by on Tuesday, 28 April, 2015

by Alexander Prikhodko

During the last few years the topic about IP effect (induced polarization) in the EM (electromagnetic) transient method (mostly in airborne time-domain) has been actively raised by many authors through geophysical magazines, conferences and meetings.

Here we will look into the topic without formulas and deep theory for a better understanding of the IP effect by general users of electro-prospecting  methods.

The nature of the IP phenomenon is universal regardless of an electric field source inducing (causing) the phenomenon or a measurement way of the appearance. First of all, the IP theory is out of Maxwell equations solutions because the process is accompanied by mass transfer and connected with EM field transformations. In contrast to IP theory Maxwell’s equations deal with electromagnetic induction which the time-domain (transient) method is built from.

In the case of IP the term “induced” means “caused” and does not relate to the concept of EM induction.

The concept of Induced Polarization (a substance ability to separate opposite charges) incorporates different phenomenons but related processes that occur:

1) in heterogeneous fluids or in pores filled with fluids;

2) due to electrochemical processes.

These two phenomenons – electrokinetic (1) and electrochemical (2), is a key to understanding how IP is used in applied geophysics.

Electrokinetic processes occur on contacts between ionic conductive fluids and a solid phase.

Electrochemical processes occur on contacts, or surfaces, between phases with electronic (metallic) and ionic (non-metallic) conduction. This is fundamental when IP method used when exploring for sulfide mineralization, especially if the sulfides are disseminated as the IP effect will be stronger than for massive sulfides of the same volume because its surface area is less.

Historically electrochemical nature of IP phenomenon first investigated and used in geophysics by Conrad Schlumberger (published in 1920). Later, during further electronic industry development and equipment sensitivity and bandwidth increasing, IP effect began to be observed all over the geologic environment due to the possibility of measurement of rapid and comparatively weak IP signal of the electrokinetic nature.

Generally, the IP effect of both natures potentially may affect data obtained with any electro-prospecting method including inductive time-domain method, regardless that the strongest IP effect occurs in the geologic environment at galvanic (grounded) way of the current inducing and the voltage measuring.

So, the IP component in transient or time-domain data is a parasitic effect which is not under Maxwell’s EM theory. (By the way, in the widely employed original DC-IP method, the inductive component is considered as a source of noise.) There are some technical requirements to sensitivity, bandwidth and geometry of a time-domain system to get better the parasitic signal superimposed on the inductive, native to the method, component.

Fortunately the IP parasitic signal is opposite to the inductive secondary field component allowing to recognize it and separate out it in some cases from the measured total secondary field. The favorable condition to get IP component from time-domain data and investigate it is rapid decaying inductive secondary field, i.e. resistive environment in general is favorable, but there are cases  when a strong IP component is prominent in presence of long inductive decay.

Unfortunately the existing theories of the electrokinetic and electrochemical natures of the IP phenomenon are on a qualitative basis. It means there is no chance to get petrophysical or/and petrochemical parameters of the geologic environment and to classify the IP sources according to their nature. On practice, empirical approximations are used for the IP process description with limited controlled parameters (in particular, Cole-Cole formula and the corresponded parameters) despite the nature of the phenomenon. To our delight it enables creative and thoughtful geological interpretation of the IP data if we get it correctly.


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


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

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. Right now it is a shareware web application developed for pre-processing and 1D inversion of transient (time-domain) electromagnetic data. The software can be used for ground and airborne time-domain EM data.

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

 


Recent investigations of geophysics abilities in aquifer mapping and resource evaluation

Posted by on Thursday, 13 March, 2014

Buried beneath the glaciated terrain, valleys filled with coarse-grained permeable sediments  potentially are great sources of fresh ground water. During the last several years Geological Survey of Canada has been investigating geophysical methods potential, particularly airborne electromagntics, for mapping and resource evaluation of buried valleys.   Spiritwood valley aquifer in southern Manitoba has been chosen for the investigations. Heliborne AeroTEM, VTEM, fixed-wing TEMPEST and MULTIPULSE, ground electrical resistivity and time-domain methods, seismic reflection and borehole data have been involved into the complex analysis. Recently collected ground TEM data for Spiritwood and the report (G.A. Oldenborger and K. Brewer, 2014) has been released: http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=293700.

One of the successful heliborne TEM examples (Legault, J.M., Prikhodko, A., Dodds, D.J., MacNae, J.C., Oldenborger, G.A., 2012. Results of recent VTEM helicopter system development testing over the Spiritwood Valley aquifer, Manitoba. Symposium on the Application of Geophysics to Environmental and Engineering Problems. Environmental and Engineering Geophysical Society, 114–130.):

VTEM-ground

 

 

 

 

 

 

 

 

 

 

 

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Another recent example of the results of a combined seismic and airborne electromagnetic (AEM) interpretation of the shallow Quaternary sedimentsand  bedrock but in British Columbia (Horn River Basin) was presented on Geoconvetion-2013  .

 

 


Graphite discoveries in Northeastern Ontario

Posted by on Thursday, 16 May, 2013

Zenyatta Ventures Ltd. announced a drilling update on the 100% owned Albany (Hydrothermal) Graphite Deposit, located in northeastern Ontario, Canada.

The first drill hole (Z13-4F10) intersected 363 metres (‘m’) of graphite mineralization from 47.0 m to 410.0 m.  This represents the widest zone of graphite material intersected to date on the Albany deposit.  The hole, which was drilled at a 180 azimuth and -65 dip, was designed to test between previously drilled holes 5 and 9.  From surface to 41.0 m hole 10 intersected overburden and from 41.0m to 47.0 m intersected Paleozoic limestone.  Graphitic overprinting was encountered from 47.0 m to 87.0 m, while the strongest graphitic mineralization was intersected from 87.0 m to 410.0 m. Drilling shows different types of graphite mineralization consisting of clasts of graphite vein material, disseminated graphite matrix and discrete graphite veins / veinlets as part of a large breccia pipe.  Geometry and true width of the graphite breccia pipe is difficult to determine at this point and will require much more drilling.

The Company will continue to define the size and grade of this rare, ‘vein-type’ or hydrothermal-style graphite deposit.  The goal of the current program will be to expand on a 2012 drilling campaign that intersected a large mineralized zone of graphitic breccia and veining from widely spaced drill holes.  This previous nine (9) hole drill program succeeded in establishing widespread graphite mineralization laterally for several hundred metres and to a vertical depth of 400m, where it remains open. The current drilling will consist of a minimum of 10,000m and will further test the extent of the Geotech VTEM airborne conductor. The program will require 40 holes and is expected to continue until August, after which a NI 43-101 resource estimate will be calculated. The Company anticipates a steady flow of information from drilling activities and continued metallurgical work from this fully funded $4 million exploration program for the balance of 2013.

14 May 2013

Zenyatta Ventures Ltd. announced the following significant assay results from the first hole (#10) of the current campaign on the 100% owned Albany (Hydrothermal) Graphite Deposit, located in northeastern Ontario, Canada.   Drill hole 10 intersected 360.8 metres (‘m’) of graphite mineralization from 49.0 m to 409.8 m yielding an average grade of 5.1% Carbon (‘C’).  This represents the widest zone of graphite material intersected to date on the Albany deposit.  The hole, which was drilled at a 180° azimuth and -65° dip, was designed to test between previously drilled holes 4, 5 and 9.  Five more holes have since been completed, all of which yielded broad intervals of graphite mineralization from visual observations of drill core as described below.  Holes 11 through 15 have been designed to start outside the limit of the indicated anomaly and were angled to help define and confirm the overall geometry of the pipe-like body.  Drill hole data from all 15 holes is shown in a table at the end of this press release.

• Drill hole 11 intersected 202.0 m of graphite mineralization from 393.0 m to 595.0 m.

• Drill hole 12 intersected 195.0 m of graphite mineralization from   90.0 m to 285.0 m.

• Drill hole 13 intersected 219.0 m of graphite mineralization from   96.0 m to 315.0 m.

• Drill hole 14 intersected 286.9 m of graphite mineralization from 108.8 m to 395.7 m and a second zone of 127.3 m of graphite mineralization from 431.3 m to 558.0 m

• Drill hole 15 intersected 301.9 m of graphite mineralization from   63.3 m to 365.2 m.   (All lengths reported are drill intersected core lengths and do not represent true widths)

Aubrey Eveleigh, President and CEO stated “These latest results confirm the exceptional size potential of the Albany graphite deposit and along with the previously announced ultra-high purity (>99.99% C) values, underpins Zenyatta’s extraordinary graphite project. Hole 10 represents the best grade drill intersection obtained to date and the more recent drill holes are confirming both the internal continuity and the extent of the deposit.”   Graphite mineralization appears to consist of graphitic breccia pipes which are typically surrounded by a zone of graphite overprinted syenite. Carbon analyses for drill holes 11 through 15 will be released once received.  Drill hole 16 has commenced, and the current campaign will continue until sufficient drill holes have been completed, following which a NI 43-101 compliant resource estimate will be prepared.  A plan map, section and drill hole table will be placed on the website today.

The Company has also completed a ground geophysical survey to better define the geometry of the Albany graphite breccia pipes and expects the full data to be released in the next few days once a final report has been completed by Crone Geophysics and Exploration Ltd. The survey has defined two adjacent, strongly conductive, geophysical (EM) anomalies that are roughly circular in shape.  Holes 10 through 15 were drilled on the eastern most anomaly (Eastern breccia pipe), and are suggesting an oval shaped body approximately 200 metres in a NW-SE long axis by approximately 125 metres NE-SW.  Additionally, hole 11 intersected mineralization at approximately 500 metres vertical depth.  Drill intercepts appear to be correlating well with the shape of the ground geophysical anomaly with additional drilling required to confirm this model. The western anomaly (Western breccia pipe), which appears to be larger, will also be fully tested during the current drill campaign.


USGS: Iowa Meteorite Crater Confirmed

Posted by on Wednesday, 13 March, 2013

Recent airborne geophysical surveys near Decorah, Iowa are providing an unprecedented look at a 470- million-year-old meteorite crater concealed beneath bedrock and sediments.

The aerial surveys, a collaboration of the U.S. Geological Survey with the Iowa and Minnesota Geological Surveys, were conducted in the last 60 days to map geologic structures and assess the mineral and water resources of the region.

“Capturing images of an ancient meteorite impact was a huge bonus,” said Dr. Paul Bedrosian, a USGS geophysicist in Denver who is leading the effort to model the recently acquired geophysical data. “These findings highlight the range of applications that these geophysical methods can address.”

In 2008-09, geologists from the Iowa Department of Natural Resources’ (Iowa DNR) Iowa Geological and Water Survey hypothesized what has become known as the Decorah Impact Structure. The scientists examined water well drill-cuttings and recognized a unique shale unit preserved only beneath and near the city of Decorah. The extent of the shale, which was deposited after the impact by an ancient seaway, defines a “nice circular basin” of 5.5 km width, according to Robert McKay, a geologist at the Iowa Geological Survey.

Bevan French, a scientist the Smithsonian’s National Museum of Natural History, subsequently identified shocked quartz – considered strong evidence of an extra-terrestrial impact – in samples of sub-shale breccia from within the crater.

“The recognition of this buried geological structure was possible because of the collaboration of a local geologist, water well drillers, the USGS STATEMAP program, and the support of the Iowa DNR concerning research on fundamental aspects of Iowa geology,” said McKay.

The recent geophysical surveys include an airborne electromagnetic system, which is sensitive to how well rocks conduct electricity, and airborne gravity gradiometry, which measures subtle changes in rock density. The surveys both confirm the earlier work and provide a new view of the Decorah Impact Structure. Models of the electromagnetic data show a crater filled with electrically conductive shale and the underlying breccia, which is rock composed of broken fragments of rock cemented together by a fine-grained matrix.

“The shale is an ideal target and provides the electrical contrast that allows us to clearly image the geometry and internal structure of the crater,” Bedrosian said.

More analysis of the data will provide additional detail. These data show the impact as a nearly circular region distinct from the surrounding area to a depth of several hundred meters.

“These data, when coupled with physical property measurements on drill core samples, will form the basis for modeling efforts to constrain the impact geometry and energy of the meteorite,” said Dr. Andy Kass, a USGS geophysicist working on the effort.

The Iowa and Minnesota airborne geophysical surveys are targeting an igneous intrusion, known as the Northeast Iowa Igneous Intrusive complex, that may be similar to the Duluth layered igneous complex exposed in the Lake Superior region of northern Minnesota. Known copper, nickel, and platinum group metal resources were deposited during the formation of the Duluth complex. Both of these complexes are associated with a large structural feature known as the Midcontinent Rift, which is exposed in the Lake Superior Region but is covered by younger rocks as it extends to the south through Iowa, Nebraska, Kansas, and Missouri.

This geophysical survey is part of a larger USGS effort to evaluate the concealed mineral resource potential of the greater Midcontinent Rift region that formed about 1.1 billion years ago.

U.S. Department of the Interior, U.S. Geological Survey
Office of Communications and Publishing
12201 Sunrise Valley Dr, MS 119
Reston, VA 20192
Heidi  Koontz 1-click interview

Robert McKay


EMIT Maxwell Configuration File for VTEM system

Posted by on Sunday, 10 March, 2013

PDF file


Airborne EM and Magnetic Gradiometer for Palladium-Platinum-Gold Project in Timmins

Posted by on Friday, 14 December, 2012

Gold Dynamics Corp. contracted with Geotech Ltd. to complete a helicopter borne Versatile Time Domain Electromagnetic (VTEM Plus) and Horizontal Magnetic Gradiometer Geophysical Survey on the Hoyle North Palladium-Platinum-Gold Project located in Timmins, Ontario. A total of 84 line kilometers of geophysical data were acquired, flown at 100 meter spacing on the property.

Analysis of the preliminary data from the VTEM Plus indicate mineralized targets exist in the eastern portions and also a mineralized trend from the southeast to the northwest of the property at approximate depths of 200 meters. The survey also identifies a system of dykes which are very common in mineralized zones on this trend and are also common to the known geology of this area.

Further results and analysis are expected in the next few weeks. This information will be evaluated to select targets for ground follow-up in order to help prioritize anomalies for drilling.

Gary Kirk, CEO/President of Gold Dynamics Corp. said, “I am extremely pleased that we were able to contract with Geotech Ltd. who are a leader in their field, utilizing state of the art technology to help us build our base of knowledge on the Hoyle North project. With targets in hand, knowing the depth and location of these targets brings us much closer to finally drilling. The known geology common to the areas where other major international mining companies (Goldcorp, Xstrata Copper, Lakeshore Gold and Brigus Gold), whom are adjacent to our project, are currently producing large quantities of gold and other precious metals out of geologic structure very similar to what the VTEM Plus has identified in ours; is very encouraging for us.”

The Hoyle North property is contiguous to Goldcorp’s Hoyle Pond mine and is within short distances to significant resources such as Owl Creek and Bell Creek. The Hoyle North property remains relatively unexplored near to expansive mining and exploration efforts by significant companies such as, Goldcorp, Xstrata, Lakeshore Gold, San Gold, Osisko Mining and VG Gold and others.


Airborne geophysics results on Mexico’s Guerrero gold belt

Posted by on Saturday, 8 December, 2012

Citation Resources Inc. announces preliminary results of its airborne versatile time-domain electromagnetic (“VTEM“) survey completed in October 2012 over a substantial portion of the Biricu Gold Project located within Mexico’s Guerrero gold belt.

The VTEM survey was conducted by Geotech Ltd. and covered approximately 1,400 line kilometres at 150 metre spacing over three specific high-priority areas of the concession within a broader survey coverage at 200 metre spacing. Condor Consulting Inc. experts in the field of airborne electromagnetics, has been retained to perform a detailed interpretation of the results and their final report regarding the significance of the survey is still pending.

The preliminary interpretation by Condor has identified 19 potential target zones as defined by conductivity and magnetic geophysical anomalies on the Biricu Project. Six of these target zones are aligned along a 5 kilometer northeast trending corridor, which to date has only been partially ground tested. A field crew has been mobilized to conduct further mapping and sampling over the geophysical anomalies in order to prioritize areas for possible drill testing. Upon receipt of the final geophysical interpretation, the results will be integrated with the analysis of the field work completed and drill targets will be prioritized. The details of the final results will be presented in a future news release.


Results of an Airborne Geophysical Survey in Tanzania

Posted by on Monday, 27 August, 2012

Continental Nickel Limited reports the identification of twenty-five new high priority VTEM anomalies from the recently completed 2,409 kilometer airborne magnetic and electromagnetic (EM) survey within the regional land holdings comprising the Nachingwea Project located in southeast Tanzania. The project is part of the 75:25 joint venture between CNI and IMX Resources Limited of Australia.

Highlights of the 2012 Airborne Survey

  • Large, high amplitude late time EM anomaly coincident with the Hog gold prospect
  • Twenty-five high priority targets selected for ground follow-up
  • 1,500-2,000 metres of RC drilling planned

Patricia Tirschmann, VP Exploration, commented: “We are pleased to have completed another successful regional VTEM survey and are very encouraged by the number of high quality targets generated. The identification of an EM anomaly coincident with the Hog gold prospect further enhances the exploration potential of this target and we look forward to drill testing it and other high priority targets beginning in September.”

The airborne geophysical survey was carried out by Geotech Limited of South Africa employing the Versatile Time-Domain Electromagnetic (VTEM) geophysical system. The survey ran from July 29th to August 11th and a total of 2,409 kilometers were flown in five flight blocks. The location of the survey is shown in Figure http://media3.marketwire.com/docs/VTEMjpeg.pdf.

The flight blocks comprising the 2012 airborne VTEM survey were selected by prioritizing areas based on results of the 2010 airborne magnetic and radiometric survey in combination with results of geochemical sampling and geological mapping. Preliminary data from the new VTEM survey is currently being evaluated, and targets are being selected for ground follow-up in order to help prioritize anomalies for drill testing later in the year.

Analysis of the preliminary VTEM data indicates that EM anomalies have been detected on each of the five flight blocks and approximately twenty-five of these represent high priority anomalies with late channel responses. Of potential significance is a high amplitude late time EM anomaly detected on three 200 metre spaced flight lines which is coincident with the Hog gold prospect where surface gossan grab samples returned values of up to 4.96 g/t gold and 0.64% copper (May 25, 2012 Press Release). Several other VTEM anomalies are also confirmed to have coincident copper and/or nickel in soil anomalies.

The Company plans to carry out 1,500-2,000 metres of reverse circulation drilling to test selected high priority regional VTEM and geochemical anomalies including the Hog gold prospect. This drilling is currently expected to begin in mid-September.


Airborne TDEM Survey over Graphite Mousseau East property in Quebec

Posted by on Thursday, 2 August, 2012

Standard Graphite Corp. announces that the results from an airborne geophysical survey flown over its Mousseau East property coincide with the outline of the known mineralization. The survey has also identified targets in other sectors of the property where no historical work has been reported.

Airborne magnetic (MAG) and time domain electromagnetic (TDEM) surveys were flown by Prospectair Geosurveys over the Mousseau East property during the month of June to precisely locate the conductors associated with the graphite-bearing units in preparation for the field program (see press release 21 July, 2012). Results clearly outline the main Mousseau East zone where a historical resource has previously been outlined and also traces the along-strike extension towards the west. The extension of the main zone will be targeted for resource expansion during the upcoming diamond drilling program scheduled to commence soon.

During the survey, some conductors were also reported outside of the known mineralized area and its direct extension, notably towards the east of Oat Lake. These conductors are currently being investigated for graphite outcropping by Standard’s field team.

To view a map of the TDEM results please click here:

http://www.standardgraphite.com/i/pdf/EM/mousseau.pdf

Chris Bogart, President and CEO comments on the progress at Mousseau East: “The geophysics has proven its efficiency at outlining the known graphite zones at our historic Mousseau deposit. We are excited at the prospect of expanding our current historic resource both along-strike and at depth and potentially discovering new zones as suggested by the TDEM survey.”


Airborne EM Survey over the Oldest Meteor Impact Site

Posted by on Tuesday, 24 July, 2012

North American Nickel Inc. reports that fifty zones of conductivity, many with significant strike lengths, have been identified in preliminary data from its recently completed VTEM Plus helicopter time domain electromagnetic survey over its 100% owned Maniitsoq project in Southwest Greenland.

The Geological Survey of Denmark and Greenland (GEUS) had recently announced the discovery of the oldest-known meteorite impact site in the world, rousing the company’s interest in its Maniitsoq project.

More than twelve of the fifty have already been identified as higher priority zones which have the potential to become targets for the company’s upcoming drill program in August. A more detailed analysis of all the VTEM Plus data is underway.

NAN CEO, Rick Mark, states: “We are very pleased that the VTEM Plus system has been successful in delineating fifty new conductors. With this data, we already have a dozen new targets similar in priority to the three drill targets previously identified in last fall’s smaller SkyTEM survey, some with apparent strike lengths in excess of 1 km. Now that we can point conclusively to conductors occurring throughout the 75 km long belt, we are more comfortable than ever in describing this as a camp-scale exploration play.”

The Greenland Norite Belt (GNB) is a 75 km long by 15 km wide belt of crustally contaminated noritic intrusions with numerous historical, high-grade nickel sulphide showings (e.g. 9.85 m averaging 2.67% Ni and 0.60% Cu at the Imiak Hill showing). Mineralization within the belt has consistently high nickel tenor (6-8% Ni in 100% sulphide according to work done by Falconbridge in 2000).

Despite its obvious high prospectivity, the GNB has seen little drilling. A total of 119 holes totalling only 6,300 m, for an average hole length of less than 53 m, were drilled in the 1960’s and 70’s. More recent exploration programs stopped short of drilling due to a lack of EM anomalies to guide drilling. NAN’s strategy at Maniitsoq has been to use modern helicopter borne TEM systems to develop drill targets and it has proven successful. This technology was not available to previous explorers.

The VTEM Plus survey, combined with a SkyTEM survey flown by NAN last year, provides the company with high resolution TEM coverage over a total area of 860 square kilometers centred on the Greenland Norite Belt).

Data from the VTEM Plus survey is currently being processed and interpreted. All significant electromagnetic anomalies will be checked in the field and ranked. The highest priority targets will be tested during a drill program that is planned to commence in August.

The survey, which ran from June 20 to July 17 and comprised 3,532 line-km of surveying, was performed by Geotech Ltd. of Toronto, OntarioCondor Consulting Inc. of Lakewood, Colorado provided daily QA/QC analysis of the data.

http://media3.marketwire.com/docs/nan-0724-image1.pdf


“Detecting vanadium and graphite deposits with EM methods”

Posted by on Monday, 23 July, 2012

CARMELA BURNS on JULY 19, 2012

“The recent rush to find graphite and vanadium deposits to satisfy potential demand in green energy applications is reigniting airborne electromagnetic (EM) methods as highly effective exploration tools.”

read more..


Airborne Geophysical Survey Over Henry Property

Posted by on Friday, 20 April, 2012

First Graphite Corp.  announces that that it has retained Geotech Ltd. to conduct an airborne Versatile Time Domain Electromagnetic (VTEM) and a horizontal magnetic gradiometer survey over its Henry Property. The property is comprised of six mineral claims and covers 22,850 hectares of land near the community of Southend Saskatchewan. Based on the results of historical exploration and its proximity to the Deep Bay Deposit, the Company believes that the Henry Property has the potential to host near-surface graphite deposits containing scarce, large-flake, high purity graphite.The purpose of the survey is to confirm the historically identified graphite-bearing outcrops and conductors, and to identify new targets for follow-up work. The interpretation of this data, along with the historic drill-hole intersections of graphite and existing structural information, will be used for advanced forward plate modelling of the graphitic horizons at depth. This interpretation will be conducted by Living Sky Geophysics Inc., of Saskatoon, Saskatchewan, and will guide future exploration. Future exploration is anticipated to include surface sampling, mapping and drilling.The helicopter-borne VTEM survey, which is expected to commence within the next few days, will cover the entire property (1452 line kilometres), at 200-meter line spacing, and is expected to take about one week to complete. Geotech’s VTEM plus system is excellent for locating discrete conductive anomalies as well as mapping lateral and vertical variations in resistivity. The VTEM plus system is equipped with a high-sensitivity magnetic gradiometer for mapping geologic structure and lithology. VTEM plus offers the industry’s highest signal/noise ratio and spatial resolution of conductors and unparalleled depth of investigation.

Read more: http://www.digitaljournal.com/pr/672357#ixzz1scEcNgz1


Butler Project – Exploration Overview with Geophysics

Posted by on Tuesday, 14 February, 2012

MacDonald Mines Exploration Ltd. provides an exploration update in the mineral-rich Ring of Fire region of the James Bay Lowlands.

MacDonald began exploring in the Ring of Fire starting in 2003, shortly after the first volcanogenic massive sulphide (VMS) discovery at McFaulds Lake by Spider Resources and KWG Resources. The McFaulds VMS discovery is characterized by very high-grade intersections of VMS mineralization (McF-04-57 intersected 18.8 meters of 8.02% Copper (Cu), Mc-03-18 averaged 4.83% Zinc (Zn) over 25.75 meters) and at 250 meter-plus depths.

Exploration in the James Bay Lowlands is challenging due to the area being almost entirely a wetland. As a result, there is minimal outcrop, helicopter support is required and exploration time lines are longer. Over $18 million dollars has been spent to date on the Butler property and we have discovered six zones of multi-element mineralization with copper-zinc VMS systems, vandiferous titano-magnetite and magmatic nickel sulphide. This was accomplished through comprehensive exploration programs including geophysics, diamond drill holes and geochemistry.

Magnetic map (TF) of the Butler Property showing the location of identified multi-element, mineralized zones.

The lack of outcrop requires that a significant amount of attention and detail has to be paid to the geophysical techniques used in the area. Historically the programs focused on shallow targets; however down-hole surveys, ground magnetic and gravity surveys have indicated that the potential deposit(s) of interest lies deeper in the structural sequence.

A comprehensive suite of geophysical tools has applied at Butler:

Airborne EM, Magnetics & Gravity

  • 2004 VTEM – 2138.9 line kilometers of data were collected
  • 2008 VTEM – 1325.6 line kilometers of data were collected
  • 2010 AeroTEM IV – 261 line kilometers of data were collected
  • 2011 HeliGeoTEM – 261 line kilometers of data were collected
  • OGS/GSC Airborne Gravity Gradiometer

Surface EM

  • Butler 1 – 13 line kilometers of data were collected
  • Butler 3 – 39.3 line kilometers of data were collected
  • Butler 5 – 12.5 line kilometers of data were collected
  • Butler 3, 5, 6, and 7 – 30.17 line kilometers of data were collected

Surface Magnetics

  • 7 Ground Magnetic surveys completed in 2011 covering 81.1 line kilometers

Down hole EM

  • 64 diamond drill holes probed and modeled

The Company is currently enhancing the geophysical model to include the geochemistry data results. Collectively, all of the above geophysical results have consistently shown that an electrically conductive unit with magnetic properties and high density lies below those prospective zones.  These are the characteristics expected from a sulphide rich zone.

Magnetic map (TF) of the Butler 3 area showing the location of the EM target and magnetic susceptibility anomaly

MacDonald’s upcoming drill program will focus on the Butler property: Prior to drilling, the targets will first be refined using a deep penetrating geophysical method, similar to that used to detect the HudBay – Lalor deposit at Snow Lake, Manitoba.