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Earth Explorer: About Insightful geophysics..

Posted by on Thursday, 2 April, 2015
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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.

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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.

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DIGHEM survey

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

(conductors in red, resistors blue colors)

DIGHEMConVoxel

 

 

 

 

 

 

 

 

 

 

 

 

 

sections

 

condmap

 

 

 

 

 

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VTEM survey

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

TAU

 

 

 

 

 

 

 

 

 

 

 

 

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

rdisections

 

 

 

 

 

 

 

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

RDIvoxel

 


Supervised Neural Network Targeting and Classification Analysis for Mineral Exploration

Posted by on Tuesday, 29 April, 2014

Karl Kwan (Geotech LTD) presented at Canadian Exploration Geophysical Society meeting (8 April 2014) methodology and examples of using Neural Network Targeting and Classification at mineral exploration.

“Geophysical survey contractors routinely offer multi-parameter data to clients. For example, a helicopter-borne survey may acquire Time-domain electromagnetic (TDEM), magnetic gradiometer and even gamma-ray spectrometer data (i.e., VTEMplus, Geotech LTD). Exploration geophysicists can certainly take advantage some of the readily available multi-disciplinary (geology, geophysics and remote sensing) and multi-parameter (potential field, EM, gamma-ray spectrometry, and others) datasets for mineral exploration. However, the integration and interpretation of these datasets can be time-consuming and even challenging, especially for large-scale datasets covering large areas with diverse geological conditions. The Supervised Neural Network (NN) Targeting and Classification technique for mineral exploration described and demonstrated by Reford, Lipton and Ugalde, 2004, “Predictive Ore Deposit Targeting Using Neural Network Analysis” (http://www.pgw.on.ca/downloads.html), can be a useful and promising tool for the analysis of multi-disciplinary and multi-parameter data.

In this presentation, the properties or responses of the two feed-forward multilayer Neural Networks, Levenberg-Marquardt (NN with LM training) and Fast Classification (FCNN), as implemented in the current version by PGW, are studied in detail. The supervised NN simulations are performed on specially constructed synthetic data. Intended as a tutorial and the NNs treated as black boxes, the objectives of the exercise are twofold, to demonstrate the targeting as well as classification capabilities of the Neural Networks, and at the same time to show one of the known limitations and to suggest a way to get around it. The utility of the NN tool is demonstrated again with real cases from the Republic of Niger.”

Geosoft is delighted to host the online portion of the Canadian Exploration Geophysical Society meeting with keynote speaker Karl Kwan, Geotech LTD.

YouTube:  


Airborne TEM impels VMS discoveries in Manitoba

Posted by on Thursday, 29 September, 2011

VMS Ventures Inc. announces follow-up results from the new copper zone discovery “Reed North” on its Super Zone property located 1.8 kilometres northeast of the Reed Copper deposit. The Super Zone is part of a parcel of four property packages adjacent to the Reed Copper deposit which are under option to HudBay Minerals Inc.  Reed North was previously referred to as the Super Zone Discovery.

To view “Figure 1. VTEM EM Anomalies” and “Figure 2. VTEM Anomalies with Magnetic Tilt” accompanying this press release, please click on the following link: http://media3.marketwire.com/docs/vms929i.pdf

HIGHLIGHTS

  • Hole RLE021 Intersects 3.95 m of 9.31% Cu, 1.87% Zn, 3.59 g/t Au, and 35.53 g/t Ag
  • Hole RLE022 Intersects 4.15 m of 2.16% Cu, 0.18% Zn, 0.71 g/t Au, and 8.01 g/t Ag

Neil Richardson, VMS’ Chief Operating Officer states: “The drilling results and the follow-up borehole pulse electromagnetic surveys on the Reed North discovery support our interpretation that this is a highly prospective area. The mineralization is at, and around, bimodal volcanism. This is especially encouraging as it is the setting in which the larger deposits tend to be located, in VMS camps around the world.”

The bimodal volcanism and the strong alteration over a large area suggest a large hydrothermal mineralizing system. HudBay has now drilled twelve (12) holes, for a total of 3,591 metres, on this discovery. Two mineralized horizons have been recognized and a possible third, a deeper target, has been identified by deep penetrating geophysical surveys over the area. Drilling will continue to focus on this area where the geophysical anomaly associated with the mineralization has been traced for more than 1 kilometre. The mineralization seen to date is semi-massive to stringer (remobilized) type sulphides. Variable amounts of pyrrhotite and chalcopyrite occur, with lesser amounts of sphalerite and magnetite.

PREVIOUSLY RELEASED SUPERZONE HIGHLIGHTS

  • Hole RLE004 Intersects 0.34 m of 5.41% Cu, 0.27% Zn, 1.58 g/t Au,
    and 7.57 g/t Ag (May 17, 2011)
  • Hole RLE006 Intersects 7.18 m of 7.44% Cu, 0.23% Zn, 0.48 g/t Au, and 7.57 g/t Ag
    and 44.9 m of 0.79% Cu, 0.39% Zn, 0.16 g/t Au and 1.58 g/t Ag (May 17, 2011)
  • Hole RLE007 Intersects 2.23 m of 5.94% Cu, 0.27% Zn, 0.40 g/t Au and 5.50 g/t Ag
    and 24.70 m of 0.21% Cu, 1.18% Zn, 0.08 g/t Au and 0.79 g/t Ag (August 9, 2011)

DRILL SUMMARY FOR THE HUDBAY JV AND OPTIONED PROPERTY PACKAGES: MARCH THROUGH SEPTEMBER, 2011

  • Reed Lake joint venture: two holes were completed for a total of 724 metres,
  • Super Zone option: nine holes were completed for a total of 2,482 metres,
  • Tower Zone option: one hole for a total of 1,082 metres,
  • Northwest option: three holes completed for a total of 820 metres and
  • Northeast option: one hole for a total of 349 metres.

One drill will continue to explore the option properties concentrating on the Reed North discovery zone until winter freeze up.


DARNLEY BAY – summer results and discoveries

Posted by on Tuesday, 14 September, 2010
Base Metal Targets
The exploration and drill targets for base metals, shown in Figure 1, were prepared from analysis and modelling of the recently completed gravity, electromagnetic and magnetic surveys flown over a large portion of its properties near Paulatuk, NT. The analysis was prepared in conjunction with mapped geology, topography, satellite imagery and previously acquired airborne and ground geophysical data.
The following provides a summary of the 41 separate base metal exploration targets selected as a result of the analysis and modelling:
Gravity (22 targets) 76 km2; Magnetic (7 targets) 108 km2; Electromagnetic (12 targets) 54 km2.
The methods indicate the data type where the target is most evident, although many targets incorporate coincident or complementary geophysical responses from at least two data types. The base metals targets are broken into several categories, depending on the nature of their responses and their estimated depths. Nine of these targets are designated for assessment by geological prospecting and sampling as they may outcrop.
Location map showing the 41 base metals targets on the 100%-owned properties of Darnley Bay Resources Limited. The red dashed outlines indicate the two areas of highest priority for follow-up.
3D Gravity Modelling
Geoscientists study the earth’s gravity field to determine the density of the rocks in the subsurface. Changes in density from surface to tens of kilometers in depth affect the gravity field that we measure. The more basic (mafic) classes of igneous and metamorphic rocks, and most metallic minerals, have higher densities and produce stronger gravity responses. The 132 mGal Darnley Bay gravity anomaly is perhaps the strongest of its kind in the world, reflecting an isolated intrusion.
In 2007, Darnley Bay contracted Mira Geoscience, through its Vancouver office, to apply 3D modelling to the ground gravity and airborne magnetic data available over the Darnley Bay anomaly and surrounding region. A 3D model of a large, deep-seated mafic/ultramafic intrusion was developed to explain the anomaly on a regional scale. The effect of this model was subtracted from the gravity and a more detailed model of the upper 10 km of the earth’s crust was prepared from the residual gravity field, to ascertain the shape of the anomaly source at depths of economic interest. The modelling in 2007 resulted in the reassessment of the geological models to explain the anomaly source and its mineral potential. Darnley Bay realized that it required gravity data in much greater detail before embarking on a drill program.
Northtech Drilling Ltd. commenced drilling Darnley Bay’s first 2010 base metals target on August 28.
Target EM-8 is currently being drilled, an electromagnetic anomaly with coincident magnetic response interpreted from the 2010 VTEM survey (see target map on the home page at www.darnleybay.com). It will be followed by target M-7, a magnetic anomaly with coincident electromagnetic response. Both drill holes are at 65° from the horizontal with a length of 300 m. Concurrently, other targets are being followed up on the ground with gravity and magnetic surveys, and geological prospecting, to prioritize targets for the continuing drill program.
The airborne gravity survey (Sander Geophysics) completed in April 2010 confirmed the size, shape and amplitude of the Darnley Bay anomaly and greatly improved the resolution and detail. Mira Geoscience was once again contracted to prepare a 3D model. Mira utilized the same regional model for the intrusive body and prepared a new model of the upper 10 km of the earth’s crust from the airborne survey’s residual gravity field. It utilized the free-air gravity field and incorporated a correction for the surface topography. Since the surface rocks incorporate a range of gravels and sediments with different densities, their effects cannot be fully corrected for and as a result, some topography is visible in the model.
The software used to prepare the new 3D model is Mira’s implementation of the GRAV3D module developed by the Geophysical Inversion Facility at the University of British Columbia.  The 3D inversion was constructed as follows:
1. Preparing a representation of the earth as a volume measuring 63.5 km E-W by 66.0 km N-S by 10.25 km vertically. The cells within the volume measure 500 m x 500 m x 250 m.
2. Implementing geological constraints, incorporating the sediments mapped on surface and their densities, and the log of Darnley Bay’s 2000 drillhole.
3. Applying the GRAV3D inversion, which determines a geologically reasonable density to each cell in the model while best-fitting the observed gravity data. This process takes several days of continuous iteration on a massively parallel computer.
The result is a 3D volume model where the density varies between each cell. For display purposes, a series of density surfaces are extracted from the model to better appreciate the geometry and concentrations of higher density material.
DISCOVERY OF THREE KIMBERLITE PIPES
Darnley Bay Resources Limited and Diadem Resources Ltd. announce that they have completed the first phase of 2010 drilling on their 50/50 joint venture package of 33 claims on the Parry Peninsula, Northwest Territories. Of the four targets drilled, three have resulted in the discovery of new kimberlite pipes. These are in addition to the ten kimberlite pipes discovered in 2000, of which six have proven diamondiferous. The kimberlite material intersected in the 2010 drilling is being prepared for shipping to CF Mineral Research Ltd. in Kelowna BC for analysis.
Darnley Bay and Diadem are quite encouraged by the initial success of the drill program. Numerous high priority targets remain untested. The results of this first phase are being incorporated in planning for the second phase of 2010 drilling, as well as determining the targets that are better suited for drilling from frozen lakes in February-April 2011. Diadem is funding the 2010 program.
Hole MT112-01
This hole targeted a 1.7 ha ground magnetic low of 10 nT amplitude, partially covered by a lake. It intersected 15.35 m of kimberlite, hosted in dolomite. The kimberlite intersection is described as “Dark green to black, fine grained matrix consisting of dark green ferro-magnesian minerals and 10 to 35% green partially altered olivine and peridotite fragments, some being completely talc altered. Contains numerous greenish, subrounded possible mantle derived fragments to 100 mm.”
Hole MT102-01
This hole targeted a 3.6 ha ground magnetic low of 325 nT amplitude, partially covered by a lake. It intersected 7.6 m of kimberlite, hosted in dolomite. The kimberlite intersection is described as “Dark gray to blackish-green, massive, fine to medium grained kimberlite (micro breccia). The mass of the kimberlite comprises dark green 1-5 mm mafics in a white clay – calcite matrix.”
Hole MT10-03
This hole targeted a 10.2 ha ground magnetic low of 105 nT amplitude, partially covered by a lake. It intersected 0.6 m of kimberlite, hosted in dolomite. The kimberlite intersection is described as “Dark gray to black, loose packed, sub-rounded to sub-angular wall rock and some mantle derived fragments in a fine to medium grained matrix. Fragments consist of 1 to 25 mm black mudstone and chert, gray dolomite and some greenish-gray, rarely apple green, serpentinised mantle-derived xenoliths.”

The new Matagami-type VMS Camp

Posted by on Monday, 31 May, 2010
MacDonald Mines Exploration  has announced today that the 2010 exploration drilling program on its McNugget Property has discovered new volcanogenic massive sulphide (VMS) mineralization of substance. Preliminary assays are reported below with follow-up full assays pending and will be reported when received. An analysis of technical data completed in February 2010 found magnetic and electromagnetic (“EM”) targets that were not previously explained. During the May portion of the 2010 drilling campaign, a Crone Geophysicsdown-hole EM system was used for drill target control – it has been established that McNugget VMS horizons show strongest conductivity where copper (Cu) content is highest.
A new VMS camp with characteristics similar to those seen at Matagami or Noranda in Quebec is now conceivable (i.e., larger VMS deposits with satellite deposits along strike).”
Massive sulphides were intersected in all May 2010 drill locations with widths varying from 2m to greater then 30m. One of the drill sites (two holes) on the McNugget Property intersected massive magnetite as well as associated ultra mafic materials. This location is characterized by a long magnetic high (magnetite) with an associated electromagnetic conductor (VTEM). These characteristics are very similar to those of the Freewest/Cliffs chromite discovery. The core from these two intersections is currently being tested for chromite. Additonal geophysics will be planned along this long trend (1.5 kilometres) to aid in interpreting the potential of this zone to host chromite.
Big Mac Property
MacDonald’s February 2010 re-interpretation created an initial program of 5 high-priority high-resolution ground gravity survey transects for both chromium (Cr) and nickel-copper (Ni-Cu) mineralization. Transect models were based directly on known mineralization signatures discovered within the “Ring of Fire”. The Company’s claim block contains both discrete and strike-extensive coincident airborne magnetic-VTEM and gravity anomalies within stratigraphically favorable geological packages with geophysical signatures similar to the significant Cr discoveries of Freewest and KWG-Spider near McFaulds Lake. Three gravity drill targets all exhibited anomalous densities coincident with local magnetic trends and have been interpreted to be steeply plunging dense bodies. Drilling was completed on one these targets in April 2010. Assays are pending. One of the gravity transects identified a density anomaly coincident with a discrete conductivity (VTEM) anomaly and offset magnetic feature that will be drill investigated for nickel.
Hulbert-Salo Property Exhibits Voisey’s Bay-type Targets
MacDonald is designing an exploration program for its highly prospective Hulbert-Salo Property which appears to host an intact intrusive complex with potential for Voisey’s Bay-type targets, as interpreted by Dr. Larry Hulbert. The Company’s airborne geophysical survey (VTEM) outlined very conductive, discrete targets within a layered magnetic structure. The high conductivities observed are typical of magmatic massive sulphides containing nickel. To optimize the Company’s chances of success, a surface time domain geophysical survey is being designed that will focus on the potential nickel targets. A Crone Geophysics‘ system will be used in the event that other more conductive (superconductors) and/or deeper targets were not detected by the airborne survey.
Exploration to Recommence June 2010
The next phase of exploration will commence in late June 2010. MacDonald believes that there is potential for its James Bay properties to host both Nickel and Chrome on the McNugget, Big Mac and Hulbert/Salo Properties.
As the assays become available, 3D target modeling will be based on assays, geology, magnetic susceptibility, conductance and so forth. Further drilling will provide greater detail on three selected VMS targets as well as the strongest potential Ni-Cu targets. It is anticipated that deeper drilling will be required to test the high conductance targets mapped by the geophysical programs used during May.

Pigeon River – the new geophysically promising area

Posted by on Sunday, 14 March, 2010

In January 2009, Pele Mountain announced the staking of more than 1,000 mining claim units totaling approximately 18,750 hectares in the Pigeon River area of Northwest Ontario, about 80 kilometres west of Thunder Bay. The 100-percent owned property covers very large unexplored magnetic targets with potential to host nickel (“Ni”), copper (“Cu”), and platinum group elements (“PGE”) mineralization.

The property lies in the Proterozoic Superior Mid Continent Rift, a geological setting with proven potential to host mafic-ultramafic igneous systems associated with the rifting of the Archean cratons.  Pele’s exploration target at Pigeon River is a massive sulphide deposit similar to recently discovered magmatic sulphide deposits hosted in an ultramafic body or conduit, such as Kennecott`s Ni/Cu/PGE deposits at Eagle (in Michigan) and Tamarac (in Minnesota) and Magma Metals’ PGE deposit northeast of Thunder Bay.

Pele Mountain Resources Inc. March 5, 2010  announced the completion of a 1,015 line-kilometre Versatile Time-Domain ElectroMagnetic (“VTEM”) airborne survey over its Pigeon River property in the Thunder Bay area of Northern Ontario. Pele has staked more than 500 additional mining claim units since introducing the project in January and its total land package now exceeds 24,000 hectares (240 km2). Pele President and CEO Al Shefsky stated, “Our property is ideally situated in the Mid Continent Rift, near the basal contact of the Duluth Complex. The survey shows magnetic and conductive trends with similarities to known Ni/Cu/PGE deposits in similar geological settings. We are particularly encouraged by the correlation of conductivity with a known, anomalous, Geological Survey of Canada (GSC) Ni/Cu lake sediment sample. These results have increased our confidence in the potential of the Pigeon River property and we will prioritize exploration in this area in the months ahead.”
The VTEM survey was flown over the Pigeon River East Block by Geotech Ltd. of Aurora, Ontario. The survey has defined linear magnetic features with the potential for mafic/ultramafic conduit systems and feeder dykes into larger mafic/ultramafic intrusions. Preliminary analysis by the geophysical contractor indicates the presence of a number of, possible sulphide-related conductors, coincident with conduit-type magnetic features and other, larger, conductive anomalies with similarities to known mineralized layered mafic/ultramafic complexes. Conductive zones, possibly sulphide-related, are also found in the vicinity of a GSC lake sediment anomaly which gave anomalous values of 234 parts per million (ppm) Ni and 298 ppm Cu. Geotech has identified several high-priority, drill-ready, targets from the survey. Other priority targets require further definition through prospecting and follow-up geophysical surveys, which are planned after spring breakup. The targets are generally till or swamp covered and no previous prospecting, mapping, or geophysical surveys, other than an airborne magnetic survey flown by the GSC in 1964, are known.

HudBay Minerals wins award for pushing deep hole geophysics technology that led to discovery

Posted by on Tuesday, 9 March, 2010
HudBay Minerals Inc.’s geophysics team, led by Alan Vowles, and its exploration team, headed by Kelly Gilmore, has presented with the Bill Dennis Award for a Canadian discovery by the Prospectors and Developers Association of Canada (PDAC). The award recognizes the company for its Lalor zinc discovery near Snow Lake, Manitoba, and presented on March 2, during the PDAC’s annual convention in Toronto.

The Lalor deposit was discovered in March 2007. The deposit is located in the Chisel Basin portion of the Flin Flon Greenstone Belt and is believed to be the largest VMS deposit found in this region to date.

Zinc rich base metal zone: Mineralization occurs in six separate stacked lenses of zinc rich polymetallic near solid to solid sulphide mineralization approximately 570 meters to 1,170 meters below surface. In October 2009 an Indicated Resource of 12.3MT 1.6 g/t Au, 24.2 g/t Ag, 0.66% Cu, 8.70% Zn, and an Inferred Resource of 5.0MT 1.4 g/t Au, 25.5 g/t Ag, 0.57% Cu, 9.39% Zn were disclosed.

Gold zone: Low sulphide precious metal intersections associated with chalcopyrite and galena. In January 2009, HudBay reported the discovery of a new gold zone with the potential to have principal credits derived from gold mining and on October 8, 2009 announced a conceptual estimate of a potential gold zone, interpreted as five discrete mineralized lenses that can contact the near solid sulphide zinc rich mineralization.

Copper-Gold zone: Disseminated to near solid chalcopyrite with lesser pyrrhotite and minor pyrite, sphalerite and galena located to the north of Gold zone 27 at approximately 15 to 20 degrees down plunge and at vertical depths of between 1,200 and 1,300 meters.

For more details on the Lalor deposit, including the resource estimate for the zinc-rich base metals zone and the conceptual estimate of the potential Gold zone, please refer to the NI 43-101 compliant technical report for Lalor dated October 8, 2009 and the company’s September 22, 2009, October 8, 2009 and December 17, 2009 news releases, available at www.SEDAR.com.

The Lalor deposit is approximately 15 kilometers from HudBay’s concentrator in Snow Lake, Manitoba, an area that is a significant past producer of gold. The ongoing evaluation, exploration and development of the Lalor deposit is a primary focus for the company, as the Lalor deposit could be of significant financial benefit to HudBay and support substantial long term activity in the Snow Lake area.


EM geophysics on VMS Vetures Inc. projects in Manitoba

Posted by on Monday, 22 February, 2010

 

The RN-10-05 hole, targeting an airborne geophysical survey (VTEM) anomaly, has been started, with an anticipated hole length of 500 m. These holes are testing targets in the Magoo Lake area, located approximately 1.5 km northwest of the Discovery Zone. Five additional holes ranging in depth between 325 m and 700 m are planned and will target VTEM, DeepEM surface survey and Borehole Pulse EM geophysical survey anomalies. Total drilling anticipated in this program is estimated to be 3,000 m.

Hole RN-10-10 will target a large conductive modeled plate near the recently completed drilling on the Tower Zone, and is planned to be 700 m in length. Company geologists have recognized the potential extension of the Discovery Zone rhyolite in this area. This target will be drilled later in the program, as it can be drilled from ground that is accessible all year round.

Deep penetrating ground geophysical surveys have identified new conductive targets northeast and along strike of the Tower Zone over a strike length of approximately 1 km. These are untested anomalies and deeper than any previously drilled in the northeast Tower area. Three holes, each testing a new anomaly, will be drilled. Anomalies have been modeled below 300 m from surface. Hole RN-10-09 will test the deepest target in the area and has a planned length of 700 m.

drill holes RN-10-07 and RN-10-08 will test geophysical conductors located in the vicinity of an historical drill hole which reported multiple intervals of disseminated, stringer and near solid to solid sulphide, with anomalous copper, zinc and silver values in altered volcanic rock. Reprocessed historical geophysical survey data, including bore hole survey data, has been merged with VMS VTEM airborne survey data and more recent ground deep EM survey results.

These three drill targets, located on mining claim P6805E, are spatially associated with the Company’s recent surface pulse electromagnetic survey that outlined several highly conductive plates directly associated with, or flanking, a magnetic response.

A VTEM anomaly with a coincident magnetic high defined on mining claim P5643E will also be drilled. It is located approximately 2 km east-northeast of the Phase 1 Tower Zone drilling area.  This target has a lateral extent of over 700 m and based on modeling of electromagnetic data is suggestive of stacked conductive zones. Historical drilling results in the area have reported strongly altered volcanic rock and sulphide mineralization with anomalous copper and zinc. The geological setting of these conductors is interpreted to be very favorable for hosting base metal massive sulphide-type deposits of the Flin Flon-Snow Lake belt.

Drilling on mining claim P1019F will target two separate VTEM anomalies near Magoo Lake.  Historical work completed by Noranda Exploration in this region outlined highly anomalous copper and zinc values in a highly chlorite-altered volcanic host rock. This geological setting is also favorable for the formation of base metal massive sulphide mineralization and two holes are planned to test the targets.


DC resistivity and IP survey over Tesoro Gold Project in Peru

Posted by on Friday, 12 February, 2010

Everyone can look at the results of Titan-24 survey over the Gold Project.

Maps direct link http://www.steliasmines.com/titan24/images.pdf and interpretation model sections http://steliasmines.com/titan24/titan2d_xsectionFigures.pdf

St. Elias Mines Ltd. is owner of the Tesoro Gold Property located in Peru.  The Property covers approximately 1,700ha and is located in the Acari District within the prolific Nazca-Ocoño gold belt of southwestern Peru.  The Nazca-Ocoño gold belt is a 300km x 30km belt paralleling the Pacific coast of southwestern Peru.  Gold is associated with disseminated sulfides that seeped into quartz veins or rock fractures within the intrusive body.  The continuity of the quartz veins and fractures is very impressive in the Nazca-Ocoño belt since these veins are often hosted within fractures and shears that show continuity along several kilometers.  To date, more than 70 gold deposits have been exploited in this region since as early as the 17th century.
The veins located immediately north of the Property are being mined by Dynacor (TSX-DYN) who published an inferred gold resource of 606,611 ounces at 16.4g/t (on only 3 of 10 veins discovered to date).  The veins located immediately south of the Property have been in continuous production since the 1970’s and have produced over 700,000 ounces to date.  These veins have been mined over a 2,000m strike length to a depth of 1,000m.  Barrick Gold has recently acquired claims that adjoin St. Elias’ Property to the south.

Since the Property acquisition in March 2004, the Company has completed a Phase I exploration program and a Phase II exploration program is ongoing.  Prior to these programs, the Property was primarily unexplored.

The Phase I program consisted of control grid emplacement, reconnaissance geological mapping and prospecting over the entire Property, detailed geological mapping and sampling of all identified veins, trenching and sampling of wider structures that flank the veins and underground sampling of the Canchete 1 vein.

Since the completion of the Phase I program, the Company has assessed and prioritized the five main concentrations of gold mineralization (“zones”), as well as, other gold bearing areas within the Property.

The Phase II exploration program is ongoing with initial exploration efforts focused on the Zona Canchete Vein #1 (“ZCV#1”).  The ZCV#1 is a first priority target and is one of eight gold-bearing quartz veins located at Zona Canchete.

The Phase II program consists of detailed geological mapping, sampling, development of additional underground workings and the collection and processing of an initial 150-200 tonne bulk sample at the ZCV#1.  This work will assist in determining the horizontal and vertical extent of the vein, as well as, the vein’s physical and gold grade characteristics.

Detailed sampling from the existing underground workings confirms that both the gold values and the vein width are getting stronger with depth.  On the 40m-level, the overall grade and continuity of the veins are improving with distance away from the winze both to the east and to the west.  For example, the average grade of the vein between 10.5m east and 22.6m east (a distance of 12.1m) is 3.0 oz/T gold.  The average grade of the vein between 20m west and 24m west is 1.36 oz/T gold over an average vein width of 31.6cm.

St. Elias Mines Ltd.  provides further information following the recently announced results from the Titan 24 Geophysical survey conducted by Quantec GeoScience Limited on the Property.


18 CONDUCTORS IDENTIFIED FROM NARRACOOTA (Australia) VTEM SURVEY

Posted by on Tuesday, 9 February, 2010
Richmond Mining Limited announces that 18 anomalies have been defined from the initial review of the VTEM survey flown to detect for bedrock conductors under cover at the Narracoota project (http://explorationgeophysics.info/?p=509) , 80 kilometres north of Meekatharra Western Australia. Preliminary analysis of the versatile time domain electromagnetic (VTEM) data has initially highlighted 18 VTEM conductors within the Narracoota Volcanics, the same rocks hosting Sandfire Resources’ DeGrussa VMS copper-gold discovery. The initial review has noted that three of the anomalies are near historic drill holes with elevated copper values in weathered rocks.
Figure below shows the electromagnetic response for the dB/dT of Channel 25 of the VTEM data and can be considered to represent conductive responses in the target rocks at 80-100 metres depth. Some initial anomalies have been selected from other VTEM channel responses, which are not represented by the Figure. Some strong responses apparent in Figure have not been selected as anomalies as they are considered to be due to the current Murchison River drainage system and its ancient tributaries or palaeochannels.

Final results from VTEM survey in Australia confirm existence of at least 13 copper-gold targets

Posted by on Monday, 8 February, 2010

Alchemy Resources Ltd announced today that it is about to embark on an aggressive exploration drilling campaign which will see it test at least 13 copper-gold targets adjacent to Sandfire Resources NL’s Doolgunna discovery in the Gascoyne region of Western Australia. Alchemy’s Managing Director Michael Hannington said the Company has received the final results from its VTEM survey in recent days and has commenced the interpretation and assessment of the data. The final interpreted results will be released to the market within the next few weeks. Drilling at Alchemy’s Magnus Project is scheduled to start in early March 2010 and will initially test 13 bedrock conductors identified by its extensive VTEM survey. Three of these conductors span the border between Alchemy’s tenements and those containing Sandfire’s high-grade Doolgunna copper-gold orebody. A separate VTEM survey carried out by Sandfire also identified these three conductors. Mr Hannington, who is a qualified geophysicist with 20 years experience, said the 13 EM targets resulting from the survey were strong and persistent bedrock conductors, sparking the Company’s decision to accelerate the exploration program and its commitment to drill testing every one of them. Alchemy’s tenements at Magnus cover 178km2, extending from the Sandfire border on the western side. They are also located on the same Narracoota Formation which hosts Doolgunna. “The latest results from the VTEM survey give us every reason to be optimistic about the prospectivity for copper-gold mineralisation at Magnus,” Mr Hannington said. “These strong EM anomalies, combined with the fact that our tenements boast the same key geological characteristics as Sandfire’s ground, have prompted us to accelerate an extensive drilling program to explore the full potential of Magnus.” Alchemy expects the drilling program to generate a steady flow of news over coming months, with the first assay results due in early April 2010.



Aggressive geophysical activity of Pure Nickel in Alaska

Posted by on Friday, 5 February, 2010

The 2009 Exploration Program at the MAN, Alaska project included a new ZTEM airborne survey (Z axis Tipper Electromagnetic system), extensive geological mapping and a proprietary fluxgate time domain ground EM surveys (full waveform streaming multi sensor fluxgate array).  The 2009 geophysical programs (ground fluxgate TEM, ZTEM, and BHEM) were considered a great success.  These very compelling geophysical targets, are the best discovered to date on the MAN property and the foundation for a productive 2010 exploration program.

3D inversions of aeromagnetic data, as well as several widely spaced deep drill holes show a consistent presence of abnormally thick ultramafic bodies with localized deep feeders. Last year’s results add to the evidence that the MAN property is the main intrusive centre for Triassic magmatism that generate the extensive nickel, copper and PGE (platinum group elements) bearing ultramafic intrusions and coeval lavas within the Alaska, Yukon and BC, segments of the Wrangelia terrain.  Drill results to date come from the holes targeted using the proprietary ground time domain EM survey (TEM), in conjunction with the new ZTEM airborne survey and previous ground gravity and VTEM airborne surveys.

Interpretation of the 2009 MAN drilling results assays indicates the presence of a disseminated NI-Cu PGE (platinum group elements) concentration build up extends beyond 600 meters in DDH PNI-09-024 and over 1000 meters in DDH PNI-09-025.  Geophysical surveys show that these conductive bodies are associated with the strongest Fluxgate TEM anomalies on the property,  in addition, strong responses to the BHEM surveys indicates late channel (high conductance channels) conductivity build up beneath the drill holes.

The surveys described below were used to model the interpretation of conductive anomalies on the property. The analysis concludes that the anomalies are deep, large and very compelling.

  1. ZTEM Survey – has for the first time identified at depth the shape structure, and conductive zones of the mafic and ultramafic intrusions.
  2. Ground TEM – proprietary long time constant, time domain electromagnetic surveys allowed for deep search (> 800 meters) for high conductance bodies commonly associated with Ni-Cu sulphides that have been missed by previous surveys methodologies.
  3. Ground and Airborne Magnetic Survey’s – these survey’s help to define the magnetic bodies below surface that often correlate to the ultramafics and mafic rocks on the property.  In addition, UBC 3D inversions and Euler 3D inversions are employed to help determine the location of the form, internal structure, and deep kneels or feeder dykes associated with the intrusive bodies.
  4. BHEM Survey – a borehole electromagnetic survey is performed down the drill hole to detect conductive anomalies within, beside and below the drill hole to aid in the correlation with the new high priority, long time constant, surface TEM survey results constraining more accurate location of the conductor.

One of the most exciting targets from the 2009 geophysical program was the identification of the location for drill-hole PNI-09-025 based on the initial results from the TEM surveys.  The hole was drilled to a depth of 1066 metres and terminated due to the limitations of the drill.  The BHEM (down hole geophysical survey) showed an increasingly large response towards an anomaly below the hole’s final depth.

Low-frequency borehole electromagnetic surveys (BHEM) were carried out in five of the 2009 drill holes, as well as seven older drill holes. A number of moderate to strong off-hole conductors were detected and are being evaluated as follow-up drill targets for the 2010 program. Three holes (07-001, 09-023 and 09-025) show anomalous increases in late time channels indicative of deep conductors below the base of the holes. These deep conductive zones correlate with high-priority long time-constant surface TEM anomalies.

Extensive geophysical work was conducted concurrent to the drilling program.  In particular, a new ground time domain EM system (full waveform streaming multisensor fluxgate array), was deployed extensively through the latter half of the exploration season.  This was the first instance of this technology being used in North American nickel exploration.  This ground based EM technology developed by Dr. Mark Shore (Magma Geosciences Inc.) provided Pure Nickel exploration team with the ability to collect low-noise late time data under challenging conditions and identify electromagnetic anomalies at greater than  800 metres depth.

Dr. Mark Shore is going to represent example of using of lower frequencies induction coil, SQUID and fluxgate sensors on the nearest PDAC in Toronto: http://www.pdac.ca/pdac/conv/2010/pdf/presentations/ts-mark-shore.pdf.


Snow Lake projects under support of geophysics

Posted by on Thursday, 28 January, 2010

One of the known volcanogenic massive sulphide (VMS) districts is  Snow Lake which is located in central Manitoba. The VMS mineralization is associated with juvenile rocks of the Flin Flon greenstone belt. The belt is one of the most prolific VMS belts and the largest Paleoproterozoic VMS district in the world. There are several recent examples of geophysical supporting of the exploration programs on the region.

At the end of last year Rockcliff Resources Inc. announced that Geotech Ltd. of Aurora, Ontario has commenced a 3,000 line kilometre airborne survey on the Company’s Snow Lake VMS Project. The ZTEM survey focused on Rockcliff’s Squall and Tramping Properties. Both properties are located approximately 6 km north and south of HudBay’s recently discovered (2007), buried Lalor Deposit where recent deep drilling intersected a new gold/copper zone grading 34.5 m of 5.33% copper and 13.35 g/t gold. The survey also covered Rockcliff’s five near surface copper-rich deposits and additional areas with VMS potential. The survey has the capability of locating conductive bodies down to depths of over a kilometer.

The purpose of the survey was to integrate Rockcliff’s existing VTEM database (13,000 line km) on the project with Geotech’s state of the art ZTEM geophysical technology. The combined surveys allows for complete geophysical coverage and locate conductors buried from near surface to depths in excess of a kilometre. All conductors identified in the survey prioritized based on their conductivity, resistivity and proximity to juvenile arc rocks.

The survey utilized Geotech’s ZTEM or Z-Axis Tipper Electromagnetic system, an innovative airborne EM system which uses the natural or passive audio frequency fields of the Earth as the source of transmitted energy.

Now Rockcliff Resources Inc. announces the drilling program. A minimum of 5,000 metres (m) of drilling are planned in approximately 30 holes. Drilling is planned on the Rail, Reed, Freebeth, Tramping and Squall properties. The targets include extensions of a known copper-gold rich horizon (Rail), additional testing of DPEM & BHPEM anomalies (Reed), an untested borehole anomaly (Freebeth) and untested, buried ZTEM targets (Tramping and Squall). Drilling at the Reed property will focus on a series of deep, off-hole anomalies indicative of multiple, stacked, highly conductive lenses with conductivities typical of massive sulphide mineralization. Four off-hole anomalies at vertical depths of 500 m, 750 m, 880 m and 930 m will be tested.

VMS Ventures Inc. has completed  its diamond drill testing of phase one targets, at the Tower Zone, on  its 100% held Reed 5188 and Reed 5196 claims.  The program consisted of three holes and the extension of a previous hole for a total of 1809 metres.   Diamond drill hole (TZ-08-01) was extended to assess a Borehole Pulse Electromagnetic (BHPEM) anomaly. All drill holes intersected sulphide mineralization explaining the Surface Pulse Electromagnetic (DPEM) and coincident Versatile Time-Domain Electromagnetic (VTEM) anomalies. The Super Zone has been defined on the basis of “AdTau” (see image 2), which is a calculated measurement derived from the analysis and interpretation of VTEM data. AdTau is a direct indication of rock conductivity. The metal-rich mineralization that comprises VMS-type deposits typically produces strong conductivity responses. The 550 hectare Reed Lake Super Zone is interpreted to be highly prospective for this style of deposit. The Company is building its Super Zone exploration plans based on the hypothesis that it may host a VMS camp of several deposits.

Deep-EM and Magnetic Survey Results Map

Troymet Exploration Corp.  announces the commencement of its winter program on the McClarty Lake project located near Snow Lake, Manitoba. The property lies ~45 km south of HudBay Minerals’ Chisel Lake and Lalor Lake volcanic massive sulphide (VMS) deposits.

The establishment of a 10.6 km grid on Troymet’s 100% owned MAC 3 claim is expected to be completed this week, followed by a fixed large loop surface pulse electromagnetic (PEM) survey under contract to Crone Geophysics of Mississauga, Ontario. The grid is centred over the Mac EM conductor that was identified by the Company’s 2008 deep penetrating VTEM helicopter-borne survey and is on trend with the Discovery zone.

The Mac conductor is a high priority target that offers the potential for immediate and significant new VMS discoveries on 100% owned Troymet ground. A 2010 winter diamond drilling program (~1,500 metres) is planned to follow up on results of the PEM survey.


The geophysical basis of Cree East uranium project

Posted by on Wednesday, 27 January, 2010

CanAlaska Uranium Ltd. has commenced exploration on its Cree East uranium project in the Athabasca Basin, Saskatchewan, Canada.



Previous geophysical modelling and initial drill tests have outlined four zones of uranium mineralization and hydrothermally-altered rocks associated with major basement offsets along a 4 km mineralizing trend. Drill-hole spacing in the target areas from previous drilling in 2008 and early 2009 is from between 100 to 200 metres. Most of the 2010 targets are located between existing holes, or are short step-outs from existing holes. The new drilling will attempt to cross-cut the fault and alteration modelled by the existing holes, geology and geophysics.

Additional targets on the Cree East project have been defined following intensive airborne and ground geophysical work over summer 2009.

CanAlaska carried out VTEM airborne surveys across the property area in 2005 and determined priority targets. In 2006, detailed collection of over 2,000 surface rock samples and over 400 lake sediment samples by CanAlaska’s field crews defined three large areas of dravite and clay alteration on surface, and localized boulder samples containing anomalous uranium. Before April 30, 2007, initial ground geophysical data from the first lines of IP-Resistivity surveys, provided the CanAlaska with evidence of strong alteration in the sandstone horizons overlying these basement conductors. Additional IP-Resistivity and Audio Magneto Telluric geophysical surveys were used to further define these targets this year. Drill programs started on the project in late February 2008 and large zones of alteration were intercepted. Extreme clay alteration and unconsolidated sands prohibited the CanAlaska from completing the majority of the drill holes.

During the summer of 2008, CanAlaska undertook a multi-faceted $1.6M exploration programme at its consisting of IP/Resistivity surveying on land and high-resolution single channel seismic data collection on Cree and McIntyre Lakes, lake sediment sampling on Cree Lake, and a 5- hole diamond drilling programme. All of the drill holes reached their target depth in basement.

In summer 2009 detailed geophysical surveys, and infill VTEM surveys were used to prioritize target areas for 2010 drilling.


Wildcat’s EM targets are drilled

Posted by on Monday, 11 January, 2010

The Wildcat project is located 90 kilometres west of Watson Lake, in the Rancheria District of southern Yukon, Canada.  1,940 hectares in size (19.4 sq km), widespread silver-lead-zinc mineralization occurs across the property. Mineralization on the Wildcat was discovered in the early 1940s where early work focussed on a series of narrow, high-grade argentiferous galena veins and fracture filings, hosted primarily within dolomite and limestone.  More recent work, including diamond drilling in the mid 1980s, was directed at the ‘Main Zone’, a zone of manto-style silver-lead-zinc mineralization.

From 1983 – 85 most work tested a large gossan zone in the central part of the property (the Main Zone). Butler Mountain Minerals completed a Pulse EM survey over the gossan zone and identified a strong, 600 meter long, north-northeast trending conductor. From 1983-85, 35 diamond drill holes were drilled, the majority of which tested this target. Drilling successfully intersected multiple zones of massive pyrrhotite-sphalerite mineralization, with results including 12 feet grading 6.2% Zn, 1.09 oz/t Ag and 0.32% Pb (ddh 83-3), 7 feet grading 5.06% Zn and 9.86 oz/t Ag (ddh 83-6), and 10 feet grading 11.58% Zn, 1.05 oz/t Ag and 0.7 % Pb (ddh 85-10).

During 2008, Killdeer Minerals Inc. completed a horizontal loop electromagnetic (HLEM) survey over the central portion of the Wildcat property. The purpose of the survey was to confirm, re-locate and better define the EM conductor at the Main Zone, as a guide to subsequent drilling, and to test for other conductors elsewhere on the property.

Seven HLEM conductors were identified by the Killdeer Minerals’ 2008 survey. Two of these anomalies are high priorities for follow-up, anomaly H-A (the Main Zone anomaly) and anomaly H-F (1 kilometer to the northwest of H-A) on the lower east flank of Little Guy Hill.

The Main Zone HLEM anomaly is a 1200 meter long, complex north-northeast trending conductor, which is coincident with Pulse EM and VLF-EM conductors identified by previous surveys and with a significant positive magnetic field response. Based on the geophysical response, two styles of mineralization are interpreted, a north-northeast trending, steeply west-dipping mineralized fault zone and, east of this, moderate east-dipping conformable sulfide mineralization, on the east flank of an anticlinal structure. The associated positive magnetic field response results from the pyrrhotite-dominant mineralization. While the fault-controlled mineralization is well tested by previous drilling, drilling has been poorly oriented to test for east-dipping mineralization east of the fault. This is a high priority for follow-up drilling. The other high-priority target for follow-up drill testing is a 200 meter long, north-northeast trending HLEM conductor, also with an associated positive magnetic response, located 1 kilometer to the northwest of the Main Zone in an area of widespread manganese gossan and elevated soil geochemistry.

One of the 2009 drill holes tested a HLEM conductor related to a distinct tectonic zone situated approximately 900 metres east from the Main Zone. At shallow depth the hole intersected a very strongly leached, stratabound zone of limonite-hematite mineralization enriched in base metals related to paleo-karst settings. The hole did not reach target depth and due to technical problems was prematurely terminated in a fault zone enriched in gold related to pyrite-chalcedony mineralization.
Additional geological mapping, soil sampling and electromagnetic surveys are required to identify other geological settings favorable for occurrence of manto-style mineralization of
better integrity prior to further drilling of the Wildcat property.

The new geophysical targets – the new expectancies

Posted by on Friday, 8 January, 2010

PC Gold Inc. reports that more than a dozen excellent new targets have emerged from a recently concluded geophysical survey carried out over the Pickle Crow Gold Mine Property (details, below). The new targets, none of which have previously been drilled, lie beneath swamp both within the core mine trend and in areas lateral to it. Drill crews have been remobilized to the Property following the holiday break, and drilling of the first of these new targets has now commenced with a single shallow drill. To expedite testing of all targets while the winter cold-weather window allows, a second shallow-intermediate capable drill is expected to be added to the program later this month. This will bring to three (two shallow, one deep) the number of drills active on the Property. The two shallow drills will be active continuously in the January through April period, with testing of the new shallow targets to be concluded prior to spring break-up. Concurrently, drilling of a deep mother hole (PC-09-052) and wedges designed to test well below the deepest workings of the former mine will also continue.

In a press release dated June 1, 2009, the Company announced that potential exists for the Pickle Crow Gold Mine
Property to host previously unrecognized deposit types associated with sulphides, particularly beneath largely
unexplored areas of swamp and muskeg north and south of the core mine trend. In follow up, Quantec Geoscience
Ltd. carried out a 115 line kilometre magnetometer survey as well as a 70 line kilometre ground based Titan 24 DC
Resistivity / Induced Polarization survey, designed specifically to detect disseminated sulphides. The presence of
the new targets beneath previously unexplored portions of the Property is considered strongly encouraging.
Below is Geophysics (IP) grid lines over core mine trend / PC-Confederation contact and nearby areas, August 2009: