Posts Tagged Geotech Ltd.

EM surveys over Green Giant graphite property in Madagascar

Posted by on Tuesday, 24 February, 2015
FacebookTwitterGoogle+Share

by Alexander Prikhodko, 24 Feb., 2015

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

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

Geological position and characteristics of the property:

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

-Vertical to sub-vertical nature;

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

-Graphitic zones consist of multi-folded graphitic strata;

-Graphitic schist and gneiss with vanadium mineralization.

 Geologic map (magnetic field interpretation)

Green_Giant_quick_Mag

 

AEM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

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

____________________________________________________________________

DIGHEM survey

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

(conductors in red, resistors blue colors)

DIGHEMConVoxel

 

 

 

 

 

 

 

 

 

 

 

 

 

sections

 

condmap

 

 

 

 

 

 ________________________________________

VTEM survey

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

TAU

 

 

 

 

 

 

 

 

 

 

 

 

__________________________________________________

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

rdisections

 

 

 

 

 

 

 

___________________________________________

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

RDIvoxel

 


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

Geology For Investors about an airborne EM technology for exploration

Posted by on Monday, 1 December, 2014

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

ZTEM

 

 

 

 

 

 

 

 

Overview

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

History

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

How ZTEM works

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

What does a ZTEM survey look like?

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

A few Geotech case studies

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

Further reading

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

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


Unlocking Australia’s hidden mineral potential with geophysics

Posted by on Friday, 1 August, 2014

Dr Richard Blewett:

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

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

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

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

 

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

 

 

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

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

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

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


Advanced airborne geophysics technologies for new industry development and innovations in Kazakhstan

Posted by on Tuesday, 8 July, 2014

2 July 2014 – Astana, Kazakhstan

The President of Kazakhstan and the Government took part in the  meeting-report of the Ministry of Industry and New Technologies in the new high tech building “Nazarbayev Cener” (project of famous British architect Norman Foster) in Astana.

Astana- Nazarbayev Center

 

 

 

 

 

 

 

 

 

 

 

 

 

(“Nazarbayev Center”,  Astana)

Geotech Ltd., a world leader of airborne geophysics had been presented to the government, Prime Minister and the President. “Kazgeology” as a part of the Ministry is going to work together with Geotech Ltd. for geophysical surveying of Kazakhstan territory and providing the airborne geophysical service for exploration and mining companies in Kazakhstan and other countries of Central Asia.

Geotech-PresidentKazakhstan

(Keith Fisk, Managing Director of Geotech with the President Nursultan Nazarbayev)

GT-Minister

 

 

 

 

 

 

 

 

 

 

 

 

 

(with the Minister of Industry)

GT-clients

 

 

 

 

 

 

 

 

 

 

 

 

 

(future surveys discussions with Rio Tinto and Iluka Resources)

GT-interview

(Keith Fisk, Managing Director of Geotech  interview to central TV channel)

 

 

 


Geophysical Survey helicopter in promotional filming at Elko Regional Airport

Posted by on Tuesday, 24 June, 2014

ELKOGeotech takes to the air to figure out what’s underground with its geophysical surveys.

On Monday, a AW-119 “Koala” helicopter and an 85-foot geophysical survey apparatus were at Elko Regional Airport to film promotional footage for Geotech. The film crew works for Cineplex, a company based in Canada.

Geotech specializes in airborne geophysical survey systems, according to Field Operations Manager Darren Tuck. The company’s clients are usually mineral exploration businesses that are interested in starting up a mine, and use the survey to find promising mineral deposits, including coal, silver, iron and copper.

Tuck said an apparatus carried by a helicopter will produce an electromagnetic pulse into the ground it flies over. Those pulses reflect off magnetic readers, and Geotech makes a map of the area after the process.

“It provides our client with a map of what the underlying layers of a structure looks like,” Tuck said.

Geotech is a global company based in Canada. Tuck said the company has worked for local mines, although he wouldn’t name any of the company’s clients in order to protect their confidentiality.

Tuck said the Elko airport was selected as the location to film Geotech’s equipment, known as Versatile Time Domain Electromagnetic surveying. Tuck said Geotech has more than 30 VTEMs. The apparatus comes in a variety of sizes.

For information, visit www.geotech.ca.


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:  


World class geophysics for Republic of Kazakhstan

Posted by on Sunday, 6 April, 2014

April 3, 2014, Astana. Vice Minister of Industry and New Technologies of the Republic of Kazakhstan Nurlan Sauranbayev and Chairman of the Board of JSC “Kazgeologiya” Galim Nurzhanov met with the Ambassador of Canada Stephan Millar and leading world class Canadian geophysical companies Phoenix Geophysics and Geotech Ltd.

“I want to thank you for the meeting. I see great potential for fruitful cooperation in the field of exploration, “- said Stephen Millar. Vice Minister of Industry and New Technologies Nurlan Suranbaev suggested for further cooperation JSC “Kazgeologiya”, which held preliminary talks with the companies.

 

 

 

 

 

 


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

 

 

 

 

 

 

 

 

 

 

 

———————————————————————————————————-

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  .

 

 


Exploration drilling for gold initiated by airborne geophysics results in Ghana

Posted by on Friday, 14 February, 2014

Asante Gold Corporation  announces final results and interpretation of the exploration drilling completed to date on the Fahiakoba gold concession in Ghana.

Drill holes were spotted to test sections of airborne geophysical (MAG/VTEM) and ground auger soil geochemical anomalies. Initial drill holes were spaced from 400m to over 1km apart and later tightened to 100m step-outs where gold mineralization was noted. A total of 30 drill holes were completed in two phases, for 4985 m. A collar map is available at:http://www.goknet.net/Asante/FAHcollarsNRJan20.pdf.

Geotech conductivity depth inversion

With the exception of four significant gold intersections (to 0.50 m @ 295 g/t Au), initial sampling results were low. VTEM conductors correspond with favourable graphitic shear zones in meta-greywacke or regional scale graphitic meta-phyllite/argillite units. Weak gold anomalies in core from saprolite have generally accounted for the anomalous auger soil geochemical targets tested in the program.

However, wide zones of moderate to strongly quartz veined meta-greywacke, and carbonate alteration were noted in the program. These zones correspond with elevated to locally significant gold values, as noted in the table below, and are considered high priority targets for additional drilling.

Further drilling is also required along the trend to the NE of Perseus Mining Ltd’s discovery hole NSRC010 located ~1 km south of the Asante Fahiakoba concession boundary and which yielded 30m at 2.2 g/t Au, including 4m at 9.0 g/t Au (Perseus Quarterly Report, December 30, 2012 – true width unspecified).

 

Property Geology

The property is underlain by favourable Birimian meta-sediments, with more than 70% of the Fahiakoba concession covered by transported alluvial material. No modern exploration or drilling has taken place to date. Recent airborne geophysical surveys have outlined some 20 km of strong NE trending shear and fold zones, some of which have associated VTEM conductors. These type of structural targets at Perseus and elsewhere in Ghana host significant gold deposits and will be the target of our ongoing exploration efforts. Anomalous gold values have been noted in a pit with quartz stockwork in granite that is associated with one of the airborne geophysical targets. Phase 1 auger drilling to test below the alluvial cover has been completed with anomalous gold trends identified.


High Resolution Airborne Geophysical Survey in Tanzania

Posted by on Sunday, 19 January, 2014

Geological Survey of Tanzania (GST) and Ministry of Energy and Minerals of Tanzania have organized the Workshop “Launching High Resolution Airborne Geophysical Data at Julius Nyerera Convention Center (17 January, 2014, Dar es Salaam, Tanzania). Around 150 delegates have attended the workshop from government and private sectors.

tanz03

Geotech Ltd. and Sander Geophysics have finished the airborne magnetic, gravity, electromagnetic (VTEM), radiometric surveys in 31 districts and presented some results of the surveys.

Permanent Secretary (PS) of Ministry of Energy and Minerals Mr.Eliakim Maswi said – the surveys were carried out under the Sustainable Management of Mineral Resources Project, saying the purpose of the survey was to identify potential zones of mineralization. “The main objective of the project is to improve the socioeconomic impacts of mining for Tanzania and Tanzanians and therefore enhance local and foreign investments”, said PS.

GST Chief Executive Officer , Prof. Abdulkarim Mruma said: “geophysical data acquired through the high resolution airborne geophysical surveys allow fast and accurate delineation of mineralised targets and when augmented with geological and geochemical datasets are highly effective in attracting new exploration ventures.” Prof. Mruma noted that the availability of the modern geo-scientific  data will stimulate investments into mineral and other sectors and will improve the effectiveness of exploration programs.

tanz07

tanz01 tanz02 tanz04 tanz05

Photo: A.Prikhodko


Linking Porphyry Deposit Geology to Geophysics via Physical Properties

Posted by on Tuesday, 7 January, 2014

Geoscience BC Releases the Report:

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

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

GBC_Report2013-14a

 

 

 

 

 

 

 

 

 

 

 

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

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

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

 

 

 

 

 

Geophysical Surveys

 

 

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

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

Report Components


VTEM Survey Identifies Five Main Conductive Anomalies on Miller Lump/Vein Graphite Property

Posted by on Tuesday, 8 October, 2013

Canada Carbon Inc. announces that it has received the final results of the Geotech VTEM airborne survey performed over the Miller graphite property. Processing of the VTEM data allows for the derivation of multiple products used collectively in identifying priority targets for follow-up work. Five high priority targets were identified, two of which are known to correspond with marble rocks that host the graphite elsewhere on the property.  Additionally, the calculated time constant processing (or ‘Tau’ constant) has identified 86 clusters of smaller-sized EM anomalies on the property which show a strong relationship in signal between each other. Assessment of these anomalies will continue, with testing of the targets through trenching and/or drilling under consideration.

R. Bruce Duncan, CEO & Director of Canada Carbon Inc. stated, “Canada Carbon is very pleased with the results of the Geotech survey, which highlights an impressive number of high-priority exploration targets that are widely distributed over the Miller property. Our excellent road access to the property will allow our team to quickly prioritize these anomalies and focus on those with the greatest potential. These geophysical results are an important technical asset that will continue to lead to new graphite discoveries in the very near future at the Miller graphite property.”

The survey entirely covered two claim blocks (named East and West) that constitute the Miller Property. Principal sensors for the survey included a Time Domain EM system and two magnetometers to measure horizontal gradient. The total surveyed area is 25 kilometres (km)2 and the total line coverage is 336 line-km. Signals due to known cultural sources such as power lines and houses were removed from the EM data. On the East block, survey lines were flown in a northeast to southwest direction, with a line spacing of 100 meters (m). A spacing of 50m was implemented in the central part of the block where historic mining took place, and where graphite veins and pods are currently being tested through trenching and drilling (see news release September 18, 2013). Two major anomalies (E1 and E2) are present on the East block, occurring respectively at 100m depth and 80-100m depths. Anomaly E1 is located 800m north of the mine pit, with an approximate diameter of 400m.  Magnetic maps show that E1 is located between two magnetic anomalies that could correspond to the contact of two geological units with a similar geological context to the known Miller mineralization.  Anomaly E2 is located next to the current trench work area. Anomaly E1 is positioned where Canada Carbon recently obtained an access agreement for exploration work, with E2 partly included along its north extension (see news release September 5, 2013).

The West block was flown in a northwest to southeast direction with line spacing of 100 m.  The West block hosts three major anomalies (W1 to W3).  Anomaly W1 is located in marble and is sub-vertical at 100m depth, and W2 is also located on a contact zone of a marble with intrusive rocks. Both W2 and W3 are close to the surface according to the survey results.

The five main conductive targets were selected for their high amplitude conductivity, along with their significant extent (hundreds of metres) and detailed morphology.  Additional conductive anomalies of lesser amplitude form dense clusters on both claim blocks.  These clusters were selected on the basis of their spatial distribution and by the nature of the EM signal in between them as depicted on time constant image generated by Geotech.

On the East block, 40 EM clusters consisting of one or more EM anomalies are present, with the clusters having a mean diameter of approximately 100 meters.  Among these anomalies, a 500m along-strike anomaly with a depth of at least 100 meters is present in the vicinity of the Miller mine pit and will be subject of further resolution by Geotech.  Southeast of the Miller mine pit, an anomaly is also present that shows along-strike continuity with the mine pit anomaly.  Many small historic trenches are found along these anomalies at surface, and Company geologists believe that it is very likely that graphite is the cause of these new anomalies.

The West block hosts 46 clusters with a mean size of approximately 200m, and is scheduled to be tested through prospecting and beep-mat surveys to prioritize their potential.  Geotech will also continue to assess the data to resolve the centers of the five main conductors.  This will also include detailed resistivity depth imaging and plate Maxwell 3D models.  This information will be used to establish a drill program for the most promising anomalies.

Previous EM methods used on the property resulted in the discovery of many graphite veins (see press release dated June 27th 2013).  The many historic graphite pits and trenches on the property indicate that graphite is distributed widely and the Company expects that many of the clusters will be correlated with graphite mineralization.  Each of the anomaly clusters has the requisite size and EM response to represent potential new individual graphite discoveries. On-ground prospecting and beep mat surveys are planned over the main anomalies as well as over several of the clusters.  The Company intends to complete these activities during the fall, with the results used to focus upon the best exploration targets.


Airborne EM and radiometric surveys for Saskatchewan uranium exploration

Posted by on Thursday, 8 August, 2013

Noka Resources Inc. announces that the members of the Western Athabasca Syndicate; Noka Resources Inc.Skyharbour Resources Ltd., Athabasca Nuclear Corp., & Lucky Strike Resources Ltd.(“the Syndicate”) have completed large-scale VTEM plus and radiometric geophysical surveys on the Western Athabasca Syndicate Project located near Alpha Minerals’ and Fission Uranium’s  Patterson Lake South (“PLS”) uranium discovery. The original airborne coverage was expanded to provide for the infill and extension of conductive anomalies and structural features identified by a preliminary review of the geophysical data. Based on this initial encouraging data, the Syndicate has elected to immediately commence the second phase of its summer program consisting of follow-up field work and ground-truthing of geophysical targets.

Western Athabasca Syndicate Project Claims Map: http://www.nokaresources.com/images/NX-Western-Basin-Syndicate.jpg

Completion of Regional Airborne Geophysical Survey:

A total of 4,840 line kilometres was flown for the VTEM plus time domain survey with an additional 4,400 line kilometres flown for the radiometric survey all of which was on the Syndicate’s Preston Lake Property. The VTEM plus system has been used successfully to locate basement conductors similar to the structures that host the high-grade uranium discoveries at the nearby PLS project. The high resolution radiometric survey was flown to locate uranium boulder trains, in-situ uranium mineralization and alteration associated with uranium mineralization which is what ultimately led to the PLS discovery by Alpha and Fission. Phil Robertshaw (P.Geo., Saskatchewan) is reviewing the collected data and will be providing detailed interpretation of the VTEM plus and radiometric surveys shortly.

Western Athabasca Syndicate Airborne Survey Coverage: http://nokaresources.com/images/NX-Geophysics-coverage.jpg

The areas flown include two blocks in the northern part of the Preston Lake Property. The Preston Lake South block is contiguous with Fission Uranium and NexGen Energy and includes a large area of partially exposed pre-Cambrian shield rocks. The Preston Lake West block claims are contiguous with claims controlled by Aldrin Resources and Forum Uranium. The claims are underlain by Phanerozoic rocks (limestone and sandstone) similar to the PLS discovery area. At Fission and Alpha’s PLS high-grade discovery it is interpreted that the uranium has been mobilized along the fault zones and has been concentrated in the sandstone under the limestone. A review of historic data on the Preston Lake Property has identified a sample collected by the Geological Survey of Canada which returned a value of 5.4 ppm U3O8, considered to be significant in an area with a background uranium value of 1 ppm U3O8. This high U3O8 value may indicate either the down-ice glacial transport of uranium boulders from source or an in-situ source of uranium. For comparison, the highest value down-ice from the PLS discovery is 3.2 ppm U3O8. Management cautions that past results or discoveries on proximate land are not necessarily indicative of the results that may be achieved on the Western Athabasca Syndicate Project.

Commencement of Field Program at Preston Lake Property:

The initial data and results from the airborne surveys have led the Syndicate to expedite the planned summer field program with a number of high-priority targets at the Preston Lake Property being the focus of the work. A sophisticated targeting matrix is being used to further identify and prioritize areas for ground-based follow-up. Field work will include ground-truthing of high-priority geophysical targets using water and soil radon sampling, biogeochemistry, geochemical lake sediment and soil sampling, prospecting, and scintillometer surveying. The Syndicate will employ a systematic, proven and cost-efficient exploration methodology that has led to numerous uranium discoveries in the region and throughout the Athabasca Basin. By the end of this summer’s field program, a total of $1.5 million will be spent in exploration on the project between airborne geophysical surveys and follow-up ground work.

Uranium and the Athabasca Basin:

The Athabasca Basin of northern Saskatchewan hosts the world’s largest and richest high-grade uranium deposits accounting for just under 20% of global primary uranium supply. Athabasca uranium deposits have grades substantially higher than the world average grade of about 0.1% U3O8. The Patterson Lake area has received escalating exploration attention and claim acquisition activity as a result of the new, shallow discoveries made by Alpha and Fission which includes the recently reported drill interval of 6.26% U3O8 over 49.5 metres in drill hole PLS 13-053. This mineralized zone is located approximately 400 metres to the northeast of discovery hole PLS 12-024 which returned 2.49% U3O8 over 12.5 metres. Consistent high grade, near surface U3O8 assays from Alpha and Fission demonstrate the potential for high grade uranium mineralization on the margins of the western side of the Athabasca Basin. There are still areas in the Athabasca region that are highly prospective and underexplored for high grade uranium as illustrated by Alpha’s and Fission’s recent discovery.


Airborne EM and radiometry in Western Athabasca

Posted by on Tuesday, 23 July, 2013

Noka Resources Inc. announces that the members of the Western Athabasca Syndicate; Noka Resources Inc. Skyharbour Resources Ltd. , Athabasca Nuclear Corp., & Lucky Strike Resources Ltd.(“the Syndicate”) have completed an additional 720 line kilometres to the 4120 line kilometre VTEM plus time domain geophysical survey on the Western Athabasca Syndicate Project. The additional coverage consisted of infill and extension of conductive anomalies and structural features identified by a preliminary review of the geophysical data.

The Syndicate is also pleased to announce that the high resolution airborne radiometric survey on the Western Athabasca Syndicate Project has started. The contract was awarded to Goldak Airborne Surveys who will be collecting radiometric data be using a digital acquisition system that is proprietary to Goldak. A total of 4400 line kilometres at 200 metre line spacing will be flown using a 50.4 liter crystal volume detector to locate uranium boulder trains, in-situ uranium mineralization and alteration associated with uranium mineralization systems.

The Syndicate is using Phil Robertshaw (P.Geo., Saskatchewan) to review the VTEM plus and radiometric data and provide detailed interpretation when the surveys are completed.

Western Athabasca Syndicate Project claims map


VTEM09 VMS Prospect in Northern Ethiopia drilling results

Posted by on Tuesday, 23 July, 2013

Tigray Resources Inc. announces assay results from preliminary diamond drill-hole tests of the VTEM09 VMS Prospect on the Harvest Property and the Adi Gozomo Gold target on the Adyabo Project, in Northern Ethiopia. Single diamond drillholes tested both targets as an initial appraisal of prospectivity.

The results include:

  • 10.69 metres grading 3.47% copper, 4.2 grams per tonne gold, 3.69% zinc, and 91 grams per tonne silver from 19.81 metres, including 3.06 metres grading 5.75% copper, 8.00 grams per tonne gold, 0.70% zinc, and 107 grams per tonne silver (TVD001), at VTEM09
  • 7.5 metres grading 2.04 grams per tonne gold from 15.1m (AD001) at Adi Gozomo.

VTEM09 prospect

The high-grade copper and precious-metal enriched VMS mineralization intersected by TVD001 compares favourably with the metal tenor encountered at the Terakimti and Mayshehagne discoveries, and marks the third significant VMS discovery made at Harvest.

The VTEM09 prospect, located 5 kilometres ENE and along strike of Terakimti, was identified by an Airborne VTEM survey, and is characterized by a >200m strike length bedrock conductor. VTEM09 was further defined through mapping, soil sampling and trenching (refer to Tigray’s news release dated Jan 24th, 2013), and is interpreted to be a southwest-dipping, eastward-plunging mineralized VMS shoot. Additional drilling is required to test this prospect along strike, down dip and down plunge.

Adi Gozomo

One short diamond drillhole was targeted below the main artisanal workings, and encountered gold mineralization associated with the upper contact of a granodiorite hosted within mafic volcanic rocks. As the results to date indicate that gold mineralization appears directly proportional to the amount of pyrite present, additional ground exploration will be required prior to further drill testing at Adi Gozomo.

Diamond Drill Hole Results

DDH ID From (m) To (m) Interval (m)* Copper (%) Au (g/t) Ag (g/t) Zn (%) Prospect
TVD001 19.81 30.50 10.69 3.47 4.20 91 3.69 VTEM09
including 21.34 24.40 3.06 5.75 8.00 107 0.70
AD001 15.10 22.60 7.501 0.00 2.04 0 0.00 Adi Gozomo

* Intersection true widths are estimated at 60-90% of interval stated.

The Map


Montoso zone in Mexico drilling intersects pyrite-rich porphyry alteration containing broad intervals enriched in silver

Posted by on Tuesday, 9 July, 2013

Westminster Resources Ltd. has compiled results from five core holes drilled on the Montoso Target of the Company’s Cumbral-San Bartolo project in Sonora, Mexico. This portion of Westminster’s concessions is being explored through an earn-in Option Agreement with Capstone Mining Corp. (“Capstone”) who have 49% interest in the project having funded $3.3 million to date on exploration. A further contiguous 9,615 hectares of new mineral concessions have been added to the project.

A total of 4,163 meters was drilled in the five holes to test a complex geophysical anomaly system coincident with variably anomalous soil geochemistry and extensive leached gossanous zones. The geophysical surveys produced strong IP chargeability/resistivity responses associated with both high and low magnetic anomalies. The holes were designed to test various gradations in IP response intensity. All holes were drilled on angled (not vertical) projections. This drilling was a portion of the second phase of the project’s exploration with Capstone which also included alteration mapping, prospecting, soil geochemical sampling and geological mapping.

All holes encountered abundant pyrite as disseminations, on fractures and in veinlets in intrusive host rocks (granodiorite, feldspar porphyry, igneous breccia and magnetic mafic intrusive) which exhibit weak to moderate porphyry-related alteration (potassic-phyllic) and sparse veining to minor sheeted vein and stockwork development (“B and D veins”) occasionally containing molybdenite. The nature of the metal content, and geologic interpretation of the core suggests that this first phase of drilling at the Montoso Zone has encountered a pyritic peripheral silver-enriched halo component of a laterally extensive porphyry hydrothermal system.

The Montoso Zone drilling showing elevated results. Holes 1, 2 and 5 tested the central and south high chargeability and magnetic high and low patterns while holes 3 and 4 were designed to test the northern edge of the Montoso target and a blanket-like conductivity anomaly extending further to the north. (See Drill Hole Location and Alteration Maps athttp://www.westminsterres.com/drillholesandlocation.pdf )

Mineralization is characterized by high-grade, gold-copper-silver veins, breccias associated with porphyry deposit-style systems and hematite-magnetite-sericitized zones and structures containing copper-gold-silver mineralization in an IOCG / Porphyry setting.

Recent airborne VTEM and MAG geophysical survey results for the newly-discovered Cumbral-San Bartolo area identified district-scale alteration and magnetic highs and lows associated with regional structures and intrusive emplacements. Completed ground magnetic highs and lows associated with regional structures and intrusive emplacements. Completed ground magnetic and IP geophysical surveys confirmed airborne anomalous patterns and mapping identified surface mineralization associated with a large hydrothermal system.

Completed aggressive exploration in 2012 included expanded 3D-IP and ground MAG coverage (219 Line kilometers), soil sampling (5,000 samples), mineralization mapping and diamond drilling (7 holes, 1,641 meters). The new 3D-IP chargeability survey identified the 1 X 1-1/2 kilometer high chargeability Montoso target and numerous other copper-silver-gold mineralized zones. 2013 drilling at Montoso is directed at this large porphyry system.