Posts Tagged magnetic

Fault reconstructions in Northwest Territories using aeromagnetic data

Posted by on Tuesday, 5 May, 2015
FacebookTwitterGoogle+Share

Canadian Journal of Earth Sciences has published an article “Fault reconstructions using aeromagnetic data in the Great Bear magmatic zone, Northwest Territories, Canada” written by Nathan Hayward, Louise Corriveau from Geoligical Survey of Canada

The authors have chosen for the investigation the Great Bear magmatic zone (interpreted as a Paleoproterozoic magmatic arc)  which includes economically important mineralization of vein-type silver, radium, and uranium deposits, polymetallic iron oxide copper–gold and iron oxide ± apatite.

 

 

 

 

 

 

 

 

 

 

__________________________________________

Geological development of the Great Bear magmatic zone is described in details in the paper including magmatism, tectonic (folding and faulting) events. A model of conjugate transcurrent faulting with the principal shortening direction and the boundary of the system has been presented.

The aeromagnetic data used for the study has been compiled and integrated from different sources including public archival aeromagnetic data and data from private sector. In the result of the integration, nearly complete high-resolution coverage of the Great Bear magmatic zone was obtained.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

______________________________________________________

The magnetic data interpretation process included regional magnetic interpretation and detection of magnetic lineaments related to faults and dykes.

In the result of this work authors made structural reconstruction of the Great Bear magmatic zone, analysed horizontal offsets on fault zones and developed Vertical Offset Rotation Model and Maximum Offset Model. In the conclusion the authors made an analysis of mineralization distribution in connection with the structural units.

The full paper with tables and all pictures is here..


The next UAV magnetic system

Posted by on Wednesday, 29 April, 2015

Abitibi Geophysics together with GEM Systems announced about creation of  the partnership AeroVision™ for using UAV magnetic system which explores two potassium sensors. The system is going to be available since June, 1.  Sampling interval is promised 2 meters and resolution of .0001 nT, absolute accuracy  +- 0.05 nT. Laser-altimeter, GPS and auto-pilot are included.

The UAV mag surveys cost is going to be over 50% of the present ground geophysics pricing.


EM surveys over Green Giant graphite property in Madagascar

Posted by on Tuesday, 24 February, 2015

by Alexander Prikhodko, 24 Feb., 2015

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

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

Geological position and characteristics of the property:

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

-Vertical to sub-vertical nature;

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

-Graphitic zones consist of multi-folded graphitic strata;

-Graphitic schist and gneiss with vanadium mineralization.

 Geologic map (magnetic field interpretation)

Green_Giant_quick_Mag

 

AEM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

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

____________________________________________________________________

DIGHEM survey

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

(conductors in red, resistors blue colors)

DIGHEMConVoxel

 

 

 

 

 

 

 

 

 

 

 

 

 

sections

 

condmap

 

 

 

 

 

 ________________________________________

VTEM survey

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

TAU

 

 

 

 

 

 

 

 

 

 

 

 

__________________________________________________

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

rdisections

 

 

 

 

 

 

 

___________________________________________

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

RDIvoxel

 


Fresh insights on magnetic field from Geosoft

Posted by on Friday, 20 February, 2015

 

 

Virginia Heffernan: “Magnetization Vector Inversion (MVI) is a modern technique which is gaining acceptance as an effective tool for subsurface exploration in areas where magnetization does not necessarily run parallel to the earth’s magnetic field, a more common scenario than geoscientists have traditionally appreciated.”

– See more at: Earth Explorer

 


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:  


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


Training Course: Gravity and Magnetic Geophysical Methods in Oil Exploration

Posted by on Wednesday, 23 October, 2013
Location:
Calgary, Alberta
Date:
Wednesday, April 9, 2014

8:30 AM – 4:30 PM

spacer
Course Description
This basic one-day course reviews the fundamental geological and physical concepts behind oil exploration using gravity and magnetic methods. It is presented in plain English with minimal math or technical jargon, and it includes hands-on exploration examples and case studies.

Delineation of regional and local fault networks, which gravity and magnetic data enable, is crucial in both conventional and unconventional exploration and production. In frontier regions, these data help to delineate the raised and subsided crustal blocks and depocenters, as well as the distribution of igneous rocks.

The course reviews all stages of gravity and magnetic survey design, as well as data acquisition and geological interpretation. These steps are put in the context of designing and executing overall exploration programs for both conventional and unconventional targets.

A complete set of course materials and lunch is included in this course.

spacer
Who Should Attend
This course is designed for professional and technical personnel who need to understand the basics of gravity and magnetic methods in order to assess their effectiveness in various exploration circumstances. The course is intended for all staff levels including geological, geophysical, administrative and management personnel.
spacer
Course Outline
  • Geological Meaning of Geophysical Anomalies: Anomaly-Lithology Relationships and Relevant Rock Properties
  • Forms of Rock Bodies Encountered in Oil and Mineral Exploration
  • Gravity Exploration Methods
  • Magnetic Exploration Methods
  • Design of Gravity and Magnetic Surveys for Geologic Targets
  • Processing Methods for Gravity and Magnetic Data to Separate and Enhance Desirable Anomalies
  • Data Display and Anomaly Enhancement
  • Exploration Example: Gravity and Magnetic Studies of Alberta Basement Structure
  • Exploration Example: Gravity and Magnetic Studies in a Frontier Basin Offshore British Columbia
spacer
Instructor
Dr. Henry Lyatsky

Henry Lyatsky is a Calgary-based geophysical and geological consultant who has worked across Canada, northern and western U.S., and internationally in oil and mineral exploration.

He was born in St. Petersburg, Russia and moved to Calgary as a teenager. He holds a B.Sc. in geology and geophysics (1985, University of Calgary), an M.Sc. in geophysics (1988, University of Calgary) and a Ph.D. in geology (1992, University of British Columbia). He is the first or sole author of three books (Springer-Verlag) on the regional geology and geophysics of western Canada, two gravity and magnetic atlases of the Alberta Basin (Alberta Geological Survey) and many papers. He is a member of CSEG, MEG and APEGA.

Henry is a past president of the Mineral Exploration Group, a province-wide mining-industry association in Alberta. To avoid the downtown rat-race and congestion, he works from home, enjoys the free space of the Alberta outdoors, and loves nothing better than in-depth history books and good hikes in the mountains.


The results of the EM/Magnetic airborne survey over the Borden Lake Extension

Posted by on Wednesday, 29 May, 2013

Nikos Explorations Ltd. announces the results of the high-resolution VTEM (Versatile Time-Domain Electromagnetic System) and magnetic airborne survey recently completed over the Borden Lake Extension by Geotech Ltd. A total of 391 line kilometers were flown to cover the Property. The VTEM and magnetic surveys were completed in order to identify electromagnetic and magnetic anomalies that may be associated with gold mineralization and to help in the geological interpretation of this underexplored area.

Results of the surveys indicate electromagnetic and/or magnetic anomalies in four areas of interest (see map at http://nikosexplorations.com/projects/borden_lake/) described below in order of priority for follow up:

1. Several magnetic lineaments, one of which is interpreted to be a fault, intersect near the boundaries of claims 4260529 and 4260530. Such lineaments can reflect structures that are known to be important in the transport of gold-rich fluids. A north-east south-west lineament, apparent on a shaded relief map of the region, also crosses the Nikos claims in this area giving further reason for follow up.

2. Cross cutting NNW-SSE and NE-SW trending positive magnetic anomalies in claim 4259808 may represent major structures. There are also coincident weak electromagnetic anomalies that could indicate the presence of sulphide.

3. Similar cross-cutting magnetic anomalies and electromagnetic anomalies seven to eight hundred metres east of 2, but not as strong.

4. This area in the east of the property is characterised by a small positive magnetic anomaly with a coincident electromagnetic anomaly.

Nikos is planning a follow up program of mapping, sampling and prospecting to investigate the cause of the anomalies.

The Borden Lake Extension Project is located near the town of Chapleau, Ontario in an area of good infrastructure including road, rail and power. It covers an area of 1,598 hectares immediately east of Probe Mine’s Borden Lake gold property where recent exploration has defined pit constrained indicated resources of 3,686,000 ounces of gold (112.8 M tonnes grading 1.02g/t gold) and inferred resources of 625,000 ounces of gold (18.04 M tonnes grading 1.08g/t gold) at a 0.5g/t cutoff grade. This is the first discovery of significant gold in the Kapuskasing Structural Zone.

The Borden Lake Extension property covers Archean aged metamorphic rocks in an underexplored portion of the Kapuskasing Structural Zone.

Nikos is planning an airbourne geophysical survey using VTEM (versatile time domain electromagnetics) and magnetics to explore for Borden Lake type gold mineralization. Gold at Borden Lake is associated with a continuous zone of disseminated sulphide (pyrite and pyrrhotite) mineralization that gives rise to electromagnetic anomalies. The airbourne survey is expected to be completed during the first quarter of 2013.


Practical Inversion for Geoscientists

Posted by on Wednesday, 10 April, 2013

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

Presented by the B.C. Geophysical Society

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

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

Date: April 24th – 26th 2013

Address: SFU Downtown Campus; Vancouver BC

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

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

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

– Background on inversion

Unconstrained/constrained
Joint and collaborative
The future of inversion

– Before inversion – forward modeling

forward modeling
petrophysics drives the story
complexity vs. adequacy

– Case studies

Potential fields
EM
IP-resistivity

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

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


Potential fields for basement investigations

Posted by on Wednesday, 30 January, 2013

Often not given its due in oil and gas geophysics, knowledge of basement geology can be critical to exploiting reservoirs including the unconventional.

by GRAHAM CHANDLER on JANUARY 24, 2013

There is an article in the last Earth Explorer issue:

New Approach to Basement Studies for Oil and Gas Explorers



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

Posted by on Friday, 14 December, 2012

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

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

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

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

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


Airborne geophysics results on Mexico’s Guerrero gold belt

Posted by on Saturday, 8 December, 2012

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

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

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


Airborne EM in Colombian Porphyry Gold Copper Project

Posted by on Saturday, 8 December, 2012

Bellhaven Copper & Gold Inc. reports the commencement of the previously announced ZTEM (airborne electro-magnetics) survey over the entire La Mina property (1,800 Ha). The survey is also being extended to include an adjacent concession, which the Company is currently in discussions to acquire. The work is contracted to Geotech Ltd., a Canadian geophysical survey company specializing in leading edge airborne technology. The survey is designed to help refine the targets at La Mina, with a particular emphasis on the Garrucha and Cristalina target areas.

The helicopter-borne geophysical survey will result in approximately 132 line kilometres of data along east-west lines, spaced at 200 metres. The Z-TEM Electromagnetic (EM) system is an innovative technique making use of naturally occurring or passive EM fields from worldwide thunderstorm activity as the source of transmitted energy. The passive source combined with a proprietary receiver design, advanced digital electronics, and signal processing results in low noise levels, exceptional resolution, and unparalleled depth penetration. It has been used successfully to identify and map porphyry style mineral systems from Alaska to Chile.

Patrick Highsmith, Bellhaven’s CEO, commented on the program: “We are pleased to bring the ZTEM technology to the Middle Cauca Belt for the first time. It is a proven technique for porphyries in the Americas. This will enable us to prioritize existing geochemical and magnetics anomalies, including on concessions that we are in negotiations to acquire. This is a very cost effective tool that adds immediate value in an emerging mineral district such as La Mina. By sharing the mobilization and some of the administrative costs with neighboring explorers, we have made it even more cost effective.”

Discussion of ZTEM Survey

The survey is expected to identify conductive and resistive features that are associated with large mineral systems such as gold-copper porphyries from surface to considerable depth. The electromagnetic data is sensitive to sulfide minerals, as well as silicification and clay alteration; all of which are associated with the porphyry and epithermal deposits in the Middle Cauca Belt. This will be an important addition to the magnetics data that drove the initial discoveries. The EM data will advance the geologists’ knowledge of the known resource areas, particularly at depth, but it will also upgrade the targeting arsenal elsewhere on the property. This work will also enhance understanding of large structures in the district. Many of these structures have previously been mapped from both surface exposures and drill intercepts; and the Bellhaven team is focused on their importance in controlling mineralization.

The survey crew arrived on site November 17, and began conducting reconnaissance flights a few days later. They are currently flying the survey as cloud cover permits. It is expected that a total of 6 to 8 days of favorable conditions is needed to complete data collection, so the survey should be completed before the end of December.

La Mina Porphyry Gold Copper Project

La Mina is a resource stage porphyry gold-copper project located in the Middle Cauca volcano-plutonic belt in the Department of Antioquia about 45 km southwest of Medellin. The Middle Cauca belt is known to host large porphyry gold deposits such as AngloGold’s La Colosa Deposit (24 Moz Au) and Sunward Resources’ Titiribi Project (11 Moz Au).

Exploration Targets

The La Mina concession includes almost 2,000 hectares. A number of anomalous features are evident from the initial airborne magnetic survey, completed by AngloGold. As surface sampling and drilling progressed, a number of multi-faceted targets emerged. Through the first half of 2012, a total of four known mineralized porphyry systems have been identified; two of these deposits are host to NI 43-101 compliant inferred mineral resources. The two remaining known porphyries will be the focus of future drilling, meant to advance these prospects to the resource stage as well. The exploration pipeline at La Mina includes a number of other targets that, based on geology, geochemistry and geophysics, have characteristics similar to porphyry or porphyry related deposits. There are at least 7 of these discrete targets undergoing additional work, but they have not yet been drilled. The figure below shows total magnetic intensity (reduced to pole) from an airborne magnetics survey. Many of the targets are identified on this map; and more detailed information is available below.


The Magnetic/VLF survey in Newfoundland

Posted by on Thursday, 18 October, 2012
Silver Spruce Completes Airborne Survey and Receives Check Assays for the Big Easy Gold/Silver Property, Eastern Newfoundland


Silver Spruce Resources Inc. announces that the high resolution magnetic / VLF-EM airborne survey has been completed and preliminary results received on the road-accessible, Big Easy gold/silver property in eastern Newfoundland. The Big Easy prospect is a large, altered (silicified) system that covers an area of approximately 1.7 kilometres by up to 300 metres wide.   The prospect was drilled in 2011 and 2012 — a total of 12 holes over a 1.2 km strike length, giving significant gold (Au) and silver (Ag) values in a number of the drill holes (news releases September 18, 2012, August 16, 2012 and June 7, 2011).

Airborne Survey
The airborne, high resolution magnetic / VLF-EM survey was carried out in late September by Terraquest Ltd. of Mississauga, ON.    The aim of the survey was to improve the understanding of the geological setting of the area by a lithological/structural interpretation based on the survey results, drilling and surface geology.

The preliminary magnetic data shows a broad, NNE (025 degrees) magnetic high trending through the main portion of the claim group with narrow linear, NNE trending magnetic lows within the overall magnetic high.   The magnetic  lows are offset by linear zones and possible dikes / faults, trending NNW (340 degrees). A sinuous magnetic  low joins the BE and ET zones, continuing to the south of the ET zone.    The preliminary VLF-EM data shows NNE and NNW trending, as well as a number of E-W to ENE-WSW trending conductive zones cutting through the property.

“We are pleased with the resolution of both the magnetic and VLF-EM data.    Based on what we are able to tie into our existing geological and structural compilation, the final results should enable us to better target continued exploration, including drilling,” states Peter Dimmell, President and CEO of Silver Spruce Resources.

Line spacing was 200 m in the known mineralized areas (Big Easy and ET) and 300 m over the rest of the property, at a mean terrain clearance of approximately 70 m. The survey was flown using E-W lines and N-S tie lines for a total of 349 line km. The VLF-EM used two orthogonal receivers, with the main transmitter Cutler, ME.

Read more..


Drilling results after the Airborne EM-Mag in Northern Ireland

Posted by on Tuesday, 9 October, 2012

Dalradian Resources Inc. has received final assays from hole 12-CT-162, which was drilled to test a geochemical anomaly from a recently released survey. The hole is located approximately 1700 metres along trend from the Company’s wholly owned Curraghinalt deposit in Northern Ireland.

From previous news about the property:

The recently-completed 1,034.3 line kilometre VTEM and magnetics survey that was flown along 10 km of the Curraghinalt Trend, which is both over and along strike from the Curraghinalt gold deposit. The tightly spaced survey (50m line spacing) will assist with targeting further drilling based on an improved three dimensional understanding of the geology, structure and alteration zones associated with mineralization.

The Curraghinalt Deposit is a mesothermal gold system consisting of a series of approximately east-west trending gold bearing high grade narrow veins in meta-sedimentary host rocks.


The New Copper Oxide Zone at the Escalones Project in Chile

Posted by on Wednesday, 19 September, 2012

South American Silver Corp. announces the results of a 5 hole diamond drilling program and the interpretation of the ZTEM Conductivity and Magnetic geophysical surveys at the Escalones copper-gold project, approximately 100 km southeast of Santiago, Chile and 35 km east of El Teniente, the world’s largest underground copper mine. Escalones, as previously announced and supported by a NI 43-101 technical report, contains a defined Inferred Resource of 420 million tonnes of mineralized material containing 3.8 billion lbs of copper, 56.9 million lbs of molybdenum, 610,000 ozs of gold and 16.8 million ozs of silver using a 0.2% Cu Equivalent cut-off grade (see December 19, 2011 News Release). The detailed NI 43-101 Technical Report is available on SEDAR under the Company’s profile and on the Company’s website at www.soamsilver.com.

The Escalones property lies within the well-known central Chilean porphyry copper belt that runs north-south through Chile in the central Andes Mountains. It is located approximately 100 km southeast of Santiago and 35 kilometers due east of El Teniente, the world’s largest underground copper mine. The project has excellent infrastructure including road access and a gas pipeline that crosses the 70 square kilometer property.

The Escalones project hosts a four-square-kilometer area of hydrothermal alteration with coincident geophysical anomalies that has demonstrated significant grades of copper, gold and silver in replacement-style “skarn” mineralization hosted in limestones and in porphyry related mineralization.

Diamond drill hole ES-35, located 300 metres E of ES-24, intersected 71 metres of near surface, oxide copper mineralization averaging 0.64% copper equivalent (“CuEq”). This near surface mineralization correlates with a ZTEM conductivity anomaly which is approximately 500 metres wide and at least one km long. Drill testing, starting when the snow clears in November, will further test this target. ZTEM is a geophysical tool that helps to identify mineralized areas that are conductive.

Diamond drill hole ES-35 also intersected high grade skarn mineralization at 456 metres intercepting 4.5 metres of copper mineralization averaging 4.32% CuEq within a 9.25 metres zone averaging 2.39% CuEq. A copper skarn is a carbonate rock that has been “cooked” and mineralized by the heat and fluids from nearby copper bearing intrusions. Examples of copper porphyry plus skarn deposits include the well-known Bingham Canyon Mine in Utah and the Twin Buttes Mine in Arizona.

The skarn at Escalones has now been traced by drilling approximately 1.7 km horizontally and 1.1 km vertically. A large magnetic anomaly is associated with much of the known skarn mineralization and this anomaly extends several hundred meters further to the north of the drilled area, at least 500 meters to the south and approximately 500 metres further east. The anomaly also extends to a depth of several km, many hundreds of metres below the level of current drilling.

Ralph Fitch, Executive Chairman, stated “This is the first time we have located a good thickness of near surface copper oxide mineralization at Escalones. The importance of this type of mineralization is that it is often the least expensive type of copper to recover because it is typically heap leachable. If future drilling shows that this zone is extensive it will be an important new body of mineralization that is not in the present resource. This new zone combined with that found on the west side of the property in holes ESC-26 (46m@0.53% copper) and ESC-28 (34m@0.52% copper) represents an important part of the mineralized system found to date at Escalones because of its likely low cost leachability. Also, the deep skarn intercept is important, both because of its grade and also because it demonstrates the huge column of copper mineralization present at Escalones which extends from surface to depths of greater than one kilometer. Our upcoming drill program will start to convert this vast column of mineralization into a resource.”

Upcoming Drilling Campaign

Up to 30 holes are planned to confirm and expand the resource in the 3 categories reported previously, oxide/sulphide, skarn and porphyry. The results from this drilling will be combined with earlier results and an updated resource will be developed and reported in compliance with NI 43-101.

The true thickness of the intercepts reported is not known at this time.

Magnetic susceptibility anomalies are only an indication of the presence of the skarn mineralization and the reader should not assume that “ore grade” mineralization will be intersected.

ZTEM conductivity anomalies are only an indication of the presence of mineralization and the reader should not assume that “ore grade” mineralization will be intersected.

Samples were analyzed by Andes Analytical Assay Laboratory located in Santiago, Chile. Gold was analyzed using fire assay and the AA (Atomic Absorption) method while silver, copper, gallium, indium, molybdenum and 38 additional elements were analyzed by ICP AES HF43 method with a four-acid digestion. The copper equivalent has been calculated using the following prices: copper $3.50/lb, gold $1,600/troy oz, silver $30.00/troy oz, molybdenum $11.00/lb, lead $0.90/lb and Zinc $0.90/lb. Values have not been adjusted for metallurgical recoveries.


The New Potential Ni-Cu targets in Tanzania

Posted by on Friday, 7 September, 2012
IMX Resources Limited reports the identification of twenty-five new high priority VTEM anomalies from the recently completed airborne magnetic and versatile time-domain electromagnetic (VTEM) survey over selected areas within the Nachingwea Nickel-Copper JV Project located in southeast Tanzania.
The delineation of multiple late time EM anomalies further enhances the regional prospectivity of the Nachingwea JV property. Of potential significance is the identification of a high amplitude late time EM anomaly coincident with the Hog gold prospect, where surface gossan sampling returned values of up to 4.96 g/t Au and 0.64% Cu (ASX: May 28, 2012).
Patricia Tirschmann, VP Exploration, commented: “We are pleased to have completed another successful regional VTEM survey and are very encouraged by the number of high quality targets generated. The identification of an EM anomaly coincident with the Hog gold prospect further enhances the exploration potential of this target and we look forward to drill testing it and other high priority targets beginning in September.”
The airborne geophysical survey was carried out by Geotech Limited of South Africa employing the Versatile Time-Domain Electromagnetic (VTEM) geophysical system. The survey ran from July 29th to August 11th and a total of 2,409 kilometers were flown in five flight blocks.
The flight blocks comprising the 2012 airborne VTEM survey were selected by prioritizing areas based on results of the 2010 airborne magnetic and radiometric survey in combination with results of geochemical sampling and geological mapping. Preliminary data from the new VTEM survey is currently being evaluated, and targets are being selected for ground follow-up in order to help prioritize anomalies for drill testing later in the year.
Analysis of the preliminary VTEM data indicates that EM anomalies have been detected on each of the five flight blocks and approximately twenty-five of these represent high priority anomalies with late channel responses. Of potential significance is a high amplitude late time EM anomaly detected on three 200 metre spaced flight lines which is coincident with the Hog gold prospect where surface gossan grab samples returned values of up to 4.96 g/t gold and 0.64% copper (May 25, 2012 Press Release). Several other VTEM anomalies are also confirmed to have coincident copper and/or nickel in soil anomalies.
The Company plans to carry out 1,500-2,000 metres of reverse circulation drilling to test selected high priority regional VTEM and geochemical anomalies including the Hog gold prospect. This drilling is currently expected to begin in mid-September.

Exploration activity at Nachingwea has identified several zones of nickel sulphide mineralisation, at Ntaka Hill, where a combined Measured and Indicated Resource of 12.79 million tonnes (Mt) grading 1.21% Ni (using a 0.2% Ni cut-off) has been announced. The resource equates to an estimated 154,700 tonnes of contained nickel.

In addition, an Inferred Mineral Resource of 45.04Mt @ 0.3% Ni (using a 0.2% Ni cut-off) has been identified at Ntaka Hill.

A positive scoping study for an open pit mining operation means that the Nachingwea project is now advancing towards a potential production commencement date in 2015.

Read more..