Archive for category Ground

Newly discovered historical gravity data pushes exploration activity

Posted by on Thursday, 28 May, 2015

The Aston Bay‘s Storm Project in Nunavut is focused on exploring high-grade sedimentary hosted copper mineralization.

The company recently has undertaken a review of the project data to gain further insight into the untested anomalies identified in the 2011 Versatile Time Domain Electromagnetic (VTEM) survey conducted by Geotech Ltd.

The results of the survey confirmed that the mineralized zones of the Storm deposit can be accurately mapped and modeled with electromagnetic techniques and the data suggests there remain portions of multiple zones that have not been adequately drill-tested along strike and beneath existing known mineralization.

One of the drill-ready VTEM anomalies is oval in shape and called SE anomaly with approximate dimensions of 4.0km x 1.5km. The anomaly is coincident with elevated levels of copper in the rocks and soils at surface and located along the structural system that hosts mineralization identified in previous drilling.

In 2013 Aston Bay acquired the ground gravity survey data collected in 1999 by Quantec IP Incorporated.  APEX Geoscience Ltd. confirmed the quality and veracity of the data and analysis of the data shows a coincident gravity high over the southern third of the SE Anomaly (see picture below).














SE Anomaly Comparison (VTEM vs Gravity) – Coincident Anomalies Suggestive of Large Prospective Target

“The combination of geochem data, gravity data, electromagnetic data and historic drilling encountering high-grade copper sulphides, reinforces the potential for a large sedimentary-hosted copper target at the Storm Project. The discovery of a compelling gravity anomaly also underscores the value of our on-going investigation and evaluation of the extensive historical database that the Company acquired from Teck. This also makes a stronger case for a larger gravity survey on the property to identify other potential targets within this basin scale system”, commented Benjamin Cox, President and CEO of Aston Bay.

Read in detail..

GEOMODEL – online time-domain EM data inversion

Posted by on Tuesday, 19 May, 2015

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


















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

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

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


















The next procedures can be done with TDEM Geomodel webapp:

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

-Viewing and analysis of transient field decay curves;

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

-Runing 1D inversion and compiling resistivity sections;

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

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

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


The development team welcomes user’s comments and suggestions.

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

Posted by on Tuesday, 28 April, 2015

by Alexander Prikhodko

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

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

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

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

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

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

2) due to electrochemical processes.

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

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

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

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

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

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

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

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

Earth Explorer: About Insightful geophysics..

Posted by on Thursday, 2 April, 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.

See more


Novel technologies for greenfield exploration – GEOLOGICAL SURVEY OF FINLAND 2015

Posted by on Wednesday, 1 April, 2015

The Geological Survey of Finland (GTK) reports about new mineral exploration and mapping methods which were developed in the project ‘Novel technologies for greenfield exploration’ (NovTecEx) carried out in 2012–2014. The project was a part of the Green Mining Programme funded by Tekes. The research partners of the project were the Geological Survey of Finland and the University of Oulu. The main study areas were in the SavukoskiPelkosenniemi area and in the Lätäseno area in Finnish Lapland.

The methods include a tool for Audiomagnetotelluric (AMT) measurements, GUI developing for 2D MODELLING AND INVERSION SOFTWARE FOR AIRBORNE TIME-DOMAIN EM DATA, and description  THE EQUIVALENT SOURCE METHOD for CALCULATION OF THE DERIVED BOUGUER ANOMALY.

The report pdf

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)


















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)
























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.















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.










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



Inversion electromagnetic survey data in web app

Posted by on Monday, 22 December, 2014

TDEM geomodel is an online software designed for editing, inversion, and interpretation of transient electromagnetic (TDEM) data. It outputs resistivity cross sections and maps which can be superposed on Google maps. Right now it is a shareware web application developed for pre-processing and 1D inversion of transient (time-domain) electromagnetic data. The software can be used for ground and airborne time-domain EM data.

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


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.”

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” (, 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.


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.







Seismic Exploration for Minerals

Posted by on Thursday, 20 February, 2014

Graphite discoveries in Northeastern Ontario

Posted by on Thursday, 16 May, 2013

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

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

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

14 May 2013

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

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

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

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

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

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

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

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

Advances in Airborne and Ground Geophysical Methods for Uranium Exploration

Posted by on Tuesday, 30 April, 2013

IAEA (International Atomic Energy Agency) has published a book “Advances in Airborne and Ground Geophysical Methods for Uranium Exploration”.

“Due to growing global energy demand, many countries have seen a rise in uranium exploration activities in the past few years, and newly designed geophysical instruments and their application in uranium exploration are contributing to an increased probability of successful discoveries. This publication highlights advances in airborne and ground geophysical techniques and methods for uranium exploration, succinctly describing modern geophysical methods and demonstrating their application with examples.”


About Seismic Interpretation

Posted by on Sunday, 9 December, 2012

Robin Westerman : “Absolute BME: Quantitative Seismic Interpretation”

Roxar Software: “RMS 2012 – Seismic Inversion and Attributes”

Induced Polarization Survey in Ghana

Posted by on Saturday, 8 December, 2012

Castle Peak Mining Ltd. announces Promising Surface Sampling Results at the Dansuom Target on the Pow Concession at the Company’s Akorade Project in the Southern Ashanti Belt in Ghana, West Africa. the Reported Results Represent Approximately 25% of the Road Samples Collected to Date. Concurrently a Gradient Induced Polarization Survey and Subsequent Pole-Dipole Induced Polarization Survey was Completed in Order to Better Refine Drill Targets in the Area.

Highlights of the Sampling Include:

  • Channel POWCS008: 70.0m of 1.01 g/t Au including 26.0m of 1.76 g/t Au;
  • Channel POWCS007: 12.0m of 0.54 g/t Au;
  • Channel POWCS005: 2.0m of 2.38 g/t Au.

Highlights of the geophysical survey include several kilometer scale coincident resistivity and chargeability anomalies. Two of these significant anomalies are spatially associated with the large, 1,500m by 250m, Dansuom gold in soil anomaly defined by soil values greater than 0.2 g/t gold. (To see Figure 1: Anomalies in Dansuom Target Area, please visit the following link:

Commenting on the results Darren Lindsay stated, “Although dealing with a less than predictable rainy season this year, we have been able to forge ahead with geophysical surveying, mapping and sampling to better determine the resource potential in the Dansuom target area. Strong geophysical anomalies coincident with our existing geochemical anomalies and new road cuts exposing vein stock works, alteration zones and contact zones are showing the promise of this exceptional target.”

Update on Regional Exploration

A total of 690 samples for multi-element analysis have been collected across the Akorade project area, with approximately 300 samples remaining to be collected across the mineral licenses at 400m by 400m spacing. To date all samples from Enyinase, Bonsaso, Kedadwen and Dompem have been collected, while mapping and sampling still continues across the POW and Great Yorkshire licenses. Mapping from these efforts is being compiled to refine our existing base map.

Geology & Mineralization

The properties are underlain by NNE-SSW Birimian Age metavolcanics and Tarkwaian metasediments of the Ashanti Belt of southwestern Ghana. These rocks are intruded by two (2) chemically distinct granitic suites which consist of: 1) Belt associated Dixcove intrusive and 2) Basin associated Cape Coast intrusions.

Deformation and metamorphism of Birimian metavolcanics and Tarkwaian metasediments (conglomerates, arkose, sandstones, siltstones and shales) are related to the Eburnean II orogeny with five (5) distinct successive deformation phases, (D1 to D5) with D2 faults and D5 reactivation for major deformation events such as strike slip, dilatants breccias, quartz veins and lens networks with pinch and swells (boudinage) hosted within faults and shear zones.

Shear zones on the property are developed within the metavolcanics. The granitoid intrusions have been accompanied by hydrothermal activity evidenced by the numerous lenses of quartz veins and veinlets within the metavolcanics. The most prominent quartz structure, in a shear zone and within the metavolcanics on the Apankrah hills, has a NE-SW orientation and dips steeply to the southeast. The quartz vein, more than 1 metre in width and strike length of more than 100 metres is shattered and pyritized in few places.

The most favourable areas of gold mineralization in the Birimian and the Tarkwaian are found:

  1. In a major shear system in early Proterozoic rocks, e.g., Prestea and Obuasi
  2. In intermediate and mafic intrusions, mainly within the “greenstone” belts
  3. In mafic volcanics in some areas, especially in the Ashanti belt, e.g., Konongo
  4. In transitional zones between the belts and the basins
  5. The banket conglomerates of the Tarkwa district
  6. Oxide and laterite occurrences

The Bonsaso concession is dominated by well-foliated Birimian metasedimentary units. Detailed geological mapping of the concession is ongoing, but is hindered by the presence of a significant weathering profile. The geology is currently thought to be similar to that of the Iduapriem mine.

Gold mineralization in the area has been observed in shallow dipping quartz stockworks and veins. Quartz veins occur as a series of shallow dipping, thin, en-echelon quartz veins up to and greater than 10 centimetres wide. The veining is also associated with a quartz-pyrite alteration halo that extended several metres into the hanging wall and foot wall of the veins. This is thought to represent the type of deposit that typically forms along regional fault and fracture systems within Ghana, whereby fractures act as pathways for Au-bearing hydrothermal fluids. Precipitation of gold and quartz then results from changes in pressure, temperature and/or wall rock interaction. Mineralization is also associated with Tarkwaian conglomerates, probably of the Banket series and representative of placer mineralization, which is analogous to that at the Iduapriem mine. 

Drilling program after airborne geophysics for VMS

Posted by on Saturday, 8 December, 2012

VMS Ventures Inc.  announces plans for a 2013 winter drilling program on its 100% owned Manitoba properties.

Neil Richardson, VMS Ventures COO states: “We have many quality targets this winter, but we are particularly excited to get the drills turning on our newly acquired Reed East and Reed West properties. We consider them highly prospective as they cover a large area of the same volcanic rock package that hosts our high grade Reed Copper Deposit and Reed North base metal occurrences. VMS deposits tend to occur in clusters, within a specific package of these types of volcanic rocks.”

Diamond drilling is scheduled to begin in February and is expected to continue through April. Plans call for a budget of approximately $1.2 million which includes drilling 3,000 to 3,400 metres in 16 to 20 diamond drill holes. All target areas are within the Flin Flon – Snow Lake VMS greenstone belt of Manitoba.

Reed East and Reed West are adjacent to our Joint Venture property with Hudbay Minerals, which hosts the Reed Copper Deposit, currently being developed into a mine. These properties include targets with coincident Mobile Metal Ion (MMI) zinc anomalies and VTEM anomalies.

—             The other winter 2013 targets on VMS Ventures’ 100% owned properties vary in their specific characteristics, but all are associated with geophysical EM conductors generally with associated magnetic anomalies and within interpreted volcanic host rocks. More detail will be provided on these targets in the New Year.

Applications for drill permits have been submitted to the Manitoba government. After drilling is concluded, holes with favourable mineralization, alteration or geology, will be surveyed with down the hole TEM using Koop Geotechnical. Koop will utilize borehole pulse electromagnetic equipment manufactured by Crone Geophysics.

The New Near-surface Resistivity Method

Posted by on Monday, 22 October, 2012

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


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