Mineral exploration tr ends and developments in 2000
The Geological Survey of Canada (GSC) is Canada’s national agency for geoscientific information and research. It has supplied Canadian Mining Journal with unbiased reportage about the trends and developments in geophysics every year since 1965.
Part of Natural Resources Canada, the GSC, together with Canada’s provincial and territorial geological surveys, supplies the fundamental geoscience knowledge required to support effective mineral and hydrocarbon exploration and development across Canada; to provide the geological basis necessary to understand and address health, safety and environmental issues; and to advocate the interests of Canadian geoscience at the international level.
The GSC has an extensive capability in onshore and offshore geoscience surveys and in interpreting and managing geoscience information. This expertise is applied to assessments of mineral, energy and water resources, natural hazards, environmental and policy issues, and the development of exploration technology.
Further information about the GSC is available from the Communications Office, Geological Survey of Canada, Room 244, 601 Booth Street, Ottawa, ON, K1A 0E8, e-mail [email protected], or at the GSC web site: www.nrcan.gc.ca/gsc/
In the year 2000, companies were stabilizing after mergers, new companies were formed, and co-operative agreements were signed. Both increased and decreased activity were reported. Nearly all areas of exploration geophysics saw significant new geophysical software and hardware developments.
Fugro Airborne Surveys (FAS) was created early in the year 2000 by the merger of Geoterrex-Dighem and High-Sense Geophysics (in Canada), World Geoscience Corp. (WGC) (in Australia) and Geodass (in South Africa). The new company has regional operational offices in Canada (Ottawa and Toronto), Europe (Guildford, UK), South America (Santiago and Rio de Janeiro), Africa (Johannesburg), and Australia (Perth and Sydney). In addition to airborne surveys, FAS also offers ground geophysics on a global basis.
Geosoft Inc. (Toronto) announced the opening of a new office, its fifth, in Pretoria, South Africa, to provide technical support for the African exploration sector. In 2000, the Geosoft Plus Partner Program was launched to provide access to inversion, 3D visualization and other new technologies from OASIS montaj. Partners include Northwest Geophysical Associates, Paterson, Grant & Watson, Interpex, and Geophysical Software Solutions.
In April 2000, GF Instruments, s.r.o. (Brno, Czech Republic) was established. The company provides geophysical equipment (sales and rental) and geophysical survey services, and continues with the instrument production of the former Division of New Activities of Geofyzika, a.s.
Paterson, Grant & Watson Ltd. (PGW) (Toronto) reported a busy year in 2000. PGW joined with EarthScan Inc. (Toronto) to establish SkyMapper Ltd. (Toronto), which provides acquisition, processing and interpretation services in hyperspectral scanning. In May, PGW established a new office in Dublin, Ireland, serving its clients in Europe, Africa and the Middle East.
During 2000, Sander Geophysics Ltd. (SGL) (Ottawa) reported excellent results with its new Airborne Inertially Referenced Gravimeter (AIRGrav), and the company purchased a fourth Cessna Grand Caravan, increasing its fleet to seven aircraft.
In August 2000, Scintrex Ltd. (Concord, Ont.) announced a new internal restructuring. Scintrex is now composed of two divisions: Earth Science Instrumentation Division and Surveys and Exploration Technology Division. The latter (Scintrex Surveys) is the geophysical surveying division of Scintrex; it conducts airborne surveys from its Toronto headquarters and through its affiliate company, Megafisica Survey Aerolevantamentos S/A in Brazil. Ground geophysical surveys in Australasia are conducted by Scintrex Pty. Ltd. in Perth, Australia. Scintrex Ltd. itself has been a division of IDS (Intelligent Detection Systems) since March 1998.
During 2000, Sial Geosciences Inc. of Montreal participated for the first time in airborne surveys in Brazil through a co-operative venture with Scintrex and Megafisica.
Airborne Geophysical Surveying
The Council for Geoscience of South Africa (formerly the Geological Survey) in joint venture with industry partner Southern Exploration Surveys is using ultralights as airborne geophysical platforms to simultaneously record total field magnetic, gamma-ray and near infrared (NIR) spectrometry. The ultralights are a Streak Shadow and a Jabiru, both powered by 2.2-litre 85-hp jet-fuel driven engines. Nominal flying height is 50 m flying at 120 km/h.
In 2000, FAS, which now operates 31 aircraft, conducted several diamond exploration surveys in the NWT (over 55,000 line-km) and almost 50,000 line-km in Ontario, the majority of which was performed for the Ontario Geological Survey’s (OGS) Operation Treasure Hunt. FAS continued to acquire data in Morocco, where over 100,000 line-km of DighemV helicopter EM, magnetics and radiometrics have been flown. DighemV systems were also employed in exploration projects in Ireland, Russia (through its strategic alliance with AeroGeoPhysica), Romania and several South American countries. In Eastern Europe three mineral exploration surveys were completed flying helicopter magnetics and radiometrics.
In 2000 Hyvista Corp. of Australia covered approximately 50,000 km2 with airborne imaging spectrometer surveys with its Hymap 128-channel instrument in Brazil, Germany, Spain, Britain, Finland, Greenland, the United States and Australia. Integrated Spectronics Pty. Ltd. (Baulkham Hills, NSW) manufactures the Hymap series of airborne imaging spectrometers of which four are currently being flown around the world and a fifth is being constructed for a major international mining company.
PGW completed magnetic compilations of China in co-operation with the Aero Geophysical Survey and Remote Sensing Centre, Ministry of Geology and Mineral Resources (Beijing), and GETECH, a geophysical consultant based in Leeds, UK. The company also completed project AAIME (Aeromagnetics of Arabia, India and the Middle East) in co-operation with ITC (International Institute for Aerospace Survey and Earth Sciences, Delft, The Netherlands). PGW S.A. completed a multi-client 65,000 line-km magnetic/radiometric survey over porphyry copper exploration terrain in northern Chile, in co-operation with Scintrex Surveys. Scintrex Ltd. and Megafisica were active in Brazil in 2000 flying fixed-wing aeromagnetic and radiometric surveys as well as several helicopter frequency-domain EM surveys using the six-frequency Impulse system by Aeroquest Ltd. (Milton, Ont.). Scintrex also conducted airborne surveys in Canada, the United States, Mexico, Chile, Paraguay and Bolivia.
SGL reports completion of a large combined radiometric/magnetic/VLF survey in northern Saskatchewan for the GSC.
The fixed-wing survey fleet of Sial Geosciences now comprises six aircraft of four types providing a range of capabilities. Sial conducted large helicopter-borne EM surveys in northern Spain and the Red Lake mining camp of Ontario, with simultaneous acquisition of EM, magnetic and radiometric data.
In Airborne Data Acquisition and Processing news, CGI Controlled Geophysics Inc. (Thornhill, Ont.) spent the better part of 2000 focussed on processing data from T.H.E.M. Geophysics’ (Old Chelsea, Que.) new helicopter-borne TDEM system. The EmFlow software from Encom Technology Pty. Ltd. (Sydney, Australia) was also acquired and adapted to the T.H.E.M. data-processing stream. EmFlow is used to generate conductivity-depth-inversion sections for time- and frequency-domain EM systems. Encom has developed several new software products including Profile Analyst, which enables visualization and analysis of data sets stored in a Geosoft OASIS montajdatabase. Profile views, image views and spreadsheet views are dynamically linked for seamless communication with an OASIS montaj. GEMeX combines the use of Profile Analyst with a range of transient EM analysis tools
. The company also announced that it has been awarded a A$700,000 Australian Federal Government R&D Start Grant to assist it with the development of QuickMag, an expert system. The project will apply the knowledge of an experienced geophysical interpreter to routine magnetic interpretation problems.
FAS reported it is continuing development of the data interpretation software C-in-3D from the former WGC. GEM Systems Inc.’s (Richmond Hill, Ont.) AirNAV airborne data acquisition and navigation system has a new software configuration to a full 12-channel differential global positioning system (DGPS), and new touch screen display hardware with pilot preferences optimized for pilot-only operation. In 2000, Geometrics (San Jose, Calif.) improved its MagLog marine and airborne data logging and display software to interface to more geophysical systems. Also MagMap2000 now imports any ASCII columnar data for positioning, GPS filtering, destriping and contouring.
Geosoft released version 5.0 of its OASIS montaj, which includes a free software interface that enables users to access, convert and print data, grids and images in a variety of formats via the Internet. Geosoft has also added 3D Perspective Presentation in the 5.0 release. The first sets of airborne data from Ontario’s Operation Treasure Hunt (OTH) have been released in Geosoft format. OTH data can be viewed with Geosoft’s Oasis montaj interface available on the company web site. PGW is participating in the new Geosoft Plus Partner program through the September release of six software tools for incorporation into Geosoft’s OASIS montaj. Designed for airborne geophysical processing and interpretation they include: Coastplot, Compu-drape, Gridkimb (to locate kimberlite pipes from magnetic grids), Microleveling, SED (source edge detection), and SPI (Source Parameter Imaging).
In Aeromagnetic Surveying, the newly merged FAS magnetics platforms now include the MIDAS and HM3. The company completed a 700,000-line-km magnetic survey in Namibia in 12 months, utilizing five fixed-wing aircraft. Major offshore non-exclusive surveys were also carried out in eastern Canada and Brazil (in association with LASA Engenharia e Prospeces).
The GEM Systems GSMP-20GS high resolution potassium gradiometer development was concluded in 2000, and two systems were delivered to the U.S. Navy. The SuperGrad features the highest sensitivity (30 fT/ sqrt (Hz)) magnetic field measuring device ever developed. GEM is currently seeking research partners to adapt this equipment for multi-sensor aeromagnetic gradiometer surveying.
Scintrex formally started work on the CS-3, a new upgrade of the CS-2 high sensitivity cesium magnetometer sensor. The CS-3 sensor will retain the CS-2 features and also include automatic hemisphere switching, increased input voltage (to 24-35V), and electronic circuitry upgrades and improvements. All existing CS-2 sensors will be upgradeable to CS-3. SGL reports flying a large aeromagnetic survey in the Canadian Arctic for the GSC as well as numerous smaller surveys for industry clients. Also in 2000, Vanguard Geophysics Inc. (Toronto, Ont.) sold its Vanguard Magnetometer Array (VMA) to Oak Ridge National Laboratory. This boom-mounted helicopter magnetometer system used for extremely high resolution mapping projects was upgraded from a five- to eight-sensor array by Geosensors Inc. (Toronto), and included a prototype time-domain EM system based on the Geonics EM61.
Airborne Advances in 2000 saw Aeroquest (Milton, Ont.) improve its AeroTEM digital helicopter-borne time-domain EM system, by doubling the transmitter dipole moment, dropping the lowest frequency to 30 Hz and introducing streaming data. Developed by Aeroquest in 1999, it has flown over 25,000 line-km of production surveys. Unlike other airborne time-domain systems, the AeroTEM system has a coincident dipole geometry. The receiver coils are at the centre of a rigid 5-m-diameter, vertical dipole transmitter coil with a dipole moment of 18,000 NIA. Aeroquest’s Impulse EM, frequency-domain HEM system utilizes a single high-output transmitter to power single horizontal coplanar and vertical coaxial transmitter coils, producing a total of six frequencies and over 700 NIA in each orientation. Scintrex Surveys currently flies the Impulse system in Canada and internationally.
Time-domain AEM surveys (GeoTEM, MegaTEM and/or TEMPEST) were flown by FAS in Argentina, Australia, Brazil (in association with LASA), Canada, Chile, Denmark, Finland, India, Namibia, Sweden and Togo primarily for mineral exploration. The OGS, as part of OTH, awarded FAS some 30,000 line-km of AEM, split roughly 60/40 between MegaTEM and GeoTEM. The company also completed several surveys using the DighemVRES all-coplanar five-frequency system.
PGW implemented a complete suite of processing algorithms for digital data acquired by the new AeroTEM system developed by Aeroquest. PGW was appointed “OTH Geophysicist” for the period from August 1999 to March 2001, to manage the geophysical component of Operation Treasure Hunt. This includes the management and quality control for eight magnetic/EM surveys totaling 135,500 line-km and six different time-domain and frequency-domain EM survey systems. As part of OTH, PGW documented the newly established Reid-Mahaffy Airborne Geophysical Test Site for airborne geophysical systems, and an atlas of airborne geophysical surveys for Ontario.
Sial Geosciences designed and manufactured a new helicopter-borne EM system called the ‘Phoenix’, which was initially field-tested in November 2000. The company also planned to fly further tests over Nighthawk Lake (Timmins, Ont.). The Phoenix HEM system is a towed boom system with a receiver-to-transmitter separation of 8.35 m. Dipole moments range from 400 NIA for the low frequencies (1 kHz ) to 50 NIA for the highest frequency (36 to 60 kHz).
T.H.E.M. Geophysics refined its new helicopter-borne transient EM system. The company improved the blimp stability, tested several versions of a B field sensor, increased the moment to 300,000 NIA peak, and demonstrated that THEM can be used in very steep terrain. In 2000, T.H.E.M. flew large surveys in eastern Canada and northeastern Africa.
In Airborne Gravity Developments, SGL flew several airborne gravity surveys in 2000 and the AIRGrav system demonstrated its excellent stability by successfully surveying in moderate turbulence in the Rocky Mountains using a drape surface. Recent AIRGrav surveys demonstrated an accuracy of 0.2-0.5 mGal with a resolution of 1.8-2.0 km in a fixed wing aircraft, and the same accuracy with a resolution of 0.6-0.7 km in a helicopter.
Ground Survey Techniques
Integrated Spectronics introduced its new Pima SP field portable infrared spectrometer for the identification and mapping of alteration minerals around mineral deposits. The instrument has a mineral identification algorithm that identifies semi-quantitatively the relative proportions of the minerals in about 40 seconds. Spectra are stored together with the grid position at which the spectrum was measured. In 2000, Terraplus Inc. (Richmond Hill, Ont.) became a distributor for the Pima.
A new physical property database is being jointly developed by Mira Geoscience (Montreal), Noranda Technology Centre (Pointe Claire, Que.), Quantec Geoscience Ltd. (Porcupine, Ont.) and the GSC. Eventually, all collected data will be standardized and archived, particularly from physical property logging of boreholes, and will be available along with querying tools for accessing geological rock property data. Quantec has also developed a physical property lab to provide resistivity, IP, density and susceptibility measurements on hand samples.
There were several new developments in the area of Data Processing and Positioning. In July, Interpex Ltd. (Golden, Colo.) joined the Geosoft Plus Partner program, signing an agreement to deliver integrated modeling and inversion solutions for Oasis montaj, which will streamline the interpretation of IP targets. In October, Geophysical Software Solutions (GSS) (Canberra, Australia) announced that it had joined the Ge
osoft Plus Partner program. GSS has integrated its new PotentQ inversion application into the Oasis montaj product suite. PotentQ performs rapid semi-automatic modeling of a single magnetic and/or gravity anomaly.
Lamontagne Geophysics (Kingston, Ont.) has been working for several years on MultiLoop 3, a software tool for EM modeling to solve problems involving thin sheet conductors with irregular outlines, variable conductance, curved surfaces, and galvanic connections. MultiLoop 3 is expected to be available commercially in the second half of 2001 with a prototype version demonstrated at the Prospectors and Developers Association of Canada Convention this March, in Toronto.
In Borehole Geophysics, Antares Datensysteme GmbH (Stuhr, Germany), which manufactures logging equipment and associated software, released the A-SGR1405, a new 52-mm-diameter spectral gamma-ray logging tool. The tool registers the natural gamma radiation, potassium, thorium and uranium content of the formation using a BGO detector and a new processing technique. (“BGO” stands for bismuth germanate, a scintillation material twice the density of NaI.) The 256-channel tool transmits the full gamma energy spectrum digitally via a single conductor cable to the surface data acquisition system.
GF Instruments now provides direct measurements of concentrations of elements (H, S, Fe, Ti, Si, Mn, Cl, Hg) in boreholes via gamma-ray spectral analysis from neutron capture using the GRS-2000 gamma-ray spectrometer with a BGO detector.
IFG Corp. (Brampton, Ont.) announced several new developments including the completion of its Rate Gyro orientation probe. The probe is a dual-axis gyro sensor, combined with a two-axis tiltmeter. The operating range is from 5* to 80* from vertical. Both axes of the gyro have a rate sensitivity of 0.0001*/sec and are sampled two times per second. The maximum rate change of the gyro is 100*/sec. A new high sensitivity inductive conductivity probe (the BIC-01) was also developed for ore grade measurements in base metal mining. The new BW-100M borehole winch, designed for portable and underground application, has 150 m of mono cable, automatic level winder, depth encoder, and includes the BIN-07 digital data interface console. IFG’s editing and processing software, PC-Log, has also been rewritten to operate with Windows.
In 2000, Mount Sopris Instrument Co. completed development and began shipping its new 44.5-mm-diameter user-configurable, monopole-dipole, multi-frequency full waveform sonic tool. Mount Sopris also completed development of its new Windows-based MSLog data acquisition software for use with acoustic and optical televiewer tools from ALT srl (Luxembourg), and with the spectral gamma and borehole gyro tools manufactured by IFG Corp. (Canada).
Quantec Logging Services Inc., a division of Quantec Geoscience, has added full waveform sonic logging capabilities for exploration and geotechnical applications to its multi-parameter logging truck.
Robertson Geologging Ltd. (Deganwy, UK) introduced the 2.8-kg Micrologger-2 borehole logging and closed circuit TV acquisition unit. It connects to the USB port of a notebook PC to operate any of over 30 digital logging probes including optical and acoustic televiewers. Other new developments include: a range of lightweight stackable probes that can be combined in the field, a 42-mm TV camera with orientation module, a high-resolution digital acoustic televiewer and addition of a digital version of the P- and S-wave suspension logging probe manufactured by OYO Corp. The company also expanded its contract logging service capability and can now undertake short- or long-term logging surveys within Canada.
In Ground Electromagnetic news, Dualem Inc. (Milton, Ont.), which was founded in November 1998, now manufactures near-surface EM instruments with a z-axis transmitter, and dual z-axis and x-axis receivers. The 2-m length of the new DualEM-2 EM instrument is short enough for manoeuvring through thick vegetation, yet long enough to enable the measurement and interpretation of in-phase information. The DualEM-2 was used in base metal exploration in 2000.
Geonics Ltd. (Mississauga, Ont.) announced the EM31-SH, a 2-m coil separation version of the EM31 ground conductivity meter with improved lateral resolution and sensitivity to smaller targets. The new EM61-MK2 time-domain metal detector has multiple time gates and a computer-based system controller as an integral part of the instrument, providing real-time data display and interfacing to GPS receivers. Also new are the new EM38-DD, a 1-m coil separation ground conductivity meter for simultaneous measurement of ground conductivity in the vertical and the horizontal dipole mode, and the EM38B which provides simultaneous measurement of ground conductivity and susceptibility.
In 2000, IRIS Instruments (Orleans, France) announced two new Slingram-type EM profiling systems. The Promis 4 features four transmitter-receiver spacings (10, 20, 40 and 80 m) and two frequency settings. The Promis 10 features a three-component receiver and 10 frequencies from 110 Hz up to 56,320 Hz and transmitter-receiver spacings of up to 400 m.
Lamontagne developed a new surface sensor for the UTEM 4 system, which measures all three components of the rate of change of the magnetic field simultaneously and incorporates three axis accelerometers for orientating the components. The new sensor was being field-tested at the time of writing
The GDP-32II is Zonge Engineering’s (Tucson, Ariz.) fourth generation multi-channel receiver for collection of controlled and natural source geo-electrical and EM data. Enhancements over the GDP-32 include a faster digital processor (40 MHz 486), an expanded keyboard, a 1/2 VGA graphics display and complete Windows compatibility. Zonge’s new NT-32 integrates the NanoTEM early-time transient EM system transmitter into the GDP-32II receiver, simplifying the collection of NanoTEM data.
In Gravity Surveying, Allan Spector and Associates (Toronto, Ont.) specialists in the application of gravity and magnetic methods, has developed an efficient and economical procedure for reconnaissance gravity surveys that has been extensively applied in Canada, the United States and Mexico. The procedure employs a dual digital barometric altimeter system, a “rover” unit and a monitor unit that through a datalogger monitors diurnal barometric variation. Elevation accuracy is reported as better than one metre and can be achieved at half the cost of alternative procedures.
Scintrex Surveys completed a 7,400-point gravity survey in the western Gulf of Mexico. The survey, which was started late in 1999, is one of the largest combined land and ocean bottom surveys with most of the surveying in 2000 done at water depths to 200 m using Scintrex’s SeaGrav meters to measure the 3,000 sea-floor points.
Induced Polarization Developments saw Encom release IP Vision for the management, quality control, analysis, display and model simulation of induced polarization data. The software provides data import from common instrument types and data export using a wide choice of industry formats. Zonge’s new Zeta IP system is an integrated computer-controlled system that allows rapid collection of IP data using short dipoles (10 m or less). The core of the system is the MX-30, which allows connection of both transmitter and receiver subsystems of up to 30 electrodes simultaneously.
In Ground Magnetic Surveying, both the GEM high resolution GSMP-30 potassium magnetometer/gradiometer system and the new GSM-19 v6.0 Overhauser magnetometer system consoles have been outfitted with Cold Fire RISC processors (from Motorola) and up to 32 Mb of memory. The new consoles can display real-time navigation capability including real-time conversion to UTM co-ordinates, grid rotation and lane guidance with DGPS corrections in real-time or by post-processing.
Ground Penetrating Radar (GPR) Developments saw MAL GeoScience AB (Sweden) release a new radar control unit for the Ramac/GPR systems. The new model CU-II control unit has a unique docking feature for exp
ansion from single-channel to multiple-channel operation. The CU-II standard configuration as a single channel GPR can be easily upgraded with the addition of multiple channel antenna modules such as the Model MC-4 or the Model MC-16 for up to four or 16 channels of radar data. Easy 3D software for Windows 95/98/NT is now available, which will display 3D cubes, time slices, front and side views of GPR data sets.
Ground Radiometric Surveying includes GF Instruments’ introduction of the GRM-260, a 256-channel hand-held gamma-ray spectrometer for measurement of K, U, Th concentrations and dose rates. The weatherproof GRM-260 unit is equipped with a 2-inch x 2-inch NaI(Tl) detector. The measured spectrum and concentration values are shown on the backlit graphic screen with data stored in memory. The GRS-2000 gamma-ray spectrometer is now also available in several versions for surface, borehole or laboratory measurements, equipped with 3-inch x 3-inch, 2-inch x 2-inch NaI(Tl) or BGO detectors.