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Geophysics & Elements



  • Ag - SilverBack to top

    Silver is usually found in its native form and is associated with disseminated sulphides. It is often a by-product of other mineral deposits.

    Native silver has high electrical and thermal conductivity. However, it does not occur in large concentrations and these properties cannot, therefore, be used to explore silver. Typically, geophysics is used to detect the associated sulphide minerals.

    Recommendations for SILVER Exploration

    • IP/resistivity: When silver is associated with disseminated sulphides.
    • TDEM, FDEM and Gravity: When silver and gold represent a by-product of massive sulphide deposits.
    • Magnetics and Spectrometry: On a regional scale to map geological lithology and structure, and locally to map alteration, enrichment and/or zonation within deposits.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Au - GoldBack to top

    Gold is commonly found in its native form, usually associated with other disseminated sulphide minerals. It is often produced as a by-product of other mineral deposits.

    Native gold is very conductive; however, like other precious metals, it occurs in extremely small concentrations. Conductivity cannot, therefore, be used to directly detect the occurrence of gold. Typically, geophysics is used to detect the associated sulphide minerals.

    Abitibi Geophysics: Recommendations for GOLD Exploration

    • IP/resistivity: When gold is associated with disseminated sulphides.
    • TDEM, FDEM and Gravity: When gold occurs as a by-product of massive sulphide deposits.
    • Magnetics and Spectrometry: On a regional scale to map geological lithology and structure and locally to map alteration, enrichment and/or zonation within deposits.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • C - CarbonBack to top

    Carbon in its native form may be found in the form of graphite, coal or diamonds (see Geophysics and Exploration for Diamonds, which is discussed separately).

    Stratigraphic graphitic sediments can be closely associated with Cu-Zn or Ni massive sulphide deposits, or along an unconformity associated with uranium deposits. Graphite can also be closely associated with fractures in lode gold deposits. Often graphitic horizons are mapped and used to provide a stratigraphic marker for other minerals. Graphite is both polarizable and conductive, has a low density and low magnetic susceptibility compared to metamorphic or igneous rocks.

    In higher metamorphic grades, it can form thick layers of coal.

    Recommendations for GRAPHITE Exploration

    • TDEM and FDEM: To map stratigraphic units or fracture patterns filled with graphite. Advanced TDEM and FDEM can, in some cases, differentiate between graphitic and sulphide conductors.
    • IP/Resistivity: To map graphitic zones that are important geological markers.
    • Magnetics in addition to the TDEM: To differentiate graphitic horizons that have a low magnetic susceptibility from sulphide conductors that may contain magnetite.
    • Gravimetry in addition to TDEM: To differentiate graphitic horizons characterized by a lack of excess mass compared to a sulphide conductor.

    Recommendations for COAL Exploration

    • TDEM and FDEM: To map coal beds below overburden and to identify intrusions within the coal (e.g., dykes).
    • IP/Resistivity: To map depth of overburden, thickness of coal bed, delineate boundaries of coal deposit and intrusions.
    • Magnetics: To map basin structure and intrusions in the coal deposit, that may contain magnetite.
    • Gravimetry: To map basin structure.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Co - CobaltBack to top

    Cobalt rarely occurs in its native form. It is usually produced as a by-product of copper and nickel sulphide or oxide deposits.

    Native cobalt is radioactive, dense and conductive. However, cobalt exploration is usually focused on the host base metal sulphides or oxides, which occur in larger concentrations and may also be conductive and/or polarizable, dense and magnetic.

    Recommendations for COBALT Exploration

    • IP/resistivity: When cobalt is associated with polarizable disseminated sulphides.
    • TDEM and FDEM: When cobalt is associated with conductive massive sulphide deposits.
    • Gravity: When cobalt is associated with dense massive sulphide deposits.
    • Spectrometry: To map enrichment and/or zonation within deposits.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Cr - ChromiumBack to top

    Chromium usually occurs as an oxide mineral, most often chromite.

    There are two main types of chromite deposits:

    • Stratiform deposits, consisting of laterally persistent chromite-rich layers.
    • Podform chromite deposits, consisting of pod to pencil-like, irregularly shaped massive chromite bodies.

    Chromite is commonly associated with magnetic minerals (magnetite, pyrrhotite, pentlandite).

    Recommendations CHROMIUM Exploration

    • Magnetics: For mapping geological lithology.
    • IP/resistivity: To search for associated minerals such as magnetite, this may, under certain conditions, be polarizable.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Cu - CopperBack to top

    Copper can occur in its native state; however, most commercial deposits are disseminated or massive sulphides (chalcopyrite, etc.) and to a lesser extent, oxide minerals (bornite, etc.).

    Native copper and copper sulphide minerals are highly conductive. Oxide copper minerals are associated with magnetic oxide minerals such as magnetite or pyrrhotite.

    Recommendations for COPPER Exploration

    • TDEM or FDEM: For massive sulphide copper-rich ore bodies.
    • IP/resistivity: For disseminated sulphide deposits.
    • Gravity: To detect excess mass that may be attributed to a sulphide conductor.
    • Aeromagnetics: To delineate stratigraphic or structural trends associated with iron oxide copper ore bodies.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • DiamondBack to top

    Diamonds occur in native form usually in kimberlite pipes or as secondary, alluvial deposits from eroded pipes. A diamond is formed from carbon at high temperature and pressure at depths greater than 100 km below surface. It is the hardest known rock and is associated with dense minerals, usually within a kimberlite pipe. Exploration for diamonds is focused on locating a kimberlite pipe. The geophysical signature of a kimberlite may vary considerably relative to its environment. For example, the weathered kimberlite cap may be conductive in an igneous host, or if the weathered cap has been glaciated, the kimberlite may appear resistive in a sedimentary host.

    Recommendations for DIAMOND Exploration

    • Magnetics: To locate circular anomalies that could represent a kimberlite.
    • Airborne Electromagnetics: Airborne EM is used in a reconnaissance to identify isolated conductive features which may represent pipes.
    • Ground Electromagnetics: Both TDEM and FDEM are used to delineate the conductive weathered layer over the pipe.
    • Gravimetrics: To delineate the kimberlite pipes that typically appear as circular anomalies, which may be positive or negative with respect to the host environment.
    • IP/Resistivity: To delineate the pipe boundaries.
    • Spectrometry: To detect associated radioactive minerals.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Fe - IronBack to top

    Bedded Iron formation is a chemical sedimentary rock that can be divided on the basis of the dominant original iron mineral into four principal facies. The classic facies zonation from shallow to deep water deposition is oxide to silicate to carbonate to sulphide. Graphite is often associated with the sulphide facies.

    Most of the economic deposits are associated with the Iron oxide facies known as Superior type. Other deposits are associated with Iron Oxide-Silicate-Sulphide facies known as Algoma type.

    Recommendations for SUPERIOR type:

    Iron oxide minerals such as the one in the Labrador Trough are magnetic. In this case, Abitibi Geophysics recommends:

    • Magnetics: To delineate stratigraphic magnetic trends.
    • Borehole Logging: To delineate iron enrichment.

    Recommendation for ALGOMA type:

    Iron Oxide-Silicate-Sulphide minerals are more conductive.

    • Magnetics: Since pyrite is not a magnetic mineral, the survey helps to delineate low mag responses along stratigraphic magnetic trends.
    • TDEM and FDEM: To delineate sulphide enrichment with associated graphite.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • Li - LithiumBack to top

    Lithium never occurs as a free element in nature. The majority of the world’s lithium production comes from:

    • Salars, or salt lakes, where prospective lithium mineralization is generally found in brine horizons.
    • Pegmatite minerals associated with plutonic rocks. Granitic pegmatite provides the greatest concentration of lithium-containing minerals, with spodumene being the most commercially viable source.

    Recommendations for LITHIUM Exploration in BRINES

    Since brine deposits form in evaporate depositional environments where brines have generally obtained lithium from geothermal waters, Abitibi Geophysics recommends:

    • IP/resisitivity: to calculate the brine bearing horizon within the northern portion of the salar using a resisitivity cut-off.
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    Recommendations for LITHIUM Exploration in PEGMATITES

    Since pegmatite is usually associated with intrusive rock, Abitibi Geophysics recommends:

    • IP/Resistivity: To delineate major pegmatitic dykes, which are usually more resistive than the surrounding rocks.
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    • Magnetics: To delineate major plutonic masses and fracture trends where dykes may have occurred.
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    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies

  • Mo - MolybdenumBack to top

    Molybdenum never occurs free in nature, but rather as oxidized mineral such as molybdenite and wulfenite. Molybdenum is mined as a principal ore and is also recovered as a by-product of some copper and tungsten deposits. Exploration focuses on the plutonic intrusive body setup, rather than the search for the mineral itself.

    Recommendations for MOLYBDENUM Exploration

    • Aeromagnetics: To delineate plutonic rocks.
    • IP/resistivity: To delineate the associated disseminated sulphide minerals.
    • Spectrometry: To delineate potassic alteration associated with these deposits.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies

  • Ni - NickelBack to top

    Nickel does not occur free in nature. It is commonly found as disseminated or massive sulphide minerals (pentlandite, etc.) in magmatic environments or as oxide minerals in laterites. Nickel sulphide minerals are highly conductive to superconductive and are often associated with pyrrhotite, which is highly conductive.

    Recommendations for NICKEL Exploration

    • TDEM and FDEM: To delineate massive sulphide-rich ore bodies.
    • Magnetics: To delineate magnetic ultramafic horizons and associated magnetite minerals.
    • IP/resistivity: For disseminated sulphide ore bodies.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies

  • PGE - PlatinumBack to top

    The platinum group elements (PGE) include platinum, palladium, iridium, ruthenium, osmium and rhodium. PGE can be native, although it is generally associated with sulphide minerals in Ni-Cu and chromite ore bodies. PGE associated with sulphide are highly conductive

    Abitibi Geophysics: Recommendations for PGE Exploration

    • Magnetics: To delineate magnetic ultramafic horizons and associated magnetite minerals.
    • TDEM and FDEM: For massive sulphide-rich ore bodies.
    • IP/resistivity: For disseminated sulphide ore bodies.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies

  • REE - Rare EarthBack to top

    Rare earth elements (REE) consist of 17 elements generally found in, or associated with, alkaline igneous rocks and carbonatites.

    Despite the name, rare earth elements (cerium, yttrium, etc.) are relatively plentiful in the earth's crust, with cerium being the 25th most abundant element. However, because of their geochemical properties, rare earth elements are typically dispersed and not often found in concentrated and economically exploitable forms.

    Recommendations for REE Exploration

    The first step is to identify environments where these complexes occur.

    • Airborne Magnetic and Gravity: To delineate host rocks. Because many carbonatite complexes are surrounded by mafic alkaline rocks, they often show up as a magnetic bull’s eye combined with a gravity low ringed by a gravity high.
    • Radiometrics: Useful in mapping the lithology, which often has traces of K, Th and U.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

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  • U - UraniumBack to top

    Uranium could be native or associated with oxide minerals. Uranium occurs in a number of different igneous, hydrothermal and sedimentary geological environments. Uranium deposits worldwide can be grouped into 14 major deposit-type categories, based on the geological setting of the deposits, the major being:

    • Unconformity-related deposits, which constitute approximately 33% of world deposits;
    • Iron oxide such as Olympic Dam deposits;
    • Sandstone (roll-front) deposits.

    Uranium is radioactive and commonly associated with other radioactive minerals.

    Recommendations for URANIUM Exploration

    • Radiometrics: For detection of the deposit and to trace the stratigraphic layers of an anomaly.
    • Gravimetry: As the unconformity occur between basement and sediment, that can also represent a contrast of density between both units.
    • Seismic: To map the unconformity between homogeneous basement and layered sediments.
    • Magnetics: To map the magnetic basement and determine the basin depth and underlying basement structure.
    • To map magnetic horizons when the uranium is associated with the magnetic minerals of iron oxide deposits.
    • IP/Resistivity: To map the alteration zone above the deposit and to determine basin depth.
    • Electromagnetics: To trace conductive graphitic/stratigraphic layers commonly associated with the unconformity.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies

  • Zn - ZincBack to top

    Zinc occurs as a sulphide (sphalerite, etc.) in disseminated or massive deposits commonly associated with copper minerals in volcanic settings and with lead minerals in sedimentary settings. Zinc and sphalerite are poor conductors, unlike copper and nickel sulphides.

    Recommendations for ZINC Exploration

    • TDEM and FDEM: For zinc-rich massive sulphide deposits, especially when the zinc is found in association with Cu sulphides, which increase the conductivity of the deposit.
    • IP/resistivity: For disseminated sulphide ore bodies.
    • Gravity: To determine the excess mass of the mineral deposit.
    • Magnetics: To map the lithology and structure of the geological environment.

    The above information is a guideline only. Each exploration project requires an in-depth assessment in order to select the best possible geophysical application from the tools available. See our Case Study Tool for examples of how the correct geophysical tool has helped others find mines.

    view case studies