Prospecting and Exploration.docx

Prospecting and Exploration Tuesday, 18 June 2024 12:08 pm **Mineral Exploration**   Basic Mining Steps 1. Prospecting and Exploration -- define ore extent and value - Sampling to determine grade and economic viability - Make decisions for further sampling - Filter deposits for best...

Prospecting and Exploration Tuesday, 18 June 2024 12:08 pm **Mineral Exploration**   Basic Mining Steps 1. Prospecting and Exploration -- define ore extent and value - Sampling to determine grade and economic viability - Make decisions for further sampling - Filter deposits for best development prospect 1. Resource Estimation - ore size and grade - resource (preliminary reserves) 1. Pre-feasibility -- theoretical economics of ore 2. Feasibility Study - evaluate financial and technical viability - make decisions whether to develop project or not - convert resources to reserve - economic evaluation 1. Development - access to ore body - plant and equipment 2. Operation - extraction and processing - exploration to extend mine life, identify new resources 1. Mining Closure - Rehabilitation and Reclamation   Ore - specific mineral resource, mined economically base on economic conditions Prime commodity - principal ore mineral Associated commodities - by-products along with main mineral Trace elements - number of valuable mineral contained in all ore deposits - can be recovered during processing Mineral resource - in-situ mineral occurrence - quantified by geological data and with cut-off grade Ore reserve - mineable deposit, highest positive NPV for operation Cut-Off grade - lowest content of valuable minerals of ore - makes exploitation and processing profitable Waste - \"gangue\" - unwanted minerals in rock Protore - initial but uneconomic mineral, natural process upgrade ore level Grade - concentration of a metal in ore - in % or ppm (parts per million) - for coal \"ash content\" - lower grade - greater tonnage needed to provide economic deposit - properties of mineral govern existing technology to process it - Ex. Nickel is more readily recovered from sulphide than silicates ore - price is also vital factor - daily fluctuations may occur - shape and nature of ore - affects workable grade - public reporting codes: JORC - Australia; PMRC (Philippine Mineral Reporting Code) - Philippines Assaying - determining concentration   **Bre-X Scandal** - biggest mining and gold scandal, biggest stock scandal in Canada - March 1993 - Busang, Indonesia - gold deposit salting     **Mineral Deposits: Types and Associations**   **Geological requirements of deposit to form** 1. Source -- magmatic, hydrothermal, sedimentary, or metamorphic origins. 2. Transport mechanism -- to ore deposit site -- either allows concentration or residual concentration (remove non-ore) 1. Depositional mechanism -- trap, fix components of ore body 2. Preservation mechanism - protect the deposit from erosion, metamorphism, or destruction, including tectonic stability, burial, encapsulation, and isolation   **Geological parameters (for classification)** 1. Composition -- minerals/metals contained 2. Form and tectonic setting -- size, shape, orientation, and distribution 3. Host rock and geological setting -- enclosing rock and ore associations 4. Genesis - geological processes and controls forming deposit   **Mineral classification based on composition** 1. Metalliferous -- metal-bearing minerals -- melted to obtain new products a. Ferrous -- iron dominant metal a. Magnetic. b. Prone to rusting a. Non-ferrous - do not contain iron a. Non-magnetic. b. Corrosion-resistant. c. Lightweight (aluminum), high conductivity (copper), or high strength (titanium). 2. Industrial/Non-metallic -- not used as metals or fuels a. Construction materials -- gypsum (plaster, wall boards, etc.) a. Agriculture - nitrate, rock phosphate, potassium (fertilizers) b. Industrial use - graphite (lubricant), halite (food preservative), sulfur (fertilizer, acid), barite (drilling mud), fluorite (toothpaste, teflon, steel, plastics), bentonite (cement, oil well drilling), pumice (abrasive) c. Household - silica sand (glass ware), talc (lubricating, cosmetic powder), borate (cleaning) 3. Coal -- fossil fuel- energy source - high carbon content 4. Petroleum (crude oil) and natural gas -- hydrocarbons -- energy source and petrochemical industry - plastics, synthetic rubber, and chemicals 5. Renewable resources - natural resources -- can be replenished and is sustainable - solar, wind, hydropower, biomass, and geothermal energy.   **Mineral classification based on form** 1. Veins - filling of fissures, fractures, or faults - transverse to structural features (e.g. bedding) 2. Replacements - \"chimneys/pipes\' and filing in country rock - highly irregular form 3. Disseminations - minute/large units of economic mineral - scattered irregularly in country rock   **Mineral classification based on theory of origins** 1. Magmatic - cooling and solidifying of molten rock 2. Hydrothermal - hot water/ hydrothermal solutions from molten rock 3. Syngenetic - near surface - formed same process and time as the enclosing rock 4. Epigenetic - formed later than the host rock - introduced to pre-existing rock after formation via metal bearing fluids 5. Sedimentary - evaporation, biochemical extraction and precipitation - Surface/near surface - enclosed bodies of water 6. Secondary - unworkable deposits converted to economic deposits by later process of enrichment 7. Placer - accumulation of erosional debris - found in below waterfalls, inside meander loops, tributaries, undulations of ocean floor, behind rock bars, rock holes a. Alluvial - flowing water - riverbeds and floodplains - well-sorted sediments, like gold b. Colluvial - gravity - base of slopes - poorly sorted sediments (less economical) c. Eluvial - in-situ weathering - hilltops and plateaus - residual matters may rich in minerals, like bauxite and laterite   **Reconnaissance and Prospecting**   **Stages of Exploration** **Stage 1: Prospecting - Reconnaissance (Strategic Phase)** 1. Prospecting Stage **(Regional appraisal)** - researches - field and library - survey - reconnaissance and geologic - rock sampling and laboratory testing - plotting - geologic data - map interpretation 1. Preliminary Exploration Stage **(Detailed reconnaissance of favorable areas)** - more researches - preliminary geological mapping - field traverse - river, creeks, roadcuts - aerial photo geologic study - stream sediment sampling - laboratory testing (petrographic/mineralographic) - plotting - geologic data - map interpretation - prelim report   **Stage 2: Exploration - Target Investigation (Tactical Phase)** 1. Detailed Exploration Stage **(Detailed surface appraisal of target areas)** - geologic mapping - indicative areas - geochemical testing - geophysical investigation - drilling - laboratory testing - geologic report 1. Ore Reserve Determination **(Detailed three dimensional sampling and preliminary investigation)** - Geologic modelling and interpretation - Reserve estimation - Mine evaluation - Pre-feasibility report   1. **Economic mineral deposit**   Geological reconnaissance - survey - geological features and regional characteristics - look for rock outcrops - collect samples - chemical analysis - initial broad reconnaissance exploration survey - through wing aircraft - early morning hour photos - low sun angle enhances features of interest - Insufficient planning - geologic criteria - Inadequate observation record - Few samples taken - Premature data evaluation - results termination/original plan modification Geological survey - investigate area of interest (regional or local geology) - understanding of regional and local geology - identify environments to host economic quantities of mineral - build base maps (rock unit distribution, stratigraphic and structural details, landforms. etc.) regional - large areas; local - small, specific areas Geological map - visual record of geological facts   Equipment used in geological mapping 1. Maps - latest available map as reference 2. Aerial photographs and stereoscope - large geological features (volcanoes, folds, faults, craters, etc.) - satellites - high resolution imageries 1. Geographic Positioning System (GPS) - global radio navigator satellite system - determine exact location and time - locate lithology, structural elements, sample points, elevations, etc. - log geological traverse, \"en route\" 1. Field camera - record interesting features 2. Compass/clinometers 3. Geological hammer 4. Hand-held lens 5. Sample bags 6. Field notebooks and pen 7. First aid kit   Digital elevation model (DEM) - digital cartographic dataset in XYZ Coordinates - derived from contour lines or photogrammetric methods - data from remote sensing techniques and land surveying build DEMs - radiometric and geometric corrections for terrains - 2 methods of generating elevation data a. Stereogrammetry using air photos or radar data b. Radar inferometry   Prospecting - discloses ore information occurrence/mineralization for area of interest - together with geological work - find quality of mineral (reserves) and grade to meet industry requirements Can provide these data: 1. Size and shape 2. Attitude of ore body 3. Thickness variation along dip and strike 4. Nature of enclosing and overburden rocks 5. Degree of uniformity 6. Quality and distribution of country rock 7. Mineralogical and chemical composition 8. Change in mineral quality Prospect - potential ore occurrence - geophysical, geochemical, geological studies   Types of prospecting 1. Float sample tracing - mineral-bearing boulders (floats) moved down slope under gravity; source: mountain/cliffs 2. Panning - rough and ready method - separation by greater specific gravity with water 3. Trenching - elimination of unpromising grounds - if deep overburden - series of closed-spaced pits - dig at right angles to the rock structure/ strike of vein - long, narrow, and shallow excavations 1. Test pitting - explore subsurface conditions at specific points - square or rectangular pits   Evidence from outlying areas 1. Regional guides - broad and general - used in selecting regions for exploration a. batholiths and major rock bodies b. volcanic rocks c. igneous rocks a. acid intrusive - tin, tungsten, molybdenum b. basic intrusive - nickel c. ultrabasic intrusive - chromium, nickel, platinum 1. Age relations - metallogenic epoch 2. Ore zones with major fault zones 3. Sedimentary rocks; occurrence of iron formations 4. Climatic and topographic conditions a. tropical: lateritic weathering - manganese and bauxite b. arid (dry) with deep water level favoring supergene enrichment - porphyry copper c. long periods of weathering - erosion - placer deposits Categories of guides based on nature of guiding features 1. Physiographic guides - physical features of earth a. eminences and depressions - eminences - fault scraps (steep slopes/cliffs formed from faulting) and hogbacks (sharp ridges formed by erosion) - depressions - low areas (spread out material) - weathering of soluble minerals/veins b. oxidational subsidence - depressions - erosion of soft materials or ore bodies shrinkage - oxidation c. topography: iron ores - large ore bodies = major ridges and mountain ranges - iron and bauxite are found in large masses d. in relation to placer deposits - weathering of heavy minerals; water/air as concentration agents 2. Stratigraphic and lithologic guide - rock layers (strata) and relationship a. stratigraphic - ore bodies hosted by specific sedimentary beds b. lithologic - ore bodies hosted by intrusive bodies or volcanic flows\' 3. Mineralogic guides - formation processes - alteration, mineralization, and oxidation a. target rings of alteration - changes in surrounding rock of epigenetic ore - forms alteration zones b. hypogene zoning - discovering primary mineralization at depth indicates enrichment zones c. oxidation products - oxidized ore bodies are rich enough to mine d. leached outcrops - gossans (iron cap overlying sulfide ore) e. metals in oxidized zones - resistant metals (native gold) accumulate in oxidized zones - high assay values (residual enrichment) 4. Structural guides - fractures, contacts and folds a. contacts - ore deposits are formed when strong intrusive bodies meet weaker sediments - \"contact\". b. fracture - channels for mineralizing fluids, ore deposition sites, and zone of replacement c. folds - crests of anticlines, troughs of synclines, or limbs between the two 5. Geochemical guides a. biogeochemical analysis - specific plants (indicator plants) might show presence of elements (geobotany) b. animals - burrowing animals and aquatic creatures - behavior and abnormal body concentration of elements     Remote Sensing - acquire information of spectral and spatiotemporal nature of objects - no direct contact - uses \"electromagnetic radiation\" EMR - energy is reflected, absorbed, and transmitted upon material on earth features - color - resultant optical effect due to spectral difference - provides lithostratigraphy - distribution, description, and classification of rock layers (strata) - satellites orbit in altitude between 700-920 km LANDSAT - US Govt. SPOT - French Govt. AVIRIS - Advanced Visible/Infrared Imaging Spectrometer ASTER - Advanced Spaced Borne Thermal Emission and Reflectance Radiometer ATLAS - Joint venture of US and Japan, 1999   Application of remote sensing 1. Regional and local scale geological mapping and fracture patterns a. Surficial/lithological and structural mapping b. Mineral/hydrocarbon exploration c. Geo-environmental and geohazard mapping d. Baseline infrastructure e. Sedimentation mapping and monitoring f. Geobotany g. Sand and gravel exploration 2. Hydrothermal altered rocks and associated minerals   Satellite imageries advantage 1. Rapid creation of regional geological maps - essential in planning and scheduling of ground surveys 2. Identification of locations and relationship of geological units to earths surface 3. Regional scale - broad geological structures than localized ground surveys 4. Reference material for more geological analysis 5. Use for lithological unity and geomorphic features through digital imaging 6. Cost-effective-free LANDSAT data sources 7. Advanced computer processing 8. Global coverage without restrictions - for remote and inaccessible regions   Digital Imaging Processing - Image restoration - ensuring image look the same on ground - Information extraction - diverse features of information sets - Image enhancement - better image substance a. contrast enhancement - expanding original gray level range of image b. spatial filtering - enhance natural features - faults, folds, joints c. density slicing - grey tone range to density ranges d. false color composite images - MSS (multispectral scanner) bands 4 (Red),5 (Blue),6 (Green) a. enhance natural color images - highlights vegetation and water features   **Geological Exploration** - collection of available geologic data - soil and rock types - geologic structure - physical and chemical properties - interpretation and integration of geologic data on maps   Activities 1. Geologic mapping - surface investigation - outcrops are primary consideration 2. Trenching and test pitting - trial pits and trenches to expose outcrop - determines overburden thickness and deposit character 3. Field sampling and laboratory testing - petrographic and mineralogic analysis 4. Surface mapping - surficial geologic information plotted in map 5. Underground mapping - subsurface activity geologic information and plotted in map 6. Air photograph mapping - use of aircraft for geologic information - high polarizing cameras   Geophysical Exploration - geophysics, uses physical methods to measure physical properties - subsurface, abnormalities and surface properties - detect presence and position of geological deposits - if economical - underlying structures - folds, faults, intrusive rocks - detect changes in geological conditions   Anomaly - statistically significant departure from the normal values   Geophysical Methods   +-----------+-----------+-----------+-----------+-----------+-----------+ | Method | Physical | Types of | Device | Applicabi | Limitatio | | | Propertie | Field | | lity | ns | | | s | | | | | +===========+===========+===========+===========+===========+===========+ | Gravity | Density | Gravity | a. Groun | a. 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