Exploration information systems – A proposal for the future use of GIS in mineral exploration targeting

Structural and hydrothermal alteration mapping related to orogenic gold mineralization in part of Kushaka schist belt, North-central Nigeria, using airborne magnetic and gamma-ray spectrometry data

“…Under dehydration and devolatilization metamorphic conditions, the presence of iron-rich mineral assemblage (pyrite, chalcopyrite, covellite, chalcocite, molybdenite, galena) and metapelitic minerals (chlorite, sericite, quartz, epidote, albite and calcite) present in phyllites and greenschists in the study area promoted the formation of metamorphic fluids and gold ligand (HS − ) [15,30,38,44,45,47,[55][56][57][58]. Due to melt/magma mixing, crystal segregation, adsorption, phase immiscibility and sulfur globulization during granitoid emplacement, the mixing of the oxidized magmatic fluids with the metamorphic fluids and gold ligands (HS − ) resulted to an increment in oxygen fugacity, thereby promoting the precipitation of orogenic gold minerals [15,30,40,47,52,53]. Geologic structures such as faults, shear zones, fractures, and lithological contacts (where rheological contrast is significant) constitute migration pathways for the deepseated hydrothermal fluids comprising of gold thiosulfate complex [Au(S 2 O 3 ) 2 ] 3− to precipitate and localize gold minerals at higher crustal [30,53].…”

“…The mineral systems approach [48][49][50][51][52][53][54] can be employed to better understand hydrothermal alteration subsystem that is related to orogenic gold mineralization in the study area. Under dehydration and devolatilization metamorphic conditions, the presence of iron-rich mineral assemblage (pyrite, chalcopyrite, covellite, chalcocite, molybdenite, galena) and metapelitic minerals (chlorite, sericite, quartz, epidote, albite and calcite) present in phyllites and greenschists in the study area promoted the formation of metamorphic fluids and gold ligand (HS − ) [15,30,38,44,45,47,[55][56][57][58].…”

“…Due to melt/magma mixing, crystal segregation, adsorption, phase immiscibility and sulfur globulization during granitoid emplacement, the mixing of the oxidized magmatic fluids with the metamorphic fluids and gold ligands (HS − ) resulted to an increment in oxygen fugacity, thereby promoting the precipitation of orogenic gold minerals [15,30,40,47,52,53]. Geologic structures such as faults, shear zones, fractures, and lithological contacts (where rheological contrast is significant) constitute migration pathways for the deepseated hydrothermal fluids comprising of gold thiosulfate complex [Au(S 2 O 3 ) 2 ] 3− to precipitate and localize gold minerals at higher crustal [30,53]. Under suitable temperature and pressure conditions, the interactions between metamorphic fluid (composing of auriferous fluid, gold ligands, water, silica, sulphide and chlorine compounds, carbonates, and ions of potassium, sodium, calcium, iron and magnesium) and tectonically deformed rocks led to the emergence of hydrothermal alteration targeting element.…”

“…Hydrothermal alteration is one of the constituent processes of a syn-mineralization subsystem, i.e. a chemical scrubber that promotes the precipitation of potassium, sulfur, and gold minerals [30,53]. Consequently, potassic (KAl 3 Si 3 O 10 (OH) 2 ), phyllic (KAl 2 (AlSi 3 O 10 ) (OH) 2 ) and prophylitic (Al 2 Si 4 O 10 (OH) 2 ) alteration haloes are formed with orogenic gold mineralization [14,30].…”

Development of complex methodology of processing heterogeneous data in intelligent decision support systems

“…In [15], an intelligent system for processing various types of data circulating in geographic information systems is proposed. This intelligent system is designed to solve problems of geological exploration in geographic information systems.…”