The application of the mise-a-la-masse electrical technique in Greenstone belt gold exploration

1989 ◽  
Vol 20 (2) ◽  
pp. 113
Author(s):  
L.G.B.T. Polomé
Keyword(s):  
Greenstone Belt ◽  
Electrical Potential ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Current Electrode ◽  
Barberton Greenstone Belt ◽  
A Current ◽  
Ore Zones ◽  
Gold Bearing

Most of the gold deposits in the Barberton Greenstone belt of South Africa are relatively small and in structurally complex geological areas.The mise-a-la-masse electrical technique, where a current electrode is earthed in a mineralised zone, was used on one of our exploration projects consisting of a sulphides/gold-bearing carbonaceous banded iron formation within a succession of mafic, ultramafic and sedimentary rocks. The technique was successful in delineating individual mineralised units within a broad lithological sequence. During the survey, electrical potential measurements were recorded on surface, in underground drives and in twenty five boreholes. Measurements were also repeated by earthing the mineralised zone in a number of boreholes. Major discontinuities were recognised within the ore zones and used to interpret geological structures. These were then used to define specific units for ore reserve calculations and the application of selected mining techniques.

An epigenetic origin for Archean banded iron-formation-hosted gold deposits

1984 ◽  
Vol 79 (1) ◽  
pp. 162-171 ◽  
Author(s):  
G. N. Phillips ◽  
D. I. Groves ◽  
J. E. Martyn
Keyword(s):  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation

scholarly journals Textural and fluid inclusion constraints on the origin of the banded-iron-formation-hosted gold deposits at Maevatanana, central Madagascar

2007 ◽  
Vol 42 (4) ◽  
pp. 385-398 ◽  
Author(s):  
Prosper Andrianjakavah ◽  
Stefano Salvi ◽  
Didier Béziat ◽  
Damien Guillaume ◽  
Michel Rakotondrazafy ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation

Concentration of gold during retrograde metamorphism of Archean banded iron formations, Slave Province, Canada

1993 ◽  
Vol 30 (8) ◽  
pp. 1566-1581 ◽  
Author(s):  
R. Craig Ford ◽  
Norman A. Duke
Keyword(s):  
Hydrothermal Activity ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formations ◽  
High Background ◽  
Multistage Processes ◽  
Slave Province ◽  
Sulphide Precipitation ◽  
Iron Formations ◽  
Gold Bearing

Gold-bearing iron formations are widely distributed within extensive metasedimentary terranes of the Archean Slave Province, situated in the northwestern Canadian Precambrian Shield. Mineralized iron formations occur within thick turbidite sequences overprinted by a protracted history of deformation, metamorphism, and plutonism. Economically significant gold prospects are specifically sited at structural culminations characterized by polyphase folding. Based on garnet–biotite geothermometry on the stable prograde metamorphic assemblage of enveloping metapelites, peak metamorphic conditions are approximated to be 570 °C and 4 kbar (1 kbar = 100 MPa). Diagnostic prograde mineralogy reveals that two facies of silicate iron formation are represented at the five gold occurrences investigated: (1) amphibolitic iron formation (AIF), characterized by quartz + grunerite + hornblende + pyrrhotite ± garnet ± graphite + ilmenite, and (2) pelitic iron formation (PIF), consisting of quartz + biotite + garnet + ilmenite ± grunerite ± hornblende. Textures reveal that grunerite crystallization preceded hornblende and garnet. Within AIF, banded pyrrhotite is in textural equilibrium with prograde metamorphic minerals. Retrograde hornblende, garnet, zoisite, apatite, carbonate, ferroactinolite, and gold-bearing sulphide minerals replace the prograde mineral assemblages on the margins of quartz veins that intensify at AIF fold hinges.It is hypothesized that the iron-formation-hosted gold deposits of the Slave Province are a result of multistage processes. Gold concentrated at high background levels within pyrrhotite-bearing AIF was remobilized during fluid migration into brittle AIF fold hinges in subsequent metamorphic and deformational events. Metamorphic fluid, ponded in fractured AIF hinge domains, caused retrogressive replacement, quartz veining, and gold-bearing sulphide precipitation during waning temperature. Although the mineralized hinge zones commonly display evidence of late chloritization, this alteration did not further affect gold distribution. The gold precipitated with destabilization of thio complexes due to sulphidation prior to low-temperature hydrothermal activity.

Sign in / Sign up

Export Citation Format

Share Document