| Era | Precambrian (3000-570)* | Paleozoic (570-225)* | Mesozoic (225-65)* | Cenozoic (65-0)* |
| Age of host rocks | Gold-quartz deposits mainly in Archean rocks (>2500 m.y.); extensive deposits in Proterozoic quartz-pebble conglomerates; some large gold-quartz and varied stockwork deposits in Proterozoic rocks | Mainly Paleozoic; some deposits in Precambrian or both Paleozoic and Precambrian rocks | Mainly Mesozoic but also Paleozoic and Precambrian
|
Mainly Tertiary but also all older rocks |
| Principal type of host rocks | Gold-quartz deposits mainly in mcta-volcanics, iron-formation and meta-sediments of greywacke-slate type; also in associated quartz- feldspar porphyries and other granitic rocks.
Largest deposits in quartz-pebble conglomerates and associated quartzites (modified placers)
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Gold-quartz and skarn-type deposits mainly in metasediments, especially in
greywacke-slate sequences; similar deposits in meta-volcanics, in porphyries and in granitic rocks |
Gold-quartz and skarn-type deposits in meta-sediments and meta-volcanics | Andesites. dacites, tuffs, rhyolitcs and a great variety of meta-volcanic and meta-sedimentary rocks
|
| Principal type of deposits | Modified placer (?) deposits in quartz-pebble conglomerates; gold-quartz veins, lenses, saddles, silicified zones, etc.; skam types; auriferous polymetallic veins, lodes and massive sulphide bodies
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Gold-quartz veins, lodes, lenses, silicified zones; saddle reefs and bedding-plane veins are characteristic in many areas. Skam and homfels types. Auriferous polymetallic veins, lodes and massive sulphide bodies
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Gold-quartz veins, lodes, lenses, silicified zones; skarn-type deposits; auriferous polymetallic veins, lodes and massive sulphide bodies | Gold-quartz veins, lodes, lenses and silicified zones; auriferous polymetallic veins, lodes and massive sulphide bodies
|
| Principal gangue minerals | Quartz-pebble conglomerates – pyrite, quartz, hematite, sericite. Gold-quartz type – quartz, pyrite, arsenopyrite, pyrrhotite, carbonates
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Quartz, pyrite, arsenopyrite and carbonates
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Quartz, pyrite, arsenopyrite and carbonates
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Quartz, pyrite, arsenopyrite carbonates, adularia, alunite, fluorite, barite; rhodochrositc and rhodonite are characteristic
|
| Principal metallic minerals | Quartz-pebble conglomerates – free gold, average size 80 microns. Gold-quartz type – free gold and as a lattice or submicroscopic constituent of pyrite, arsenopyrite. Sulphosalts
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Pyrite, arsenopyrite, pyrrhotite, chalcopyrite, galena, sphalerite, stibnite and sulphosalts
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Pyrite, arsenopyrite, pyrrhotite, chalcopyrite, galena, sphalerite, stibnite and sulfosalts | Pyrite, arsenopyrite, chalcopyrite, galena, sphalerite, argentite, sulphosalts, stibnite and silver selenides
|
| Nature of the gold | Quartz-pebble conglomerates – free gold, average size 80 microns. Gold-quartz type – free gold and as a lattice or submicroscopic constituent of pyrite, arsenopyrite. sulphosalts, etc; in tellurides
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Generally free; in some deposits much of the gold is present as a lattice or submicroscopic constituent of pyrite, arsenopyrite, sulphosalts, etc; in tellurides
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Generally free; in some deposits much of the gold is present as a lattice or submicroscopic constituent of pyrite, arsenopyrite, sulphosalts, etc; in tellurides
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Generally free; in some deposits much of the gold is present as a lattice constituent or submicroscopic constituent of pyrite and various sulphosalts; in tellurides
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| Characteristics associated elements+ | K, Na, Cu, Ag, Zn, Cd, B, Th, U, rare earths, SiO,,
Pb, As. Sb, Bi, Te, (Se), Mo, W, Cr, Mn, Fe, (Co), (Ni), (Pt metals). U, Th, and rare earths are characteristic of quartz-pebble conglomerates
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K, Na, (Sr), (Ba). (Mo), W. (Co), (Ni). Cu, Ag, Zn, Cd, (Hg), B, (Sn), Pb. As, Sb. Bi, (Se), Te, (F)
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K, Na, (Sr), (Ba), (Mo), W, (Co), (Ni), Cu, Ag, Zn, Cd, (Hg), B. (Sn), Pb. As, Sb, Bi, (Se), (Te), (U), (F) | K, (Sr), Ba, (U). Mo, W, Mn. (Co), (Ni), Cu, Ag, Zn, Cd, Hg, (B), Tl, (Sn), Pb, As. Sb, Bi. Se, Te, F
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| Characteristics wall-rock alteration process | Pyritization, arsenopyritization. carbonatization, serialization, biotitization, tourmalinization, chloritization, silicification, albitization and development of skarn minerals. Development of pyrite. sericite, pyrophyllite in quartz-pebble conglomerates | Pyritization, arsenopyritization, carbonatization, sericitization, tourmalinization, chloritization, silicification, listvenitization, bcresitization, albitization and development of skarn and hornfels
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Pyritization, arsenopyritization, carbonatization, sericitization, tourmalinization, chloritization, silicification, albitization, listvenitization, beresitization, (alunitization), development of adularia; development of skarn and hornfels |
Pyritization,
Carbonization, Sericitization, Chloritization, silicification, Alunitization; propylitization is widespread in most auriferous areas. |
http://www.nrcan.gc.ca/earth-sciences/science/geology/gsc/17100