By Sergey M. Rodionov1, Alexander A. Obolenskiy2

Geologic Time Scale and Time Spans

Geologic time scale units are according to the IUGS Global Stratigraphic Chart (Remane, 1998). For this study, for some descriptions of metallogenic belt and geologic units, the term Riphean is used for the Mesoproterozoic through Middle Neoproterozoic (1600 to 650 Ma), and the term Vendian is used for Neoproterozoic III (650 to 540 Ma).

According to the main geodynamic events and the major deposit-forming and metallogenic belt-forming events for Northeast Asia, the following twelve time spans are used for groupings of metallogenic belts.

Archean (> 2500 Ma)

Paleoproterozoic (2500 to 1600 Ma)

Mesoproterozoic (1600 to 1000 Ma)

Neoproterozoic (1000 to 540 Ma)

Cambrian through Silurian (540 to 410 Ma)

Devonian through Early Carboniferous (Mississippian) (410 to 320 Ma)

Late Carboniferous (Pennsylvanian) through Middle Triassic (320 to 230 Ma)

Late Triassic through Early Jurassic (230 to 175 Ma)

Middle Jurassic through Early Cretaceous (175 to 96 Ma)

Cenomanian through Campanian (96 to 72 Ma)

Maastrichnian through Oligocene (72 to 24 Ma)

Miocene through Quaternary (24 to 0 Ma)

Mineral Deposit Models

For descriptions of metallogenic belts, lode mineral deposits are classified into various models or types. Detailed descriptions are provided in the companion paper by Obolenskiy and others (2003B). The following three main principles are employed for synthesis of mineral deposit models for this study. (1) Deposit forming processes are close related to rock forming processes (Obruchev, 1928) and mineral deposits originate as the result of mineral mass differentiation under their constant circulation in sedimentary, magmatic, and metamorphic circles of formation of rocks and geological structures (Smirnov, 1969). (2) The classification must as understandable as possible for the appropriate user. And (3) the classification must be open so that new types of the deposits can be added in the future (Cox and Singer, 1986).

For this study, lode deposits are grouped into the hierarchic levels of metallogenic taxons according to such their stable features as: (a) environment of formation of host rocks, (b) genetic features of the deposit, and (c) mineral and (or) elemental composition of the ore. The six hierarchial levels are as follows.

Group of deposits

Class of deposits

Clan of deposits

Family of deposits

Genus of deposits

Deposit types (models)
The deposit models are subdivided into the following four large groups according to major geological rock-forming processes: (1) deposits related to magmatic processes; (2) deposits related to hydrothermal-sedimentary processes; (3) deposits related to metamorphic processes; (4) deposits related to surficial processes and (6) exotic deposits. Each group includes several classes. For example, the group of deposits related to magmatic processes includes two classes: (1) those related to intrusive rocks; and (2) those related to extrusive rocks. Each class includes several clans, and so on. The most detailed subdivisions are for magmatic-related deposits because they are the most abundant in the project area. In the below classification, lode deposit types models that share a similar origin, such as magnesian and (or) calcic skarns, or porphyry deposits, are grouped together under a single genus with several types (or species) within the genus.

Some of the below deposit models differ from cited descriptions. For example, the Bayan Obo type was described previously as a carbonatite-related deposit. However, modern isotopic, mineralogical, and geological data recently obtained by Chinese geologists indicate that the deposit consists of ores that formed during the Mesoproterozoic in a sedimentary-exhalative process along with coeval metasomatic activity and sedimentary diagenesis of dolomite, and alteration. The sedimentary-exhalative process consisted of both sedimentation and metasomatism. Later deformation, especially during the Caledonian orogeny, further enriched the ore. Consequently, the Bayan Obo deposit type is related to sedimentary-exhalative processes, not to magmatic processes. However, magmatic processes also played an important role in deposit formation. This deposit model is part of the family of polygenetic carbonate-hosted deposits. Similar revisions are made for carbonate-hosted Hg-Sb and other deposit models.

Deposits related to magmatic processes

Deposits related to intrusive magmatic rocks

I. Deposits related to mafic and ultramafic intrusions

A. Deposits associated with differentiated mafic-ultramafic complexes

Mafic-ultramafic related Cu-Ni-PGE

Mafic-ultramafic related Ti-Fe (+V)

Zoned mafic-ultramafic Cr-PGE

B. Deposits associated with ophiolitic complexes

Podiform chromite

Serpentinite-hosted asbestos

C. Deposits associated with anorthosite complexes

Anorthosite apatite-Ti-Fe-P

D. Deposits associated with kimberlite

Diamond-bearing kimberlite

II. Deposits related to intermediate and felsic intrusions

A. Pegmatite

Muscovite pegmatite

REE-Li pegmatite

B. Greisen and quartz vein

Fluorite greisen

Sn-W greisen, stockwork, and quartz vein

W-Mo-Be greisen, stockwork, and quartz vein

C. Alkaline metasomatite

Ta-Nb-REE alkaline metasomatite

D. Skarn (contact metasomatic)

Au skarn

Boron (datolite) skarn

Carbonate-hosted asbestos

Co skarn

Fe skarn

Sn skarn

WMoBe skarn

Zn-Pb (Ag, Cu) skarn

E. Porphyry and granitoid pluton-hosted deposit

Cassiterite-sulfide-silicate vein and stockwork

Felsic plutonic U-REE

Granitoid-related Au vein

Polymetallic Pb-Zn  Cu (Ag, Au) vein and stockwork

Porphyry Au

Porphyry Cu (Au)

Porphyry Cu-Mo (Au, Ag)

Porphyry Mo (W, Bi)

Porphyry Sn

III. Deposits related to alkaline intrusions

A. Carbonatite-related deposits

Apatite carbonatite

Fe-REE carbonatite

Fe-Ti (±Ta, Nb, Fe,Cu, apatite) carbonatite

Phlogopite carbonatite

REE (±Ta, Nb, Fe) carbonatite

B. Alkaline-silisic intrusions related deposits

Alkaline complex-hosted Au

Peralkaline granitoid-related Nb-Zr-REE

Albite syenite-related REE

Ta-Li ongonite

C. Alkaline-gabbroic intrusion-related deposits

Charoite metasomatite

Magmatic and metasomatic apatite

Magmatic graphite

Magmatic nepheline

Deposits related to extrusive rocks

IV. Deposits related to marine extrusive rocks

A. Massive sulfide deposits

Besshi Cu-Zn-Ag massive sulfide

Cyprus Cu-Zn massive sulfide

Korean Pb-Zn massive sulfide

Volcanogenic Cu-Zn massive sulfide (Urals type)

Volcanogenic Zn-Pb-Cu massive sulfide (Kuroko, Altai types)

B. Volcanogenic-sedimentary deposits

Volcanogenic-hydrothermal-sedimentary massive sulfide Pb-Zn (Cu)

Volcanogenic-sedimentary Fe

Volcanogenic-sedimentary Mn

V. Deposits related to subaerial extrusive rocks

A. Deposits associated with mafic extrusive rocks and dike complexes

Ag-Sb vein

Basaltic native Cu (Lake Superior type)

Hg-Sb-W vein and stockwork

Hydrothermal Iceland spar

Ni-Co arsenide vein

Silica-carbonate (listvenite) Hg

Trap related Fe skarn (Angara-Ilim type)

B. Deposits associated with felsic to intermediate extrusive rocks

Au-Ag epithermal vein

Ag-Pb epithermal vein

Au potassium metasomatite (Kuranakh type)

Barite vein

Be tuff

Carbonate-hosted As-Au metasomatite

Carbonate-hosted Hg-Sb

Clastic sediment-hosted HgSb

Epithermal quartz-alunite

Fluorspar vein

Hydrothermal-sedimentary fluorite

Limonite from spring water

Mn vein

Polymetallic (Pb, Zn, Ag) carbonate-hosted metasomatite

Rhyolite-hosted Sn

Sulfur-sulfide (S, FeS₂)

Volcanic-hosted Au-base-metal metasomatite

Volcanic-hosted Hg

Volcanic-hosted U

Volcanic-hosted zeolite

Deposits related to hydrothermal-sedimentary processes

VI. Stratiform and stratabound deposits

Bedded barite

Carbonate-hosted Pb-Zn (Mississippi valley type)

Sediment-hosted Cu

Sedimentary exhalative Pb-Zn (SEDEX)

VII. Sedimentary rock-hosted deposits

Chemical-sedimentary Fe-Mn

Evaporate halite

Evaporate sedimentary gypsum

Sedimentary bauxite

Sedimentary celestite

Sedimentary phosphate

Sedimentary Fe-V

Sedimentary siderite Fe

Stratiform Zr (Algama Type)

VIII. Polygenic carbonate-hosted deposits

Polygenic REE-Fe-Nb deposits (Bayan-Obo type)

Deposits related to metamorphic processes

IX. Sedimentary-metamorphic deposits

Banded iron formation (BIF, Algoma Fe)

Banded iron formation (BIF, Superior Fe)

Homestake Au

Sedimentary-metamorphic borate

Sedimentary-metamorphic magnesite

X. Deposits related to regionally metamorphosed rocks

Au in black shale

Au in shear zone and quartz vein

Clastic-sediment-hosted Sb-Au

Cu-Ag vein

Piezoquartz

Rhodusite asbestos

Talc (magnesite) replacement

Metamorphic graphite

Metamorphic sillimanite

Phlogopite skarn

Deposits related to surficial proceses

XI. Residual deposts

Bauxite (karst type)

Laterite Ni

Weathering crust Mn (Fe)

Weathering crust and karst phosphate

Weathering crust carbonatite REE-Zr-Nb-Li

XII. Depositional deposits

Placer and paleoplacer Au

Placer diamond

Placer PGE

Placer Sn

Placer Ti-Zr

REE and Fe oolite

Exotic deposits

Impact diamond