**Preliminary Description of Mineral Deposit Models (Types) for
Mongolia**

**By Gunchin Dejidmaa**

**(Institute of Geology and Mineral Resources, Mongolian Academy of
Sciences, Ulaanbaatar)**

**Dangindorjiin Dorjgotov**

**(Institute of Geology and Mineral Resources, Mongolian Academy of
Sciences, Ulaanbaatar)**

**Ochir Gerel**

**(Mongolian Technical University, Ulaanbaatar)**

**Ayurzana Gotovsuren**

**(Monrud Co, Ltd., Mineral Exploration and Mining Company)**

**Sodov Ariunbileg**

**(Institute of Geology and Mineral Resources, Mongolian Academy of
Sciences, Ulaanbaatar)**

# INTRODUCTION

This report provides a preliminary description of the major mineral
deposit models (types) for Mongolia. This preliminary description is
being compiled as part of a project on the Mineral Resources,
Metallogenesis, and Tectonics of Eastern and Southern Siberia, Mongolia,
Northeast China, South Korea, and Japan. For additional information on
the project, please refer to the companion project summary by Nokleberg
(this volume). In future publications of the project, the descriptions
of mineral deposit models will be expanded.

# 

# CLASSIFICATION OF MINERAL DEPOSITS

Metalliferous and selected non-metalliferous lode and placer deposits in
this report are classified into various models, or types, described
below. This classification was derived mainly from the mineral deposit
types of Eckstrand (1984), Cox and Singer (1986), Nokleberg and others
(1987, 1993, 1994a, b, 1997), cited references for specific models, and
unpublished data of the Mongolian authors. The mineral deposit types
used in this report consist of both descriptive and genetic information
that is systematically arranged to describe the essential properties of
a class of mineral deposits. Some types are descriptive (empirical), in
which instance the various attributes are recognized as essential, even
though their relationships are unknown. An example of a descriptive
mineral deposit type is the basaltic Cu type in which the empirical
datum of a geologic association of Cu sulfides with relatively Cu-rich

metabasalt, or greenstone, is the essential attribute. Other types are
genetic (theoretical), in which case the attributes are related through
some fundamental concept. An example is the W skarn deposit type in
which case the genetic process of contact metasomatism is the essential
attribute. For additional information on the methodology of mineral
deposit types, the reader is referred to the discussions by Eckstrand
(1984) and Cox and Singer (1986).

# COMMODITY GROUPINGS OF DEPOSITS

## Gold Deposits

## By Gunchin Dejidmaa

The lode gold mineralization of Mongolia has been described by Marinov
(1963), Dornfeld and Kraft (1964), Borzakovskii and others (1971),
Kraft, Taubert and others (1974), Tsypukov and Lombo (1975), Blagonravov
and Shabalovskii (1977), Blagonravov and Tsypukov (1977), Poznyak and
Dejidmaa (1977), Gottesman (1978), Tsherbakov, Roslyakov and others
(1979), Blagonravov, Byambaa., and Podkolzin (1980), Tsherbakov and
Dejidmaa (1984), Blagonravov, Blagonravova and others (1984),
Tsherbakov, Dejidmaa, and Kalinin (1986), Dejidmaa (1980, 1985), Alkin,
Kunytsyn and others (1989), Blumen and others (1989), Bolotova, Dejidmaa
and others (1990), Bokulev (1991), Blumen (1991), Dejidmaa, Eideliman
and others (1993), Mironov and Trofhimov (1993), Mironov and Soloviev
(1993), and Dejidmaa (1996). Gold deposit types discussed below are
derived from above references, from Eckstrand (1984), and Cox and Singer
(1986), with revisions by Gunchin Dejidmaa. The principal gold deposit
types are Au-Ag epithermal vein (low sulfide epithermal Au),
conglomerate-hosted clastic Au, granitoid-related Au, Au skarn (Contact
metasomatic replacement), and porphyry Au.

# 

## Hg Deposits

## By Gunchin Dejidmaa

Hg deposits in Mongolia have been studied by Blagonravov (1977) and
Obolenskii (1971, 1984, 1985), and Metallogeny of the Mongolian Peoples'
Republic (1986). Hg occurrences of Mongolia are classified into the
following subtypes: (1) magnesium-carbonate-cinnabar or listvenite
subtype with examples of the the Khangi ovoo occurrence in the
Sulinkheer terrane and the the Olgii occurrence in Mongol Altai terrane;
(2) quartz-dickite-cinnabar subtype with examples of the Ulaanhus
occurrence occurring along the deep-seated Tolbonuur fault in the Mongol
Altai terrane, and the Kharzat occurrence in northeastern Mongolia; and
(3) the fluorite-cinnabar-sulfide type with examples of the Idermeg
Bayankhaan Uul occurrence occurring along the deep-seated Onon fault in
northeastern Mongolia; (4) the quartz-sericite-cinnabar subtype with
examples of the Tunkhel and Balj occurrences along the Eroogol regional
fault in the North Khentii terrane; and (5) the quartz-barite-cinnabar
subtype with examples of the Dalai Am gol and Khotol nuur occurrences
occurring along the Ulzgol fault in northeastern Mongolia.

The first subtype occurrence is hosted in ultramafic rocks. The second
and fourth subtypes are hosted in clastic sedimentary rocks. The third
and the fifth subtypes are hosted in granitic rocks.. These subtypes can
be readily classified by the following host-rock lithologies: (1)
clastic sediment-hosted Hg deposits (quartz-dickite-cinnabar and the
quartz-sericite-cinnabar subtypes); (2) silica-carbonate (listvenite) Hg
(magnesium-carbonate-cinnabar subtype); and (3) volcanic-related Hg
(fluorite-cinnabar-sulfide and quartz-barite-cinnabar mineral subtypes).

## Fe and Mn Deposits

## By Gunchin Dejidmaa

Fe and Mn deposits of Mongolia have been described by Philippova and
Vydrin (1977), Bakhteev and Chijova (1984), Izokh, Polyakov, and
Krivenko (1984), Samoylov, Ivanov, Kovalenko and others (1984),
Podlessky, Aksuk, Vlasoova, Baikova, Shuleshko, and Kozakov (1987),
Podlessky, Vlasova, and Kudrja (1988), Kovalenko, Koval and others
(1988), Tsend-Ayuush and Chrbotarev (1989), Antonov, Blyumen and others
(1989), Chebotarev, Chebotareva, and Tsend-Ayuush (1990), Sokolov and
Zaitsv (1990), and Izokh, Polyakov, Krivenko, Bognibov, and Bayarbileg
(1990). The Fe and Mn deposit types of Mongolia discussed below are
derived from Eckstrand (1984) and Cox and Singer (1986) using data from
the above references and unpublished data of Gunchin Dejidmaa. The Fe
and Mn deposit types are grouped according to host rock lithology and
origin. The Fe and Mn deposit types are volcanogenic-sedimentary Fe-Mn,
ironstone (clastic magnetite in sedimentary rocks), and
chemical-sedimentary Fe or ironstone (Fe-Fe, Mn-Mn).

# 

## REE Deposits

## By Ochir Gerel

REE model deposit types in Mongolia include economically important
deposits that are relatively well studied. The deposit types include REE
carbonatite, REE pegmatite, peralkaline granite-related REE (Nb-Zr-REE),
ongonite-hosted Ta-Li, Cs Glass, Be Tuff, REE-albite, and Ta-granite
(Kovalenko and others, 1986; Kovalenko and Yarmolyuk, 1995). Many REE
deposits and occurrences have complex mineralization and are sometimes
very difficult to classify. Most of the REE deposits and occurrences are
spatially and genetically related to calc-alkaline and peralkaline
granites and alkaline rocks. The REE ore minerals occur in the apical
part, endocontact, or sometimes in the exocontact that are mainly
hypabyssal or subvolcanic facies plutons composed of highly fractionated
magma. These REE deposits and occurrences are interpreted as forming
mainly in continental postaccretion or rift tectonic environments. The
commercial REE mineral deposits and occurrences are mainly of Mesozoic
age, and formed within collisional intracontinental belts. Some also
along a middle and late Paleozoic active continental margin.

## Fluorspar Deposits

## By Dangindorjiin Dorjgotov

Fluorite mineralization occurs mainly in eastern Mongolia (Khrapov,
1977). Fluorspar deposits and occurrences of Mongolia were first
classified into: (1) vein type (with quartz-fluorspar,
barite-quartz-fluorspar mineral type; and (2) vein/replacement type
(calcite-quartz-fluorite mineral deposit type). For exploration and
prospecting, fluorite (fluorspar) deposits are classified into two
types: fluorspar vein; and fluorspar-carbonate-hosted. These fluorspar
deposit subtypes are hosted mainly in Late Mesozoic volcanic-tectonic
grabens containing Early Cretaceous bimodal volcanic and sedimentary
rocks in eastern Mongolian and southern Mongolian. These host rocks are
part of various late Mesozoic intercontinental volcanic belts that occur
along active deep faults that border large, uplifted blocks.

## Pb-Zn Deposits

## By Dangindorjiin Dorjgotov

Mesozoic Pb-Zn deposits of Mongolia are classified into following three
deposits types: (1) Fe-Zn skarn (contact metasomatic) related to
subalkaline granite; (2) Ag-bearing Pb-Zn hydrothermal vein related to
subalkaline polyphase intrusion; and (3) Ag-Pb epithermal vein related
to subalkaline subvolcanic rocks. This classification is mainly based on
mineral association, rocks related to mineralization, host-rock
lithology, alteration, and ore structure (Table 1).

## Table 1. Classification of Pb-Zn Deposits related to Mesozoic subalkaline magmatic rocks in Mongolia.

  ----------------------- -----------------------------------------------
  **Type of Deposit**     **Example**

  Contact-metasomatic     Bayandun, Erdenetolgoi, Gurvansaikhan,
  (skarn)                 Tumurtiin-Ovoo, Salkhit, Tumurtei, Kharaat and
                          others.

  Hydrothermal vein and   BaitsBuilst, Tsav, Delger-munkh, Khavtsgait and
  stockwork               others, Ulaan, Mukhar, Bayan-Uul.

  Epithermal vein         Bayankhaan, Modon, Salaa-Undur, Modon,
                          Khartolgoi, Mungun 24-Biluut, Boorch.
  ----------------------- -----------------------------------------------

**Copper Deposits**

**By Gunchin Dejidmaa**

Copper deposits and Cu deposit types of Mongolia have been described by
Yakovlev, (1977), Sotnikov, Berzinaand, and others (1985) and Sotnikov,
Jamsran, and others (1985). Cu deposits and occurrences of Mongolia are
classified into: (1) Cu-Mo; (2) Cu skarn; (3) native copper; (4) Cu-Ni
veins and masses in gabbroic rocks; (5) sandstone and shale- hosted Cu;
and (6) Cu-kolchedan formation types. Cu deposits and occurrences of
Mongolia, have been studied by Berzina and others (1983), Volchanskaya,
(1980), Gumbina and others (1979), Demidovand others (1975), Jamsran
(1971, 1975, 1977), Polyakov and others (1984), Sotnikov and others,
(1980a), Sotnikov and others (1981), Sotnokov and others (1980b),
Sotnikov and others (1985), Sotnikov, Sanduijav, and others (1978),
Yudin and others (1975), Yakovlev and others (1979), Davaasambuu and
others (1976a), Davaasambuu and others (1976b), Sotnikov and others
(1976), Movsesyan and Isaenko (1974), Khasin and others (1977), Sotnikov
and Berzina (1985), Sotnikovand others, (1979, 1981, 1984), Gerel (1989,
1990), Gerel and others (1984, 1985), Koval and Gerel (1986),
Gavrilovaand others, (1984, 1988, 1989).

The Cu deposit types of Mongolia discussed below are derived from
Eckstrand (1984) and Cox and Singer (1986) using data from the above
references. The Cu deposit types are grouped according to host rock
lithology and origin. The Cu deposit types are: (1) porphyry Cu-Mo with
Cu, Cu-Mo and Mo-Cu subtypes; (2) mafic-ultramafic related Cu-Ni
sulfide; (3) Cu skarn; (4) basaltic Cu; (5) sediment-hosted Cu; (6) Cu
vein/stockwork related to granite rocks; (7) Cu-(Ag) vein in regionally
metamorphosed rocks; and (8) volcanogenic-massive and disseminated Cu
(±Zn, Au, Ag) sulfide.

# 

# STRATABOUND DEPOSITS IN CLASTIC SEDIMENTARY ROCKS AND SUBAERIAL BASALT

## Sediment-Hosted Cu Deposit Type

## By Gunchin Dejidmaa

This sediment-hosted Cu deposit type first was defined by Yakovlev
(1977) as Cu-bearing sandstone formation and subsequently by Sotnikov,
Berzina, and others (1985) who named the deposit type as Cu-bearing
sandstone and shale formation. Significant sediment-hosted Cu
occurrences are distributed in the Mongol Altai and in Kharkhiraa
terranes and are hosted in upper Ordovician, in middle to upper Devonian
and Lower Jurassic sedimentary rocks.

The Omnogovi and Bayanbulag occurrences are hosted in Late Ordovician
Erdeneburen unit that contains sandstone and siltstone, in the Kharhiraa
terrane. The occurrences consist of sandstone, rare siltstone lense, and
tabular bodies with visible chalcocite, malachite, and azurite.
Covellite and chalcopyrite also are identified by microscope. The
thickness of ore bodies ranges from 5.0 m to 50.0 m, and the length
ranges up to 1.5 km. The grade of Cu ranges from 0.01 to 1.47%, and Ag
ranges up to 20.0 g/t.

A few Cu occurrences of sediment-hosted Cu deposit are present in the
western part of the Deluun basin in the Middle to Late Devonian
Bardamgol and Khatuugol units in western Mongolia (Obolenskiy and
others, 1989). The basin contains thick Devonian deposits (up to 9 km)
that unconformably overlie the early Paleozoic units of the Altai and
Kharhiraa terranes. The lower part of the Devonian units consists of
volcanic and sedimentary rocks of the Otogiin unit (rhyolite, andesite,
andesite-dacite porphyry, tuffs, volcanic breccia, tuffaceous sandstone,
tuff-graywacke and conglomerate), the middle part consists of the
Bardamgol unit in the Sagsai River basin, and the middle part consists
of the Khatuugol unit near Tolbo Lake. The Middle and Upper Devonian
units consist of black-gray siltstone, black shale, and sandstone. A
special feature of the sedimentary rocks in the Khatuugol unit is a high
grade of carbonaceous material (up to 5.5% of organic C in carbonaceous
siltstone) and sulfides (Borisenko and others, 1992). Sulfides consist
of stringer-impregnations, concretions mostly of pyrite-marcasite. There
also are Cu-bearing sandstone strata horizons (for example, the
Khatuugiin Gol River occurrences). Exceptions are epigenetic
pyrite-pyrrotite stringers that occur in hornfels and are the result of
contact metamorphism. In this area, the sulfide-bearing zone occurs
conformably with host rock for strike distances of several tens of km
and ranges up to 1.5 to 2.0 km wide (Borisenko, 1992). There are several
strongly mineralised sandstone lenses, from 1.0-7.0 m thick, tabular
bodies that contain malachite, melaconite, chalcopyrite, and pyrrotite.
In grab and rock chip samples, the grade of Cu ranges from 0.5 to 3.0%,
and Ba from 0.1 to 0.5%.

Sediment-hosted Cu occurrences in Jurassic sedimentary rocks, occur
along the deep-seated Tsagaanshiveet fault that separates the Kharhiraa
terrane from the Nuuryn terrane. Examples of the latter are the Kupol
and The Khargait occurrences that are hosted in Jurassic sedimentary
rocks, mainly conglomerate, greywacke, and sandstone. Cu mineralization
consists of chalcocite, malachite, and azurite and occurs in sandstone
horizons and lenses with thicknesses of 0.1 to 3.0 m, and lengths up to
400.0 m. The grade of Cu ranges from 0.1 to 2.5%.

## Clastic Sediment-Hosted Sb-Au Deposit Type

## By Gunchin Dejidmaa

The clastic sediment-hosted Sb-Au deposit type consists of simple and
complex ladder, and concordant carbonate-quartz veins and veinlets. The
host rocks are terrigenous and volcanic-terrigenous units in
accretionary wedge terranes, and are silicified, carbonatized,
pyritized, and rarely argillized and sericitized. The ore minerals are
pyrite, stibnite, arsenopyrite, chalcopyrite, gold, rare galena,
sphalerite, tetrahedrite. The gangue minerals are quartz, ankerite, and
lesser calcite, dolomite, sedirite, and sericite. The deposit type
occurs mainly in linear fold zones that are associated with regional
strike-slip faults, sometimes in thrust fault zones. Where localized in
thrust fault zones, extensive alteration occurs, including
silicification, carbonatization, and argillization. The thrust zones
generally contain vertical, quartz-carbonate veins with high grade Sb
and moderate grade Au. The deposits of this type in linear fold zones
generally contain ladder and concordant carbonate-quartz veins and the
Au grade is higher than the Sb grade. The Talyn Meltes and Khatansuudal
occurrences in the Tomortein Nuruu belt in southwestern Mongolia.
examples of this deposit type in thrust zones are the Sb-Au occurrences
in the Baitag district of the Baruun Khuurai belt.

## 

## Clastic-Sediment-Hosted Sb Deposit Type

## By Gunchin Dejidmaa

The clastic-sediment-hosted Sb deposit type consists of quartz veins or
mineralized breccia hosted in Paleozoic terrigenous rocks. The ore
minerals are stibnite and antimony oxides that occur as impregnations,
nests and stringers. The host terrigenous rocks may also contain minor
stibnite. A few Sb occurrences, possibly belonging to this deposit type
are located near the Shar Us gol River in the Khangai mountain range
(Arhoviin Am, Urt Am, Metegiin Ovoo occurrences) and in northeastern
Mongolia (Khuts Ondor and Gorkhitbulag occurrences and others). These
occurrences were first described by Khasin (1977).

## Ironstone (Clastic Magnetite in Sedimentary Rocks) Deposit Type

## By Gunchin Dejidmaa

The ironstone deposit type is herein defined and consists of massive and
disseminated magnetite that occurs in bed-like and lens-like bodies in
sandstone and conglomerate. Magnetite is mainly of clastic origin. The
deposit type is interpreted as ancient lithified sea beach placers. A
few small occurrences of this deposit type are known in the Lower
Carboniferous molasse that is interpreted as forming in a marine beach
environment.

## 

## Conglomerate-Hosted Clastic Au Deposit Type

## By Gunchin Dejidmaa

The conglomerate-hosted clastic Au deposit type consists of clastic
gold-bearing bed-like and lens-like bodies in layers of sandstone and
conglomerate in Permian, Jurassic and Cretaceous molasse that form
overlap assemblages (Sherbakov and others, 1986**)**. The deposit type
is interpreted as ancient lithified sea and lake-beach placers. Known
occurrences are in the Uyanga-Taragt, Delgerhaan, and Eroogol districts.
They are a primary source of several economic placer Au deposits of
Neogene and Quaternary age in Mongolia. Exploration is needed to clarify
their economical importance.

# 

# STRATIFORM DEPOSITS IN FINE-GRAINED AND SILICEOUS SEDIMENTARY ROCKS

## 

## Volcanogenic-Sedimentary Fe-Mn Deposit Type

## By Gunchin Dejidmaa

The volcanogenic-sedimentary Fe-Mn deposit type consists of stratiform
massive and disseminated magnetite-hematite that occur in sheet-like or
lens-like tabular bodies that are interbedded with marine
volcanic-sedimentary and sedimentary rocks including quartzite, chert,
sandstone, siltstone, shale, and siliceous rocks. Filippova and others
(1977) called this deposit type jasper-quartzite Fe-Mn formation. The
host rocks are mostly chert, quartzite, siliceous rocks, jasper, and
jasperoid. Ore minerals of the deposit type, Fe and Mn minerals, are
complex. According to mineralogy and Fe and Mn grade, this deposit type
is divided into three subtypes: (1) volcanogenic-sedimentary Fe; (2)
volcanogenic-sedimentary Fe-Mn; and (3) volcanogenic-sedimentary Mn. The
ore minerals are magnetite, hematite, pyrolusite, hausmannite, and
braunite. The depositional environment consists of marine epicratonal
and intracratonic basins, back arc basins, and in volcanic-terrigenous
units of ophiolite complexes. Deposits and occurrences of this deposit
type are widespread in Mongolia. They are located in the Khangai
metallogenic belt (in the Devonian to Carboniferous
volcanogenic-terrigenous Khangai Seri Formation), the Govi-Altai
metallogenic belt (in the early Paleozoic Togrog volcanogenic and
Ukhinnuruu volcanic-terrigenous Formations), in the Urgamal metallogenic
belt (in the Upper Proterozoic siliceous-carbonate Shuvuun Formation),
and in other metallogenic belts.

# DEPOSITS IN CARBONATE AND

# CHEMICAL-SEDIMENTARY ROCKS

## Chemical-Sedimentary Fe or Ironstone (Fe-Fe, Mn-Mn) Deposit Type

## By Gunchin Dejidmaa

The chemical-sedimentary Fe or ironstone (Fe-Fe, Mn-Mn) deposit type
consists of sheet-like and lens-like horizons containing massive and
disseminated Fe and Mn oxide and carbonate minerals that are hosted in
sedimentary and clastic carbonate rocks, including limestone and
dolomite. The ore-bearing horizons consist of sedimentary chert,
quartzite, quartz-sericite-chlorite schist, and clastic carbonate.
Filippova and others (1977) called this deposit type iron-quartzite
formation. According to mineralogy, and Fe and Mn grade, the deposit
type is divided into Fe, Fe-Mn, and Mn subtypes. The ore minerals are
magnetite, hematite, siderite, pyrolusite, hausmannite, braunite, and
rhodochrosite.

Occurrences of this deposit type exist in early Paleozoic
chemical-sedimentary carbonate rocks formed in basins overlying
Precambrian granitic and metamorphic complexes, and in Late Cretaceous
and Neogene, intracratonic lake basins. An example of the first is in
the Khovsgol carbonate basin located in northern Mongolia where Fe,
Fe-Mn, and Mn occurrences are associated with sedimentary phosphate,
allunite, and vanadium deposits. These occurrences are confined to a
single stratigraphic level but exhibit no regular, spatial distribution.
Zaitsev and others (1984) noted that where phosphate deposits are
extensively developed, low-grade sedimentary Fe, Mn, and Al deposits
also occur, and where Fe, Mn and Al deposits are extensively developed,
low-grade phosphate deposits also occur. Occurrences of the Fe subtype
are located in southern and southeastern Mongolia. Occurrences of the
Fe-Mn subtype are associated with sedimentary gypsum, alunite, and rare
barite and bauxite deposits and occurrences.

## Chemical sedimentary V deposit type

## By Gunchin Dejidmaa

The chemical sedimentary V deposit type consists of V-bearing
chert-carbonaceous shale and cherty, sheet-like horizons. The
chert-carbonaceous shale horizon consists of intercalated siliceous
shale, carbonaceous-calcareous shale, clay-shale, siltstone, chert, and
rare limestone. The chert horizons consist of chert and sedimentary
quartzite. Main examples of the deposit type are V occurrences in the
lower Paleozoic Khovsgol Shelf basin (Poznaikin and others, 1990). The
grade of V ranges from 0.01 to 1.0%. These V-bearing horizons vary from
20.0 m to 70.0 m wide and from 0.5 km to 2.7 km long. The mineralogy of
these occurrences is not studied.

## Bedded Barite Deposit Type

## By Sodov Ariunbileg

This deposit type consists of veinlet and nodular barite interbedded
with marine cherty and calcareous sedimentary rocks, mainly dark chert,
shale, sandstone, and dolomite (Marinov and Hasin, 1977 ). This deposit
type is often associated with sedimentary deposits. Calcite-barite
veinlet deposits mainly occur in the southern Gobi depression. The
associated minerals are minor calcite, hematite, pyrite, sulfide ocher,
galena, and sphalerite. The most important bedded barite occurrences are
in Precambrian recrystallized limestone. The depositional environment is
stable shallow marine basins commonly on passive continental margins.

# DEPOSITS RELATED TO MAFIC CONTINENTAL VOLCANIC ROCKS

### 

## Fluorspar Vein Deposit Type

## By Dangindorjiin Dorjgotov

The fluorspar vein deposit type consists of quartz-fluorite and
quartz-sulfide-fluorite veins, and fluorite-altered zones that occur in
various rocks intruded by mafic Cretaceous dikes (Khrapov, 1977). The
ore bodies are steeply dipping, and the length along strike varies from
several hundreds meters to 3,000 meters, up to 300-500 m down dip. The
thickness of ore bodies varies from 1 to 30 meters. Large scale
silicification is the most important alteration. Brecciated silicified
rock is the main host rock and is developed in multiple, large layers.
The mineral assemblage for this deposit subtype is a simple, quartz and
fluorite. Minor minerals are barite, adularia, pyrite, galena, stibnite,
and Ag minerals. The deposit subtype has three major stages:
quartz-sulfide, quartz-fluorite and quartz-carbonate. Examples of this
deposit type are at Berkh, Khar-Airag, Khavirga, Khongor, and Bor-Undur.

### 

## Fluorspar-Carbonate-Hosted Deposit Type

## By Dangindorjiin Dorjgotov

This fluorspar-carbonate deposit type consists of metasomatic
calcite-quartz-fluorite in lenses and wedges that are hosted in
Proterozoic carbonate intruded by mafic Cretaceous dikes (Khrapov,
1977). The ore bodies are steeply dipping, and the length along strike
varies from several hundreds meters to thousand meters, and up to 100 m
down dip. The thickness of the ore bodies ranges from 1 to 30 meters.
Large-scale silicification and fluoritization are the most important
alterations. The major mineral are quartz, fluorite, and calcite. Minor
mineral are barite, adularia, siderite, ankerite, dolomite, and clay
minerals. Examples of this deposit tpe are at Zuuntsagaandel, Bujgar,
Zam, Maihant, Bilh-Uul, and Shanaga.

## Basaltic Cu Deposit Type

## By Ayurzana Gotovsuren and Gunchin Dejidmaa

This basaltic Cu deposit type was originally named as Cu-zeolite
formation (Yakovlev, 1977), and as native Cu formation (Sotnikov,
Jamsran, and others, 1985 and Sotnikov, Berzina, and others, 1985). This
deposit type occurs in two regions of Mongolia: (1) the Orkhon-Selenge
volcanic belt; and (2) the Khan Khohii mountain range. Cu occurrences of
this deposit type in the Orkhon-Selenge belt are hosted in andesite
porphyry, amygdaloidal basalt, and basaltic tuff of Early and Late
Permian, and Early Triassic age. Cu occurrences in the Khan Khohii
region are hosted in amygdaloidal basalt and andesite porphyry in Lower
to Middle Devonian volcanic and sedimentary rocks. In most cases, native
Copper occurs in epidote-altered andesite and basalt, and more rarely in
amygdules and in the matrix of less altered volcanic rocks (Sotnikov,
Berzina, and others, 1985). Native Cu is associated with quartz,
epidote, carbonate, and chlorite. Main examples of the deposit type are
the Bots, Baruunburen, Mech Uul, Zuunturuu Gol, Orkhon, and other
occurrences are in the Orkhon-Selenge volcanic belt. The Baga Nuur and
Khordaga occurrences are in the Khon Khohii Montain Range.

# DEPOSITS RELATED TO CALC-ALKALINE TO SUBALKALINE PLUTONIC ROCKS

## 

## Porphyry Cu-Mo Deposit Type

##### By Ayurzana Gotovsuren

This porphyry Cu-Mo deposit type was first defined by Movsesyan and
Isaenko (1974) for Mongolia**.** The deposit type consists of
quartz-sulfide, quartz-carbonate-sulfide and quartz-sericite-sulfide
stockworks that occur in or near porphyritic intermediate to felsic
intrusion, mainly in stocks and breccia pipes that intrude granitic,
volcanic, or sedimentary rocks. The depositional environment is
high-level granitic porphyries. The main ore mineral are pyrite,
chalcopyrite, molybdenite, bornite, chalcocite, and covellite.
Associated minerals are rare sphalerite, galena, and gold. Porphyritic
intrusion and host rocks are intensive silicified, sericitized,
K-feldsparized, biotitized, chloritized, propyllitized. Most deposits
exhibit argillic overprints. The tectonic environment is mainly weakly
to strongly alkalic granitic plutons emplaced in active continental
margins and in interplate rifting environments. The deposit type
consists of three subtypes, porphyry Cu, porphyry Mo-Cu, and porphyry
Cu-Mo. Main examples of the deposit type are the Erdenetiin-Ovoo Cu-Mo,
Tsagaansuvarga, and Avdartolgoi Mo-Cu and porphyry Cu deposits, the
Bayan Uul and Khongoot porphyry Mo-Cu deposit, and the Zost Uul, Shand,
Oyuut, and Khatavch porphyry Cu-Mo occurrences.

**Cu Skarn Deposit Type**

**By Ayurzana Gotovsuren**

The Cu skarn deposit type consists of chalcopyrite, magnetite, and
pyrrhotite in calc-silicate skarn that replaces calcareous sedimentary
rocks and mafic igneous rocks along intrusive contacts with plutons. The
plutons range in composition from felsic to intermediate granite. The
tectonic environment is mainly weakly alkalic granitic plutons emplaced
along active continental margins or island arcs. Cu-rich skarns occur
mainly in sedimentary rocks. Main ore minerals are chalcopyrite,
bornite, chalcocite, and covellite. Associated minerals are pyrite,
hematite, galena, molybdenite, sphalerite, and scheelite. The main
examples of the deposit type are in the Nuuryn terrane.

## Porphyry Mo, W, Sn Deposit Types

## By Ochir Gerel

Porphyry Cu-Mo deposits are very important in Mongolia. The operating
Erdenetiin Ovoo mine is well known. Cu grade ranges from 0.4 to 0.7% and
Mo grade ranges from 0.002 to 0.007 g/t. Although other localities are
not well studied, Cu-Au deposits have a large potential in the southern
and central Mongolian (Sillitoe and others, 1996). Occurrences are known
at Bayan Uul, Shuuten, Tsagaan Suvraga, and Oyuut Ovoo. These deposits
occur in felsic to intermediate porphyritic intrusions that associated
with volcanic depressions. A genetic association consists of subalkaline
andesite volcanic rocks that are superimposed on gabbro-syenite-granite
intrusives. Volcanic rocks are enriched in Rb, Sr, Ba, Ree, Nb, Zr, Ta,
Cr, and Ni (Koval and Gerel, 1986; Koval and others, 1988). The ectonic
settings of deposits (as at Erdenetiin Ovoo and Bayan Uul) is
interpreted as continent-continent collision in contrast with the
southern Mongolian belt where many deposits and occurrences are
interpreted as subduction-related. The primary ore minerals are pyrite,
molybdenite, chalcopyrite, tennantite, galena, sphalerite, and enargite.
Secondary enrichment zone includes chalcosite, covellite, and bornite
(Gavrilova and others 1984). Porphyritic, quartz-sericitic and argillic,
and incipient K-feldspar alteration also occur (Sotnikov, Berzina and
Bold, 1984).

## Granitoid-Related Au Deposit Type

## By Gunchin Dejidmaa

The granitoid-related Au deposit type consists of quartz veins and
veinlet-stockwork zones that are often localized in altered wall rocks
with sulfide stringer-zones. The deposit type was previously called
vein/replacement type (Dejidmaa, 1996). Free gold occurs in veins and
stockworks and also as disseminatations in altered wall rocks. The
deposits and occurrences generally exhibit a close spatial and possible
genetic relation to small, complex, granitic intrusions of variable
composition. The granitic rocks include gabbro, diorite, granodiorite,
and granite of both calc-alkaline and sub-alkaline compositions. The
tectonic environment is interpreted as epizonal plutons that formed in
island arcs, continental margin arcs, or continental rift zones. Most
deposits and occurrences in Mongolia are related to granitoids formed in
Mesozoic interplate epeirogenic uplifts and continental rift zone
environments.

Wall rock alteration, mineralogy and geochemistry are divided into the
following subtypes: (1) Au-beresite, (2) Au-listvenite, (3)
Au-sheelite-quartz vein-stockwork, (4) Au-sulfide-quartz vein, (5) Au-As
-Sb vein-stockwork, (6) Au-Te quartz vein-stockwork, (7) Au-Cu-Ag
-quartz vein-stockwork, (8) Au-Pb-Zn-Ag -quartz vein-stockwork, and (9)
Au-magnetite-hematite-quartz vein-stockwork. The host rocks are
generally intensively altered. The Au-beresite and Au-listvenite
subtypes contain most of the gold, as disseminations, in these subtypes.
Alteration in the Au-beresite subtype often occurs in siliceous and
intermediate composition host rocks. Alteration in the Au-listvenite
subtype often occurs in mafic and ultramafic rocks. Disseminated sulfide
minerals in wall rocks, especially pyrite and arsenopyrite in the
Au-beresite subtype, and pyrite, arsenopyrite and chalcopyrite in the
Au-listvenite subtypes, are commonly enriched in gold. The main examples
of the Au-beresite subtype are the Boroo deposit in the Boroo-Zuunmod
district, and the Tsagaanchuluut Khudag 1 occurrence in the Turgen
district. The main example of the Au-Listvenite subtype is the Khyargas
occurrence in the Khyargas district. Host rocks are variably altered in
other subtypes, but gold occurs mostly along with sulfides in quartz
veins and stockworks that contain disseminated gold-bearing sulfide
minerals.

The Au-sulfide-quartz vein subtype is very closely related to the
Au-beresite subtype. Ore composition of these two subtypes are very
similar, but ore-body shapes are different. The differences result from
characteristic ore-hosting tectonic structure. The main examples of the
Au-sulfide-quartz vein subtype are the Tsagaanchuluut, Narantolgoi,
Sujigt, and other deposits in the Boroo-Zuunmod district.

The Au-scheelite-sulfide-quartz vein/stockwork subtype is widely
distributed in western Mongolia, but rarely occurs in central and
eastern Mongolia. However, additional exploration is required. Known
occurrences consist of fissure veins, en-echelon vein systems, and
veinlet-stockworks that contain free gold and scheelite, and sulfide
minerals that occur in apical and periphery part of granodiorite-granite
calc-alkaline intrusions. The subtype is closely related to Mo-W vein
and greisen types and sometimes as overprints.

The Au-As-Sb, Au-Te, Au-Pb-Zn-Ag subtypes are generally associated
spatially with polymetallic vein deposits and are widespread in eastern
Mongolia. They consist of en-echelon vein systems with disseminated
gold-bearing sulfides, sulfosalts, and free gold. Gold-telluride
minerals are common in Au-Te subtype. The fineness of gold is lower
(680-800) for these subtypes than for other subtypes of the
granitoid-related Au deposits.

The Au-Cu-Ag quartz vein/stockwork is sometimes closely related to
porphyry Cu-Au, porphyry Cu and Au-Fe-Cu skarn subtypes. The Au-Cu-Ag
quartz vein-stockwork subtype consists of fissure veins, en-echelon vein
systems, and veinlet-stockwork zones, mostly with disseminated gold,
sulfide minerals, and rare free gold. Cu-sulfides are more common, and
except for Au, Cu, and Ag grades are high. This subtype contains complex
ores of Au, Ag, and Cu. The main examples are the Tavt deposit and a few
occurrences in the Teshig district.

The Au-magnetite-hematite-quartz vein/stockwork subtype occurs only
rarely, and potential exists for additional discoveries. The main
occurrences are in the Narsynhondlon district in eastern Mongolia. This
subtype consists of en-echelon veins and veinlet-stockwork zones of
magnetite-(hematite)-sulfide-quartz. The host rocks are silicified,
sericitized and pyritized. Gold is generally disseminated. Most gold is
related to sulfide minerals. Some deposits contain replacement
magnetite-actinolite-chlorite-quartz vein-like bodies.

## Porphyry Au Deposit Type

## By Gunchin Dejidmaa

The porphyry Au deposit type deposit type consists of stockwork and
veinlets of quartz, pyrite, and chalcopyrite in granite porphyry,
granodiorite porphyry, and diorite porphyry stocks, dikes and breccia
pipes that intrude granitic, volcanic or sedimentary rocks (Dejidmaa,
1996). The tectonic environment is mainly sub-alkaline diorite,
granodiorite, or granite porphyry intrusions that are parts of
subduction-related, late Paleozoic or Mesozoic active continental
margin. This deposit type is divided into a porphyry Cu-Au subtype, and
a porphyry Au subtype. The deposit type has a large potential in
Mongolia.

The porphyry Cu-Au subtype consists of magnetite-sulfide-quartz
stockwork veinlets, and breccia-pipes that contain sulfide stringers.
The main ore mineral are chalcopyrite, pyrite, magnetite, and gold. Gold
is mostly free and fine-grained. Alteration minerals are quartz,
sericite, kaolinite, biotite, potassium feldspar, and chlorite. The
grade of gold varies 0.1 to 15 g/t, and the average Cu grade is 0.3 to
0.4%. The host porphyry intrusions are mainly diorite-and granodiorite
porphyry stocks. The main examples of the subtype are the Khadat deposit
in the Ugtaaltsaidam district, and the Kharmagtai, Ovoot Khyar, Ukhaa
Khudag deposits and occurrences in the Kharmagtai district.

The porphyry Au subtype is related mainly to granite-porphyry stocks and
dikes that contain quartz -pyrite stockwork veinlets. The dikes are
generally silicified, sericitized, and pyritized. Gold is mostly free.
This subtype is related to porphyry Cu-Au subtype and occurs in the
periphery of porphyry Cu-Au deposits. The main examples of the subtype
are the Ulaangozgor, Ulaanhad, Erdenetsog Ovoo occurrences in the
Ugtaaltsaidam district.

## 

## Au Skarn (Contact Metasomatic Replacement) Deposit Type

## By Gunchin Dejidmaa

The Au skarn (contact metasomatic replacement) deposit type forms at the
contacts between calc-alkaline and sub-alkaline granitic intrusions that
intrude carbonate or calcareous rocks (Dejidmaa, 1980; Sherbakov, and
Dejidmaa, 1984; Dejidmaa, 1996**)**. This subtype is divided into Au-,
and Au-rich Fe-Cu; Cu skarn. The skarns are usually are composed of
calc-silicate and sometimes magnesium-silicate minerals. Au skarn and
Au-rich Fe-Cu skarns are related closely to granitoid-related Au deposit
type.

For Au skarns, Au is main commodity and Cu is a byproduct. The major ore
minerals are gold, pyrite, chalcopyrite, bornite, arsenopyrite, and
bismuth minerals. Minor minerals are sphalerite, enargite, tetrademite,
cubanite, bittehenite, magnetite, stannite, millerite, and linneaite.
The major calc-silicate minerals are garnet, scapolite, epidote,
clinopyroxene, amphibole, biotite, chlorite, albite, and calcite. Au
skarns are related to sub-alkaline diorite-granite intrusions that
intruded terrigenous-carbonate, and ophiolite formations in active
continental margin arc and continental rift tectonic environments. The
main example of this subtype is the Khohbulgiin Khondii deposit in the
Bayanhongor belt.

Au-rich Fe-Cu skarn deposit type is related to sub-alkaline
gabbro-diorite-granite intrusives that intrude terrigenous-carbonate,
and carbonate formations in island arc, active continental margin arc,
and continental rift tectonic environments. The main ore minerals are
magnetite, chalcopyrite, pyrite, bornite, and gold. The minor ore
minerals are arsenopyrite, sphalerite, enargite, sheelite, and
ludwigite. The calc-silicate minerals are garnet, pyroxene, actinolite,
chlorite, epidote, and calcite. The main examples of this subtype are
the Bayanhairkhan and Erdenehairkhan occurrences in the Urgamal belt,
the Teshig group occurrences in the Teshig district, the Oyuuttolgoi
occurrence in the Bayangol belt, the Buutsagaan group occurrences of the
same name belt, and the Erdenetolgoi occurrence in the Dochgol district.

## Fe and Fe-Sulfide Skarn Deposit Type

## By Gunchin Dejidmaa

The Fe and Fe-sulfide skarn deposit type consists of magnetite and rare
magnetite-hematite that are associated with magnesium-silicate and
calc-silicate contact metasomatic replacements (Podlessky and others,
1984, 1988). The deposit type is associated with calc-alkaline granitic
rocks.

Magnetite-bearing magnesium-silicate skarn is genetically and spatially
related to early Paleozoic granodiorite and granite intrusions. The
skarns generally occur along the contacts between the intrusion and host
dolomite marble, and rarely along contacts between dolomite and gneiss.
The main skarn minerals are fassaite, spinel, forsterite, diopside,
phlogopite, and serpentine. Magnesium-silicate skarn has following
idealized zonation as described (Podlessky and others, 1984,1988): (1)
granitoid rock; (2) pyroxene-plagioclase rock; (3) spinel-pyroxene
skarn; (4) pyroxene-forsterite or spinel-forsterite skarn; (5)
forsterite calciphyre; and (6) dolomitic marble. Magnetite occurs mostly
in the periphery of the skarn in forsteritic calciphyre, spinel-pyroxene
zones. Magnetite succeeds deposition of phlogopite, serpentinite and
tourmaline. In magnesium-silicate skarn, the ore minerals form massive,
coarse to fine disseminations, vein-like, lens-like, and
irregularly-shaped bodies. Magnetite-bearing magnesium-silicate skarn,
with insignificant amount of sulfide minerals, are also classified as Fe
skarn. Most deposits and occurrences of the Fe skarn deposit type
(Dorvoljin and Ovoot deposits, and occurrences in the Buutsagaan and
Uliastai groups) occur in the central Mongolian skarn belt that is
associated with Proterozoic metamorphic basement rocks that are intruded
by early to late Paleozoic calc-alkaline to subalkaline granitic rocks.

Magnetite-bearing calc-silicate skarn is genetically and spatially
related to post-magmatic (retrograde) granite rocks that intrude marble,
limestone, dolomite, and calcareous-clastic sedimentary rocks. Podlessky
and others (1984, 1988) describe the following idealized zonation: (1)
granite; (2) potassium feldspar-or amphibole-epidote; (3) epidote
monomineralic zone; (4) epidote-garnet endoskarn; (5) garnet exoskarn;
and (6) carbonate rock. The ore mineral assemblages is generally,
magnetite, magnetite-hematite, and quartz-hematite, and is generally
localized mostly in garnet, and rarely in monomineralic epidote and
epidote-garnet skarn. Ore mineral deposition occurs in a characteristic
sequence consisting of garnet, amphibole, chlorite, calcite, and quartz
with anomalous Zn, Cu, and rare Sn. Complex sulfide-magnetite minerals
may occur in the deep levels of this deposit type. For-example, the
Tomortolgoi deposit of the Bayangol belt contains sulfide-magnetite ore
at depth. Sulfide minerals are mostly insignificant in
magnesium-silicate skarn, but are significant in calc-silicate skarn.
The Fe-sulfide skarn subtype contains significant sulfides (pyrrotite,
pyrite, chalcopyrite, sphalerite, and others).

## 

## Fe-Zn Skarn Deposit Type

## By Dangindorjiin Dorjgotov

The Fe-Zn skarn deposit type occurs mainly in uplifted blocks of Late
Paleozoic and Early Mesozoic rocks located on the periphery of the Late
Mesozoic Eastern Mongolian intercontinental volcanic belt (Bakhteev,
1984; Podlessky and others, 1984, 1988). The uplifted blocks are
surrounded by Late Mesozoic volcanic grabens with Permian and Triassic
granitoids that intrude Proterozoic and Paleozoic metamorphosed
sedimentary rocks. The skarns generally occur along contacts and faults
between Proterozoic, Devonian limestone and shale sequences, and
Triassic K-subalkaline granite and leucogranite bodies. The skarns may
occur in lenses (Bayandun, Tumurtei, Kharaat, Salkhit, and other
occurrences), or in layers (Tumurtiin-Ovoo), and generally range from
tens to hundreds of meters in thickness and several hundreds meters
along strike. The intrusives are seldom altered. The dominant skarn
minerals are andradite, hedenbergite, and grossularite associated with
abundant sphalerite. Zonation is typically developed with zones of
epidote-feldspar, epidote-andradite, andradite-magnetite,
andradite-pyroxene-magnetite, and pyroxene-magnetite. Characteristic
retrograde minerals are actinolite, quartz, calcite, and chlorite. Major
ore minerals are sphalerite and magnetite. Chalcopyrite, hematite,
bismuthinite, molybdenite, pyrite, and galena may also occur. The
deposits contain minor Pb and Zn.. Fe-Zn mineralization is irregular
distribution and occurs mostly in garnet and garnet-pyroxene skarn.
Pb/Zn/Cu ratios are 0.2/4.5/0.1. Deposits have four stages of
mineralization: garnet- pyroxene skarn, andradite-magnetite aposkarn,
sulfide, and quartz-carbonate.

## 

## W Skarn Deposit Type

## By Ochir Gerel

The W skarn deposit type consists mainly of various types of scheelite
skarn that occurs along the margin of Mesozoic plutons that intrude
metamorphosed Precambrian carbonate-aluminosilicate rocks, and rarely
Paleozoic carbonate-terrigenous or volcanic-terrigenous rocks. W skarn
deposits in Mongolia presently constitute non-commercial occurrences
associated with Mesozoic granitoids in northeastern and southeastern
Mongolia. Typical examples are at Beise, Bayan-Ovoo, and Tumen Tsogt
(Koval and others, 1984).

W skarns generally form layered bodies that may extend for much as 1.2
to 2 km along intrusive contacts and range from 3.5 to 7.0 meters wide
(Podlessky and others, 1988). The skarns exhibit a very complicated
structure with rhythmically repeated zones of pyrite, arsenopyrite, and
Sn- W-, and Cu-sulfides. The varieties of skarn include
clinopyroxene-plagioclase, banded garnet-clinopyroxene, and
garnet-vesuvianite types. Scheelite with small amounts of molybdenite,
sphalerite and pyrite are the common ore minerals and may occur in both
endoskarn and exoskarn. Gangue minerals are quartz, plagioclase
(andesine), epidote, and actinolite. Scheelite may occur as
disseminations in quartz-feldspar veins in exoskarns. W skarns may
contain late-stage quartz and hematite alteration, and superimposed
sulfides (chalcopyrite and sphalerite). Calcareous skarns form
stratabound bodies up to 400 m long and up to 50 m wide.

The associated intrusive rocks are mainly calc-alkaline felsic plutons
and stocks. Two- or three-phase leucogranites are most common, and
generally consist of coarse-grained porphyritic biotite granite (first
stage), medium-grained biotite-muscovite granite (second stage), and
leucogranite (third stage). The associated granites are characterized by
high contents of REE and Zn, and low contents of CaO and lithophile
elements.

W and Sn skarn with scheelite and cassiterite are generally interpreted
as forming during by bimetasomatic processes along the contacts between
schist, volcanic rock, and granitoids with limestone or marble. The
skarns are very complicated and are characterized by alternation of
endoskarn with epidote or clinopyroxene-plagioclase and exoskarn
(clinopyroxene-garnet-vesuvianite and garnet skarns) Scheelite and
cassiterite occur as disseminations along with minor sulfide minerals
(molybdenite, chalcopyrite, sphalerite). Overprinting the skarn may be
quartz-feldspar alteration (sometimes with garnet and amphibole) and
greisen (quartz, albite, fluorite, rarely muscovite).

## Sn Polymetallic Vein Deposit Type

## By Gunchin Dejidmaa

This Sn polymetallic vein deposit type was first defined for Mongolia by
Ripp and Sudakov (1991) as for the Mongon-Ondor deposit. The deposit
type consists various replacements. The important variants are: (1)
quartz-amphibole-chlorite-feldspar replace-ment zones with polymetallic
and Sn minerals with thicknesses of 1.0 m to 6.0 m; (2).
quartz-chlorite-muscovite-carbonate replacement in stockwork with
polymetallic minerals; and (3) silicified and argillized zones with Ag
and Sb minerals that are often overprinted on the second type of
replacement stockwork (Ripp and Sudakov, 1991). The first type
replacement contains quartz-chlorite-muscovite-albite. Main ore minerals
are galena, cassiterite, sphalerite, pyrargerite and freibergite. Main
metals are Ag, Sn, Pb, Zn, Potential by-products are Cu, Cd and In.
Three types of ores occur: (1) cassiterite-sulfide
(cassiterite-quartz-arsenopyrite); (2) Pb-Zn
(galena-sphalerite-marcasite), and (3) Sb-Ag
(quartz-pyrargerite-freibergite). The deposit type is close associated
spatially with porphyry W-Mo deposit type.

## Hydrothermal Cu-Pb-Zn Vein and Stockwork Deposit Type

## By Dangindorjiin Dorjgotov

The hydrothermal Cu-Pb-Zn vein and stockwork deposit type occurs in
Jurassic domes containing polyphase intrusives that intruded along
faults (Mironovand others, 1989). These intrusives range from
monzodiorite Mongon-Ondor, Baits and others) consist of quartz-sulfide
and quartz-carbonate-sulfide veins in alteration zones. The veins are
related to small Mesozoic bodies of diorite, granodiorite, granite that
intrude metamorphosed sedimentary rocks. The mineral composition of
these deposits is complex is similar between deposits. Major minerals
are quartz, sericite, carbonate, galena, sphalerite, pyrite, and Ag
minerals, sometimes with chalcopyrite, pyrrhotite, tetrahedrite,
boulengerite, and native gold. Metasomatic wall rock alteration consists
of wide-spread propyllitic zones and narrow beresite zones composed of
quartz, sericite, carbonate, and pyrite. The metasomatic rocks exhibit a
zonal and internal structure with quartz, sericite, and pyrite commonly
occurring in the center, whereas quartz and pyrite commonly occur in the
periphery, along with an increase of carbonate and chlorite. The ore
minerals are irregularly distributed. The ore zones exhibit streaky,
massive, and brecciated structures, whereas barren zones are
characterized by disseminated to linear disseminations, occasional
encrusted, and nested structures. The deposits have three stages:
quartz-sulfide; quartz-carbonate-sulfide; and carbonate-fluorite.

The stockwork deposits at Ulaan, Mukhar and others occur mainly inside
of explosion breccia pipes that are formed along steeply dipping faults
(Mironovand others, 1989). The ore bearing pipes have trapezoid or wedge
shapes and intrude metamorphosed, Late Mesozoic sedimentary and volcanic
rocks. The breccias are intensively altered by hydrothermal-metasomatism
with a well-defined definite mineralogical zoning. In the central part
and deep horizons of the pipes, the cement varies from
epidote-actinolite-sulfide to epidote-actinolite. Other parts of pipes
are cemented by quartz-fluorite-sulfide. Polymetallic mineralization is
developed mainly in the pipes and occasionally in fractures near the
breccia pipes. The ore bodies vary from vein to stockwork, strike for
several hundred meters, with thicknesses of several tens of meters, and
extend down dip for up to 700 m. The major ore minerals are galena,
sphalerite, chalcopyrite, and pyrite. Also occurring are arsenopyrite,
pyrrhotite, magnetite, thenantite, bornite, native silver, and gold.
Gangue minerals are quartz, feldspar, fluorite, epidote, actinolite,
carbonate, and chlorite. The ores exhibit disseminated,
pocket-disseminated, and breccia structures. Deposits exhibit five
stages of mineralization: diopside-magnetite; epidote-actinolite;
quartz-sulfide; quartz-fluorite-sulfide; and quartz-fluorite.

## Epithermal Ag-Pb Vein Deposit Type

## By Dangindorjiin Dorjgotov

The epithermal Ag-Pb vein deposit type consists of quartz-sulfide veins
and mineralized zones in various rocks intruded by mafic Cretaceous
dikes. Ore minerals are related to the dikes. The ore bodies extend
along strike for several hundreds meters, and extend down-dip up to 300
m. The thickness of ore bodies ranges up to several tens of meters. The
ore bodies consist of quartz-carbonate-sulfide and carbonate-sulfide
types. The major ore minerals are galena, arsenopyrite, stibnite, and Ag
minerals. Chalcopyrite, sphalerite, cinnabar, and pyrite are
subordinate. Gangue minerals are quartz, siderite, chalcedony, kaolin,
calcite, barite, and fluorite. The principal wall rock alterations are
quartz, chalcedony kaolinite and chlorite. The deposit type has
following three major stages: quartz-galena, quartz-fluorite and
quartz-carbonate. Epithermal Ag-Pb vein deposits (Khartolgoi, Boorch,
Modon, and others) are located in the active, deep-seated fault zones of
Kerlen, Modon, Elgen-Uul, Tolbonuur, and elsewhere (Batjargaland others,
1997 and Dorjgotovand others, 1997).

## Au-Ag Epithermal Vein (Low Sulfide) Deposit Type

## By Gunchin Dejidmaa

Au-Ag epithermal vein deposits have a high potential in Mongolia. The
deposit type is divided into a low- and high-sulfide epithermal Au
subtypes (Dejidmaa, 1996).

The low-sulfide epithermal Au deposit subtype consists of
quartz-adularia, quartz-adularia-carbonate, quartz-adularia-fluorspar
veins and stockwork with a wide variety of sulfides, gold, silver,
sulfosalts, pyrite, argentite, chalcopyrite, galena, and sphalerite.
Host rocks are exhibit silicification, argillization, sericitization,
carbonatization, adularization, and propylitization. Silica minerals are
mostly chalcedony. A few low-sulfide epithermal Au occurrences exist in
eastern Mongolia. These occurrences are located in a fault zones between
grabens and horsts that contain volcanic and sedimentary rocks that
formed during Mesozoic continental rifting.

A few high-sulfide epithermal Au occurrences exist in southern Mongolia.
These occurrences are closely spatially related to porphyry Cu-Au and
porphyry Cu deposits and occurrences that formed in a late Paleozoic
continental margin arc. The known high-sulfide epithermal Au occurrences
are located in volcanic-tectonic structures, especially in caldera
structures. The host rocks are intensively silicified, kaolinitized,
alunitized, sericitized, and pyritized.

## Volcanic Hosted Zeolite Deposit Type

## By Sodov Ariunbileg

This deposit type is hosted mainly in stratified volcanic rocks and
locally in lacustrine sedimentary rocks with interlayered units (up to
60 m thick) of siliceous tuff, tuff-argillite, and tuffaceous sandstone
and conglomerate. The maximum zeolite content (60 to 90%) occurs along
contact with underlying siliceous vitreous tuff with minor amounts of
volcaniclastic rocks. The main zeolite group mineral is clinoptilotite,
and in some cases, ferrierite, chabazite, and heulandite (Petrova and
others, 1996). This deposit type is widespread in Mongolia, particularly
in the eastern Mongolian volcanic belt that contains a distinctive type
of igneous-limonite-related zeolite that is interpreted as forming in
the Late Jurassic and Early Cretaceous. Several natural zeolite deposits
occur in the southeastern and southern parts of Mongolia, including the
Tsagaantsav and Tushleg deposits that have industrial importance.

## W-Mo Greisen Deposit Type

## By Ochir Gerel

The W-Mo greisen deposit type consists of wolframite, molybdenite, and
beryl with muscovite. Accessory minerals are scheelite, pyrite,
arsenopyrite, galena, sphalerite, fluorite and topaz) that occur in
greisen zones, quartz veins, and veinlets. The deposits are generally
hosted in subalkaline, hypabyssal leucogranites (Koval and Yakimov,
1984). Greisen is associated with late-stage, fractionated granites. The
greisen occurs mainly in endocontact, apical zones. Alteration includes
greisen and albite. The main examples are at Yugzer, Tumen Tsogt,
Tsagaan Tolgoi (Khasin and Suprunov, 1977, Koval and Yakimov, 1984). The
deposit type is associated with W vein, W -Mo vein deposits.

## 

## W-Mo Vein Deposit Type

## By Ochir Gerel

The W-Mo Vein deposit type consists of wolframite, molybdenite, and
beryl that occur in various veins and breccia zones (Koval and others,
1986). The veins generally also contain various combinations of
muscovite, fluorite, carbonate, scheelite, pyrite, arsenopyrite,
chalcopyrite, sphalerite, and bismutite. The deposits occur mainly in
exocontact zones and sometimes in endocontact zones. The main examples
are at Ugzer, Buren Tsogt, Chuluun Khoroot, and Undur Tsagaan.

## 

## Sn and W Vein Deposit Type

## By Ochir Gerel

The Sn and W vein deposit type consists of veins and brecciated zones
that occur near or in shallow granitic intrusions that are highly
fractionated and enriched in lithophile elements such as Rb, Li, Be, Sn,
W, Ta, Nb, REE, and F (Kovalenko and others, 1971; Gerel, 1990).
Associated hydrothermal greisen-type alteration is common (Khasin and
Suprunov, 1977, Ivanova, 1976). Associated intrusions are highly
fractionated leucocratic granites with two-mica, or muscovite
leucogranites. The granitic rocks are mainly of late Paleozoic, and
early and late Mesozoic age. The deposit type is divided into two
subtypes, wolframite-cassiterite and cassiterite subtypes. The
wolframite-cassiterite and cassiterite-wolframite types both contain
cassiterite and wolframite with quartz, muscovite, topaz, fluorite, and
pyrite. In addition, arsenopyrite occurs in the cassiterite type, and
molybdenite and beryl in occur in the wolframite-cassiterite type.
Mineralization occur in veins, veinlets, stockworks and greisen zones
along endocontacts or exocontacts of plutons. The main examples of
cassiterite-wolframite subtype are at Modot, Bayan Mod, Bayan Ovoo,
Tsagaan Ovoo, Bayan Khan, Janchivlan, and Khujkhan. The main examples of
wolframite-cassiterite sub type are at Kumyr, Tsagaan Davaa, and Zuun
Tarc Gol. This deposit type is well studied in Mongolia.

## 

## Sn Silicate-Sulfide Vein Deposit Type

## By Ochir Gerel

The Sn silicate-sulfide vein deposit type is represented by
cassiterite-tourmaline mineralization in veins and veinlets of
exocontact zones of multiple granite and granodiorite intrusions
(Kovalenko and others, 1986). The composition ranges from granodiorite
and granite of calc-alkaline series to subalkaline granite. The main
minerals are cassiterite, quartz, tourmaline, chlorite, carbonates,
chalcopyrite, arsenopyrite, sphalerite, and molybdenite. The main
examples are at Khukh Uul and Zan Shiree.

## 

## Sn-Sulfide Vein Deposit Type

## By Ochir Gerel

The Sn-sulfide vein deposit type consists of elongated, brecciated zones
along exocontacts adjacent to subalkaline and Li-F hypabyssal granitic
plutons (Khasin and Suprunov, 1977). The deposit type is interpreted as
forming in a post-orogenic setting. The main minerals are cassiterite,
galena, sphalerite, muscovite, fluorite, tourmaline, chlorite,
carbonate, pyrite, arsenopyrite, and chalcopyrite. Alteration minerals
are tourmaline, chlorite, muscovite, and quartz. The main example is at
Khar Morit. The deposit type is associated with muscovite-microcline
pegmatite and Sn-W greisen. According to some investigators, the
Sn-sulfide deposit type may be part of the Sn-silicate-sulfide deposit
type (Kovalneko and others, 1986). This deposit type needs more study.

## Sn-W Vein and Stockwork Deposit Type

## By Ochir Gerel

The Sn-W vein and stockwork deposit type consists of individual veins,
multiple vein systems, and vein and fracture stockworks The deposit type
is one of the best studied and economically important for Mongolia
(Khasin and Suprunov, 1977; Khasin and others, 1983). The deposits occur
in or near granitic intrusions that were emplaced at relatively shallow
levels. The deposits are structurally controlled by deep faults and
fissures. Individual veins range from less than 1 cm to several meters
wide. Vein systems are hundreds of meters wide and more than a thousand
meters long. The tectonic environment is interpreted as continental
collision belt.

The principal ore minerals are cassiterite, wolframite, and scheelite.
Associated minerals are molybdenite, chalcopyrite, sphalerite, pyrite,
arsenopyrite, sphalerite, muscovite, fluorite, beryl, topaz, feldspar,
quartz, and tourmaline. Associated hydrothermal alteration assemblages
consist mainly of greisen with fluorite, topaz, tourmaline, Li-mica,
muscovite, biotite, and quartz, and other minerals such as albite and
microcline. Cassiterite, wolframite, chalcopyrite, sphalerite, pyrite,
and other sulfide minerals are disseminated in greisen-altered rocks.
The alteration is generally zonal.

The associated intrusions are calc-alkaline, or subalkaline Li-F
granites. The granites are highly fractionated, range from peraluminous
to peralkaline in composition, and are characterized by high SiO~2~ and
alkalies, Rb, Li, Be, REE, Sn, W, Ta, Nb, and F, and depleted in CaO,
MgO, Sr, and Ba (Gerel, 1990, 1995). The granites may be either A- and
S-type, are highly fractionated with two or three stages. Formation of
the Sn-W vein and stockworks is related to the second or third stage.

## 

## W-Sb (Hg) Vein and Stockwork Deposit Type

## By Ochir Gerel

The W-Sb (Hg) vein and stockwork deposit type consists of veins,
stockworks, and breccias with quartz (sometimes with chalcedony and
opal), carbonate (dolomite, siderite, ankerite, magnesite and calcite).
The ore minerals are wolframite, scheelite and minor pyrite, marcasite,
arsenopyrite, chalcopyrite, pyrrhotite, sphalerite, galena, cinnabar,
and gold. The deposits occur in regions of low-grade metamorphism along
the margins of continental terranes, and are controlled by shear zones,
nappe systems, or large faults. No proven relation exists with magmatic
processes. The wall rocks are usually argillized and sericitized. An
example is the Khovd gol and Mushguu in Mongolian Altai (Kempe and
others, 1994, Getmanskaya and others, 1995).

## 

## Barite Vein Deposit Type

## By Sodov Ariunbileg

This deposit type consists of quartz-barite, barite veins and veinlet in
stockworks that are hosted by quartz-porphyry, diabase-porphyry, tuff,
and biotite granite (Marinov and Hasin, 1977). The deposits often occur
along contacts of volcanic and sedimentary rocks. This deposit type is
commonly associated with fluorite deposits.

## 

## REE Pegmatite Deposit Type

## By Ochir Gerel

The REE pegmatite deposit type contains the majority of potentially
commercial pegmatites in Mongolia. These deposits consist of late
Paleozoic or Mesozoic REE pegmatites that are mainly associated with
calc-alkaline, Li-F leucocratic granite. Three subtypes of REE
pegmatites are defined (Kovalenko and others, 1984): Li-mica; muscovite
(muscovite-albite); and muscovite-microcline. The first two subtypes are
Ta-bearing, and the last is composed of cassiterite-tungsten (Rossovsky
and others, 1971; REE granitoids, 1971; Vladykin and others, 1974, 1981;
Gerel, 1995). The Li-mica subtype contains Ta-Nb minerals, cassiterite,
Li-mica, quartz, albite, microcline, apatite, tourmaline, topaz, beryl,
and other minerals. The main examples are at Khuh Del Uul and Unjuul.
The muscovite-albite subtype consists of columbite, tantalite, quartz,
albite, microcline, muscovite. The main example is at Berkh. The
muscovite-microcline subtype includes cassiterite, wolframite, quartz,
microcline, and muscovite. The main examples are at Tumen Tsogt, Bayan
Delger, Bayan Ovoo, and Khalzan Uul. Many of the known REE pegmatite
deposits occur in the north-east REE province of Mongolia.

The Khuh del Uul, Unjuul, and Berkh REE pegmatite deposits and others
occur as dike-like or lenticular bodies that range in size from few
meters to hundreds of meters long, and from 1 to 10 meters wide. In
these examples, the muscovite-microcline subtype is widely developed in
subalakline granite.

Associated Li-Sn-Be pegmatites (Kovalenko and others, 1986; Kovalenko,
Yarmolyuk, 1995) consist of Li-mica, Ta and Sn-W minerals that are
hosted in post-accretionary intrusions that postdate the peak of
batholiths emplacement. The associated granites are mainly calc-alkaline
and Li-F leucogranites and their volcanic and subvolcanic analogues.

## 

## Peralkaline Granite-Related REE (Nb-Zr-REE) Deposit Type

## By Ochir Gerel

The peralkaline granite-related REE (Nb-Zr-REE) deposit type is
associated with peralkaline rocks. An example is the REE-Zr-Nb Khalzan
Buregtei deposit in western Mongolia (Kovalenko and others, 1990, 1995),
the Khan Bogd deposit in southern Mongolia (Vladykin and others, 1981),
and a number of occurrences in western and southern Mongolia. The
deposit type generally occurs in the apical part of cupolas, and is
generally associated with highly fractionated magmatic phases including
peralkaline pegmatite. The host granites are composed of potassium
feldspar, quartz, albite, arfvedsonite, aegirine, fluorite, and various
REE minerals, such as elpidite, gittincite, zircon, pyrochlore,
monazite, REE fluorcarbonate, polylitionite and others. Alteration
includes replacement by epidote, orthoclase, and postmagmatic albite.
The deposits are generally hosted in microcline-albite granite and
albite metasomatic rocks composed of quartz, albite, pyroxene, and
microcline. Quartz-epidote metasomatic rocks contain zircon,
fergusonite, allanite, chevkinite and titanite in vein-like zones.
Fergussonite and zircon contain HREE and Y (Kempe, Dandar, 1995).
Acessory minerals include amphibole, magnetite, zircon, epidote,
ilmenite, fluorite, beryl, chevkinite, pyrite, and galena. REE
pegmatites and quartz-fluorite veins may also occur (Dandar and others,
1995).

According to Kovalenko and others (1985), Zr-REE mineralization is of
magmatic origin and is concentrated within highly fractionated REE
granites. In contrast, Kempe and others (1994) and Andreev and others
(1994) suggest a metasomatic origin. Their studies of the Khalzan
Buregtei deposit, and the Tsakhir, Shar Tolgoi and Ulaan Tolgoi
occurrences in the Mongolian Altai region show that these deposits are
formed in endocontacts of alkaline plutons that consist of
metasomatically-altered alkaline syenite (nordmarkite). These intrusions
are small, metasomatically altered, and range from fine-grained to
pegmatite. Nordmarkite, dolerite, and syenite are also metasomatically
altered. Associated with the alteration was emplacement of mafic and
ultrabasic dikes and volcanic rocks. The ore minerals are numerous and
include more than 70 minerals. The rock forming minerals are potassium
feldspar, albite, quartz, calcite, zircon, and Sr-fluorite. Accessory
minerals are pyrochlore, barite, rutile, titanite, epidote, REE
carbonates, and fluorite. Metasomatic rocks contain quartz, epidote,
zircon, titanite, fergussonite, pyroxene, chevkinite, and others (as at
the Tsakhir occurrence). Other examples are the Gurvan Unet and Ulaan
Unet occurrences.

# DEPOSITS RELATED TO ALKALINE IGNEOUS ROCKS

## 

## Fe-REE Carbonatite or Magnetite-Apatite Deposit Type

## By Gunchin Dejidmaa

The Fe-REE carbonatite or magnetite-apatite deposit type consists of
magnetite-apatite veins and bodies with 1 to 14.5% REE (mostly cerium
group) that occur in apatite, magnetite, phlogopite, and rare celestine
in alkaline plutonic and coeval volcanic rocks (Samoylov, Ivanov and
others; 1984; Kovalenko, Koval and others, 1988). Magnetite is mostly
altered to hematite The amount of apatite and of magnetite varies
strongly in stock-like bodies and in veins. Some bodies contain rich
bonanza ore formed of massive, very coarse-grained magnetite, or of
fine-and medium-grained apatite. The deposit type is related genetically
and spatially associated with REE-fluorspar carbonatite, REE-apatite
carbonatite and REE-strontium carbonatite deposits in alkaline plutonic
and volcanic rocks, and in explosive carbonatite breccia. Examples of
the deposit type occur in the Mushgai Khudag district in southern
Mongolia, and in the Ubs Nuur district in northwestern Mongolia.

## 

## REE Carbonatite Deposit Type

## By Ochir Gerel

The REE carbonatite deposit type includes REE,-P-Sr-Ba-fluorite-Pb
occurrences that are associated with late Mesozoic alkaline
volcanic-plutonic complexes (Samoilov and Kovalenko, 1983). These
complexes occur in intraplate areas and are controlled by major faults
and anorogenic rifts. The host rocks are potassic alkaline volcanic
rocks and carbonatite including melanephelinite, melaleucitite,
phonolite, trachyte, latite, trachybasalt, and syenite. Typical examples
are the Mushgai Khudag and Lugiin Gol occurrences in southern Mongolia.
The main deposit types are (1) carbonatite and eruptive trachyte breccia
with a carbonatite matrix containing of 0.1 to 0.8% REE, or are enriched
in light REE and contain up to 18% Sr; (2) magnetite-apatite rocks with
REE content of 1.0 to 14.5%;and (3) bastnaesite carbonatite with a REE
content of 1 to 18% (Kovalenko and Yarmolyuk, 1995). The carbonatite and
eruptive trachyte breccia deposit type forms large mineralized bodies.
The magnetite-apatite rock deposit type occur in dikes and stock-like
bodies. The bastnaesite carbonatite deposit types occurs mainly as
dikes. In all three subtypes, the ore minerals include bastnaesite,
carbonate, fluorite, celestine and barite, cerrusite, magnetite, apatit,
and monazite.

As an example, the Mushgai Khudag alkaline series include more than 200
dikes of carbonatites that range from 20 m to 2000 m long and from 0.2
to 1 m wide. Besides calcite carbonatites, quartz veins with
celestine-fluorite-calcite and calcite-celestine-fluorite-also occur.
Magnetite-apatite rocks are also associated with this carbonatite
complex. Another example is the Lugiin Gol carbonatite occurrence that
is composed of pseudoleucite and nepheline syenite with ring and radial
dikes of nepheline syenite, pulaskite, syenite-porphyry, and tingauites
(Vladykin, 1997). The main REE minerals at the Lugiin Gol occurrence are
synchysite, synchysite-parisite and synchizate-bastnaesite intergrows
(Batbold, 1977). Sr- and Nd-enriched synchysite also occur (Batbold,
1977). Other carbonatite occurrences are those at Bayan Khushuu,
Khotgor, and Ulgii, Tsogt Ovoo. In these areas, the carbonatites occur
as dikes up to 1-2 m wide within plutons or host rocks of late Paleozoic
volcanic and sedimentary rocks. The carbonatites are composed of calcite
with mica, apatite, fluorite, bastnaesite, synchizite, rutile, zircon,
and sulfides. Alterations include replacement of pre-existing minerals
and recrystallization of pyroclastic rocks, formation of
silica-jarosite, silica-fluorite, and silica-barite-fluorite metasomatic
rocks.

## 

## Nepheline Syenite Deposit Type

## By Ochir Gerel

The nepheline syenite deposit type is associated with nepheline-bearing
alkaline complexes (ijolite, urtite, juvite and foyaite, pulaskite) and
nepheline syenites (Zaitzev and others, 1984). The main examples are the
Ujigiin Gol and Beltsiin Gol areas with small plutons with
nepheline-bearing rocks that are related to a large alkaline province in
northern Mongolia. The nepheline-rich rocks occur mainly occur along
exocontacts of plutons. Al~2~O~3~ content varies from 20.4 to 30.9%, and
alkali content varies from 12.5 to 17.6% (Zaitzev and others, 1984). The
nepheline-rich rocks are composed of nepheline and pyroxene. Nepheline
content ranges from 30% (in ijolite) to 90 persent (in urtite). Other
minerals in nepheline-bearing rocks are microcline, lepidomelane,
muscovite, and cancrinite. Alteration consists of albite and potassium
feldspar replacement.

## Ongonite-Hosted Ta-Li Deposit Type

## By Ochir Gerel

This ongonite-hosted Ta-Li deposit type is subdivided into volcanic and
plutonic facies both of which are volcanic analogues of Ta-bearing
granites and pegmatites (Kovalenko and others, 1971; Kovalenko and
Kovalenko, 1976). The main ore minerals contain Ta with Rb, Nb, Be, Li,
and Sn. Plutonic ongonites are rich in Ta (up to 130 ppm, with average
content of 88 ppm) and Li (average content of 2,780 ppm) and Rb (average
content of 2,380 ppm). Ongonite is porphyritic with phenocrysts of
albite, quartz, potassium feldspar, topaz, and Li-fengite within a
fine-grained matrix of REE minerals. Volcanic ongonites (as at the Teg
Uul occurrence) are poorer in REE (Ta 37 ppm, Nb 170 ppm, Rb 1,040 ppm
and Be 90 ppm) than plutonic ongonites, but form large bodies: volcanic
cones, stratified bodies, and sheets. The volcanic ongonites are
vitreous. The main occurrences are at Teg Uul, Dorit Uul, and Durvent
Uul in southern Mongolia. The Ni content the deposit type ranges from
0.05 to 0.8%, Zr from 0.5 to 5.0%, and REE from 0.3 to 4.5%. High
concentrations of Li, Be, Sn and Zn are also characteristic. As an
example, the Teg Uul occurrence is large, extends over 1 km^2^, and is
composed of tuff with a thickness of up to 10-20 m. Associated rocks are
late Mesozoic rhyolites and ongorhyolites that formed as volcanic necks.

## 

## Cs Glass Deposit Type

## By Ochir Gerel

The Cs glass deposit type consists of glassy dikes with phenocrysts of
feldspar, quartz, and chevkinite (Kovalenko and others, 1977). The Cs
content of the glass ranges up to 0.08%, but decreases during
devitification. An example is the Braibung khiid (Khentei aimag)
occurrence. This deposit type is not well studied.

## 

## Be Tuff Deposit Type

## By Ochir Gerel

The Be tuff deposit type consists of bedded and graded-bedded tuff that
contains fragments of ongorhyolite, rhyolite, quartz, feldspar,
fluorite, and Be-bearing bertrandite (Kovalenko and Koval, 1984). The
average Be content is 0.05%. The main examples are at Durvent Dorit Uul,
and Teg Uul.

## REE-Albite Deposit Type

## By Ochir Gerel

The REE-albite deposit type forms in the endocontact of alkaline plutons
that are composed of metasomatically altered alkaline syenite
(nordmarkite) as at the Kovalenko occurrence (Andreev and others, 1994;
Kempe and others, 1995). The main occurrences are Teg Uul, Dorit Uul,
Durvebt Uul in southern Mongolia. Other examples of this deposit type
may the Khalzan Buregtei deposit, and the Tsakhir, Shar Tolgoi, and
Ulaan Tolgoi occurrences in the Mongolian Altai.

## 

## REE-Albite Nepheline Syenite Deposit Type

## By Ochir Gerel

The REE-albite nepheline syenite deposit type occurs in contrasting
volcanic peralkaline rocks (comendite, pantellerite, peralkaline
trachydacite, trachyrhyolite and trachybasalt) that contain REE-albite
nepheline syenite (Kovalenko and Yarmolyuk, 1995). The main examples are
the Bomin Khara and Gzart Khudag occurrences in South Gobi. The ore
minerals are REE-Zr-Nb minerals.

## Ta-Granite Deposit Type

## By Ochir Gerel

The Ta-granite deposit type occurs in the apical and endocontact zones
of Li-F or subalkaline plutons or in small stocks and dike-like bodies
(Kovalenko and others, 1981). The main ore minerals are columbite and
tantalite with microlite, Pb-pyrochlore, and cassiterite. The major
gangue minerals are albite, microcline, quartz, and Li-mica, and
sometimes topaz, pyrochlor, and beryl in muscovite type. The Ta-granite
deposit type is divided into two subtypes, Li-mica and muscovite. The Li
mica subtype occurs in Li-fluorine leucogranite plutons, and the
muscovite subtype occurs in calc-alkaline granites (Kovalenko and
others, 1981). Muscovite REE type contains columbite-tantalite and beryl
with albite, microcline, quartz and muscovite. Examples of the Li-mica
subtype are at Janchivlan, Borokhjir, Baga Gazar, Avdar, Baruuntsogt,
Yugzer, and others. Examples of muscovite subtype are at Yugzer,
Tumentsogt, Baruuntsogt, Yargait, Uzyg, and others. Ta-Be and W-Mo
mineralization is also associated with the Ta-granite deposit type.
Associated alteration is mainly albitization.

## Ag-Sb Deposit Type

## By Gunchin Dejidmaa

The Ag-Sb deposit type consists of mostly siderite-sulphosalts veins
hosted in carbonaceous terrigenous, terrigenous-carbonate or black shale
that are enriched in sulfide minerals adjacent to intruding igneous
rocks. This deposit type is widely distributed in western, but mostly in
northwestern Mongolia. The known deposits and occurrences are close
related spatially associated with alkaline basaltic dikes. This deposit
type is well studied by Borisenko and others (1984, 1987, 1988, 1991),
Obolenskii (1984); Berezikov and others (1986), Badarev and others
(1989), Demin and others (1989), and Khrustalev and others (1989).

The deposit type consists of extended (up to 5-6 km) veins and vein
zones containing siderite-sulphosalts. The main gangue mineral is
siderite that comprises from 50% to 95% of the veins. The major gangue
minerals are quartz, calcite, ankerite, barite, and fluorite. The
predominant ore minerals are silver sulphosalts of Cu, Pb, Ag:
tetrahedrite, chalcostibite, zincenite, bournonite, jemsonite,
boulangerite, andorite, pyrargyrite, geokronite, and meneghinite, along
with bismuth sulphosalts, bismuthinite, native bismuth, galena,
chalcopyrite, stibnite, arsenopyrite, lollingite and others The ore
minerals comprise from 1 to 5 to 50% of the veins. The major metals are
Ag, Sb, Bi, and the main byproducts are Cu and Pb. Related deposit types
are Co-Ni arsenide veins that are form in association with magmatism
related to intraplate tectonism.

The deposit type is divided into two subtypes, Cu-Bi-Ag and Pb-Ag-Sb
subtypes. The Cu-Bi-Ag subtype contains mainly Cu sulphosalts and
sulfides (tetrahedrite, chalcostibite, chalcopyrite), and bismuth
minerals. The Ag grade varies from 200 to 300 g/t to 1000 g/t. The main
example is the Asgat deposit in western Mongolia. The Pb-Ag-Sb subtype
contains predominantly Pb sulphosalts (jemsonite or zinkenite), and also
gudmundite and rare stibnite. Tetrahedrite is the main Ag-bearing
mineral. Bismuth minerals are uncommon, but always occur. Ag grade
varies from about 400 to 600 g/t. The main example is the Tolbonuur
occurrence in western Mongolia.

# 

## Co-Ni-Arsenide Deposit Type

## By Gunchin Dejidmaa

The Co-Ni-arsenide deposit type consists of epithermal hydrothermal
veins composed of carbonates (calcite, dolomite, and rare ankerite, and
siderite), and sometimes significant amounts of fluorite and barite
(Borisenko and others, 1992). The ore minerals are Co-Ni-Fe arsenides
(nickeline, shmaltine, chloatite, skutteride, rammalsbergite,
safflorite, lollingite, and also sulfoarsenids: cobaltine, glaukodot,
gersdorfite, arsenopyrite), Cu-Ag-Pb-Bi sulfosalts and sulfides, and
native Ag and Bi. The deposit type includes a series of complex of
Bi-Ag-Cu-Ni-Co-arsenic ore minerals that form in mesobyssal and
hypabyssal depths in genetic and spatial association with small
intrusions of alkaline-basalt (Borisenko A.S. and others, 1984). Most of
deposits occur along deep fault zones. The deposit type is divided into
three subtypes according to mineralogy and host rocks: (1)
Co-Ni-arsenide; (2) Co-sulfoarsenide; and (3) Cu-Co
sulfoarsenide-sulfosalt . The Co-Ni-arsenide subtype mostly occurs in
deep fault zones and at the intersections of deep-seated faults. The
Co-sulfoarsenide and Cu-Co sulfoarsenide-sulfosults subtypes occur far
from the first subtype, and mostly consist of replacement stringers and
veins (Borisenko and others, 1984).

The second and third subtypes occur in western Mongolia. Examples of the
Co-sulfoarsenide subtype are the Tsagaangol and Teht occurrences and
others in the Tolbonuur district that also contains Ag-Sb vein
occurrences. The Co-sulfoarsenide subtype is closely spatially
associated with diabase dikes in the deep-seated Tolbonuur fault zone.
The main ore minerals are cobaltine, glaukodot, scheelite, bismuth
minerals, arsenopyrite, and lollingite. Other major minerals are pyrite,
pyrrhotite, chalcopyrite, magnetite, tetrahedrite, and gold.. The host
rocks are the Middle Devonian siltstone and sandstone of the Khatuugol
unit. The host rocks are intensively silicified, sulphidised, and
chloritized.

The Cu-Co sulfoarsenide-sulfosalts subtype is more widely distributed
than the Co-sulfoarsenide subtype and occurs mainly in northwestern
Mongolia. This subtype is poorly studied. Cu occurrences consist mostly
of a replacement zones with high concentrations of Cu, Ag, and Bi, and
occur near or in deep, regional fault zones. The main ore minerals are
tetrahedrite, tennantite, chalcopyrite, pyrite, majors-bornite,
sulfides, and sulfosalts of Pb and Cu, and rare sulfosalts and arsenides
of Ni and Co. The gangue minerals are quartz, siderite, calcite,
chlorite, and barite. The host rocks are vary in terms of composition
and age from early Paleozoic to Jurassic. The host rocks are
carbonatized, silicified, sericitized, argillitized, and chloritized.
The deposit subtype sometimes is succeeded by Co-sulfoarsenide subtype
deposition (Borisenko and others, 1984).

## DEPOSITS RELATED TO SUBAERIAL FELSIC TO MAFIC EXTRUSIVE ROCKS

## Clastic-Sediment Hosted Hg Deposit Type

## By Gunchin Dejidmaa

The clastic-sediment hosted Hg deposit type consists of cinnabar in
lenses, stockwork and other structures in flysch sequences composed of
siltstone and shale. The ore bodies form stockworks, lenses, bed-like
bodies, and simple and complex veins along fault zones. The ore bodies
are generally controlled by sets of fractures (Kharzat, Tunhel, and Balj
occurrences), or by thrust faults (Ulaanhus occurrence). The main ore
mineral is cinnabar. The gangue minerals are quartz, sericite, dickite,
and carbonate minerals. The host rocks are silicified, sericitized,
argillized and carbonatized. Ore deposition is interpreted as occurring
during lower temperature, hydrothermal fluids related to mantle-derived,
alkaline basaltic magma.

## Silica-Carbonate (Listvenite) Hg Deposit Type

## By Gunchin Dejidmaa

The silica-carbonate (listvenite) Hg deposit type consists of cinnabar
formed mainly at the contact of serpentinite and graywacke, or in
serpentinite in major thrust zones and deep-seated faults that bound
serpentinite and ultramafic rocks. The host rocks are argillized,
carbonatized and mainly silicified. The main ore mineral is cinnabar,
and other minerals are tetrahedrite, gersdorfite, brovaite,
metacinnabarite, hematite, cromate, and chalcocite. The gangue minerals
are dolomite, breunnerite, and ankerite, other gangue minerals are
quartz, opal, chalcedony, calcite, dickite, and talc. The ore minerals
occur as masses, in veinlets, and as disseminations in irregular
lens-like bodies. The deposit type is closely related to
clastic-sediment-hosted Hg deposit type. For example the Olgii
occurrence, a silica-carbonate Hg deposit, and the Ulaanhus occurrence,
a clastic-sediment-hosted Hg occurrence, occur adjacent to each other
along the deep-seated Tolbonuur fault in the Mongol Altai.

### 

## Volcanic-Related Hg Deposit Type

## By Gunchin Dejidmaa

The volcanic-related Hg deposit type consist of sparse, long, argillized
and silicified zones, up to 50 m thick, that are hosted either in
variable-age granitoids (Dalai Am gol, Khotol nuur, and Idermeg Bayan
Khaan uul occurrences), or in carbonate rocks (Bituugol occurrence).
Altered zones contain quartz, quartz-carbonate with barite, and
carbonate veins, veinlets or stringers, and masses of sulfides, mostly
galena, Hg-bearing sphalerite, cinnabar, chalcopyrite, and mostly
pyrite. In the latter, the sulfides are cemented by quartz-chalcedony
and chalcedony and contain altered, sulfidized, brecciated zones with
fluorite veins. Occurrences of the volcanic-related Hg deposit type are
located in eastern Mongolia in the northwestern marginal part of the
eastern Mongolian Mesozoic continental rift system and the deep-seated
Ulzgol fault zone.

Closely, spatially-related deposits consist of polymetallic breccia,
fluorspar vein, and epithermal Au, quartz-barite vein and Hg deposits
that also occur in the eastern Mongolian Mesozoic continental rift
system. Overprinting deposit types include epithermal Au vein, fluorite
vein; polymetallic breccia, and fluorite, barite deposits that are
genetically related to the Hg deposits. Some polymetallic vein and
fluorite deposits (the Galshar group), and breccia type deposits (Ulaan
and Mukhar occurrences) are hosted in siliceous volcanic breccia. This
relation suggests that Hg deposits are genetically related to
basalt-rhyolite volcanic rocks that are widely developed along the
eastern Mongolian continental rift system.

## 

# DEPOSITS RELATED TO MAFIC AND ULTRAMAFIC ROCKS:

## 

## Zoned Mafic-Ultramafic Ti-Fe (and Apatite-Ti-Fe)

## By Gunchin Dejidmaa

The few known occurrences of zoned mafic-ultramafic Ti-Fe (and apatite
Ti-Fe) deposit type occur in differentiated, concentrically-zoned
gabbro, gabbro-anorthosite, and gabbro-pyroxenite plutons, and in rare
diabase sills (Izokh and others, 1984, 1990). Three subtypes may exist
for the deposit type, according to mineralogy and host rock composition:
(1) Ilmenite-titanomagnetite (apatite-ilmenite-titanomagnetite) subtype
related to gabbro-anorthosite; (2) Ti-Fe (titanomagnetite) subtype
related to clinopyroxenite-gabbro; and (3) Ti-Fe subtype related to
diabase sills. In all three subtypes, ore minerals formed in two main
stages. (1) Early magmatic stage ore occurs as layers and lenses
concordant to layering in host mafic-ultramafic intrusions. The ores
occur in pyroxenite and peridotite layers and lens and consist of
massive and disseminated ore minerals. And (2) post magmatic stage ore
that forms mostly veins. Only a few occurrences of this deposit type are
known in Mongolia.

The Ilmenite-titanomagnetite (apatite-ilmenite-titanomagnetite) subtype
is hosted in Proterozoic gabbro-anorthosite that is part of an Archean
and Early Proterozoic metamorphic basement. The host gabbro-anorthosite
plutons (as at Most Uul, Khojuulyngol, and Olon Khudag) consist of
anorthosite, leucogabbro, gabbro, pyroxenite, and peridotite.
Ore-bearing pyroxenite and ilmenite-titanomagnetite and
apatite-ilmenite-titanomagnetite layers, lenses and veins are occur in
the plutons (Izokh and others, 1984, 1990). The main ore mineral is
titanomagnetite; other major minerals are ilmenite, apatite,
rare-pyrrhotite, pyrite, hematite, and spinel.

The Ti-Fe subtype is hosted in Upper Proterozoic (Riphean) layered
clinopyroxene-gabbro plutons in northern Mongolia in the Khovsgol and
Urgamal terranes, and in the Khan Khohii subterrane of the Nuuryn
terrane. The host rocks are mainly high alkaline, high ferrugenous and
high titaniferous clinopyroxene-gabbro intrusions that consist of
gabbro, amphibole gabbro, clinopyroxenite, and ore-bearing
clinopyroxenite (Izokh others, 1990). The plutons contain massive and
thick disseminated titanomagnetite zones and layers in pyroxenite. Small
amounts of ilmenite and apatite also occur. Examples of this subtype are
the Khoshimgol occurrence of the Khovsgol terrane, and the Uet-Ondor
occurrence of the Urgamal terrane.

The Fe-Ti subtype occurs in diabase sills in Late Paleozoic to Early
Mesozoic volcanic-plutonic belt in northern Mongolia. In this area,
abundant diabase sills intrude Permian volcanic and terrigenous-volcanic
Khanyi Seri Formation. The diabase sills contain disseminated
titanomagnetite.

**Mafic-Ultramafic Related Cu-Ni Sulfide Deposit Type**

**By Ayurzana Gotovsuren**

The mafic-ultramafic related Cu-Ni sulfide deposit type consists of
massive, and disseminated sulfides that occur in small to medium size
mafic and ultramafic intrusions (Sotnikov, Jamsran, and others, 1985;
Sotnikov, Berzina, and others, 1985). In most areas of Mongolia, the
depositional environment consists of gabbro and metavolcanic rocks that
range in composition from dacite to basalt. The tectonic environment is
mainly mafic and ultramafic igneous rocks occurring in ophiolites and
along deep-seated fault zones. The main ore minerals are pyrrhotite,
pentlandite, chalcopyrite, magnetite, and bornite, rare pyrite.
Associated minerals are millerite, ilmenite, Ti or Cr-magnetite, and
sphalerite, cobaltine, arsenopyrite, and gold. The main examples are the
Oyuut Tolgoi deposit in the Khan Khohii area in western Mongolia, and
the Serten-Nomgon occurrence in the Bayangol terrane in central
Mongolia. These deposits also contain a relatively high grade of PGE
(Izokh and others, 1990, 1991).

**Magmatic Cr or Podiform Cr Deposit Type**

**By Gunchin Dejidmaa**

The magmatic Cr or podiform Cr deposit type occurs mainly in zoned or
layered ultramafic-mafic rocks associated with ophiolites. Podiform Cr
occurrences are located in many ultramafic massifs of Mongolia. The more
significant occurrences are the Naran, Taishir, Sulinkheer, and Ikh
Khazuum massifs (Pinus and others, 1979, 1984a, b). The main examples
are the Nogoon Tolgoi, the Bideriin Gol occurrences in the Khantaishar
ophiolite, and the Sulinkheer group occurrences in same ultramafic-mafic
massif. The host rocks are mainly dunite and harzburgite that are
commonly serpentinized. Chromite ore occurs mainly in dunite, or in the
transition zone from dunite to harzburgite (Pinus and others, 1984a, b).
Shape of ore bodies is mostly lens-like. The length of lenses ranges
from 10.0 to 100.0 m and thickness from 0.5 to 5.2 m. Massive ore is
generally surrounded by disseminated chromite. The grade of Cr~2~0~3~
ranges from 20.0% to 45.9% in the disseminated ore, and from 40% to 60%
in massive ore. (Pinus and others, 1984a, b).

## Serpentine-Hosted Asbestos Deposit Type

## By Sodov Ariunbileg

This deposit type consists of chrysotile asbestos that replaces massive
ultramafic and serpentinized ultramafic bodies (Bezubtsev and Volchec,
1963; Pinus and others, 1979a; Agafanov and others, 1983,1985; Pinus and
others, 1984a, b). The most common host rock types are dunite,
harzburgite, werhlite, and pyroxenite. The most important
chrysotile-asbestos deposits occur in the Alag-Uul, Taishir, Ikh- Hajuu,
Hotol Han-Hohiy ulmramafic massives in western Mongolia and in the
Eastern Prehobsgol area. Asbestos content ranges from 0.2 to 1%.
Associated minerals are magnetite, talc and tremolite. The depositional
environment is usually ultramafic rocks in ophiolite sequences that are
deformed and intruded by younger igneous rocks.

## Rhodusite Asbestos Deposit Type

## By Sodov Ariunbileg

This deposit type consists of actinolite-asbestos and tremolite-asbestos
that form is association with quartz-albite-epidote veins along contacts
in skarns, greenstone, and calcareous schist (Marinov and others, 1977).
The deposition environment is deep-seated fault zones along which
migrate low-temperature hydrothermal fluids. Associated minerals are
wollastonite, calcite, muscovite, and apatite.

## Talc Replacement Deposit Type

## By Sodov Ariunbileg

This deposit type consists of two types of talc replacements: carbonate
talc, and ferrous-serpentinite, talc. The carbonate talc is related to
hydrothermally-altered shear zones in limestone and marble. Most of talc
deposits and occurrences belong to the ferrous-serpentinite type that
occurs in ultramafic rocks that have undergone intensive
serpentinization (Pinus and others, 1979, 1984a, b). Associated minerals
are carbonate, serpentine, chlorite, chromite, gemotite, and magnetite.
Talc veins form as the result of hydrothermal-metasomatic replacement of
alpine-type ultramafic rocks. An example is Tsagaan-gol deposit that
formed along the deep-seated Ikh-Bogd fault zone. Talc deposits in
Mongolia have not yet been mined.

## Magnesite Deposit Type

## By Sodov Ariunbileg

This deposit type is related to alteration of ultramafic rocks and
consists of Mn-rich weathering crust of ultramafic massives (Pinus and
others, 1979, 1984a, b). The most important magnesite deposits occurs
are in the Manlay and Ih-Bogd areas of southern Gobi. A high quality
magnesite deposit is at Bideriin-Gol located 15 km southeast from the
center of the Gobi-Altai province.

**DEPOSITS RELATED TO REGIONALLY METAMORPHOSED ROCKS**

## 

## Au Quartz Vein Deposit Type

## By Gunchin Dejidmaa

The Au quartz vein deposit type was first defined for Mongolia by
Sillitoe and others (1996). The Au quartz vein deposit type consists of
the following subtypes : (1) low-sulfide Au quartz and carbonate-quartz
veins that are hosted in chert-volcanic-terrigenous units; (2)
concordant Au quartz veins that are hosted in turbidite units; and (3)
Au quartz or carbonate-quartz veins that are hosted in Fe formation. The
tectonic environments for this deposit type are accretionary wedge and
active continental margin arc. The associated intrusive rocks are
diabase and diorite sill-like dikes. The deposit type consists of
parallel, concordant, and saddle-reef veins of quartz and
carbonate-quartz. The host turbidite and chert-volcanic-terrigenous
rocks are generally metamorphosed into greenschist facies. The amount of
sulfides is low, and the sulfide minerals are rare galena, sphalerite,
chalcopyrite, and arsenopyrite. The host rocks are generally pyritized,
strongly carbonatized, and sericitized, and weakly silicified. Free gold
occurs in veins and as disseminatations in altered host rocks. Most
occurrences of this deposit type consist of low-sulfide
Au-carbonate-quartz veins that intrude volcanogenic-sedimentary units,
and sedimentary Fe-formation. The main examples of this deposit type are
occurrences in the Mergen Uul and Nukhniinuruu districts of the Baruun
Khuurai accretionary wedge belt, and occurrences in Shuvuun Uul district
of the Urgamal accretionary wedge belt, and vein deposits and
occurrences in Zaamar district of the North Khentii accretionary wedge
belt. These deposits and occurrences form the Ulziit metallogenic belt
and are hosted in chert-volcanic-terrigenous formations and that
originally formed as turbidites on a Paleozoic continental slope.

## 

## Disseminated Au-Sulfide Deposit Type

## By Gunchin Dejidmaa

The disseminated Au-sulfide deposit type is herein defined and consists
of disseminated sulfide (pyrite) minerals with subordinate quartz and
carbonate-quartz veinlets that are hosted in deformed, metamorphosed,
low-grade sedimentary rocks, mainly black and green shale with
sandstone. Gold is associated with pyrite and with pyrite-quartz
stringers hosted in sandstone. Occurrences of this deposit type are
located in the Bayanleg belt that is interpreted as forming in a
Paleozoic active continental margin arc. The associated intrusive rocks
are sill-like bodies of gabbro, tonalite, and plagiogranite. An
important lithological ore-control is coarse-grained sandstone horizons
in shale.

## Cu-Ag Quartz Vein (Vein Cu) Deposit Type

## By Gunchin Dejidmaa

The Cu-Ag quartz vein (vein Cu) deposit type is herein defined and
consists mostly of Cu-sulfides in quartz vein and stringers, in one
case, in weakly regionally metamorphosed basalt, andesite-basalt, and in
another case, in terrigenous sedimentary rocks including structural
slices of ultramafic rock that occur along regional faults that cut
conformably the terrigenous sedimentary rocks**.** The occurrences in
lower grade, metamorphosed mafic volcanics consist mainly of a zone of
sulfide-bearing quartz veins that occur over a large area. Cu-Ag quartz
vein occurrences are widely distributed in the western part of Mongolia
in the Altai, Kharhiraa, and Nuuryn terranes (Obolenskiy and others,
1989). Well-developed Cu sulfide quartz stringers may occur and Cu
sulfide quartz veins may occur in the footwall parts of the volcanogenic
Cu-Zn massive sulfide deposit type.

Ore minerals include chalcopyrite, bornite, chalcocite, covellite,
pyrite, pyrrotite, malachite, azurite, and rare native copper.
Alteration minerals are epidote, chlorite, actinolite, albite,
carbonates and quartz. Special features are: (1) quartz veins and
stringers that occur in significant size, linear zones; (2) ore textures
consisting of impregnation, stringer-impregnation, stringer, banding,
rare breccia; and (3) a high grade of Ag, Au, and Zn in some
occurrences.

Many occurrences of this deposit type are located in mafic volcanics of
Middle Riphean to Vendian age (Dulaankhar unit), and Vendian to Lower
Cambrian age (Tsol Uul unit) in the western and the southern margins of
the Nuuryn terrane. Cu-sulfide-bearing quartz veins also widely occur in
terrigeneous rocks of the Kharhiraa terrane and are part of the massive,
Ordovician-Silurian Biji unit. The hosting Toshint Uul unit, that
contains the malachite and other related occurrences, are part of the
Altai terrane. Occurrences of this deposit type are also located in the
mafic volcaniclastic units of the Zamtyn and Uzuurtolgoi units, of
Vendian to the Lower Cambrian age, that are exposed in tectonic blocks
interlayered with early Paleozoic terrigenous rocks of the Uulyn Altai
unit.

## Banded Iron Formation Deposit Type

## By Gunchin Dejidmaa

The banded iron formation deposit type consists of banded, massive, and
disseminated magnetite and quartz that occur in bed-like, sheet-like and
lens-like bodies in Archean and the Early Proterozoic rocks, and the
deposit type was called silica-iron formation (Filippova, and Vydrin,
1977; and Bakhteev, 1984). The host rocks are granitic gneiss,
migmatite, amphibolite, marble, mafic schist, and quartzite. The major
minerals are magnetite and quartz and associated amphibole, pyroxene,
garnet, epidote, phlogopite, zoisite, and diopside. Magnetite and quartz
replace the metamorphic rocks and the replacements are generally
conformable to with metamorphic layering, but locally are cross-cutting.
The deposit type is confined to Archean and Lower Proterozoic strata,.
Deposits and occurrences of this deposit type occur in the Khan Khohii,
Tarvagatai, Baidrag and Middle-Govi metamorphosed cratonal terranes.
Some authors (Sokolov and Zaitsev, 1990) interpret this deposit type as
Fe-bearing silica-replacement.

## Graphite Deposit Type

## By Gunchodov Ariunbileg

This deposit type consists of two types (Marinov and. Hasin, 1977):
contact-metasomatic or skarn zones formed between intrusive and
calcareous sedimentary rocks; and in metamorphic rocks of Early Cambrian
age. Graphite skarns contain large, blocky graphite, but the quality is
not high. Graphite in metamorphic rocks contains coarse, scaly graphite.
The content of graphite usually ranges from 2 to 6%. The graphite
deposits and occurrences of Mongolia are in the area to the west of
Khovsgol (Khargana gol deposit) lake, and in the Gobi region (Naidvar
deposit).

# DEPOSITS RELATED TO SURFICIAL PROCESSES

## Placer Au Deposit Type

## By Gunchin Dejidmaa

The placer Au deposit type consists of gold grains in alluvial,
alluvial-proluvial, proluvial, deluvial, deluvial-proluvial, and rare
glacial non-lithified deposits rich gravel and sand beds (Blagonravov,
and Shabalovskii, 1977). The main ore mineral is native gold. Most
placer Au deposits in Mongolia formed in the Neogene and Quaternary and
are widely distributed in two regions. Neogene and Quaternary placer Au
deposits occur mainly in northern and northeastern Mongolia. Neogene and
lesser Quaternary placer Au deposits occur in the central Mongolia.
Neogene Placer Au deposits also occur in southern and southwestern
Mongolia, but are mostly buried. The placer Au deposit type is very
important for Mongolia because of extensive mining of this type of
deposit. Several papers have been published about Mongolian placer Au
deposits (Levintov and others, 1984; Todor Nenov and others, 1994;
Jamsrandorj and others, 1996).

## Placer Sn Deposit Type

## By Ochir Gerel

The placer Sn deposit type consists mainly of cassiterite, rare
wolframite, and tantalite-columbite that occur in sand and gravel in
alluvial or alluvial-deluvial deposits. The depositional environment is
high energy alluvial where gradients flatten and river velocity lessen
at the inside of meanders, and below rapids and falls. The main examples
are at Janchivlan, Modot, and Kumir. More than 30 Sn placer deposits are
known for Mongolia.

**Placer Ti Deposit Type**

**By Gunchin Dejidmaa**

The placer Ti deposit type is herein defined and consists mainly of
ilmenite in gravel and sand in alluvial or alluvial-proluvial deposits.
Main economical ore mineral of the deposit type is ilmenite. Ilmenite
placer occurrences occur in southwestern Khovsgol province. The primary
source of the occurrences are Cenozoic basaltic plateaus. The main
examples are the Jargalantyn Gol, Khujirt, and Amttaihany Khondii
occurrences.

# REFERENCES CITED

Agafanov, L.V., Bayarhuu, J., and Pinus, G.V, 1985, Metallogeny of the
Mongolian Peoples' Republic (Mineral resources related with
ultrabasite., p. 38 (in Russian).

Alkin, V.S., Kunitsyn, V.V., Stepanov, O.V., Edelman, L.E., Dejidmaa,
G., and Tseren-Ochir, S., 1989, Gold mineralization of Mongolian Peoples
Republic and Zamar lode gold and placer district: Geology and
exploration of the territory of Mongolian Peoples Republic
(International Science Conference for 50^th^ year jubilee of Geological
Survey of Mongolian Peoples' Republic), Ulaanbaatar, p.71-72 (in
Russian).

Andreev, G.V., Ripp, G.S., Sharakshinov, A.O. and Minin, A.D., 1994, REE
mineralization of alkaline granitoids from western Mongolia: Institute
of Geology, Russian Academy of Sciences, Ulan-Ude, 138 p. (in Russian).

Antonov, S.A., Blyumen, B.A., Bokulev, A.A., Jdanov, V.V., Maslov, A.T.,
and Togtokh, D., 1989, Geology and metallogeny of the northwestern part
of the Mongolia: Geology and exploration of the territory of Mongolian
Peoples Republic (International Science Conference for 50^th^ year
jubilee of Geological Survey of Mongolian Peoples' Republic),
Ulaanbaatar, p. 89-91 (in Russian).

Badarev, N.P., Alkin, B.S., Kunitsyn, V.V., Amanbek, A., Dalilkhan, Kh.,
and Ulambayar, Kh., 1989, Silver mineralization in the northwestern
Mongolia, and the Asgat deposit: Geology and exploration of the
territory of Mongolian Peoples Republic (International Science
Conference for 50^th^ year jubilee of Geological Survey of Mongolian
Peoples' Republic), Ulaanbaatar, p. 91-92. (in Russian).

Baikova, V.S., Shuleshko I.K., and Kozakov I.K., 1987, Geological
setting of Magnetite occurrences in the Precambrian complexes of the
southern slope of the Mongolian Altai (Mongolian Peoples' Republic): Ore
Mineral Deposit Geology, no. 3, p. 30-35 (in Russian).

Bakhteev, R.Kh., and Chijova I.A., 1984, Iron-ore formations of Mongolia
and regularities in its spatial distribution: Endogenic ore-bearing
formations of Mongolia (Joint Soviet-Mongolian Scientific-Research
Geological Expedition): Transactions, Moscow, v. 38. p. 115-123. (in
Russian).

Baskina, V.A. and Volchanskaya, I.K., 1976, A new type of rare earth
mineralization in south Mongolia, associated with alkaline volcanics:
Doklady AN SSSR, v. 228, no.3, p. 670-672 (in Russian).

Batbold, D., 1997, Mineralogy of carbonatites from the Lugiin Gol
Alkaline pluton, south Mongolia: Masters thesis, Shimane University,
Matsue, Japan, 210 p.

Batjargal, Sh., Lkhamsuren, J., and Dorjgotov, D., 1997, Lead-zinc ore
deposits in Mongolia: Mongolian Geoscientist, Special Issue, no. 2., p.
2-15.

Berezikov, Yu.K., Bessonenko, V.V., Nikonov, I.I., and Shubin, N.A.,
1986, Results of geological works carried out by West. Siberia Geology
Geological Organization in 100 km stripe of western Mongolian border:
Soviet -Mongolian Joint Collaboration in Geology: Results and Future,
Moscow, p. 91-93 (in Russian).

Berzina, A.P., Sotnikov, V.I., Garamjav, D., and Bold, D., 1983,
Ore-bearing magmatism of the Tsagaansuvarga ore knot (Southern
Mongolia): Geology and Geophysics, no. 10, p. 56-66 (in Russian).

Bezzubtsev, V.V., and Volchek, I.V, 1963, Structural position of
ultramafic intrusions in Western Mongolia: Materials about Geology of
Mongolian Peoples' Republic, p. 138-148 (in Russian).

Blagonravov, B.A., Byambaa, J., and Podkolzin,V.N., 1980, Features of
construction and genesis of gold-quartz veins in Ulaanbaatar area:
Geology and Mineral Resources of Mongolian Peoples' Republic
(Transactions of the International Geological Expedition in Mongolian
Peoples' Republic), Issue I , p.154-16. (in Russian).

Blagonravov, B.A., Blagonravova, L.A., and Podkolzin, V.N. 1984, Natural
distribution of gold mineralization in the eastern and central Mongolia:
Geology and Mineral Resources of Mongolian Peoples' Republic
(Transactions of the International Geological Expedition in Mongolian
Peoples' Republic) Issue II, p. 60-78 (in Russian).

Blagonravov, B.A., and Shabalovskii, A.E., 1977, Gold: Geology of the
Mongolian Peoples' Republic, v. III, Mineral Resources, *in* Marinov,
N.A., Khasin, R.A., and Khurtsc, Ch., eds., Nauka, Moscow, p.217-263 (in
Russian).

Blagonravov, B.A., and Tsypukov, Yu.P. 1978, General features of gold
mineralization of the territory of Mongolian Peoples' Republic:
Geologiya and Geofizika, no. 6, p. 61-67 (in Russian).

Blagonravov, V.A., 1977, Mercury: Geology of Mongolian Peoples'
Republic, v. III (Mineral Resources, Marinov, N.A., Khasin, R.A., and
Khurtsc Ch., eds.), Moscow, p. 426-435 (in Russian).

Blumen, V.A. 1991, Comparative analyses of geological construction and
metallogeny of Nothern Khentii (Mongolian Peoples' Republic) and Chikoi
gold-bearing zones: Metallogeny and exploration of Mineral Resources
(Materials of Regional conference for Memory of Academician S.S.
Smirnov), p. 72-75 (in Russian).

Blumen, V.A., Jdanov, V.V., Kalabashkin, S.N., Maslov, A.T., Starchenko,
V.V., and Tseren-Ochir S., 1989, Gold mineralization of magmatic and
metamorphic-metasomatic complexes of Nothern Khentii gold-bearing zone:
Geology and exploration of the territory of Mongolian Peoples Republic
(International Science Conference for 50^th^ year jubilee of Geological
Survey of Mongolian Peoples' Republic), Ulaanbaatar, p. 73-74 (in
Russian).

Bokulev, A.A. 1991, Quartz vein formation of Zamar ore-area (Mongolian
Peoples' Republic): Metallogeny and exploration of Mineral Resources
(Materials of Regional conference for Memory of Academician S.S.
Smirnov), p. 158-160 (in Russian).

Bolotova, N.Ya., Dejidmaa, G., and Nikolaeva, L.N., 1990, Typomorphic
features of gold-bearing quartz and native gold of deposits of northern
Mongolia as significant genesis of quartz veins and their zonal
constructions: Geology and Mineral Resources of Mongolian Peoples'
Republic (Transactions of the International Geological Expedition in
Mongolian Peoples' Republic).v. III), p.135-139 (in Russian).

Borisenko, A.S., Lebedev, V.I., and Tyulkin, V.G., 1984, Forming
condition of hydrothermal cobalt deposits: Russian Academy of Sciences,
Novosibirsk. 172 p. (in Russian).

Borisenko, A.S., Obolenskii, A.A., and Lebedev V.I., 1987, Main features
of genetic models of epithermal silver deposits: Ore-forming Systems
Model Construction, Russian Academy of Sciences, Novosibirsk. p. 107-118
(in Russian).

Borisenko, A.S., Obolenskii, A.A., Skuridin. V.A. and others, 1991,
Relationship problem of endogenic ore with magmatism in ore districts of
the southeastern Altai and the northwestern Mongolia: Isotopic
investigation of Ore-forming Processes, Russian Academy of Sciences,
Novosibirsk. p. 87-101 (in Russian).

Borisenko, A.S., Pavlova, G.G., Obolenskii, A.A., Lebedev, V.I.,
Bedarev, N.P., Borovikov, A.A., Dyshuk, M.Yu., Koleda, A.Ya., and
Mortsev, N.K., 1992, Silver-antimony ore Formation. v. 1: Geology,
Mineralogy and Endogenic Zoning, Russian Academy of Sciences,
Novosibirsk. 189 p. (in Russian).

Borisenko, A.S., Skuridin, V.A., Lebedev, V.I., and others, 1988,
Metallogeny of ore-district of the southeastern part of the Altai
Mountains and of the northwestern part of Mongolia: Mineral Resources
Distribution, Nauka, Moscow, v. xv., Metallogeny of Siberia, p. 131-139
(in Russian).

Borzakovskii, Yu.A., Vydrin, V.N., Marinov, N.A., Khasin, R.A., and
Yakovlev, B.A., 1971, Metallogeny of Mongolian Peoples' Republic:
Magmatism and Metallogeny of Mongolian Peoples' Republic (Transactions
of the Joint Soviet-Mongolian Science-Research Expedition), Issue 4), p.
78-123.(in Russian).

Chebotarev, M.V., Chebotareva, N.A., and Tsend-Ayuush, J., 1990,
Magnetite skarn deposits of the Bayangol Belt: Geology and Mineral
Resources of the Mongolian People's Republic (International Geological
Expedition in Mongolia), Transactions, Moscow, v. 3. p. 145 -151 (in
Russian).

Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S.
Geological Survey Bulletin 1693, 379 p.

Cox, D.P., and Singer, D.A ,1988, Distribution of gold in porphyry
copper deposits: United States Geological Survey, Open File Report
88-46, 22 p.

Davaasambuu, D., Togtokh, D., Baatarkhuyag, A., and Jantsan, D., 1976,
Khaiguulchin, no. 2. P. 49-54 (in Mongolian).

Dejidmaa, G., 1980, Lode gold-formation types of Mongolia and their
exploration signs: Kaiguulchin, no. 2, p. 11-12 (in Mongolian).

Dejidmaa, G., 1985, Geochemical features of Boroo gold-field in Mongolia
(Summary of dissertation for Candidate of Science Ph.D.),Institute of
Geology and Geophysics of Sibirian Branch of Russian Academy of
Sciences, Novosibirsk, 16 p. (in Russian).

Dejidmaa, G., 1996, Gold metallogeny of Mongolia: Mongolian Geoscientist
(Project Report of Institute of Geology and Mineral Resources), no. 1,
p. 6-29.

Dejidmaa, G., Eideliman, L.E., Alkin, V.S., and others, 1993, Gold
ore-formations of Mongolian Peoples' Republic: Questions of geology and
metallogeny of Mongolia: Transactions of Kherlen geological expedition,
v. 4, p. 3-20 (in Russian).

Demidov, V.V., and Jamsran, M., 1975, Substantial composition and ore
forming sequence of Erdenetiin-Ovoo Cu-Mo deposit: Scientific
Transaction of Mineralogical Museum of Mongolian State University,
no.2., p. 13-35 (in Russian).

Demin, A.N., Kichko, A.I., Girs, V.M., Demin, P.A., Amitan, A., and
Khramtsov, V.A., 1989, Substance-structure features of REE and
silver-sulphosalts mineralization in Mongolian Altai: Geology and
exploration of the territory of Mongolian Peoples Republic
(International Science Conference for 50^th^ year jubilee of Geological
Survey of Mongolian Peoples' Republic), Ulaanbaatar, p. 100-102. (in
Russian).

Dorjgotov, D., Murao, S., Nakajima, T., and Batjargal, SH., 1997 of
Genetic types of Mesozoic lead-zinc deposits in the Dornod metallogenic
zone of Mongolia: Mongolian Geoscientist, Special Issue, no. 2, p.
15-22.

Dornfeld, G., and Kraft M., 1964, Gold deposits of Khentii located in
the northwest of Ulaanbaatar: Geology Magazine, no. 10, p. 523-530 (in
German).

Eckstrand, O.R., 1984, Canadian mineral deposit types: A geological
synopsis: Geological Survey of Canada Economic Geology Report 36, 86 p.

Eremeev. V.P., and Andreev, U.K, 1973, Asbestos occurrences in
ultrabasites of the Mongolian Peoples' Republic: Non-metallic mineral
resources of ultrabasites, p. 100-103 (in Russian).

Gavrilova, S.P., Didenko, M.I., and Orolmaa, D., 1988, The role of study
of space picture and morphology of surface for discovery of central
structure in region of paleovolcanism: A complex study of rare metal ore
area: Institute of Mineralogy and Geochemistry of Rare Elements, Moscow,
p. 8-28 (in Russian).

Gavrilova, S.P., Maximyk, I.E., and Orolmaa, D., 1984, Features of
magmatism and composition of ore of Erdenetiin Ovoo Cu-Mo deposit:
Endogenic Ore Formations of Mongolia, Nauka Moscow,, p. 101-105 (in
Russian).

Gavrilova, S.P., Maximyk, I.E., and Orolmaa, D., 1989, The Erdenetiin
Ovoo molybdenum-copper porphyritic deposit: Institute of Mineralogy and
Geochemistry of Rare Elements, Moscow, 40 p. (in Russian).

Geology of the Mongolian People's Republic, 1973, v. 2, Magmatism and
Tectonics, Nedra, Moscow, 751 p. (in Russian).

Geology of the Mongolian People's Republic, 1977, v. 3, Mineral
Resources, Nedra, Moscow, 703 p. (in Russian).

Gerel, O., 1990, Petrology, geochemistry and ore mineralization of
subalkaline Mesozoic magmatism in Mongolia: Russian Academy of Sciences,
Irkutsk, 40 p. (in Russian).

Gerel, O., 1993, Subalkaline Mesozoic magmatism and related
mineralization in Mongolia: Problems of Geology and Metallogeny of
Mongolia, Ulaanbaatar, no. 4, p.21-45 (in Russian).

Gerel, O., 1995, Mineral resources of the western part of the
Mongol-Okhotsk foldbelt. Resource Geology Special Issue, no. 18. p.
151-157.

Gerel, O., Koval, P.V., Smirnov, V.N., and Tseden, Ts., 1985, The
porphyritic association of the Erdenet area (petrography and chemical
composition): Questions of geology and metallogeny Eastern Mongolia,
Mongolian Academy of Sciences, Ulaanbaatar, p. 59-112 (in Russian).

Gerel, O., Koval, P.V., and Tseden, Ts., 1984, Geochemistry of upper
Paleozoic porphyritic intrusive of the Erdenet area: Geochemistry and
Geochemical Exploration Method of Ore Deposits, Abstract of Scientific
Conference, Ulaanbaatar, p. 37-38 (in Russian).

Getmanskaya, T.I., Dandar, S., and Kempe, U. 1995, New data about the
genesis of ferberite deposits of the Khovd gol and Mushguu (Mongolian
Altai): Gold-REE mineralization of Altan-Khohii mountain: Problems of
Mongolian Altai Geology, Ulaanbaatar, no. 3, p. 43-47 (in Russian).

Gottesman, V., 1978, Granitoids of the Boroo-Zuun mod gold-bearing
district: Khaiguulchin, no. 4, p. 26-32. (in Mongolian).

Gumbina, V.S., and Batjargal, Sh., 199\_, First discovery of millerite
in Cu occurrences of Mongolian Peoples Republic: Scientific Transaction
of Mineralogical Museum of Mongolian State University, no.6., p. 104-109
(in Russian).

Ivanova, G.F., 1976, Mineralogy and geochemistry of tungsten
mineralization in Mongolia. Nauka, Moscow, 259 p. (in Russian).

Izokh, A.E., Polyakov, G.V., and Krivenko A.P., 1984,
Apatite-ilmenite-titanium-magnetite mineralization in intrusions of
gabbro-anorthosite formation in Western Mongolia: Endogenic Ore-Bearing
Formations of Mongolia (Joint Soviet-Mongolian Scientific Research
Geological Expedition), Transactions, Moscow, v. 38. p. 144-152 (in
Russian).

Izokh, A.E., Polyakov, G.V., Krivenko, A.P., Bognibov, V.I., and
Bayarbileeg, L., 1990, The gabbro formations of western Mongolia (Joint
Soviet-Mongolian Scientific-Research Geological Expedition),
Transactions, Novosibirsk, v. 46, 269 p. (in Russian).

Izokh, A.E., Polyakov, G.V., and Anoshin, G.N., 1991, Geochemistry of
platinum metals, Au and Ag in Nomgon trocktolite-anorthosite-gabbro
massif of Mongolian Peoples Republic: Geochemistry, no. 10, p. 1398-1406
(in Russian).

Jamsran, M., 1975, Relation of Mo-Cu mineralization with porphyry
intrusions: Scientific Transactions of Mineralogical Museum of Mongolian
State University, no. 5. p. 60-74 (in Russian).

Jamsran, M., 1977, Geology and substantial composition of ore of main
porphyry Cu deposits and aspects of mining of ore objects of the
Tsagaansuvarga district: Summary of Dissertation for Candidate of
Science, Leningrad Mining Istitute, Leningrad, 32 p. (in Russian).

Jamsrandorj, G., 1989, About gold mineralization of Olziit zone: Geology
and exploration of the territory of Mongolian Peoples Republic
(International Science Conference for 50^th^ year jubilee of Geological
Survey of Mongolian Peoples' Republic), Ulaanbaatar, p. 71-72 (in
Russian).

Jamsrandorj, G., and Diatchkkov, Sergei A.., 1996, Placer deposits of
Mongolia. Society of Economic Geologists Newsletter, no. 24, p.
9-14**.**

Kempe, U., Dandar, S., Getmanskaya, T.I., and Wolf, D., 1994, The
tungsten-antimony mineralization (focussed on new occurrences in the
Mongolian Altai): Metallogeny of Collisional Orogens, Czech Geological
Survey, Prague, p. 301-308.

Kempe, U., Wolf , D., Leeder, O. and Dandar, S., 1994, Metasomatic
genesis of Zr-Nb-REE mineralization of the von TSachir and Chaldzan
BureGtei area (Mongolian Altai): Problems of Altai Geology, no. 2,
Ulaanbaatar, p. 23-24.

Khasin, R.A., 1977, Bismuth, arsenic and antimony: Geology of the
Mongolian Peoples' Republic, v. III (Mineral Resources), Moscow, p.
422-426 (in Russian).

Khasin, R.A., Marinov, N.A., Khurts, Ch., Yakimov, L.I., 1977,
Erdenetiin Ovoo Cu-Mo deposit in Northern Mongolia: Geology of Ore
Deposits, no. 6., p. 3-15 (in Russian).

Khrapov, A.A., 1977, Fluorspar: Geology of the Mongolian Peoples'
Republic, v. 3, Mineral Resources, Moscow, Nedra, p. 493-552 (in
Russian).

Khasin, R.A., and Suprunov, E.A. 1977, Geology of the Mongolian Peoples'
Republic, v. 3: Mineral Resources, Moscow, Nedra, p. 403-422 (in
Russian).

Khrustalev, V.K., Budnikov, A.L., and Barabash, G.G., 1989, Supergene
zonation of silver-polymetallic mineralization in Western Mongolia and
exploration importance (with example of the Tolbonuur occurrence):
Geology and exploration of the territory of Mongolian Peoples Republic
(International Science Conference for 50^th^ year jubilee of Geological
Survey of Mongolian Peoples' Republic), Ulaanbaatar, p. 134-135 (in
Russian).

Koval, P.V., and Gerel, O., 1986, Volcanic association of areas of
porphyritic copper mineralization of Mongol-Okhotsk zone: Geochemistry
of volcanic rocks of different geodynamical situations, Nauka,
Novosibirsk, p. 69-93 (in Russian).

Kovalenko, V.I. , and Bogatikov, O.A., eds., 1996, Magmatic
Associations: Nedra, Moscow, p. 114-159 (in Russian).

Kovalenko, V.I., and Koval, P.V., 1984, Endogenous rare-earth and
rare-metal ore formations of Mongolia: Endogenous ore formations of
Mongolia, Nauka, Moscow, p. 50-75 (in Russian).

Kovalenko, V.I., and Yarmolyuk, V.V., 1995, Endogenous REE ore
formations and REE metallogeny of Mongolia. Economic Geology, v. 90, p.
520-529.

Kovalenko, V.I., and Kovalenko, N.I., 1986, Ongonites: Nauka, Moscow,
127 p. (in Russian).

Kovalenko, V.I., Goreglyad, A.V., and Tsareva, G.M., 1985,
Khalzan-Buregtei massif: New occurrence of REE alkaline granitoids in
Mongolia: Doklady AN SSSR, v. 280, no. 4, p. 954-959 (in Russian).

Kovalenko, V.I., Koval, P.V., Yakimov, V.M., and Sherchan, O., 1986,
Metallogeny of the Mongolian People's Republic (tungsten, tin, rare and
rare-earth elements): USSR Academy of Sciences, Siberian Branch, 52 p.
(in Russian).

Kovalenko, V.I., Kuzmin, M.I., Zonenshain, L.P. and others, 1971, REE
granitoids of Mongolia (petrology, trace element distribution and
genesis), Nauka, Moscow, 196 p. (in Russian).

Kraft M., Taubert P., Ungethum, H., 1974, Influence of supergene
processes on distribution of gold of hydrothermal gold deposits for
central part of Mongolian Peoples' Republic: Geology Magazine, no. 20,
p. 495-520 (in German).

Levintov, M.e., Kleiner, Yu. M., and Konopleva, V.I., 1984, Natural
distributrion regularity of placer gold, tin and tungsten deposits in
eastern and central Mongolia: Geology and Mineral Resources of Mongolian
Peoples' Republic, Nedra, Moscow, v. 11., p. 93-101 (in Russian).

Marinov, N.A. 1963, Natural distribution of magmatogenic deposits of
mineral resources in the territory of Mongolia: Materials of Geology of
Mongolian Peoples' Republic, p. 149-171 (in Russian).

Marinov, N.A., Khasin, R.A., and Khurtsc, Ch., 1977, Geology of
Mongolian Peoples' Republic, Mineral Resources, v. 3.

Metallogeny of the Mongolian Peoples' Republic (Mercury), 1986, USSR
Academy of Sciences, Siberian Branch, Novosibirsk, 48 p. (in Russian).

Mironov, Yu. B., Soloviev, N.S., Lyvov, V.K., and Pecherkin, Yu. N.,
1989, Special features of the geological structure and presence of ore
of Dornot volcano-tectonic structure (eastern Mongolia): Geology and
Geophysics, no. 9, p. 22-32. (in Russian).

Mironov, Yu. B., and Trofimov N.S. 1993, New information on gold
mineralization of northeastern part of Mongolia: Questions of geology
and metallogeny of Mongolia: Transactions of the Kherlen Geological
Expedition, no. 4, p. 53-66. (in Russian)

Mironov Yu.B., and Soloviev, N.S., 1993, Geology and metallogeny of
North-Choibalsan area of Mongolia: Questions of geology and metallogeny
of Mongolia (Transactions of the Kherlen Geological Expedition), v. 4,
p. 97-118 (in Russian).

Movsesyan, S.A., and Isaenko, M.P., 1974, Complex Cu-Mo deposits, Nedra,
Moscow, 344 p. (in Russian).

Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck,
Donald, Robinson, M.S., Smith, T.E., Yeend, Warren, 1987, Significant
metalliferous lode deposits and placer districts of Alaska: U.S.
Geological Survey Bulletin 1786, 104 p., 2 plates, scale 1:5,000,000.

Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck,
Donald, Robinson, M.S., Smith, T.E., Yeend, Warren, 1994a, Metallogeny
and major mineral deposits of Alaska, *in* Plafker, G., and Berg, H.C.,
eds., The Geology of Alaska: Boulder, Colorado, Geological Society of
America: The Geology of North America, v. G1, p. 855-904.

Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck,
Donald, Robinson, M.S., Smith, T.E., Yeend, Warren, and 54 contributors,
1994b, Metallogenic map of significant metalliferous lode deposits and
placer districts of Alaska, *in* Plafker, G., and Berg, H.C., eds., The
Geology of Alaska: Boulder, Colorado, Geological Society of America: The
Geology of North America, v. G1, Plate 11, scale 1:2,500,000.

Nokleberg, W.J., Bundtzen, T.K., Dawson, K.M., Eremin, R.A., Goryachev,
N.A., Koch, R.D. Ratkin, V.V., Rozenblum, I.S., Shpikerman, V.I.,
Frolov, Y.F., Gorodinsky, M.E., Melnikov, V.D., Ognyanov, N.V.,
Petrachenko, E.D., Petrachenko, R.I., Pozdeev, A.I., Ross, K.V., Wood,
D.H., Grybeck, Donald, Khanchuck, A.I., Kovbas, L.I., Nekrasov, I.Ya.,
Sidorov, A.A., 1993, Significant metalliferous lode deposits and placer
districts for the Russian Far East, Alaska, and the Canadian Cordillera:
U.S. Geological Survey Open-File Report 96-513-A (paper format), 385 p.;
U.S. Geological Survey Open-File Report 96-513-B (CD-ROM format).

Nokleberg, W.J., Bundtzen, T.K., Dawson, K.M., Eremin, R.A., Goryachev,
N.A., Koch, R.D. Ratkin, V.V., Rozenblum, I.S., Shpikerman, V.I.,
Frolov, Y.F., Gorodinsky, M.E., Melnikov, V.D., Diggles, M.F., Ognyanov,
N.V., Petrachenko, E.D., Petrachenko, R.I., Pozdeev, A.I., Ross, K.V.,
Wood, D.H., Grybeck, Donald, Khanchuk, A.I., Kovbas, L.I., Nekrasov,
I.Ya., and Sidorov, A.A., 1997, Significant metalliferous lode deposits
and placer districts for the Russian Far East, Alaska, and the Canadian
Cordillera: U.S. Geological Survey Open-File Report 96-513-B, 1 CD.

Obolenskii, A.A., 1984, On genetic rows of ore-formations of
low-temperature hydrothermal deposits in Mongolia and southern Siberia:
Endogenic Ore-Bearing Formations of Mongolia (Joint Soviet-Mongolian
Scientific-Research Geological Expedition), Transactions, Moscow, v. 38.
p. 163-171 (in Russian).

Obolenskii, A.A., 1971, Prognostic criteria of Hg deposits in folded
structures in the south of Siberia and in Mongolia: Scientific
Prognostic Basis of Mineral Resources, USSR Academy of Sciences,
Leningrad, p. 387-388 (in Russian).

Obolenskii, A.A., 1984, On genetic rows of ore-formations of
low-temperature hydrothermal deposits in Mongolia and southern Sibiria:
Endogenic Ore-Formations of Mongolia (The Joint Soviet-Mongolian
Scientific-Research Geological Expedition), Transactions, Moscow, v. 38,
p. 163-171 (in Russian).

Obolenskii, A.A., 1985, Genesis of deposits of mercury ore-formation for
Southern Siberian metallogenic province and the Mongolia), USSR Academy
of Sciences, Novosibirsk, 194 p. (in Russian).

Obolenskii, A.A., Borisenko, A.S., Borovikov, A.A., Pavlova, G.G.,
Lebedev, V.I., Sherkhan, O., and Tsoodol B., 1989, Metallogeny of
ore-districts in the western Mongolia: Geology and exploration of the
territory of Mongolian Peoples Republic (International Science
Conference for 50^th^ year jubilee of Geological Survey of Mongolian
Peoples' Republic), Ulaanbaatar, p. 88-89. (in Russian).

Petrova, B.B., and Amarjargal, P, 1996, Zeolites of Mongolia:
Transactions of Geological institute of Russian Academy of Sciences, v.
496, p. 148 (in Russian).

Petrova, V.V., Badamgarav, D., and Socolova, A.L., 1987, The new type of
zeolites of volcanic-limonitic genesis: Lithology and mineral resources,
no. 4, p 88-109 (in Russian).

Philippova, I.B., and Vydrin, V.N., 1977, Black metals: Geology of the
Mongolian People's Republic, Transactions, Moscow, v. 3., p. 90-140 (in
Russian).

Pinus, G.B., Agafonov, L.V., Lesnov, F.P., 1984a, Alpine-type
ultrabasites of Mongolia: Joint Soviet-Mongolian Scientific-Research
Geological Expedition, Transactions, Nauka, Novosibirsk, v. 36, 200 p.
(in Russian).

Pinus, G.V., Agafanov, L.V., Lesnov, F.N., and Bayarhuu, J., 1984b,
Metallogeny of alpine type ultrabasites of Mongolia: Endogenic
ore-bearing formations of Mongolia, Transactions of the Joint
Soviet-Mongolian scientific-research geology expedition, v. 38, p.
152-162 (in Russian).

Pinus, G.V., Lesnov, F.N., Agafanov, L.V., and Bayarhuu, J., 1979,
Alpine type ultrabasites of Mongolia and their metallogeny: Geology and
magmatism of Mongolia, p. 145-155 (in Russian).

Podlessky, K.V., Aksuk, D.K., and Vlasova, P.F., 1984, Mineralized
skarns of central and eastern Mongolia: Endogenic Ore-Bearing Formations
of Mongolia (Joint Soviet-Mongolian Scientific-Research Geological
Expedition), Transactions, Moscow, v. 38. p. 124-143 (in Russian).

Podlessky, K.V., Vlasova, D.K., Kudrya, P.F., 1988, Skarns and connected
ores of Mongolia (Joint Soviet-Mongolian Scientific-Research Geological
Expedition), Transactions, Moscow, v. 45, 149 p. (in Russian).

Podlessky,, K.V., Vlasova, D.K., and Kudrya, P.F., 1988, Skarns and
related ores of Mongolia: Nauka, 149 p. (in Russian).

Poznaikin, V.V., and Shpilikov, A.L., 1990, Further potential of the
southern part of the Khovsgol phosphate-bearing basin, clarified in
result of airborne survey: Geology and Mineral Resources of Mongolian
Peoples' Republic; Transactions of the International Geological
Expedition in Mongolian Peoples' Republic, v. 111, p. 191-196 (in
Russian).

Poznyak, V.O., and Dejidmaa, G., 1977, Some natural distribution of gold
mineralization in the northwestern Khentii and its border parts:
Geological Construction and Natural Distribution of Deposits of Main
Mineral Resources in the Territory of Mongolian Peoples' Republic, p.
67-77 (in Russian).

Ripp, G.S., and Sudakov, V.I., 1991, The peculiarities of the structure,
the content and the substantial zoning of the Mungun-Undur
Ag-Sn-polymetallic deposit, Mongolian Peoples' Republic:
Geologic-genetic models and the local prognostication of the endogenic
mineralisation in Transbaikalye: Geological Institute of the Baikalia
Scientific Centre, Siberian Branch, USSR Academy of Sciences,
Novosibirsk, p. 114-126. (in Russian).

Samoilov, V.S. and Kovalenko, V.I., 1983, Alkaline and carbonatite rock
complex of Mongolia. Moscow, Nauka, 200 p. (in Russian)

Samoylov, V.S., Ivanov, V.G., Kovalenko ,V.I., and Smirnova, E.V., 1984,
Rare earth element-apatite and rare earth element-lead ores of the
Mushgai Khudag complex (southern Mongolia): Endogenic Ore-Bearing
Formations of Mongolia (Joint Soviet-Mongolian Scientific-Research
Geological Expedition), Transactions, Moscow, v. 38. p. 180-199 (in
Russian).

Sillitoe, R.H. , 1972, A plate tectonic model for the origin of porphyry
copper deposits: Economic Geology, v. 67, p. 184-197.

Sillitoe, R.H. 1993, Gold-rich porphyry copper deposits: Geological
model and exploration implications; *in* Kirkham R.V., Sinclair, W.D.,
Thrope, R.I.and Duke, J.M.; eds., Mineral Deposit Modeling: Gcological
Association of Canada, Special Paper 40, p. 465-478.

Sillitoe, R.H., Halls, C. and Grant, J.N. 1975, Porphyry tin deposits in
Bolivia: Economic Geology, v. 70, p. 913-927.

Sokolov, Yu. M., and Zaitsev, N.S. 1990, Metallogeny and mineral
deposits in the Precambrian of Mongolia: Evolution of Geological
Processes and Metallogenesis Mongolia (Joint Soviet-Mongolian
Scientific-Research Geological Expedition), Transactions, Moscow. v. 49.
p. 213-221 (in Russian).

Sotnikov, V.I. , and Berzina, A.P., 1985, On the place of ore porphyries
in the scheme for orogenic magmatism of Cu-Mo ore knots of Mongolia:
Geology and Geophysics, no. 5, p. 3-10 (in Russian with English
abstract).

Sotnikov, V.I., and Berzina, A.P., 1989, Prolonged discrete oriented
development of ore-magmatic systems in Cu-Mo formation: Geology and
Geophysics, no. 1., p. 41-45 (in Russian with English abstract).

Sotnikov, V.I., Berzina, A.P., and Bold, D., 1984, Regularity of
distribution of Cu-Mo mineralisation of Mongolia: Endogenic Ore
Formations of Mongolia, Nauka Novosibirsk, , p. 89-101 (in Russian).

Sotnikov, V.I., Berzina, A.P., Jamsran, M., and Myagmar, L.,1980, The
Tsagaansuvarga Cu-Mo deposit: Geology of Ore Deposits, no. 3. p. 34-46.
(in Russian).

Sotnikov, V.I., Berzina, A.P., and Skorokhodov, V.N., 1981, Metallogeny
of Cu and Mo of Mongolian Peoples' Republic: Questions of magmatism and
metallogeny of Mongolian Peoples' Republic: Institute of Geology and
Geophysics, Siberian Branch, USSR Academy of Sciences, Novosibirsk, p.
9-17 (in Russian).

Sotnikov, V.I., Jamsran, M., Berzina, A.P., Shabalovskii, A.E.,
Garamjav, D., and Bold, M., 1985, Metallogeny of Mongolian Peoples'
Republic (copper, molybdenum): Institute of Geology and Geophysics,
Siberian Branch, USSR Academy of Sciences, Novosibirsk, 40 p. (in
Russian).

Sotnikov, V.I., Berzina, A.P., Jamsran, M., Garamjav, D., and Bold, M.,
1985, Copper-bearing formations of Mongolia. Nauka, Novosibirsk, p. (in
Russian).

Sotnikov, V.I., Sanduijav, G., and Berzina, A.P., 1978, Some features of
Mo-Cu occurrences in southern Mongolia: Geology and Genesis of Rare
Metallic and Polymetallic Deposits of Siberia, Nauka, Novosibirsk, p.
43-64 (in Russian).

Sotnikov, V.I., Sanduijav, G., Berzina, A.P., and Firsov, L.V., 1976,
Absolute age of the Tsagaansuvarga deposit. Chaiguulchin Magazine, no.
6, p. 26-30. (in Mongolian).

Tcherbakov, Yu.G., and Dejidmaa, G., 1984, Gold ore-formations of
Mongolia: Endogenic ore-bearing formations of Mongolia (Joint
Soviet-Mongolian Science-Research Geological Expedition), v. 38, p.
42-50 (in Russian).

Tcherbakov, Yu.G., Dejidmaa, G., Kalinin, Yu.A., and others, 1986,
Metallogeny of Mongolian Peoples' Republic (Gold), 48 p. (in Russian).

Todor, Nenov, Nikola Katskov, and Panaiot Bakalov, 1994, Morphologic
zonation and natural distribution regularity of placer Au deposits of
the Bayankhongor zone (Mongolia): Bulgarian Geological Society Review v.
55, p. 51-63 (in Bulgarian with English abstract).

Tsend-Ayuush, J., and Chebotarev, M.V., 1989, Iron ore-formations and
their potential for mining: Geology and exploration of the territory of
Mongolian Peoples Republic (International Science Conference for 50^th^
year jubilee of Geological Survey of Mongolian Peoples' Republic),
Ulaanbaatar, p. 105-107, (in Russian).

Tsypukov, Yu.P., and Lombo, D., 1977, Geochemistry of gold in relation
to the problem of gold content of the Northwest Khentii: Main problems
of Mongolian geology (Joint Soviet-Mongolian Science-Research Geological
Expedition), Transactions, Moscow, v. 22, p. 216-226 (in Russian).

Tugarinov, A.I., Voinkov, D.M., Grinenko, L.N., and Pavlenko, A.S.,
1974, Isotopic composition and sources of molybdenum-copper
mineralization of Mongolia: Geochemistry, no. 2, p. 171-178 (in Russian
with English abstract).

Vezzilin, N.N., and Lalmikova, N.A., 1993, Zeolite-bearing Mesozoic
sedimentary rocks of Southeastern Mongolia, p. 156 (in Russian).

Vladykin, N.V., 1983, Mineralogical-geochemical features of Mongolian
rare-metal granitoids: USSR Academy of Sciences, Siberian Branch, 200 p.
(in Russian).

Voinkov, D.M., Grinenko, L.N., Garamjav, D., and Jamsran, M., 1977,
Sequence of ore formation in porphyritic Erdenetiin Ovoo copper deposit,
Mongolia: Proceedings of USSR High Educational Institute, Geology and
Exploration, no. 1, p. 77-80, (in Russian).

Volchanskaya, I.K., 1980, The regularity of distribution of endogenic
mineralization in Mongolia, as a result of morphologic analysis: Geology
of Ore Deposits, v. 22, no. 4, p. 86-96. (in Russian).

Yakovlev, B.A., 1977, Nonferrous metals: copper, lead and zinc: Geology
of Mongolian Peoples' Republic, v. 111 (Mineral Resources), Nedra,
Moscow, p. 141-216. (in Russian).

Volchanskaya, I.K., Baskina, M.A., and Favorskaya, M.A., 1978, Meridian
ore concentrated structures of central and eastern Mongolia: Reports of
the USSR Academy Of Sciences, v. 240, no. 3, p. 666-668 (in Russian).

Yakovlev, B.A., Sanduijav, G., Garamjav, D., and Ganbaatar, T., 1979,
The Tsagaansuvarga and the Mantakh copper ore knots of southeastern
Mongolia: Geological setting and natural distribution of useful mineral
deposits in the territory of Mongolia. Nedra, Moscow, p. 57-66 (in
Russian).

Yudin, I.M. and Jamsran, M., 1975, Experience on mineral types
systematic of ore of deposits of porphyry Cu-Mo formation of Mongolian
Peoples' Republic: Scientific Transaction of Mineralogical Museum of
Mongolian State University, no. 5. p. 60-74. (in Russian).

Zaitsev, N.S., Yashina ,R.M., Bogatyrev, B.A., Gram, D., Ilin, A.V., and
Pinus, G.V., 1984, The problem with aluminium raw materials in Mongolia:
Endogenic Ore-Bearing Formations of Mongolia (Joint Soviet-Mongolian
Scientific-Research Geological Expedition), Transactions, Moscow, v. 38.
p. 172-180 (in Russian).

Zaitzev, N.S., Yashina, R.M., Bogaryrev, B.A., Garam, D, Iljin, A.V.,
and Pinus, G.V., 1984, The problem with aluminium raw materials in
Mongolia: Endogenic Ore Bearing Formation of Mongolia. v.38, p.172-180.