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EAST EURASIAN GEOLOGICAL SEMINAR 2003 (Text)

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Conference Report:
East Eurasian Geological Seminar 2003
-- Geological Mapping for sustainable human society --
Memorial seminar of tenth anniversary of Geological Investigation Center

   An International Seminar entitled "East Eurasian Geological Seminar 2003" was organized during October 28-31, 2003, as memorial seminar of tenth anniversary of Geological Investigation Center, Mongolia.  A two-day conference was held at Continental Hotel in Ulaanbaatar (Oct 29-30).  Pre-seminar field excursion was performed in east of Ulaanbaatar in Oct. 28 and Post-seminar field excursion in northwest of Ulaanbaatar in Oct. 31.
   About a hundred participants from four countries (Mongolia, China, Korea and Japan) participated in the seminar and around 20 oral presentations and 20 poster presentations were made.  The following themes were covered: (1) Resource geology, (2) Petrology, (3) Tectonics, (4) Paleontology and (5) Geophysics and Geochemistry.  New geologic maps by Geological Investigation Center were also presented.  Abstracts and articles of these presentations are included in last volume and this volume (Mongolian Geoscientist, no. 22 and 23).

Organizing of the seminar
Organized by:
Geological Investigation Center

In cooperation with:
Ministry of Industry and Trade of Mongolia
Geological Association of Mongolia
Aftercare Program for "IGMR" Project

Advisor:
O. Gerel, Mongolian University of Science and Technology
J. Byambaa, Mongolian State University

Coordinator:
Yuhei Takahashi, Advisor of Geological Investigation Center

Organizing committee:
Sh. Baasandorj, Director of Geological Investigation Center
S. Batmunkh, Chief Geologist of Geological Investigation Center
Ch. Minjin, Mongolian University of Science and Technology
Kh. Bolormaa, Geological Investigation Center
D. Narantsetseg, Geological Investigation Center

Working group in Geological Investigation Center:
B. Bayaraa, D. Gaagnai, S. Purevdorj, O. Jamyandorj, Sh. Davaa

Excursion guide:
J. Lkhamsuren, Mongolian University of Science and Technology
S. Jargalan, Mongolian University of Science and Technology
G. Sersmaa, Mongolian University of Science and Technology
N. Ichinnorov, Paleontological Center, MAS

 Interpreter:
B. Munkhtsengel, Mongolian University of Science and Technology

Program of East Eurasian Geological Seminar 2003
1. Pre-seminar field excursion
(October 28) East of Ulaanbaatar (Nalayh, Gorkhi and Terelj)
Henty Group (Devonian to Carboniferous), Mesozoic granite and related pegmatite, and Pingo (one kind of periglacial morphology)

2. Conference
2.1 Oral presentation
(October 29)
Opening speech: Sh. Baasandorj

Chairperson:   J. Lkhamsuren and B.Munkhtsengel
I. Resource Geology
C. Forster and D. Bat-Erdene : Geology and mineralization of Oyu tolgoi deposit
T. Mizuta and D. Ishiyama: Geological and Geochemical Features of Kuroko-type Volcanogenic Massive Sulfide Ore Deposits in Japan
Se-Jung Chi, Soo-Young Kim, Jung-Kwon Park, J. Badamgarav and N. Tungalag: Fluid inclusion and stable isotope studies of Au-bearing epithermal quartz veins in South Korea and eastern Mongolia
P. Shaandar : Geology and mineral resources of Lake Zone, western Mongolia
Ya. Davga-Ochir : Geology of Khar uul, and Lower Proterozoic metamorphic rocks
D. Batulzii, S. Myagmarsuren, Ts. Tegshee and S. Dandar: Rhyolite related mineralization of Neoproterozoic (example of Bayan -Airag, Zavkhan area)
Ts. Naranbaatar and T. Enkhbat: Geology of Dush area (Govi-Altai aimag)
O. Jamyandorj: Geological history of Zamiin-Uud area
II. Petrology
I. Matsumoto and O. Tomurtogoo: Petrological characteristics of the Hantaishir ophiolite complex, Altai region, Mongolia
Y. Majigsuren, A. Kitakaze and S. Jargalan: Petrology and Mineral chemistry of Shavariin Tsaram and Mandalgovi basalts, Mongolia

(October 30)
Chairperson:  Yutaka Takahashi
O. Gerel, S. Oyungerel, B. Munkhtsengel, S. Myagmarsuren, B. Soyolmaa, D. Bat-Ulzii and V. Baljinnyam : Granitoid magmatism of Mongolia: GIS petrological database
B.Enkhbayar, Ch. Ochirkhuyag and D. Batbold: Layered gabbroid of Ikh Khar Mountain
S. Jargalan and H. Fujimaki: Petrology and Rb-Sr geochronology of lamprophyre dike, Tsagaan -Tsahir Uul area, Bayanhongor, Mongolia

Chairperson:  I. Matsumoto
III. Tectonics
Yutaka TAKAHASHI, Weon-Seo KEE and Bok Chul KIM: Comparison between the Honam Shear Zone and the Funatsu Shear Zone -- A study on geological correlation between the Korean Peninsula and the Hida Belt of southwest Japan
K. Tsukada: Forming process of the Hida Marginal Belt, SW Japan: as a Mesozoic tectonic zone
Ts. Naranbaatar, D. Chuluun and N. Baatar: Geological and geodynamical features of Trans-Altai Gobi

Chairperson:  Ch. Minjin
IV. Paleontology
H. Hasegawa, M. Ehiro and A. Misaki: Permian paleogeography of the South Kitakami Block (Northeast Japan) in Eastern Asia based on the ammonoid fauna
Chen Xiuqin: Study of Early Devonian brachiopod biogeography of Inner Mongolia and joined areas
P. J. Currie, D. Badamgarav and E. Koppelhus: First discovery of foot prints from the Nemegt locality (Upper Cretaceous Nemegt Formation, Mongolia)
V. Geophysics and Geochemistry
N. Baatar, T. Sengedorj and M. Davaatseren: Complex geophysical research to distinguish alteration and ore bearing zone of deep set intrusion body
A. Karibai, Sh. Gerbish, G. Ganchimeg and G. Ganbold: Bulk analysis method of determination of gold in ores using epithermal neutrons of cyclic electron acceleration microtron MT-22

Discussion and Closing

2.2 Poster session
(October 29 and 30)
T. Altantsetseg: Characteristics of copper and gold mineralization of Porphyry Cu-Au deposit Oyu tolgoi, southern Mongolia
Ts. Barsbold, Sh. Tungalag and Kh. Bolormaa: Geological and mineralogical characteristics of Cu-Au occurrence Shirdegt, Hasagt area, western Mongolia
B. Batjargal, S. Tuul, B. Davaasuren and O. Dorjrentsen: Uncertainty of sampling and analytical quality
D. Batulzii, V.S. Antipin and P. Khosbayar: Late Mesozoic volcanic series and REE characteristics of the Tsagaan delger area
B. Bayanjargal Pavel Hanzl and Ts. Naranbaatar : Dip slip tectonics in the lower Devonian rocks of the NW Erdengiin nuruu, SW Mongolia
D. Dorjnamjaa, A.B. Tolstov, E.I. Boris and Kh. Bolormaa: Diamond and gold bearing astropipe structures of Mongolia
L. Gereltsetseg: Microfauna of Shar-Teeg locality
N. Ichinnorov: Palynocomplex of the Lower Cretaceous sediments of the Eastern Mongolia
D. Javkhlanbold: Application of remote sensing for neotectonics at junction of dextral and sinistral shear zone in Altay Range, western Mongolia
K. Kashiwagi and S. Yokoyama: Structural characteristics of gravitational tilting structures caused by force of constant gravity: examples from Southwest Japan
P. Khosbayar, S. Ariunbileg and Ts. Narantsetseg: Clay mineral assemblage of lake sediments of Late Quaternary lacustrine systems in Mongolia
Kim, Soo-Young, Chi, Se-Jung, J. Badamgarav and N. Tungalag: Spatial delineation of the various components in soil around mineralized spots distributed in Mongolian quadrangle L-49-12
Ts. Naranbaatar, D. Tsoggerel, P. Hanzl and M. Rijchrt: Geology of the Trans-Altai Gobi, SW Mongolia
D. Narantsegtseg , P. Lkhagvadorj, L.Byambasuren, M. Munkhgerel and K. Okumura: Digital geological map of Gichgene area at the program "TNTmips ver.6.8" for 3D
Y. Ninomiya, D. Narantsetseg, P. Lkhagvadorj, L.Byambasuren and M. Munkhgerel: Remote sensing using "ASTER-TIR" data at the program "ER-Mapper 6.2"
Y. Nishioka: Standardized legend of plutonic rocks for the 1:200,000 quadrangle geological map series in Japan
D. Tomurhuu and O. Tomurtogoo: Geochemistry of the rocks of Bayanhongor Ophiolie in Central Mongolia: implication for its origin
S. Tuul, Ch. Tserenkhuu and Munkhgerel: The application of atomic absorption spectrometry (AAS) to the some microelemental (Hg; Se) analyses of water samples
L. Uranbileg: New plants of the Upper Permian coal deposits in South Mongolia
K. Watanabe, A. Ochi and I. Matsumoto: Geological and geochemical characteristics of river sediments from the Turumi, the Kamo and the Tama rivers, Japan (a preliminary study)

3. Post-seminar field excursion
(October 31) Northwest of Ulaanbaatar (Bayanchandman and Tsagan davaa)
Haraa Group (Early Paleozoic) and Mesozoic granite
Tungsten mine and concentration plant (MONWOLFRAM Co., LTD)

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Geological setting of the Khariin Uul and lower Proterozoic metamorphic rock

Ya. Dagva-Ochir and D. Batnyam

Geological Investigation Center

   Proterozoic metamorphic rocks are widely distributed in the study area forming more than 10 microplates, wedges and remains with 25 km of length and up to 4 km of width as south eastern end of the super terrain. There are Meso-, Neoproperozoic marble, marblized limestone, metamorphic rocks with quartzite bed and lenses, terrigenous and volcanic rocks forming active continental margin, slope and shelf basin on the Paleoproterozoic crystalline basement.
   Geological study of this area is started by discovery of gneiss and granite-gneiss (Obruchev, 1882) which are classified as Paleoproterozoic.
   Many researchers have studied (Obruchev, 1958; Stephanenko, 1937; Jelubovskii, 1940; Alekseichik, 1943; Mokshantsev, 1949; Marinov, 1957; Suetenko, 1970; Borzakovskii, 1973; Dorjnamjaa, 1978; Byamba and Batkhuu, 1985; Bumburuu, 1990) geology of this and contiguous area and some researchers (D.Galbaatar and Vokhmintsev, 1990) classified metamorphic complex of granite gneiss-gneiss as Norovzee metamorphic complex (PR1nz) in the north western continuance.
   Regional metamorphic complex in the Nukhet davaa terrain is classified as Paleoproterozoic Norovzee complex, Lower and middle Riphean Urgun suite, upper Riphean Bargilt ovoo and other suites.  In terms of 1:200 000 mapping of Geological Investigation Center, these above mentioned metamorphic rocks are classified as Paleoproterozoic Khutag Uul complex, Mesoproterozoic Norovzeeg formation and Neoproterozoic Urgun formation with oncolite and stromatolite.
   We are examining Paleoproterozoic metamorphic complex in the Khariin Uul area.

Paleoproterozoic Statherian Khariin uul metamorphic complex (PPhu)
   Metamorphic rocks of this complex occur as paleo prominence with 1-1.7 km of width and 8.7 km of length covering 9 sq. km area in the eastern end of the Khariin Uul projection (south eastern continuos of the Ulaan Uul projection) with 15 km of length (Fig.1 ). These rocks usually show north east strike and show sharp tectonic and erosional contact with Neoproterozoic metamorphic rocks of Urgun formation containing limestone with stromatolite in the eastern and south eastern parts and are covered by reddish Oligocene Ergel Zoo formation in the north and Cretaceous Sainshand formation in the south western, north and central parts.
   Khariin uul complex of crystalline basement in the Zuunbayan and Erdene uul fault zones are composed of light gray and dark gray garnet-biotite mesocrat gneiss, granite-gneiss, gneiss-granite, various crystalline schists, micro schists, quartz schist, plagiogneiss, amphibolite and rare marble, metasandstone and migmatite. They are taken place by micro folding, deformation and milonitization, carbonatization and siliciceous processes.
   Milonitized quartzite, diopside-garnet crystalline gneiss, gray porphyroblast biotite granodiorite-gneiss beds with 5-10 m, up to 80 m thick are included in granite-gneiss and gneiss-granite.
   These rocks are cut by Neoproterozoic intrusive and migmatised and in some parts pegmatite is formed. There are some beds with 3-5 m and 10-20 m of thick and it is difficult to determine exact contact of intrusive rocks. Gneiss and plagiogneisses are widely distributed and changed to micro plagiogneiss along the contact.
   It is noted schist and metasomatites of various compositions, dark gray metasandstone in the upper part of these metamorphic rocks except above mentioned crystalline schist with lesser amount of quartz. They contain 7 m of calcite-mica micro bed. Mica, feldspar, quartz and garnet are present in this rock (Dagva-Ochir, 1991). Dark colored, strongly lenses-formed and schisteous quartzite and quartzite-schist micro beds with 2-6 m of thickness are found from the Khariin uul area. Dagva-Ochir’s section (1991) suggests that the thickness of this metamorphic complex composing granite-gneiss and gneiss is not lesser than 1390 m.
   It is possible that Khariin uul metamorphic complex can be formed from primary volcanogenic-terrigenous formation and metamorphism reached to amphibolite and granulite phases and the following uplifting makes decreasing of metamorphic grade. Zoning of the almandine and basic plagioclase suggest that amphibolite phase was taken place.
   We did not examine the lower age boundary in the study area. Rocks of the northern Bargilt ovoo area are cut by Paleoproterozoic granite covered by Mesoproterozoic Calymmian-Ectasian Norovzee formation conglomerates (MP1-2nz). But, in Tsavchir khets, they are covered by Urgun formation conglomerates of Neoproterozoic Cryogenian period and tectonically bordered with them in the western continuance. In the south eastern and western Gashuun Tolgoi, the metamorphic rocks are cut by second phase granites of Neoproterozoic intrusive complex.
   All above mentioned facts suggest that most high grade metamorphic rock of the study area is similar to Paleoproterozoic Statherian Khutag Uul metamorphic complex which belongs to Khangiltsag horizon (older than 1600 Ma).

References
1. Alekseichik S.N, Stephanenko A.Ya, Likhacheva I.A. Tentative open file mapping report of geological project 56, 1943. In list of L-49-G. Ulaanbaatar, 1943, Report N384. (in Russian)
2. Bumburuu G., Lkhundev J., Burentugs J. and others. Open file report of geological mapping 1:200 000 in 1986-1988, in Dornogovi and Dundgovi aimag, Sainshand XI project. Ulaanbaatar, 1990, Report N4377. (in Mongolian)
3. Byamba J. Main stages of Precambrian evolution history of Mongolian territory. Problems of geology of Mongolia, N7. 1985, Ulaanbaatar, pp.32-47. (in Russian)
4. Galbaatar D., Vokhmintsev V.V. and Nyamdorj D. Open file report on the complete geological study of 1:50 000 scale in Bargilt ovoo uplift, 1988-1990. Ulaanbaatar 1991, Report N4414. (in Mongolian)
5. Dagva-Ochir Ya., Serchinnamjil G., Gansukh Ts., and others. Geological setting and mineral resources of the south eastern Dornogovi. Ulaanbaatar, 2001. Report N 5384. (in Mongolian)
6. Dorjnamjaa D. Problems of absolute age and metamorphism of the Precambrian rocks of Mongolia. Khaiguulchin, 1, 1978, pp.27-30. (in Mongolian)
7. Dobretsov N.L. Map of metamorphic formation of Mongolia, 1:1 500 000. Ulaanbaatar, 1992. (in Russian)
8. Minjin Ch. Mongolian stratigraphic glossary. Ulaanbaatar, 1994. (in Mongolian)
9. Obruchev V.A. Geological setting of the Gobi uplifting. V.1. Moscow, 1958. pp. 96-182. (in Russian)
10. Suetenko O.D. Main characteristics of Precambrian and Paleozoic rocks of South-eastern Mongolia. Stratigraphy and tectonics of Mongolia. V.1. Nauka, Moscow, 1970. pp.64-84. (in Russian)
11. Kurtov G.S. Methods of determination primary nature of the metamorphic rocks by chemical contents. Lithology and mineral resources, N5, 1980, pp.128-152. (in Russian)
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LAYERED GABBROIDS OF THE IKH KHAR UUL

B.Enkhbayar, Ch.Ochirkhuyag and D.Batbold

Geological Investigation Center

Introduction
   The Ikh Khar Uul complex occurs in the Ikh Khar and Baga Khar hills that are situated in the back lower slopes of the Mongol Altai ridge and in the Sharga Gobi southern edge (Tugrug sum, Gobi-Altai aimag).
   These rocks were studied during different investigation projects: V.V.Bezubtsev (1959) included them to the first phase of the mid-late Cambrian Togtokhiin shil complex; Kh.Tserenpuntsag (1975) classified these rocks as early Paleozoic.
   Mafic and ultramafic rocks distributed in the Lake zone and in the Mongolian Altai were studied by A.E.Izokh (1990), who classified them as a layered gabbroids of early Cambrian Khirgis nuur complex. Togtokh (1995) followed Izokh classification during 1:200 000 mapping project.

Geological setting
   Mafic and ultramafic rocks form 1.2x1.6 km and 0.8x1.3 km stock-like oval body are occupying Ikh Khar and Baga Khar hills. The complex is composed of dark, dark grey layered gabbro, plagioperidotite, hornblende gabbro, troctolite and pyroxenite. The age of mafic and ultramafic rocks is distinguished as a younger than late Devonian and could be early Carboniferous. It is supported by geological relation where these ultramafic and rocks cut the first phase diorite of mid-late Cambrian Togtokhyn shil complex forming apophyses from 0.5 to 10 m thick. In the western part, around the Ikher uul they cut the late Devonian Sarkhiag subvolcanic body of porphyritic andesite forming 30-100 m wide hornfels and silicic contact zone.
   The best outcrop could be observed in the Ikh Khar Uul. In the core part, in the top of Khar Uul hill, the layered gabbro predominates with subordinate troctolite, olivine gabbro, plagioperidotite, anorthozite and serpentinite. (Fig-1)
   A.E. Izokh (1990) suggests that presence of plagioperidotite and anorthozite show deep part of differentiation intrusion.

Petrochemistry
   Thirty seven samples from complex were analysed. SiO2 content varies in troctolite from 38.2 to 39.7 wt%, in peridotite 41.5 wt% and in olivine gabbro and gabbro from 42 to 49 wt%. Na2O+K2O content in troctolite and peridotite from 0.11 to 0.98 wt%, in olivine gabbro, gabbro and hornblende gabbro from 1.1 to 3.7 wt%(Fig. 2).  These gabbroids show 0.5 to 1.7 in ratio of FeOt and MgO(Fig. 2).  In the AFM diagram all rocks show tholeiitic trend (Fig. 3).
   These ultramafic and mafic rocks are plotted in Zr-TiO2 diagram, and all these rocks belong to ultramafic rock field (Fig. 4).
   Silicified rock samples contain native copper, chalcopyrite, bornite, malachite, gold, silver and two signs of platinum (?).
   Total alkalis (Na2O+K2O) are high in terms of CIPW norm. Normative nepheline, diopside and olivine are calculated in olivine gabbro and other hartsburgite, peridotite and troctolites have normative olivine, diopside and hyperstene.
   These gabbroic rocks show alkaline and normal composition. Samples are scattered in diagram suggesting their various composition.

Origin
   A.E.Izokh et al. (1990) classified these rocks as early Cambrian mid ocean ridge layered intrusion.
   Early Carboniferous gabbroids of Khar Uul area show tholeiitic trend and we suggest that they could be analogous of basaltic magma. Plotted data in MgO-FeO-Al2O3 (Pearce et al., 1977) diagram belong to island arc type. It is supported by Mn*10-TiO2-P2O5*10 diagram plot.
   Above mentioned features such as tholeiitic trend, low alkalinity and presence of peridotite layers suggest that these gabbroids could be originate in island arc environment.

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GEOLOGICAL EVOLUTION OF THE ZAMYN UUD AREA

O. Jamyandorj

Geological Investigation Center, leader of ZU-50 project

   The studied Zamyn Uud area is related to Khovsgol Ulaanbadrakh and Khutag Uul structural formation zones of South Gobian minor plate, bordered by Ulaanbadrakh deep fault.
   Although these two zones are related to Caledonides, their formations are not exposed in the studied area; only later Variscian formations of overlapped depressions are distributed.
   It has been suggested that tectonic events took place in Carboniferous from Gobi Khyangan zone, e.g. from north, in Permian from Sulinkheer zone, e.g. south and in Mesozoic from Pacific Ocean active zone, e.g. from east in studied area.
   There was no sedimentation from Neoproterozoic to Lower Carboniferous in these two zones, because of uplifting. South Gobian micro plate reactivated and subsided by Variscian movement.
   Previous researchers (Dagva-Ochir et al.) classified succession composing of lower terrigenous and upper volcanogenic subformations by earlier classification lower-upper Permian Khar nuden in Khuvsgul-Ulaanbadrakh zone and in lower Permian Bairam ovoo formation in Khutag Uul zone. We suggest that between these two subformations sedimentation break occurred. It is supported by finds of Permian Bairam ovoo granite fragments in the tuffs from lower part section of the Khashaat Ukhaa formations. Therefore, we classified the terrigenous deposits as lower Permian and volcanogenic rock as middle Permian.
   From the late Paleozoic (from upper Permian) studied area uplifted and undergone to continental regime. Then, the area activated by influence of Pacific movement. In Paleozoic, the longitudinal movement dominated and in Mesozoic it changed to latitudinal.
In lower Cretaceous, in the rift environment, the subalkaline basalts of Tsagaan tsav formation erupted in narrow NE oriented area.
Studied area changed to platform regime and became one part of Gobian plate from the upper Cretaceous.

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GEOLOGY AND MINERAL RESOURCES OF THE LAKE ZONE

P.Shaandar

Geological Investigation Center

Geological setting.
   The Lake zone covers western and south-western part of the North Mongolian Caledonian Fold Zone in terms of tectonic classification of Mongolia and borders South Mongolian Hyrcinian Fold Belt in the south. This is an individual tectonic zone with interesting arch-like structure from NW to SE. This zone borders Mongol Altai zone by Tsagaan Shuvuut fault in the west, South Mongolian Hyrcinian Fold Belt by Ikh Bogd deep suture in the south and with Zavkhan tectonic zone by Zavkhan fault in the east and the north east.
   The Lake zone belongs to linear folding zone type composing mainly of volcanic rocks and the rocks can be divided into two big complexes.
- Lower complex: Volcanites with spilite-diabase and diabase composition
- Upper complex: Mainly terrigenous deposits composing of sandstone-siltstone with tuffogenic-pyroclastic materials conformably covers lower complex with gradual transition
480-550 m molass complex covers these deposits and it is covered by 2000 m of Mesozoic and Cenozoic deposit.
   Magmatic complexes are represented by large ultramafic bodies and plutons. Tsagaan Shuvuut, Ikh Bogd and Zavkhan old deep faults trending SE-NW play important roles to geological history of the Lake zone and reactivated several times in the following stages of geological history. Main strike of folded complexes of the Lake zone is straight and compressed from two sides, isoclinally folded (dip=60-70?) and overlaps to direction of above mentioned big faults.
   The Lake zone is quite different from the Zavkhan zone which is not highly undergone by rock dislocation.
   The newly started “Geomap 1:200000” project in 2003 summarized all data from Geological Information Center and developed legend based on modern geodynamic model.

Mineral resources.
   Eastern part of the Deluun Altan Khukhii zone of the Tuva Khuvsgul metallogenic belt and Sharga-Govi Altai zone of the Central Mongolian metallogenic belt belong to Lake zone in terms of metallogenic zonation. Most mineral resources are found along the zone of the Tsagaan Shuvuut, Ikh Bogd, Zavkhan and Khangai deep faults.
   Previous researchers found precious metals such as gold, platinum, silver, copper, zinc, nickel, tin, and black metals such as iron, manganese and chromium, rare metals such as wolfram and molybdenum and asbestos, talc, epsomite, halite and soda, mineral pigments, coal deposit and occurrences and have done exploration work for building materials, lake salt, rock salt and salt-lick, gypsium, magnesite, coal and placer gold and made ready for local use. The Lake zone is rich of mineral resources and economic potential zone of our country.
   Although, many researchers proposed that Mesozoic and Cenozoic weakly cemented and loose deposits filling Lake Valley contain oil resources, the detailed study is needed.
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Characteristics of copper-gold mineralization of Porphyry Cu-Au Deposit SW Oyu-Tolgoi, Southern Mongolia.

T. Altantsetseg

Central Geological Laboratory of Mongolia.

Abstract: SW Oyu Tolgoi is near surface high-grade column of porphyry-style Cu-Au mineralization, about 250m in diameter, extending to over 800m vertically. In order to define the general mode of occurrence (mineral association), general characteristics (grain size, shape), paragenetic position, with respect to other sulphides and alteration assemblages we have performed petrological, mineragraphical and mineralogical analyses. With this goal we have analyzed about 350 samples and selected microphotographs to emphasize
Introduction
   The Oyu Tolgoi (Turquoise Hill) Cu-Au porphyry target is located in southern Mongolia, about 70 kms from the Chinese border, and 140 SE of Dalanzadghad. Four main zones of mineralization: North, Central, South and Southwest Oyu are present. The SW Oyu-Tolgoi is an exceptionally gold-rich system, with a current resource in the order of 100Mt @ 0.8% Cu, 2g/t Au.  Perello, et al (2001) Southwest Oyu is part of a lager intrusive body centred on South Oyu. Turquoise Hill was previously known as a molybdenite occurrence on regional metallogenic maps of Mongolia. Excluding possible Russian geological investigations, the area first was recognized to have porphyry Cu potential in 1996 by Magma Copper Company (now BHP-Billiton), during a reconnaissance program of Mongolia. The results of exploration and evaluation by BHP-Billiton between 1996-1999 are summarized by Perello et al., (2001). This work showed that the prospect comprises several separate porphyry centers, structurally controlled by stocks or dykes of intermediate composition, intruding a Palaeozoic island arc volcanic sequence.

Regional setting
   The regional tectonic setting for the Oyu Tolgoi prospect is well described by Perello et al., (2001), and these authors show that at a large scale, the essential tectonic feature for southern Mongolia is an early to mid Palaeozoic island arc related to north-directed subduction. Oyu Tolgoi occurs in the Barga Terrane (from Badach and Orolmaa, 1998), which is believed to comprise Palaeozoic volcanic, intrusive and sedimentary rocks. The SE edge of the Barga Terrane is marked by the East Mongolian Fault and related NE to N70E lineaments, which may be primary structural controls for distribution of magmatic-hydrothermal systems such as Oyu Tolgoi. Along the NW margin of the Barga Terrane (100-130kms to the NW of Oyu Tolgoi) several other Cu-Au porphyry systems and high sulfidation alteration zones (e.g., Kharmagtai, Shuteen), occur in a similarly trending ENE belt.
   The mid Palaeozoic arc, at 50km scale around Oyu Tolgoi is dominated by basaltic volcanics and intercalated volcanogenic sediments, intruded by plutonic-size hornblende-bearing granitoids, of mainly quartz monzodiorite to possibly granitic composition. Carboniferous sedimentary rocks with intercalated basaltic to rhyolitic volcanics, and locally coal beds overly this assemblage, including parts of the Oyu Tolgoi exploration area. In addition, the largest magmatic system near Oyu Tolgoi (7kms from porphyry alteration) is the Lower Permian, Na-alkalic Hanbogd Complex.

Whole rock geochemistry
   Limited wholerock geochemical data indicates volcanic and intrusive rocks at Oyu Tolgoi are normal to high K calc-alkaline, and may be typical of modern island arc tectonic settings.

Age
   In general, the age of Cu-Au porphyry and high sulfidation styles of alteration and mineralization at Oyu Tolgoi and region may be correlated to the mid Palaeozoic arc terrain, and more specifically to dacitic volcanics at the prospect. No radiometric age dates are available for the dacitic volcanics, but in terms of stratigraphy, they are conformable overlain by sedimentary rocks with carbonaceous siltstone, and coaly layers, which are likely to be of Carboniferous age. However, limited radiometric age dating (Perello, et al., 2001) indicates a Late Devonian age for early K-silicate alteration (biotite).

Geology of Oyu-Tolgoi
   Massive porphyritic augite basalt underlies much of the drilled area, and some drill holes in SW Oyu Tolgoi encounter augite basalt to depths of over 1000m. The augite basalts in South and North Oyu Tolgoi are underlain by laminated andesitic volaniclastics, of unknown thickness. Dacitic to andesitic ash flow tuffs, several hundred meters in thickness overlie the augite basalt. The ash flow volcanic sequence is inferred to be co-magmatic with the Cu-Au porphyry systems since it hosts extensive high sulfidation (HS) styles of alteration and mineralization. Sedimentary rocks, comprising mainly green to red siltstones, minor conglomerate and carbonaceous shale, with intercalated auto-brecciated basaltic lava and tuff overlie the ash flow tuffs. Some basalt flows in this upper sedimentary sequence are strikingly similar to the lowermost porphyritic augite basalt, and therefore suggest all the basaltic volcanics are co-magmatic.  Near the base of the sedimentary sequence, thin polymictic conglomerate beds entrain sericite-altered quartz monzodiorite, mineralized quartz vein and pyrite clasts, eroded from a porphyry system, possibly SW Oyu Tolgoi.

Summary
1. Alteration.
   In respect to petrological, mineragraphical and mineralogical examination summarize that alteration at Southwest Oyu consists of three events: 1.Potassic alteration, 2 Chlorite-sericite alteration, 3. Argillic alteration. Petrological, mineragraphical and mineralogical study summarize that main alteration minerals are as clay-sericite, hydrothermal quartz, carbonate, secondary biotite, chlorite, leucoxene, rutile, rare localized alunite, diasphore, epidote, baryte and topaz.
Clay minerals are represented as kaolinite, dickite, pyrophyllite and montimorillonite. (by XRD analyses). Mineralization as listed, variously involves pyrite, chlacopyrite, chalcocite, covellite, bornite and rare molydenite, also magnetite (primary and secondary) and hematite. Also often they associate with enargite, tennantite, sphalerite, galena and native silver. These ore minerals are variably disseminated and in some samples, specifically carried by (mostly quartz) veins.

2. Mineralization.
   Mineralization in Southwest Oyu is related to prong-shaped body of quartz monzodiorite. This body and quartz monzodiorite associated with mineralization at South Oyu may be apophyses of a larger quartz monzodiorite body at depth. Massive andesite flows are most common in the immediate vicinity of the Southwest Oyu deposit. Copper-gold mineralization at Southwest Oyu is associated with emplacement of one or more phases of quartz monzodiorite porphyry. Post-ore rhyolite and hornblende-biotite andesite dykes cut off alteration and mineralization.
   Petrological examination confirms the general impressions already apparent from both field and assay data, with majority of gold occurring in direct association with chalcopyrite-rich domains. Petrological study confirms initial visual paragenetic observations, with the chalcopyrite-dominated domains representing a single stage event. Alteration intensity shows that elevated copper values are present only in that portion of the potassic alteration zone that is close to the quartz monzodiorite intrusion.
   Whereas elevated gold values are related to more intense quartz-sulphide stockwork veining around the central quartz monzodiorite stock. This is consistent with morphology of alteration and grade zones in many copper porphyry deposits.

3. Relationship between mineralizaton and alteration.
*The bulk of the gold located in the SW Oyu Tolgoi samples occurs within a chalcopyrite dominated vein system
*The chalcopyrite occurs primarily as infill along with relatively minor pyrite and bornite, and rare hematite, molybdenite and gold. Pyrite is an early precipitated phase.
*Gold may occur in chalcopyrite, and more rarely in pyrite, quartz and carbonate, but clearly favors early-formed pyrite as a nucleation site of grains of within cracks in pyrite.
*The chalcopyrite ?dominated veins are a late stage event within an evolving porphyry related magmatic-hydrothermal system.
*No relationships of Cu-Au to magnetite were noted.
*Gold also occurs within pyrite-dominated domains and sphalerite-dominated domains.
*The relationship between pyrite and chalcopyrite is a little difficult to interpret but at this stage is suggested that they are contemporaneous, with early nucleating pyrite being disrupted by fluid pressure and fluid flow effects prior to nucleation of chalcopyrite. The case for co precipitated pyrite is quite convincing where minor chalcopyrite veins contain centimeter of pyrite.
*Molybdenite occurs as isolated flakes or small crystal clusters within chalcopyrite, although it is a rare mineral and comprises a very low percentage of the sulphide mass.
*Hematite is another minor component and occurs as isolated grains or aggregates with chalcopyrite.
*Bornite is present in significant amounts within examined samples and mostly associated with chalcopyrite.
*The gold is present as a discrete phase, and although a few grains may have formed with the early pyrite vast bulk were precipitated with chalcopyrite.
*The earliest Qmd dykes are small (meters- 10’s meters) and discontinuous in drill sections, highly altered and strongly Cu-Au mineralized, whilst later dykes are larger, partly sericite-altered and weakly Cu-Au mineralized.
*Secondary K-feldspar has not been positively identified in recent work, either in hand specimen or from limited petrographic work and sodium cobaltinitrite staining. Due to overall sodic host rock composition, it is possible that secondary K-feldspar does not form in the augite basalt, while in mineralized phases of quartz monzodiorite, intense late-stage sericite alteration may render K-feldspar difficult to recognize. Whereas, the matrix of augite basalt exhibits fine-grained biotite alteration, the augite phenocrysts are typically replaced by fine-grained actinolite, or actinolite mixed with secondary biotite.

REFERENCES
Gustafson, L. B., and Hunt, J.P., 1975: The porphyry copper deposit at El Salvador, Chile. Econ. Geol., 75 : 210-228.
Perello, J., Cox, D., Garamjav, D., Sanjdorj S., Diakov, S., Schissel., Munkhbat, T., and G. Oyun 2001: Oyu Tolgoi, Mongolia: Siluro-Devonian Porphyry Cu-Au-(Mo) and High Sulfidation Cu Mineralization with a Cretaceous Chalcocite Blanket. Econ. Geol., 96:1407-1428.
New advances in the understanding of the Oyu Tolgoi Cu-Au porphyry system, Mongolia
Charles Forster, Imants Kavalieris et.al (2003)

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TO QUESTION COMPLEX GEOPHYSICAL SEARCH FOR ALTERATION AND  ORE-BEARING ZONE FIXED BY CONCEALED INTRUSIVE BODY

N. Baatar*, T. Sengedorj** and M. Davaatseren ***

* MUST (School of Geology)
** Mongolyn Alt Corporation (MAC)
*** MRAM (Geological Information Center)

On the base of analysis of regional geophysical  material region of Khanbogdyn massif, are possible chosen several independent structures. Including one of powerful lifting, which is divide into several independent structures as: in Duulgatyn,Ulaan uulyn and Hatsavchin uplifting and nearly in central part a structure inheres a Khanbogdyn granite massif. It is divided from ?umen Ulzityn notions, Galbyn gobiyn and Nomgonyn graben-shaped trough. Tumen Ulzitun Liftings in turn, from the orient to pull over Lugin golun thrust. On our glance, under these, pull over structure, on particularities by physical fields stand out several hidden tels, similar of Khan bogdyn massif.

Under this pulling over structures clearly stand out some hidden tel of granite arrays, characterize local gravitational by minimum and shallow denuding the granites on surfaces. As well as from is here seen that, Khan bogdun massif itself is at the depth wide-spread much more on areas , than see from surfaces.

Exactly with these hide by structures are bound majority occurrence useful fossilized and to, get positive information, under geological and geophysical searching for is necessary choose areas, with similar geological, structured positions, way of careful analysis available regional geological and geophysical material. In this report authors quote results early conducted studies, including, results of detailed searching for conducted on some areas of area a Har tolgoi in the region a Khan bogda when working a geological removal with searching for scale 1:50 000.

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UNCERTAINTY OF SAMPLING AND ANALYTICAL QUALITY

B.Batjargal, S.Tuul, B.Davaasuren, O.Dorjrentsen

Central Geological Laboratory

INTRODUCTION
   Measurement uncertainty has become an important concept in analytical science that unifies many previously disparate strands of information on data quality. Chemometric techniques play a crucial role in estimating values for the overall uncertainty and also in the separation and quantification of the various components of uncertainty. These components include not just those arising from the chemical analysis, but also those arising from the sampling procedure that is used to select the primary sample from the sampling target. In the case of environmental and geochemical investigations, primary sampling is often the main source of uncertainty and dominates analytical sources such as instrumental determination or the sub-sampling of test materials within the laboratory.
   Analytical chemists generally used to recognize sampling as the first step in the measurement process, and to include its contribution in the estimation of uncertainty. The inclusion of the sampling step becomes particularly important in deciding acceptable levels of uncertainty arising from chemical analysis.
   This paper explains the terminology relating to both uncertainty and data quality, and tries to clarify their interrelationship and what they both mean for analytical measurements, and empirical estimation of sampling uncertainty.
   Analytical results are used to interpret data. Therefore, the reliability of conclusions drawn from the data, i.e. the usefulness of the information obtained from the often expensive analyses depends ultimately on the quality of sampling.
   Factors, which should be considered in the sampling are following:
*Homogeneity
*Effects of specific sampling strategy (e.g. random, stratified random, proportional etc.)
*Effects of movement of bulk medium (particularly density selection)
*Physical state of bulk (solid, liquid, gas)
*Temperature and pressure effects
*Does sampling process affect composition? E.g. differential adsorption in sampling system.

Estimating uncertainty in sampling
   The total uncertainty of a measurement is a usually a combination of the sampling uncertainty and the analytical uncertainty. The sampling and analysis should subsequently be monitored to ensure that errors occurring during routine executions of the protocols remain within the bounds defined by the fitness for purpose criteria. This last requirement comprises internal quality control (IQC).
   There are several methods for the internal quality control of sampling.
   The overall measurement uncertainty can be considered to have contributions from four components. These are the random and systematic errors arising from the procedures of both primary sampling and chemical analysis. In terms of the quality of the methods employed, these four components can be quantified as sampling precision, analytical precision, sampling bias and analytical bias.
   Analytical precision can be measured by the use of analytical duplicates or in combination with sampling precision using a balanced design of sampling and analytical duplicates. Analytical bias is usually estimated by the analysis of certified reference materials. New methods have been proposed for the estimation of sampling bias.
   Four methods for the estimation of measurement uncertainty from primary sampling have recently been proposed and tested [1]. They correspond to the four possible combinations of numbers of samplers (i.e. people taking samples) andnent is the between-location variance due to real variation of the analyte across the target. This is called as the geochemical variance (s2geochem) in the case of geochemical investigation.
   All three variances can be summed to give total variance of the survey. This can be expressed by:
    S2total = s2geochem + s2samp + s2anal

The measurement uncertainty (u) can be estimated from the combination of the sampling and analytical variance:

    u = smean = ((s2samp + s2anal)

   It is usual to increase the nent is the between-location variance due to real variation of the analyte across the target. This is called as the geochemical variance (s2geochem) in the case of geochemical investigation.
   All three variances can be summed to give total variance of the survey. This can be expressed by:

    S2total = s2geochem + s2samp + s2anal

   The measurement uncertainty (u) can be estimated from the combination of the sampling and analytical variance:

    u = smean = ÷(s2samp + s2anal)

It is usual to increase the confidence interval of the uncertainty by multiplying by a coverage factor (k=2 for 95% confidence) to give the expanded uncertainty (U).

    U = ku = 2smean

Relative contribution of sampling and analysis to uncertainty is shown in the Figure 1.

CONCLUSIONS
1.  Knowledge of the sample variance can be used in a variety of decision-making processes. Key questions are (1) how much material should be sampled, or: was the sample size sufficient? (2) is the quality of the material sufficient? (3) how much is the material.
2.  Measurement uncertainty arises both from the chemical analysis but also from the sampling procedures used to select the material from its primary source (i.e. the sampling target).
3.  The result of the analysis of variance makes it possible to compare the contributions to the uncertainty from the sampling and the chemical analysis and thereby to identify where the uncertainty can most effectively be reduced. Further criteria are suggested for the optimum balance between these two sources of uncertainty. Recommendations for the reduction of uncertainty due to sampling are given based on traditional sampling theory.

REFERENCES
1. Ramsey M.H., Argyraki A., Sci. Total Environ., 1997, 198, 243
2. Ramsey M.H., Analyst, 1997, 122, 1255
3. Eurachem/CITAC Guide, Quantifying Uncertainty in Analytical Measurement,  2000
4. International Vocabulary of basic and general terms in Metrology, ISO, Geneva, 1993
5. ISO 5725:1994 (Parts 1-6). Accuracy (trueness and precision) of measurement methods and results, ISO, Geneva, 1994.

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First discovery of footprints from the Nemegt locality (Mongolia, Upper Cretaceous, Nemegt Formation).

P.J. Currie*, D.Badamgarav** and E.Koppelhus*

* Royal Tyrrell Museum of Paleontology, Box 7500, Drumheller, Alberta TOJ OYO, Canada
** Paleontological Center, Mongolian Academy of Sciences, Box 260, Ulaanbaatar 210351, Mongolia

   First a short report of Cretaceous dinosaur footprints from Middle Mongolia made by Namnandorj (1957).  Abundant dinosaur footprints and  track ways discovered from different formations ( Bayanshiree, Djadokhta, Nemegt) of Upper Cretaceous 14 localities by Japan-Mongolia Joint Paleontological Expedition (Suzuki, Watabe, 2000; Ishigaki, 1997,1999, 2000) and from Djadokhta  Formation of Ukhaa Tolgod locality (Loope et al.,1998), recently from Nemegt.
   The Nemegt is one of South Gobian the classic dinosaur sites  but footprints have never been reported before. The first dinosaur footprints were found by first author during the “Dinotour” of Nomadic Expeditions from Nemegt Formation of Nemegt Locality in September 2001. Since then 20 footprint sites have been identified  from the three different horizons of sequences Nemegt Fm. The lowest footprint horizon is very extensive, and can be traced from the southeast to the northeast for 4.7 km. The distribution of footprints in this layer is consistent, and there are few areas where this level fails to produce tracks. The second level of ichnites is more localized, but is productive and extends for 2.2. The third and highest level extends for more than 100 meters on both sides of a narrow ridge and on the west side of a narrow gully. The linear distance of this horizon is about 250 meters, and more than 50 footprints (all hadrosaur) were counted at that level. Here, during the excavation of a sceletion of a juvenile Tarbosaurus, a trackway of three footprints was found in the quarry. One large hadrosaur had apparently even stepped on the skull of the Tarbosaurus, wich already at that time was dead and shallowly buried in wet sand.  The horizons with footprints occur in the top sediments of ephemeral lakes and swales of floodplan deposits of meandering  river paleoenvironment. In the measured section, so-called load structures occur in three levels together with unmistakable footprints. Most of the footprints were made by large animals that sunk to varying depths of 20 to 40 cm  into the mud and they  are preserved as natural casts that show good preservation of detail. It is possible to see how the foot has been sliding forward and also skin impressions  are found on some of them. The  vast  of the footprints  belonging to hadrosaur, and also theropod, sauropod have been identified. This discoveries suggest a considerable ichnological potential in Mongolia.

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THE DIAMOND AND GOLD BEARING ASTROPIPE STRUCTURES OF MONGOLIA

D. Dorjnamjaa1, A.V. Tolstov2, E.I.Boris2 and Kh.Bolormaa3

1Paleontological Center, Mongolian Academy of Sciences
2ALROSA Co.Ltd., Russian Federation
3Geological Investigation Center

This paper reports on new results of the diamond, platinum and gold-bearing Agit Khangay and Khuree Mandal astropipe structures on the territory of western and central Mongolia.

1. The Agit Khangai astropipe (impact- intrusive pipe) structure
   The structure is located in western Mongolia, some 60 km southwest of Uliastay city. The crater’s total diameter is about 10 km, and it is surrounded by a raised rim. This astropipe crater was formed at the Permian granite massive. The surroundings of the crater are made up of Upper Paleozoic magmatic assembleges, overlain by Quaternary alluvial deposits in places. The crater rim consists of a dissected ring, of hill, mountain chains, reaching a height of about 450-500 m, impact crater is filled with shattered and shocked granite (agizit) represented by ejecta, cataclasite, an autogenetic breccia. Most panned samples and hand specimens contain microdiamond of octahedron habit, gold, platinum, moissanite, metamorphic pyrope-almandine, rhenium, rutile, chrom spinel, kamacite, khangaite (tektite glass), picroilmenite, pyrite, coesite, khamarabaevite, melonite, fayalite, sheelite, graphite-2H, spherocobaltine and zircon.
   All the minerals were investigated on the basis of thin sections, X-ray spectral and structural microanalyses and scanning electron microcopy. The shock effects include presence of coesite and pseudotachylite in samples of granites and abundant vesicular and flowstructured quartz glass. The shattered granite show shock metamorphism in the form of shock melting, pseudotachylite, planar deformation features cleavage in quartz, and near-shatter-conning. Our work on acid-demineralized residues of impact melt racks from crater and panning revealed the presence of silicon carbide (moissanite) crystals, closely associated with the impact microdiamonds. Owing to the use of the tectonic-structural, and as well as have-concentrate mineralogical method we have able reveal the unique occurrences of gold association with diamonds in the Agit Khangay crater, Primary occurences of gold with contents 0.1-0.5 g/ t to 3-5 g/t are confined to crater up to 2-2.5 km in plane. The Agit Khangay primary gold occurences are accompanied by placer gold and scheelite.

2. The Khuree Mandal astropipe structure
   This circuler structure in diameter 10 km has an analogous geomorphological position as an Agit Khangay astropipe crater. The crater is located some 250 km southeast of Agit Khangai within the Upper Paleozoic Buutsagaan-Khureemaral volcanic depression in central Mongolia. The ring morphostructure is distinguished excellently on any aerial images, especially on Landsat of USA.
Main structural elements of this ring structure are following:
1.Inner (amall) ring french of flat central trough-recent unconsolidated deposits
2.Inner ring uplift or inner tectonic bar (central rise)-mesozoic mattresslike granitoids with numerous xenoliths of basic rocks
3.External ring trench or ring depression-recent unconsolidated deposits of alluvial and deluvial genesis
4.Basic branching radiolith (radiated) dykes composed of suevite, tagamite and lavabreccia
5.Inner crater trough-coptomictic gold-bearing gritstone and conglomerate with thickness of 20-25 m. Content of gold-0,16 g/t to 6,33 g/t. An average content of gold by 36 samples is 1,62 g/t.
   It should be emphasized that we have been able to establish gold in bedrocks of different composition for two last years. To today’s 60 samples from various parts of crater are giving content of gold from 0,13 g/t to 4,99 g/t.
   The suevite like rocks and lavabreccia from crater and heavy consentrate mineralogical sampling are showed the presence of microdiamond, moissanite, pyrope crystals, kamacite, tektite glass and rutile.
   These new astropipe structures are considered by the authors as immediate ones for prospecting and indusrtial exploration.

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Geology and Mineralisation of Oyu Tolgoi deposit

C. Forster

Chief Geologist of Oyu Tolgoi project

   The Oyu Tolgoi copper-gold deposits lie within the Gurvansayhan Terrane in the South Gobi Region of Mongolia. The terrane is considered to represent an island arc environment and is largely composed of Siluro-Devonian sediments and volcanics intruded by dykes, stocks and batholiths of a range of compositions. The deposits are immediately north of an ENE trending splay off the major East Mongolian Fault zone.
   The local stratigraphy includes augite basalt overlain by dacitic to andesitic tuffs and a sediment sequence. The basalts are intruded by quartz monzonite stocks which may be comagmatic with the tuffs. These stocks and the surrounding basalts are generally altered and mineralised in the southern part of the area. In the more northern mineralisation the mineralisation is more often in the tuffaceous units. The Palaeozoic rocks are covered by 10 to 20m of Quaternary colluvium.
   The mineralisation delineated by IMMI occurs in four deposits known as South Oyu, South West Oyu, Central Oyu and Far North Oyu. The first three are currently regarded as targets for open pit mining while the Far North deposit is generally regarded as a target for underground exploitation.
   Alternation patterns are complex and the subject of ongoing investigation. The strongest copper-gold mineralisation is associated with silicification, which varies from discrete quartz veining to network veining and silicia flooding. This may be accompanied by intermediate to advanced argillic alteration but this is influenced by the host rock composition. The alteration minerals associated with the strongest mineralisation varies between the deposits.
   At South West Oyu the host to most of the mineralisation is altered augite basalt. The higher grade mineralisation and quartz veining is associated with biotite-magnetite alteration. More extensive chlorite-sericite alteration grades out into propylitic alteration/. The sulphide assemblage is relatively uniform chalcopyrite-pyrite. Gold content drops off quite quickly outside the central core but copper grades decline more gradually.
   The South Oyu mineralisation and host lithology are broadly similar to those at South West Oyu, but without any distinct higher grade core. There are some occurences of secondary copper and supergene chalcocite. The drilling pattern is sparse and irregular and as a consequence the deposit is not well understood.
   At Central Oyu the higher grade mineralisation is mostly hosted by quartz monzo-diorities with accompanying silicia and sericite alteration. This appears to grade outwards into chlorite alteration. The copper mineralogy is distinctly zoned with an extensive supergene chalcocite blanket overlying a funnel-shaped covellite-pyrite zone which is underlain and enveloped by a chalcopyrite-pyrite zone.
   The Far North mineralisation is mostly related to strong quartz veining in the andesitic-dacitic tuffs and accompanied by dickite, pyrophyllite and alunite. The higher grade mineralisation tends to be bornite-chalcopyrite based with chalcopyrite more dominant as the grade weakens.
   Faulting is probably an important factor in the disposition of the mineralisation at all four deposits. Post-mineralisation faults are recognised on satellite imagery and magnetic surveys and are appearent in the core. It is clear that the eastern boundary of South West Oyu mineralisation is fault controlled and MS suspects that there are other fault controlled boundaries and offsets in the mineralisation.
   The South Gobi region is an ancient weathered surface with deep oxidation. This has an important impact on ore mineralogy and hence metallurgical performance and also on mining costs. The nature of the weathering profile is not specifically recorded in the geological logs and can only be inferred from other observation. This should be rectified as soon as possible.

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Microfauna of the Shar teeg locality

L.Gereltsetseg

Paleontological Center of Mongolian Academy of Science

   Shar Teeg locality is situated within the Gobi-Altai aimag. Between Aj Bogd to the North, the Edrengiin Nuruu Ranges to the Northeast and the Atas Bogd Mountain Range to South. It is approximately 80 km East-Southeast from Altai sum of the Gobi-Altai aimag.
   The locality was studied by the Joint Soviet-Mongolian Paleontological Expedition during the field season of 1984, 1987 and 1989.
   From the Shar Teeg locality were found ostracods, charophytes, insects, fishes, concostracans, plants, amphibians, turtles, crocodiles, dinosaurs and mammals.
   By the scientists M.N.Efimov (1988), M.A.Shishkin (1991), L.Gereltsetseg (1992), J.M.Gubin and S.M.Sinitsza (1996) was considered as the Shar Teeg deposits, Middle-Late Jurassic and Lower Cretaceous.
   The Shar Teeg sequences have subdivided (Gubin & Sinitsza, 1996) into two beds: the lower one is Shar Teeg and the upper one is Ulaan Malgait.
   We have done researching works in the Shar Teeg locality, in the year of 2002 during summer season.
   From the seven levels of the Shar Teeg beds, were found microfaunas (ostracods, charophytes).
   Ostracods: are represented by the Darwinula aff. sarytirmensis (Sh.tg.02/04, Sh.tg.02/11, Sh.tg.02/13), D.aff. grandis (Sh.tg.02/13), D.arkitensis (Sh.tg.02/13), D.isfarensis (Sh.tg.02/13), D.aff. nimia (Sh.tg.02/13, Sh.tg.02/08, Sh.tg.02/09) and Timirasevia sp. (Sh.tg.02/13).
   The species Darwinula sarytirmensis is known from the Middle Jurassic sediments Mangishlaka (Russian), Mongolia (Bachar complex, Middle-Late Jurassic) and China.
   The species Darwinula aff. grandis, D.arkitensis, D.isfarensis are known from the Middle-Late Jurassic sediments in Fergana Valley (Uzbekistan).
   Darwinula aff. nimia was determined formerly from the Late Jurassic of the Eastern Baikal.
   Charophytes: are represented by the Jurella abshirica (Sh.tg.02/13, Sh.tg.02/09), J.ovalis (Sh.tg.02/13, Sh.tg.02/07), J.ferganensis (Sh.tg.02/13, Sh.tg.02/03), J.karierica (Sh.tg.02/13, Sh.tg.02/09, Sh.tg.02/10). All charophytes are known from the Middle-Late Jurassic sediments in Fergana Valley (Uzbekistan).
   Analysis of all microfaunas data from the lower part of the Shar Teeg beds show that it is apparently Middle-Late Jurassic.

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BULK ANALYSIS METHOD OF GOLD DETERMINATION IN ORES USING EPITHERMAL NEUTRON OF CYCLIC ELECTRON ACCELERATOR MICROTRON MT-22.

A.Karivai*, Sh.Gerbish, G.Ganchimeg** and G.Ganbold***

*Central Geological Laboratory
**Nuclear research center, Mongolian National University
***Joint nuclear research institute in Dubna, Russia

1 INTRODUCTION
   The studies of gold deposits and its processing required a fast and efficient analytical  methods for determination of gold and other major or minor elements in ores. The determination of major and minor elements has provided important information about minerals resources, geochemistry data and apart from ecological consequence of heavy metals and toxic elements, which also gives possibility to improve reliability of prospecting deposits.
   The fire assay method is one of the analytical techniques, with detection limit of  0.2 mg/kg in 50 g samples weight [1,2]. The fire assay method is combined with AAS and ICP Techniques can be used to quantify the gold content.
   Presently, the instrumental analytical methods such as activation analysis with low power (~20 kW) research reactor [3], particle accelerators [4] and isotope neutron sources, with neutron flux of 10E+8 to 10E+11 neutrons per square cm and per second are applied for gold analysis. Detection limit of the nuclear methods can be in the range of  0.01 - 0.1 mg/kg for representative weight ( 30-60 g) samples [5-6].
   The cyclic electron accelerator the microtron MT-22, which was installed in 1994 at Nuclear Research Center, National University of Mongolian [7] has been widely used as a nuclear analytical method for elemental analysis including gold. The electron cyclic accelerator have some advantages over other nuclear physical equipment, such as in term of safety, low cost, easy for operation and no requirement high level radiation protection.
   Some ores samples consist of several kind of deposits were used to study of the applicability of accelerator MT-22 (All samples are collected by A.Karivai and G. Ganchimeg) for determination of gold.
   Reference gold ores materials, which were supplied by Central Geological Laboratory such as USZ 21-98 (1.06±0.16 mg/kg); USZ 23-98 (3.28±0.19 mg/kg) and USZ 31-2000 (10.72±0.81 mg/kg) are used as quality control material. These Reference materials were approved by Mongolian National Agency of Standardization. The samples with variable matrix were analyzed, which allows to estimate detection limit of gold and some other elements in real samples.

2 MATERIAL AND METHODS
   The 30-60g weight Ore’s samples were packed in polyethylene capsules (Q=7.3 cm, h =1.3 cm) and are placed inside irradiation channels of Photo neutron source ? 2.0 x 2.0 x 1.2 cubic m Graphite cube of microtron MT-22.
   In the Center of Graphite cube of microtron MT-22 a Metallic Uranium rod with  530 g weight in Al capsule as target was used. The photo neutrons emitted by 238U(g,n) reaction, having energy of electrons up to 22 MeV and the current 10-15 mA. All gold Ore’s samples and Reference materials were irradiated together on horizontal irradiation channels of cube in Cd cover.
    The ratio RCd as following:
Channel Number IRRATAITIONCHANNEL-1 IRRATAITIONCHANNEL-2 IRRATAITIONCHANNEL-3 IRRATAITIONCHANNEL-4
RCd for Au 1.87 1.93 2.0 1.94
   The low ratio RCd for gold (1.9-2.0) give possibility of decreasing Compton Radiation background in the region of 411.8keV analytical peak and analytical peaks of trace elements ( Na, Sc, Cr, K without Sb, As).Consequently, total activity of samples was decreased but not the activity of 411,8 keV of gold. Experimentally the optimized irradiation, cooling and measuring time for gold analysis  is tirr = 1- 4 h, tcool = 10 - 24 h and 20 min., respectively.

3 RESULTS AND DISCUSSION
   The distribution of neutron in channels was measured using gold monitors, which was placed between samples and reference materials. The monitors  were prepared by dropping with pipette 300 mg Au on filter paper.
   The self absorption of 411.8 keV energy peak of Au-198 in samples was calculated according exponential absorption equation as follows with thickness of sample, x:
I = Io ( Ko-1) / ( ln Ko )               (1)
Where:    Ko  is exp (-mx);  m is linear mass absorption coefficient;
          Io  is intensity of radiation at x = 0;
    I is measured intensity of radiation at thickness x.
   The Ko coefficient is determined  by measuring irradiated gold’s 411.8 keV analytical peak intensity using various samples of different matrices. Results of measurements showing that the absorption of the 411.8 keV energy line peak intensity varies from 0.5% in quartz gold ore up to 5% in sulphite base metallic ores.
   The detection limit (DL) for gold is determined using gold reference materials irradiated by mixed (thermal and epithermal) and epithermal neutrons using the following equation:
DL =  CAu x ( )    (2)

Where:    Sbg is background under the analytical line;
  SAu is analytical peak area of Au-198;
  CAu is concentration of gold in reference material.

   The activities of irradiated samples were measured using gamma spectrometer with HP Ge detector GC 3020 and PC analyzer  S-100 CANBERRA. Energy resolution of the detector was 1.9-2.2keV for 1332 keV energy line of  60Co.  The measuring time for samples 20 min and for monitors 5 min, respectively. For quantitative determination of gold content in samples 411.8 keV.
   The detection limit of gold achieved in this condition was in the range of  0.1 to 0.3 mg/kg, that is adequate for prospecting and exploitation of gold deposits purpose. In these experiments, the irradiation of samples in Cd should be used for bulk analysis method of gold, whilst for determination of other elements together with Au the samples should be without Cd cover.
   Results of comparison analysis of gold ores samples by two INAA and the fire assay methods are shown in Table 2.
 

Literature
1. Barishnicov I. F Sampling and Analysis of precious metals. (In Russian), M. 1998
2. Khaidarov A. A. Nuclear physics methods for Analysis of rocks. (in Russian), Tashcent, PhAN, 1969, p.22.
3. Benevolenscii A. M  ets. “ARGUS-21” reactor for nuclear physics method for Analysis and Control. Book “4-th conference for use of nuclear physics method for solution of science- techniques problems”.(in Russian),  Dubna, 1982.
4.  Phlerov G. N, Lascorin B. N, ets. Application of Microtron and 124Sb+Be Source for Analisis of gold contenting productions. (in Russian), Chemistry, Technology and Analysis of Gold and Silver, (in Russian), Novosibirsc, 1983
5.Matalgina G. I, Pheoctistov U. B, Shtan A. S, Estimation of productivity of Gold Analisis of geological samples in group irradiation by source of neutrons  252Cf. (in Russian) Problems of Atomic Science and Techniques. Series. Radiation Techniques, 1983 Volume, (25), p. 152
6. Phlerov G. N, Burmistenco U. N, Diadin U. B, ets. Perspective of Development the neutron- activation equipments based on powerful Source   124Sb+Be. A.E. 1982, Volume 53, p. 255-260.
7. Gerbish Sh. Investigation and Development of nuclear-physics methods for Analysis of coal and   natural materials I Mongolia. P.H doctor Dissertation, Dubna,1989, p. 113-121,  P.H doctor Thesis   18-89-790, Dubna, 1989.
8 Certificate  of  Reference Materials for  Gold contenting Ores: USZ 21-98 (1.06±0.16mg/kg), USZ 23-98 (3.28±0.19mg/kg)and USZ 31-2000 (10.72±0.81).

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Clay mineral assemblage of lake sediments of Late Quaternary
Lacustrine Systems in Mongolia

Khosbayar P., Ariunbileg S., and Narantsetseg Ts.

Institute of Geology and Mineral Resources, MAS, Ulaanbaatar, Mongolia

The survey results of lacustrine sediments, which located in different regions of Mongolia, are used for study of late Quaternary climate changes. Especially, the study of Mongolian Lake Systems record Holocene climate change is a very important part of effective study. [J. Peck and others, 2000]
This abstract is continuous part of joint project of Mongolian and American researchers that based on detailed study on clay minerals of lacustrine sediments in Mongolia. The results are compared to results of other studies and are detailing the paleo-climatic changes of Holocene period. There were obtained some continuing records of climate changes during Upper Pleistocene-Holocene, as a result of drilling carried out to mountain regions in Khangay and Khuvsgul in frame of Mongolian-American joint project labeled “High resolution, interdisciplinary paleoclimatic studies of Late Quaternary lacustrine systems in Mongolia”
   Lacustrine sediments of Baikal Lake containing diatoms and biogenic silica are presenting marks of paleoclimatic changes. Alternation of diatomic mud and terrigenic clay is corresponding to climatic changes of cold and warm periods. Climatic changes are reflecting periodic variability of sedimentary contents in lakes of Mongolia and are presented by clay association, biogenic silica and terrigenic pelite of lacustrine sediments. [4, 5, 6]
   Correlation of lithological sections  were occurred differences in muddy clay and diatom clay, which were observed in core profile of lakes Dood, Erkhel Telmen, Terkhiin Tsagaan and Ugiy (figure 1 and 2). A consistent clay mineral assemblage, containing illite, illite-smectite, smectite, kaolinite, chlorite and glauconite as the major minerals, characterizes much of the modern sediments. The relative occurrence of these minerals changes with depth in core from various parts of the lake sediments. (figure 3 and 4)
   Clay association dominated by smectite, illite-smectite, chlorite and kaolinite is related to warm periods of climatic changes. In other word, chemical weathering of clay minerals is increasing in rising temperature. Association of clay minerals formed in cold periods consists of illite, illite-smectite and chlorite. There were compiled curves of climatic changes in column for total length of lake sediment core of Mongolian lakes, based on determination of clay association. Then there were taken comparison between the climatic changes and results of radiocarbon (C14) age determination defined on study of organics distinguished from lake bottom core. These climatic changes compiled on clay association have been correlated to the data collected on diatom. The facts collected on study of the clay association formed in cold and warm periods can characterize environmental change related time intervals (figure 5).
   Qualitative estimation made on K-feldspar and plagioclase observed in sediments, and ratio terrigenous minerals allow to evaluate the degree of chemical weathering in different periods. By comparing the compositions of bottom sediments demonstrate the use of the clay mineral association as indicators of past changes of environment and climate.  Therefore clay association study can be used as paleoclimatic change indicator for survey of Late Ouaternary lacustrine systems of Mongolia.

References:
1. Williams D.F., Peck J., Karabanov E.B. et al. Lake Baikal record of continental climate response to orbital insolation during the past 5 million years // Science, 1997, v.278, No5340, p.1114-1117
2. Colman S.M., Peck J.A., Karabanov E.B., Carter S.J., Bradbury J.P., King J.W, and Williams D.F., 1995, Continental climate response to orbital forcing from biogenic silica records in Lake Baikal: Nature v.378, p.769-771
3. John A.Peck., P.Khosbayar., Sarah J.Fowell., Richard B. Pearce., S.Ariunbileg., Barbara C.S. Hansen., Nergei Soninkhishig. 2002, Mid to Late Holocene climate change in north central Mongolia as recorded in the sediments of Lake Telmen: PALAEO,183(2002). p.135-153.
4. Khosbayar P., Peck J.A., Fowell S.J., Ariunbileg S., Erdenejav G., King Y., Williams D, 1999, High Resolution Inderdisciplinary Paleoclimatic studies of Late Quaternary Lacustrine Systems in Mongolia, Mongolian Geoscientist, 14, p.48-50
5. Peck J.A., Khosbayar P., Fowell S.J., Ariunbileg S., Erdenejav G., King Y., Williams D, 1999, Late Quaternary climate change as recorded in Mongolian Lake sediments, EOS, Transactions 80. p.501
6. Peck J., Khosbayar P., Sarah Fowell at all/2000, Mongolian Lake systems Record Holocene climate change., Proceedings of the Conference on Mongolian Paleoclimatatology and Envoronmental Research, November 3-4, 2000, p. 45-54

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THE APPLICATION OF ATOMIC ABSORPTION SPECTROMETRY (AAS) TO THE SOME MICROELEMENTAL (Hg, Se) ANALYSES OF WATER SAMPLES

S.Tuul1, Ch.Tserenkhuu1, Munkhgerel2

1 Central Geological Laboratory
2 Mongolian State University

1. Introduction
   Atomic absorption spectrometry (AAS) is one of the most commonly used instrumental techniques of analysis for the quantitative determination of metals and metalloids particularly in water samples, including those from wastewater, sludges and wastes.
   The main advantages of AAS are its high specificity and selectivity, the sensitivity being variable over broad ranges depending on the type of atomization selected (flame, graphite, cold vapor or hydride technique)
   This report demonstrates that the determination of mercury and selenium using SHIMADZU-AA6501F atomic absorption spectrometer with HVG and MUV in water shows all required analytical capabilities to analyze water with high precision and accuracy and excellent sensitivity and rapid analysis.

2. Mercury
2.1 General remarks
   Inorganic mercury compounds (ionogenic) and organic compounds such as methyl mercury, ethyl mercury and so on may occur in water. It is therefore of interest in analysis to differentiate between inorganic and organically bonded mercury.
   The method of quantitative determination which has gained widest acceptance is the variant of AAS using the cold vapour technique with and without decomposition. Organically loaded water samples must also be decomposed before measurement.

2.2 Mercury AAS with cold vapour method
Principle of the method
   Mercury ions are reduced to metallic mercury with tin(II) chloride. The metallic mercury is transferred into a quartz cuvette with the aid of a current of inert gas and the absorption of the atoms is measured in the beam of an atomic-absorption spectrometer.

2.3 Procedure
   Transfer 200 ml of the stabilized water sample into the reaction vessel of the system.
   Begin measurement and at the same time continuously add 10 % tin (II) chloride solution.
   Transfer the mercury vapour by means of the carrier gas flow into a quartz cuvette and measure in the beam of the atomic-absorption spectrometer.
   Measure blank and calibration solutions in similar fashion.

3. Selenium
3.1 General remarks
   In natural waters selenium occurs only in very low concentrations. Sea water contains an average of about 0.005 mg/L. Higher concentrations are rarely found in surface waters.

3.2 Principle
   Using sodium borohydride, selenium ions are reduced to selenium hydrid transferred to a heated quartz cuvette with the aid of a current of inert gas, decomposed thermally, and the absorption of the atoms is measured the beam of an atomic-absorption spectrometer. In the hydride technique the element which is to be determined is volatilized as a gaseous hydrid and separated off from the matrix. Interferences may occur if there is considerable excess of elements such as antimony, arsenic, tin, bismuth mercury, or tellurium, which may also be volatilized using this technique
   Since the hydride technique only permits quantitative detection of selenium (IV), selenium (VI) must be converted to selenium (IV) by prereduct (boiling in a strongly hydrochloric -solution at the reflux).

3.3 Procedure
   Transfer 30 ml of the prereduced solution to the hydride system. Allow a constant current of inert gas (argon) to flow through the system at 30 l/h to expel_ the air. Following this, continuously add 3 % sodium borohydride solution using a peristaltic pump. Selenium ions are reduced to selenium hydride and directed by the current of inert gas into a quartz cuvette heated to 800 °C where they are thermally decomposed.
Measure the absorption m

4. Conclusions
For water analysis the Shimadzu provides excellent detection limits at low /ppb/ levels.
1.This method is applicable to mercury contents between 1-15 ppb in water sample using Hg 235.7 nm AA6501F by mercury cold vapor
2. This method is applicable to selenium contents between 8-50 ppb in water sample using Se 196.0 nm AA6501F by HVG

References
1.   Water analysis by SPECTRO CIROSCCD ICP-OES spectrometer
P. Heitland SPECTRO Analytical Instruments, Boschstr. 10, D-47533 Kleve
2.  W.Fresenius, K.E. Quentin, W. Schneieder,   Water analysis. A Practical guide to Physico-Chemical,Chemical and Microbiological water examination and Quality assurance
3. Method 7740 Selenium (atomic absorption, furnace technique)
4. Method 7741 Selenium (atomic absorption, gaseous hydride)
5. Analysis of soil and sewage sludge by    ICP-OES
P. Heitland   SPECTRO Analytical Instruments, Boschstr. 10, D-47533

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THE NEW PLANTS OF UPPER PERMIAN COAL DEPOSITS IN SOUTHERN MONGOLIA

L. URANBILEG

Paleontological center, MAS
(Ulaanbaatar-210351, st. Enkhtaivan-63, box-260)

   Fossil plants are stratigraphycal one of most important  groups of the Permian period of Mongolia.
   In the Upper Permian coal deposits (scheme 1: Tavantolgoi, Yamaan-us, Noyon, Erdene-bulag)  had been established 9 successive assambleges of fossil plants belonging to 28 species.
   Among them 4 species described first:? Callipteris sp. nov.1 /fig.1:Yamaan-us/ (Pinophyta ? Peltaspermales); Cordaites pseudoinsignis sp. nov. /fig. 2: Yamaan-us/ C. longissima sp. nov. /fig.3: Tavantolgoi, Yamaan-us, Noyon/, C. pseudogracilentus sp. nov. /fig.4: Tavantolgoi, Yamaan-us, Erdene-bulag/ (Pinopsida ? Cordaitanthales).
   From the upper coal series of plants in Southern Mongolia /Yamaan-us/ discovered first:  Takhtajanodoxa /fig.5/ (Lepidophyta), Peltaspermalian pteridosperms with foliage Pursongia /fig.6/ and Peltaspermopsis /fig. 7/, which is characteristic for Upper tatarian flora from the Russian stone and Southern Priuralia.
   On the basis of the established 9 succesive assemblages of fossil plants was submitted first new stratigraphycal scale (scheme) for the coal-bearing Upper Permian deposits of Mongolia.

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