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Y. Majigsuren, A. Kitakaze and S. Jargalan

Mineralogy and Petrology of Shavariin Tsaram and Mandalgobi basalts, Mongolia. Y. Majigsuren, A. Kitakaze and S. Jargalan. Location of Cenozoic volcanics in Mongolia.

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Y. Majigsuren, A. Kitakaze and S. Jargalan

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  1. Mineralogy and Petrology of Shavariin Tsaram and Mandalgobi basalts, Mongolia Y. Majigsuren, A. Kitakaze and S. Jargalan

  2. Location of Cenozoic volcanics in Mongolia I. Western Khubsugul II. Eastern Khubsugul III. Tesiin gol IV. Khanui gol V. Orkhon-Selenge VI. Ugii nuur VII. Tariat-Chuluut VIII. Southern Khangai IX. Dolina-Ozer X. Baruun khuurai XI.Dzabkhan. XII.Gobi Altai XIII. North Gobi XIV. Mandal Gobi XV. Undurshil XVI. Dariganga XVII. Khalkhiin gol

  3. Geological map of the Tariat area

  4. Cross section of the Shavariin Tsaram deposit D

  5. Location of Mandalgobi basaltoids

  6. Schematic geological map of Mandalgobi area

  7. Sanidine Pyroxene Pyrope Olivine

  8. Mandalgobi-basalt. Macrocrystals of biotite in melanocratic fine phenocrysts groundmass.

  9. Shavariin -Tsaram lherzolite. Altered garnet, brown spinel and clinopyroxene in the groundmass.

  10. Mandalgobi basalt. Contact of garnet dark glassy volcanic showing some macroxenocrysts and fine phenocrysts

  11. Shavariin Tsaram basalts. The macrocrystals include orthopyroxenes of enstatite, garnet, plagioclase and xenolyths of host rock.

  12. Mandalgobi basalts. Ground mass of limburgite basalt, showing feldspar microlites, or glassy groundmass. The macrocrystals include pyroxene, olivine and apatite.

  13. Euhedral phenocrysts of magnesium –rich olivine and more iron rich olivine occur on the rims of the phenocrysts and the groundmass. Chemical composition of olivine varies from Fo68.5 to Fo99.6. Olivines in Shavariin-Tsaram basalt (Fo69-Fo99.6) show higher Fo content comparing to Mandalgobi basalt (Fo69.5-Fo90.7).

  14. D i o p s i d e H e d e n b e r g i t e F e r r o s i l i t e E n s t a t i t e • Pyroxenes are mostly in groundmass in Shavariin-Tsaram basalt, and in phenocryst and groundmass in Mandalgobi basalt. Pyroxenes are mostly diopside, and some of them are enstatite in composition. No compositional difference observed between pyroxene in Shavariin-Tsaram basalt and Mandalgobi basalt.

  15. Plagioclases are in phenocryst and groundmass. Plagioclace varies in composition

  16. Xenocrysts of red to dark red colored garnet (pyrope) occur only in Shavariin Tsaram basalt. Pyrope is very low TiO2 and Cr2O3. Cr2O3 below levels typical of diamondiferous kimberlite or lamproite. CaO levels too high for the given Cr2O3 values for diamondiferous source.

  17. SiO2 wt% Tas Diagram Shavar Tsaram basalt is picritic basalt in composition, while Mandalgobi basalt is basaltic andesite. Geochemistry of basaltic rock shows that they are high potassium calc alkaline and composition. SiO2 content varies from 48.8 to 50.7-wt%, while it ranges from 44.2 to 45.8 wt% in Mandalgobi basalt.

  18. Major element variation diagrams for the Shavariin–Tsaram and Mandalgobi basalts. Basalts Shavariin-Tsaram having lower TiO2, Fe2O3, MgO, CaO and higher Al2O3 and Na2O than Mandalgobi basalts.

  19. On MORB normalized trace element spider diagram show basaltic rocks of two areas show similar characteristics. Rocks are enriched in LILE and almost similar to similar with MORB value in HFSE

  20. Thank you

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