Alkaline Rocks and Carbonatites of the World

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Shvanidzorskii

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Occurrence number: 
009-00-009
Country: 
Armenia
Location: 
Longitude: 46.38, Latitude: 39

Shvanidzorskii is situated in the southeastern part of the Megrinskii granitoid pluton and is confined to a fracture zone striking northwest. The massif consists of three intrusive phases (1) medium-grained melanocratic and mesocratic peralkaline syenites, (2) pegmatitic leucocratic syenites and (3) fine-grained nepheline syenites. There are also olivine-bearing gabbros of the essexite-theralite family. The most common rocks are the pegmatitic leucocratic syenites, which account for 85% of the intrusion. The principal rock-forming minerals are orthoclase-microperthite, oligoclase, nepheline, biotite and aegirine with accessory minerals including sodalite, monazite, pyrochlore, fluorite, cancrinite, calcite, ilmenite, apatite, zircon, titanite, baddeleyite and tourmaline. Fenitization of the country rocks (Devonian volcanics and diorites) is widely developed.

Economic: 
Within the massif there are rare-earth pegmatites and carbonate-bearing veins with high contents of Th, REE, U and Pb (Bagdasaryan, 1954; Meliksetyan, 1963a and b and 1971).
Age: 
K-Ar and Rb-Sr determinations gave ages from 37 to 40 Ma (Bagdasaryan and Gukasyan, 1962; Gukasyan, 1963).
References: 
ABOVYAN, S.B., AGAMALYAN, V.A. and ASLANYAN, A.T. et al. 1981. I.G. Magakyan (ed) Magmatic and metamorphic formations of the Armenian SSR. Akademii Nauk Armyanskoi SSR, Erevan. 331 pp. ADAMYAN, A.I. 1955. Petrography of the alkaline rocks of the Megrinsky region Armenian SSR. Akademii Nauk Armyanskoi SSR, Erevan. 102 pp.BAGDASARYAN, G.P. 1947. Nepheline syenites of the Pambaksky shield. Doklady Akademii Nauk Armyanskoi SSR. Erevan, 1: 19-35. BAGDASARYAN, G.P. 1954. Alkaline pegmatites of central Armenia. Doklady Akademii Nauk Armyanskoi SSR. Erevan, 19(4): 117-22. BAGDASARYAN, G.P. 1966. Intrusive rocks of the Basumo-Pambaksky region. In Geology of the Armenian SSR. Petrography. Intrusive rocks. 3: 256-308. Armenian Academy of Sciences, Erevan. GEVORKYAN, R.G. 1965. Geochemical peculiarities and petrogenesis of the alkaline rocks of central Armenia. Trudy, Moscow. 144 pp. GUKASYAN, R.X. 1963. Determination of the absolute age by the Rb-Sr method on a sample from the Megrinsky pluton Armenian SSR. Doklady Akademii Nauk Armyanskoi SSR, Seriya Geologiya. Erevan, 36 (3): 173-78. KOCHINYAN, R.E. 1975. Mineralogy and geochemistry of the alkaline rocks of the Pamback. Akademii Nauk Armyanskoi SSR, Erevan. 175 pp. KOTLYAR, V.N. 1939. Discovery of the leucitic rocks in the Caucasus. Sovetskaya Geologiya, 4-5: 4-11.MELIKSETYAN, B.M. 1963a. On the mineralogy, geochemistry and genesis of pegmatites of the Megrinsky pluton. In 70-anniversary volume dedicated to K.N. Paffengolts, 71-98. Akademii Nauk Armyanskoi SSR, Erevan.MELIKSETYAN, B.M. 1963b. Mineralogical geochemical peculiarities of the alkaline rocks of the Magrinsky pluton. Ivestiya Akademii Nauk Armyanskoi SSR, Erevan, 2: 57-80. MELIKSETYAN, B.M. 1971. Mineralogy, geochemistry and petrological peculiarities of the Tezhsarskii complex. In Petrology of the intrusive complexes of the important regions of the Armenian SSR. 117-308. Akademii Nauk Armyanskoi SSR, Erevan. TATEVOSYAN, T.Sh. 1966. Intrusive rocks of the Bargushatsk ridge. In Geology of the Armenian SSR. Petrography. Intrusive rocks, 3: 114-214. Akademii Nauk Armyanskoi SSR, Erevan.
Location: 
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