Alkaline Rocks and Carbonatites of the World

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Garnasar

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Occurrence number: 
009-00-001
Country: 
Armenia
Location: 
Longitude: 44.78, Latitude: 40.82

This complex occurs within the Prisevanskaya zone, in the central part of the Bazumsky range of the Caucasus Mountains. The Garnasar outcrops of alkaline rocks cover an area of 12 km2 and represent a subvolcanic, laccolith-like body which is confined to a system of northeast-trending faults. The rocks are alkaline syenites and trachytes in which, as seen characteristically in vertical sections, the medium- or fine-grained intrusive syenites are consistantly replaced by trachytes. The syenites are hypidiomorphic rocks with trachytic textures and vary little in composition; potassium prevails over sodium. The rocks of the effusive facies are predominantly alkaline trachytes which are commonly aphanitic but variable in composition; they have the same potassium to sodium ratio as the syenites. The main rock-forming minerals of both the syenites and trachytes are orthoclase, albite-oligolcase, stilbite, natrolite, analcime and biotite. Various types of post-volcanic alteration are manifest including zeolitization, feldspathisation, sericitization and the formation of clay minerals. The Garnasar complex is thought to be closely related to Tezhsar (No. 5).

Age: 
K-Ar on whole rocks gave 34-35 Ma (Bagdasaryan and Meliksetyan, 1966)
References: 
ADAMYAN, A.I. and MKRTCHYAN, K.A. 1959. The Garnasar intrusion of alkaline syenites in the eastern part of the Khalabsky ridge. Transactions of the Department of Geology and Mineral Deposits of Armenia, Erevan. 2: 34-37. BAGDASARYAN, G.P. 1956. Petrography of alkaline effusive rocks. Ivestiya Akademii Nauk Armyanskoi SSR, Seriya Geologiya. Erevan, 2: 25-36. BAGDASARYAN, G.P. and MELIKSETYAN, B.M. 1966. Genetic peculiarities of the Armenian alkaline rocks. Ivestiya Akademii Nauk Armyanskoi SSR, Seriya Geologiya. Erevan, 11: 82-100. DZHSRBASHYAN, R.T. and MELIKSETYAN, B.M. 1974. Geochemical and petrogenetic peculiarities of the alkaline volcanic series of the Pambaksky ridge. In Magmatism and metallogenesis of the Armenian. SR. 54-67. Akademii Nauk Armyanskoi SSR, Erevan. 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. 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.
Location: 
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