Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Dugda

stripes

Occurrence number: 
136-08-010
Country: 
Russia
Region: 
East Tuva
Location: 
Longitude: 97.97, Latitude: 52.12
Carbonatite: 
No

This 40 km2 complex cuts upper Proterozoic marbles and schists as well as gabbroic rocks and granites of Palaeozoic age. The first intrusive phase comprises amphibole-biotite syenites and the second trachytic amphibole- and amphibole-biotite-nepheline syenites; there is also a series of veins which includes feldspathoidal syenite porphyries, phonolite porphyries and nepheline-feldspar pegmatites. The pegmatites are associated with aegirine-nepheline-albite rocks. The compositions of the alkaline rocks are variable and apparently related to the composition of the country rocks. At the contact with fenites, which were formed from schists, in the northern part of the complex the intrusive rocks are amphibole-biotite pulaskites and syenites. At the contact with gabbroids, on the other hand, nepheline syenites are usually rich in pyroxene, plagioclase and nepheline. Trachytic hastingsite-nepheline syenites comprise 50-70% microcline, 20-30% hastingsite, 15-25% nepheline and secondary biotite, cancrinite, sodalite and zeolite.

Age: 
K-Ar on biotite from syenite-diorite gave 278±11 Ma (Yashina and Borisevich, 1966); Pb on thorianite and pyrochlore gave 290±10 Ma (Zykov et al., 1961).
References: 

OSOKIN, E.D., LAPIN, A.V., KAPUSTIN, Yu.L., POHVISNEVA, E.A. and ALTUHOV, E.N. 1974. Alkaline provinces of Asia. Siberian-Pacific group. In L.S. Borodin (ed) Principal provinces and formations of alkaline rocks. 91-166. Nauka, Moscow.
YASHINA, R.M. 1982. The alkaline magmatism of folded-block areas. Nauka, Moscow, 274 pp.
YASHINA, R.M. and BORISEVICH, I.V. 1966. The age of the alkaline rocks of East Tuva. InG.D. Afanas'ev (ed) Dating of the tectono-magmatic cycles and metallogenic stages. 326-36. Nauka, Moscow.
ZYKOV, S.I., STUPNIKOVA, N.I., PAVLENKO, A.S., TUGARINOV, A.I. and ORLOVA M.P. 1961. The age of the intrusions from East Tuva and the Enisei Range. Geokhimiya. Akademiya Nauk SSSR, Moskva, 7: 547-60.

Map: 
Fig. 2_171. Dugda (after Yashina, 1982, Fig. 21).
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith