stripes
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.
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.