ey) 
A N:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 1 
posterior to the displacement which probably took place at 
the same period as the eruption of the basalt, is certainly 
more than the actual height of the Sviatoy Noss mountain, 
i. e. considerably over 1,000 meters. 
The dike-rocks connected with the intrusion of he granite 
are of three principal types: 1) pegmatite, 2) aplite 
and 3) lam prophyric rocks. 
The dikes of peg matite are most closely connected 
with the granites, appearing within the masses of granite 
as primary dikes and occurring also in all parts of the mig- 
matite area. We may discriminate three different kinds of 
pegmatite 1) One kind is characterized by microcline and 
quartz as the main constituents. Dikes of this type of 
common pegmatite are equally distributed in the 
granite and in the migmatite area. 2) Another kind of 
pegmatite which will be called diopside-pegma tänk e; 
is characterized by oligoclase and diopside besides much 
titanite and a little quartz. This pegmatite occurs only in 
the limestone areas and,in their close neighbourhood. 3) A 
third kind of pegmatite will be termed as horn blend e- 
pegmatite. Its main constituents are a rather anorthitic 
plagioclase (andesine) and brown hornblende, while potash 
feldspar is absent and quartz is only sparingly present. 
A characteristic accessory of this pegmatite is orthite, 
a mineral which is, in small amounts and as minute crystals, 
also found in the granites and in the other kinds of pegmatite. 
The hornblende-pegmatite occurs only as intersecting the 
amphibolites in the northern portion:of Sviatoy Noss. 
The dikes of a p lit e are also found in evident geological 
connection with the granites, occurring within the granite 
area as well as in the migmatite. The aplitic granite forming 
a marginal zone of the granite batholith, is petrographically 
very like the aplite in the form of dikes, but having a little 
S larger quantity of micas. The aplite is the most common of 
all the dike-rocks on Sviatoy Noss. 
With the aplite are often associated dikes of I a m pr o- 
phyric rocks being either somewhat older or younger 
othan the former. Most of them are kersantites. 
