Figure 4. A relationship between of isotope compositions a concentrations of
helium in the gas phases of the fluids. The predominant component of the gas
phase is shown using a special symbol (see the legend in the figure). Where direct
data were not available, the gases of the hydrocarbon pools of the Siberian Craton
were ranked as methanic, and the waters of the West Baikal region, and nitric. The
figure shows the fields characterizing the compared parameters in the ancient
continental crust ("CRUST") and in the basalts of mid-oceanic ridges ("MORB") and
the lines of the mixing of the gases from these reservoirs (inclined shaded band).
The gently dipping black line crossing this band shows the statistically true
relationship trend between the parameters compared in the combined data sample
characterizing the Baikal Rift Zone and its eastern flank
(|r| = 0.376
> 0.26 =
r0.05sign
for
n = 57). The exclusion of the data for the eastern part of the Tunka
Basin and for the Mergitaika Spring (extreme left point in the plot) yielded
|r| = 0.648
0.29 =
r0.05sign for
n = 46. The total data set
(n = 101) also showed
significant correlation
(|r| = 0.476
0.196 =
r0.05sign). The horizontal arrows in
the upper part of the plot characterize variations in He concentration under the
effect of intracrustal processes (see the text for the explanation).