Environmental Engineering Reference
In-Depth Information
Figure 12.1 Distribution of LIPs and volcanic basins. Basalt
flows are shown in
red colour. Sedimentary basins injected by sills and dykes (i.e. volcanic basins)
mentioned in the text are outlined with heavy lines. Other major volcanic basins
are indicated by black
figure will
appear in some formats.
For the colour version, please refer to the plate section
.
filled circles. A black and white version of this
Figure 12.2 Schematic cross section through a volcanic basin, showing sills and
dykes, degassing from contact aureoles and subsequent pipe formation, and
degassing from the
flood basalts. The composition of the gases formed during
contact metamorphism depends on the composition of the sediments.
Sills and dykes are abundant throughout the Tunguska Basin, and form sheets
up to 450 m thick, locally comprising up to 70% of the basin
fill (Fedorenko and
Czamanske,
1997
; Vasil
'
ev
et al
.,
2000
). Contact metamorphism and dolerite
-
sediment mixing led to overpressure within salt-dominated lithologies and resulted
in the formation of explosion pipes that ejected tephra and a range of gases to the
