Canlaon Volcano's history consists of
both pyroclastic flow and lava flow
eruptions, including at least one major
debris avalanche event. The debris
avalanche event was followed by
rebuilding of the Canlaon edifice by
subsequent pyroclastic flow and lava
flow eruptions. Three major types of
pyroclastic flow deposits have been
identified : (a) Canlaon Block-rich
Pyroclastic Flow deposit; (b) Canlaon
Scoria-rich Pyroclastic Flow deposit;
and (c) Canlaon Pumice-rich Pyroclastic
Flow deposit. There are at least 4 main
types of lava flow units namely: (a)
pyroxene andesite; (b) hornblende
pyroxene andesite; (c) pyroxene basaltic
andesite and (d) olivine-bearing
basalt-basaltic andesite.
New set of stratigraphic data in
combination with petrochemical data were
used to establish the stratigraphic
relationship of Canlaon Volcano products
and to characterize in detail the
chemistry of its eruptive products
through time. The interspersed
relationship of the various pyroclastic
flow and lava flow units suggests shifts
in eruptive behavior from explosive to
effusive episodes.
The composition of the different
products from Canlaon generally fall
within dominantly high-K basaltic
andesite to andesite to dacitic
compositional range (with 52-63 wt% SiO2
and 1.46-3.43 wt% K2O). Mg#
of lavas fall within two separable
ranges, those with Mg# within 60-67 and
37-48. Canlaon’s chemical evolution, in
the context of its presently known
volcano stratigraphy is not a simple
progression from basaltic to silicic
trend. The chemical composition of
magmas through time has varied back and
forth from basaltic-basaltic andesite to
andesite to dacitic which suggests
possibly several episodes of magma
re-supply from depth.
Understanding the wide variety of
eruptive products and temporal variation
of compositions based on stratigraphic
relationships is crucial to the hazards
assessment of Canlaon’s future
activities.