Abstract
Many intermediate to felsic intrusive and extrusive rocks contain mafic
magmatic enclaves that are evidence for magma recharge and mixing.
Whether enclaves represent records of pro-longed mixing or syn-eruptive
recharge depends on their preservation potential in their intermediate
to felsic host magmas. We present a model for enclave consumption where
an initial stage of diffusive equilibration loosens the crystal
framework in the enclave followed by advective erosion and
disaggregation of the loose crystal layer. Using experimental data to
constrain the propagation rate of the loosening front leads to enclave
“erosion” rates of 10-5 to 10-8 cm/s for subvolcanic magma systems.
These rates suggest that under some circumstances, enclave records are
restricted to syn-eruptive processes, while in most cases enclave
populations represent the recharge history over centuries to millennia.
On these timescales mafic magmatic enclaves may be unique recorders that
can be compared to societal and written records of volcano activity.