Entrainment of Country Rock during Basaltic Eruptions of the Lucero Volcanic Field, New Mexico
As magma rises through the lithosphere it may entrain wall rock debris. The entrainment process depends on the local hydrodynamic regime of the magma (e.g., velocity, temperature, bulk density), the extent of interaction of magma with groundwater, and the mechanical properties of the wall rocks. Wall rock entrainment results in local flaring of dikes and conduits, which in turn affects the hydrodynamics of magma ascent and eruption. We studied upper-crustal xenoliths erupted from small-volume basaltic volcanoes of the Lucero volcanic field (west-central New Mexico) in order to assess the relative importance of various entrainment mechanisms during a range of eruptive styles, including strongly hydrovolcanic, Strombolian, and effusive processes. Total xenolith volume fractions ranged from 0.3-0.9 in hydrovolcanic facies to $$<10^{-4}-10^{-2}$$ in Strombolian facies. The volcanoes erupted through a thick, well-characterized sequence of Paleozoic and lower Mesozoic sedimentary rocks, so that erupted xenolith...