Abstract
COMPOSITIONAL variations in pyroclastic deposits have been used as indicators of pre-eruptive chemical gradients in magma chambers and of processes leading to compositional stratification1,2. Theoretical studies of the fluid dynamics of magma withdrawal from stratified chambers have shown that compositional gradients in the products erupted at the surface are not merely inversions of the gradients that had existed in the magma chamber. These studies predict that complex mixing can occur across stratified layers, and that withdrawal of dense underlying layers through overlying low-density layers can occur given certain combinations of discharge rate and magma density contrast3–7. These predictions have yet to be quantitatively verified, however, because simultaneous measurements of eruption dynamics and compositional gradients for a specific eruption have not been collected. Here we explore the relationship between chemical gradients observed in pyroclastic deposits and the dynamics of magma withdrawal, by modelling the temporal evolution of magma discharge rate during the AD 79 eruption of Vesuvius in Italy. The results provide evidence that compositional gradients in zoned deposits cannot be properly interpreted without consideration of the dynamics of magma withdrawal.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
