Abstract
The time history of magma withdrawal through a central vent from a flat-roofed chamber strongly stratified in density and viscosity has been numerically modeled. It is possible to distinguish continuous from discontinuous (ie, layered) pre-eruptive gradients within chambers. A mechanism for the generation of compositional gaps in ignimbrites following either a short eruption hiatus or an abrupt increase or decrease of the discharge during an otherwise quasi-steady eruption is quantitatively predicted. Most important, a compositional gap or a series of gaps within a pyroclastic deposit does not necessarily mean that one existed within the chamber before the eruption. It is impossible to invert stratigraphically controlled geochemical data to obtain in situ chamber compositional structure if one does not have detailed information regarding the location of vents and the variation of magma discharge with time during a pyroclastic eruption. -from Authors
Original language | English (US) |
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Pages (from-to) | 723-726 |
Number of pages | 4 |
Journal | Geology |
Volume | 14 |
Issue number | 9 |
DOIs | |
State | Published - Jan 1 1986 |