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Unformatted text preview: ltim a te ly
b e c o m e s d is s o c ia te d
w ith u p p e r p a r t. Cooling during flow Initial temperature (i.e., temperature when the flow
“hits the ground”) of
ignimbrites are largely a
function of initial velocity,
and hence water content. Why? Cooling of several hundred Initial temperatures of ignimbrite
ﬂows in the Sparks et al. (1978)
model. degrees may occur in the
“fountain”. In the flow itself, cooling is
very limited - perhaps 50°. Welding requires T>625°C
(898 K). 12 Other Processes During Flow Grinding and crushing particles in flows,
effectively destroying large clasts and
creating small ones. P y r o c la s tic d e p o s its r ic h e r in c r y s ta l
fr a g m e n ts th a n a s s o c ia te d fa ll d e p o s its Diffusion of remaining magmatic gas out
of fine particles Fluidization Fluidization in Flows F lu id iz a tio n o c c u r s w h e n u p w a r d d r a g e x e r te d
b y g a s o n p a r tic le s e q u a ls s e ttlin g v e lo c ity . F in e p a r tic l...
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This document was uploaded on 03/04/2014 for the course EAS 458 at Cornell University (Engineering School).
- Fall '06