• journal_title：Geology
• Contributor：Greg A. Valentine ; James D.L. White
• Publisher：Geological Society of America
• Date：2012-12-01
• Format：text/html
• Language：en
• Identifier：10.1130/G33411.1
• journal_abbrev：Geology
• issn：0091-7613
• volume：40
• issue：12
• firstpage：1111
• section：Articles

Diatremes are debris-filled structures beneath maars that result from many magma-water (phreatomagmatic) explosions during a monogenetic volcano’s lifetime. A long-standing model requires deepening explosions, due to water table drawdown, that eject progressively deeper-seated country rock from the explosion sites, while the overlying diatreme and its surface crater widen due to subsidence. A revised model is proposed wherein explosions can take place at any level within a diatreme at a given time, most effectively venting material from near-surface explosions. Deep-seated country rock lithics in tephra deposits record stepwise vertical mixing of material by upward-directed debris jets and downward subsidence, rather than direct ejection from deep explosions. Juvenile and lithic clasts erupted during a given explosion may have had a complex history within the diatreme and need not directly reflect fragmentation or brecciation during the explosion that ejects them.