Revised conceptual model for maar-diatremes: Subsurface processes, energetics, and eruptive products
Revised conceptual model for maar-diatremes: Subsurface processes, energetics, and eruptive products
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修订后的 maar-diatremes 概念模型：地下过程、能量学和喷发产物
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
J. White
中科院分区：
文献类型：
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作者：
G. Valentine;J. White
地掷石是玛耳下面的碎屑填充结构，是单成因火山在其生命周期中多次岩浆-水（蒸汽岩浆）爆发的结果。一个长期存在的模型需要加深爆炸，由于地下水位下降，从爆炸现场喷射出越来越深的围岩，而覆盖的直径和表面火山口由于沉降而扩大。提出了一个修正模型，其中爆炸可以发生在任何级别内的一个diatreme在给定的时间，最有效地通风材料从近表面爆炸。火山灰沉积物中的深层围岩岩屑记录了向上定向的碎屑射流和向下沉降的物质逐步垂直混合，而不是直接从深层爆炸中喷出。在一次特定的爆炸中喷发的幼年碎屑和岩屑碎屑在碎屑岩中可能有一个复杂的历史，不一定直接反映在使它们喷发的爆炸过程中的碎裂或角砾化作用。
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.