Systematic tapping of independent magma chambers during the 1 Ma Kidnappers supereruption
Systematic tapping of independent magma chambers during the 1 Ma Kidnappers supereruption
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DOI：
10.1016/j.epsl.2011.11.006
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发表时间：
2012-01-01
影响因子：
5.3
通讯作者：
Smith, Euan G. C.
中科院分区：
文献类型：
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作者：
Cooper, George F.;Wilson, Colin J. N.;Smith, Euan G. C.
新西兰陶波火山区Mangakino火山中心1.0 Ma的绑架者超喷发（类似于1200 km（3）DRE）产生了一个大型的蒸汽岩浆瀑布存款，随后是一个非常广泛的熔结凝灰岩。通过近4.0米部分的下降存款，代表了前三分之二的喷发外破火山口材料的玻璃碎片和矿物相的详细采样和分析已经进行。玻璃碎片的主要和微量元素化学定义了三种不同的人群（类型A，B和C），通过秋季存款系统的比例变化，并推断代表三种岩浆类型。B型玻璃和黑云母首次出现在同一水平（类似于0.95米以上的基地），在秋季存款，建议后来的攻丝含黑云母岩浆。斜长石和Fe-Ti氧化物组合物显示双峰分布，这与A型和B型玻璃组合物有关。温度和压力（T-P）估计从角闪石和Fe-Ti氧化物平衡从每种岩浆类型是相似的，因此，这三个岩浆体相邻，而不是垂直堆叠，在地壳中。大多数角动量模型T-P估计值的范围为770至840摄氏度和90至170 MPa，对应于类似于4.0-6.5 km的储存深度。Hornstellar模型T-P估计加上原位微量元素指纹意味着岩浆体单独混合良好，而不是分层。三种玻璃成分类型之间的组成差距意味着这些岩浆之间没有发生混合。我们解释这些数据，再加上在整个秋季存款的碎片成分比例的系统变化，以反映三个独立的熔体占主导地位的岩浆机构作出了很大的贡献，（A，类似于270公里（3）），中等（B，类似于90 km（3））和小（C，类似于40 km（3））体积（如瀑布沉积物所反映的），并在喷发期间系统地挖掘。我们认为，三个独立的岩浆体的系统疏散意味着有构造触发和喷发的联系。我们的研究结果表明，超级喷发可以产生几乎同时多个喷发从独立的岩浆房，而不是疏散一个大的单一的岩浆房。(C)2011 Elsevier B. V.保留所有权利。
The 1.0 Ma Kidnappers supereruption (similar to 1200 km(3) DRE) from Mangakino volcanic centre, Taupo Volcanic Zone, New Zealand, produced a large phreatomagmatic fall deposit followed by an exceptionally widespread ignimbrite. Detailed sampling and analysis of glass shards and mineral phases have been undertaken through a proximal 4.0 m section of the fall deposit, representing the first two-thirds of erupted extra-caldera material. Major and trace element chemistries of glass shards define three distinct populations (types A, B and C), which systematically change in proportion through the fall deposit and are inferred to represent three magma types. Type B glass and biotite first appear at the same level (similar to 0.95 m above base) in the fall deposit suggesting later tapping of a biotite-bearing magma. Plagioclase and Fe-Ti oxide compositions show bimodal distributions, which are linked to types A and B glass compositions. Temperature and pressure (T-P) estimates from hornblende and Fe-Ti oxide equilibria from each magma type are similar and therefore the three magma bodies were adjacent, not vertically stacked, in the crust. Most hornblende model T-P estimates range from 770 to 840 degrees C and 90 to 170 MPa corresponding to storage depths of similar to 4.0-6.5 km. Hornblende model T-P estimates coupled with in situ trace element fingerprinting imply that the magma bodies were individually well mixed, and not stratified. Compositional gaps between the three glass compositional types imply that no mixing between these magmas occurred. We interpret these data, coupled with the systematic changes in shard compositional proportions through the fall deposit, to reflect that three independent melt-dominant bodies of magma contributed large (A, similar to 270 km(3)), medium (B, similar to 90 km(3)) and small (C, similar to 40 km(3)) volumes (as reflected in the fall deposits) and were systematically tapped during the eruption. We propose that the systematic evacuation of the three independent magma bodies implies that there was tectonic triggering and linkage of eruptions. Our results show that supereruptions can be generated by near simultaneous multiple eruptions from independent magma chambers rather than the evacuation of a large single unitary magma chamber. (C) 2011 Elsevier B.V. All rights reserved.