Collaborative Research: RUI: Probing Caldera-Forming Magmatism: Crystal Accumulation in Large, Upper Crustal Silicic Magma Chambers

合作研究：RUI：探测火山口形成的岩浆作用：大型上地壳硅质岩浆室中的晶体积累

• 批准号: 1249821
• 负责人: Jennifer Wenner
• 金额: $ 10.9万
• 依托单位: University of Wisconsin-Oshkosh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1249821&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Probing; Caldera

The next volcanic super-eruption will have global consequences for humanity. During one of these large eruptions, the explosive potential and the amount of lava and ash erupted are largely controlled by what happens in shallow magma reservoirs in Earth's crust. This project combines the study of frozen magma reservoirs trapped below-ground - plutons - with their associated above-ground volcanic rocks for two ancient super-volcanoes: the Lake City Caldera, Southern Rocky Mountain Volcanic Field in Colorado and the Turkey Creek Caldera in Arizona. The results of this study will provide unprecedented insight into processes occurring within shallow magma reservoirs that lead to super-eruptions, and ultimately will be applied to predict the behavior of potentially extremely hazardous active volcanic regions such as the Taupo Volcanic Zone, the Bay of Naples, and the Aegean Arc. The hypothesis being tested is that the plutonic porphyries in both the Lake City Caldera and the Turkey Creek Caldera are the quenched magma reservoirs remaining in the crust following caldera collapse. If this hypothesis is confirmed, these porphyries provide a unique snapshot of the evolution and post-eruptive conditions of the mushy rootzone associated with a super-eruption. The methods that will be applied to the volcanic and plutonic lithologies are: (1) detailed field mapping of the plutonic porphyries and field sampling of the volcanic units, (2) geochemical characterization of all units, (3) quantitative investigation of primary and accessory crystals in all units using electron microprobe analysis (EPMA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and electron backscattered diffraction (EBSD), and (4) high resolution U-Pb dating and trace element analysis of zircons (CA-TIMS-TEA) in selected lithologies. This multi-analytical approach to the sub-volcanic intrusions and overlying silicic volcanic units is applied to establish the genetic relationship between the large, zoned ignimbrites and their plutonic roots, and to unravel the processes involved in chemical differentiation of large silicic magma chambers.

下一次超级火山爆发将对人类产生全球性影响。 在这些大爆发中，爆发的可能性以及熔岩和火山灰的数量在很大程度上取决于地壳浅层岩浆库中发生的事情。 该项目结合了对两个古代超级火山的地下冻结岩浆库--深成岩--及其相关的地上火山岩的研究：湖城火山口、科罗拉多的南落基山火山场和亚利桑那州的土耳其溪火山口。 这项研究的结果将为浅层岩浆库中发生的导致超级喷发的过程提供前所未有的见解，并最终将被应用于预测潜在的极端危险的活火山地区的行为，如陶波火山区，那不勒斯湾和爱琴海弧。正在测试的假设是，湖城破火山口和土耳其溪破火山口的深圳质斑岩是破火山口崩塌后留在地壳中的淬灭岩浆库。如果这一假设得到证实，这些斑岩提供了一个独特的快照的演变和爆发后的条件下，糊状根区与超级爆发。适用于火山岩和深成岩岩性的方法有：（1）详细的深成斑岩野外测绘和火山单元野外取样，（2）所有单元的地球化学特征，（3）使用电子探针分析（EPMA）、激光烧蚀电感耦合质谱法对所有单元中的原生和副晶体进行定量研究（LA-ICP-MS）和电子背散射衍射（EBSD），以及（4）选定岩性中锆石的高分辨率U-Pb测年和微量元素分析（CA-TIMS-TEA）。这种多分析方法的次火山侵入体和上覆火山岩单位的应用，以建立大型，分区熔结凝灰岩和它们的深成岩根之间的成因关系，并解开大型岩浆房的化学分异的过程。