Holocene record of large explosive eruptions from Chaitén and Michinmahuida Volcanoes, Chile
Holocene record of large explosive eruptions from Chaitén and Michinmahuida Volcanoes, Chile
复制标题
智利柴腾火山和米钦马维达火山全新世大规模喷发记录
DOI：
10.5027/andgeov40n2-a03
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发表时间：
2013
期刊：
影响因子：
0.9
通讯作者：
V. Smith
中科院分区：
文献类型：
--
作者：
A. Amigo;L. Lara;V. Smith
火山碎屑瀑布沉积物和一个大的熔结凝灰岩靠近Chaiten和Michinmahuida火山进行了化学和放射性碳年代分析，以确定喷发单位和喷发时间。这些数据表明，这两座火山是整个全新世大规模（VEI ≥5）和小到中等规模（VEI <5）爆发的源头。四个矿床与柴腾火山的火山活动有关，其中两个来自9.9-9.5和5.3-4.9（cal）ka BP的普林尼火山喷发，也产生了火山碎屑密度流。Chaiten的最后一次事件（2008年之前）发生在几百年前，产生的沉积物与2008年的火山爆发相似。柴腾的所有产品都是高硅流纹石;全岩成分难以区分，但玻璃成分在某些单元中略有不同。7个矿床与Michinmahuida火山喷发有关，其中包括7.6- 7.3kaBP的普林尼阶瀑布存款和10.5- 10.2kaBP的大型熔结凝灰岩存款。这些产品的化学成分范围从安山岩到英安岩。Michinmahuida火山的最后一次大规模爆发事件似乎是0.5-0.3 ka BP次普林尼期喷发，尽管也发现了可能来自当地火山碎屑锥的较年轻的火山渣沉积物。这两座火山对该地区构成了各种各样的潜在危害，从熔结凝灰岩形成的喷发到火山碎屑锥形成。火山附近的山谷是受火山活动影响最严重的地区，因为它们被火山碎屑密度流和火山泥流淹没。然而，即使是位于火山以东和以北数十公里的地区也经历了火山灰的积累，如果今天发生类似的事件，这可能会损害农业和基础设施。
Tephra fall deposits and one large ignimbrite close to Chaiten and Michinmahuida Volcanoes were analyzed for chemistry and radiocarbon dated to correlate the eruptive units and establish the timing of eruptions. These data suggest that both volcanoes were the source of large (VEI ≥5) and small to moderate (VEI <5) explosive eruptions throughout the Holocene. Four deposits are associated with volcanic activity from Chaiten Volcano, with two from Plinian eruptions at 9.9-9.5 and 5.3-4.9 (cal) ka BP that also generated pyroclastic density currents. The last event recognized from Chaiten (prior 2008) occurred a few hundred years ago, producing deposits that are similar to those of the 2008 eruption. All products from Chaiten are high-silica rhyolites; whole-rock compositions are indistinguishable but glass compositions are subtly different for some of the units. Seven deposits are related to eruptions of Michinmahuida Volcano, including a Plinian fall deposit at 7.6-7.3 ka BP and a large ignimbrite deposit at 10.5-10.2 ka BP. The chemical compositions of these products range from andesite to dacite. The last substantial explosive eruption event from Michinmahuida Volcano appears to have been a 0.5-0.3 ka BP sub-Plinian eruption, although younger scoria fall deposits likely derived from local pyroclastic cones are also found. Both volcanoes pose a wide variety of potential hazards to the region ranging from those derived from ignimbrite-forming eruptions to pyroclastic-cone formation. Valleys adjacent to the volcanoes were the areas most heavily affected by volcanic activity, because they were inundated by pyroclastic density currents and lahars. However, even regions located tens of kilometers east and north of the volcanoes experienced accumulations of tephra, which could harm both agriculture and infrastructure if similar events occurred today.
2008 年 5 月智利 Chaitén 喷发的火山灰地层和喷发量
影响因子：
3.5
作者：
Alfano F
通讯作者：
Alfano F
影响因子：
5.8
作者：
D. Douglass;B. Singer;M. Kaplan;R. P. Ackert;D. Mickelson;M. Caffee
通讯作者：
D. Douglass;B. Singer;M. Kaplan;R. P. Ackert;D. Mickelson;M. Caffee