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Modeling the multi-level plumbing system of the Changbaishan caldera from geochemical, mineralogical, Sr-Nd isotopic and integrated geophysical data
Geoscience Frontiers ( IF 8.9 ) Pub Date : 2021-02-17 , DOI: 10.1016/j.gsf.2021.101171
Jian Yi , Pujun Wang , Xuanlong Shan , Guido Ventura , Chengzhi Wu , Jiannan Guo , Pencheng Liu , Jiahui Li

Changbaishan, an intraplate volcano, is characterized by an approximately 6 km wide summit caldera and last erupted in 1903. Changbaishan experienced a period of unrest between 2002 and 2006. The activity developed in three main stages, including shield volcano (basalts), cone-construction (trachyandesites to trachytes with minor basalts), and caldera-forming stages (trachytes to comendites). This last stage is associated with one of the more energetic eruptions of the last millennium on Earth, the 946 CE, VEI 7 Millennium Eruption (ME), which emitted over 100 km3 of pyroclastics. Compared to other active calderas, the plumbing system of Changbaishan and its evolution mechanisms remain poorly constrained. Here, we merge new whole-rock, glass, mineral, isotopic, and geobarometry data with geophysical data and present a model of the plumbing system. The results show that the volcano is characterized by at least three main magma reservoirs at different depths: a basaltic reservoir at the Moho/lower crust depth, an intermediate reservoir at 10–15 km depth, and a shallower reservoir at 0.5–3 km depth. The shallower reservoir was involved in the ME eruption, which was triggered by a fresh trachytic melt entering a shallower reservoir where a comenditic magma was stored. The trachytes and comendites originate from fractional crystallization processes and minor assimilation of upper crust material, while the less evolved melts assimilate lower crust material. Syn-eruptive magma mingling occurred during the ME eruption phase. The magma reservoirs of the caldera-forming stage partly reactivate those of the cone-construction stage. The depth of the magma storage zones is controlled by the layering of the crust. The plumbing system of Changbaishan is vertically extensive, with crystal mush reservoirs renewed by the replenishment of new trachytic to trachyandesitic magma from depth. Unlike other volcanoes, evidence of a basaltic recharge is lacking. The interpretation of the signals preceding possible future eruptions should consider the multi-level nature of the Changbaishan plumbing system. A new arrival of magma may destabilize a part of or the entire system, thus triggering eruptions of different sizes and styles. The reference model proposed here for Changbaishan represents a prerequisite to properly understand periods of unrest to potentially anticipate future volcanic eruptions and to identify the mechanisms controlling the evolution of the crust below volcanoes.



中文翻译:

利用地球化学,矿物学,Sr-Nd同位素和综合地球物理数据模拟长白山火山口的多级管道系统

长白山是板内火山,其特征是约6公里宽的顶峰破火山口,最后一次爆发是在1903年。长白山经历了2002年至2006年的动乱时期。该活动的发展分为三个主要阶段,包括盾构火山(玄武岩),锥状火山-构造(菱形山铁矿到带有次要玄武岩的菱形铁矿)和火山口形成阶段(菱形铁矿到粉煤灰)。这最后一个阶段与地球上一个千年以来最活跃的一次喷发有关,即946 CE,VEI 7千年喷发(ME),其喷发超过100 km 3火山碎屑。与其他活跃火山口相比,长白山的水暖系统及其演化机制仍然受限制。在这里,我们将新的整块岩石,玻璃,矿物,同位素和地压数据与地球物理数据合并,并提供了管道系统的模型。结果表明,该火山具有至少三个不同深度的主要岩浆储集层:莫霍面/下地壳深处的玄武岩储层,10–15 km深度处的中层储层和0.5–3 km深度处的浅层储层。浅层的储层参与了ME的喷发,这是由新鲜的层状熔体进入浅层的储层中而触发的,该浅层的储层中储存了粉状岩浆。菱形和陨石来源于部分结晶过程和上地壳物质的少量同化作用,而较少演化的熔体则吸收下地壳物质。在ME喷发阶段,发生了火山爆发的岩浆混合。破火山口形成阶段的岩浆储集层会部分激活锥构造阶段的岩浆储集层。岩浆储存区的深度由地壳的分层控制。长白山的水暖系统在垂直方向上是广泛的,随着从深部向新的曲折岩浆向曲折岩浆岩岩浆的补充,水晶浆储层得以更新。与其他火山不同,缺少玄武质补给的证据。在对未来可能爆发之前的信号进行解释时,应考虑长白山水暖系统的多层次性质。岩浆的新到来可能破坏整个系统的一部分或整个系统的稳定性,从而引发不同大小和样式的喷发。

更新日期:2021-02-26
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