Contrasting fragmentation and transportation dynamics during the emplacement of Dikkartın rhyodacitic dome; Erciyes stratovolcano, central Turkey
Contrasting fragmentation and transportation dynamics during the emplacement of Dikkartın rhyodacitic dome; Erciyes stratovolcano, central Turkey
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土耳其中部埃尔吉耶斯层状火山形成过程中的碎裂和运输动态对比；
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发表时间：
2019
期刊：
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通讯作者：
A. Gourgaud
中科院分区：
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作者：
O. Ersoy;E. Aydar;E. Şen;A. Gourgaud
Dikkartın是位于土耳其安纳托利亚中部埃尔奇耶斯层状火山(3917米)南侧的单生熔岩穹顶。介绍了地层、粒度、形态和结构的变化，以获得定量的物理火山学见解，并解释Dikkartın喷发序列的喷发和侵位机制。对比Dikartın喷发地层序列中的碎屑和运移动力学与各期活动中岩浆与外部水的比例有关。我们建议有四个喷发阶段。喷发开始于一次干燥的纯岩浆普林尼安喷发，柱子高度为20公里。根据等值线和等厚图，该热柱沿NNE-SSW方向伸展。与岩浆相互作用的水量改变了迪卡特ın喷发的过程。在以熔融作用为主的阶段，形成了一个爆炸坑和一个凝灰岩环。随着时间的推移，环境中的水被耗尽，最初的岩浆挥发物被耗尽，导致熔岩穹顶被挤出。顺序碎裂/传输(SFT)理论已应用于苔藓样品，以使用粒度数据来评价碎裂和传输动力学。从数值上论证了每一次爆炸序列所蕴含的岩浆和云雾岩浆特征。通过对火山灰进行详细的扫描电子显微镜分析和粗糙度计算，研究了孔隙时间与岩浆-水相互作用时间的关系。对火山灰的表面分析表明，产生凝灰岩环的大多数火山喷发是干燥的，带有过热的蒸汽，但很少发生蒸汽凝结，使细小的物质附着在表面上。考虑到为顶峰喷发柱(第一阶段)计算的约20公里的羽流高度，当时的风向将云团导向南方，但由于羽流高度的降低(第二阶段)，云团后来转向东北。根据季节风向推测，Dikartın火山在冬季喷发。
Dikkartın is a monogenetic lava dome emplaced on the southern flank of Erciyes stratovolcano (3917 m) in central Anatolia, Turkey. Stratigraphic, granulometric, morphometric and textural variations are presented to obtain quantitative physical volcanological insight and to interpret eruption and emplacement mechanisms in Dikkartın eruptive sequence. Contrasting fragmentation and transportation dynamics in the stratigraphic sequence of the Dikkartın eruption is related to the ratio of magma and external water during each phases of the activity. We suggest four eruptive phases. The eruption begins with a dry, purely magmatic Plinian eruption with a column height of 20 km. According to the isopleth and isopach maps, the plume stretched in a NNE-SSW direction. The amount of water interacting with magma modified the course of the Dikkartın eruption. During a phase dominated by phreatomagmatism, an explosion crater and a tuff ring were formed. Exhaustion of the water in the environment and depletion of initial magmatic volatiles in the course of time resulted in extrusion of a lava dome. Sequential Fragmentation/Transport (SFT) theory has been applied on tephra samples to comment on fragmentation and transportation dynamics using grain size data. The magmatic and phreatomagmatic characters contained in each explosion sequence were numerically demonstrated. The relationship between the porosity time and the magma-water interaction time was investigated by detailed SEM analysis and roughness values calculated on volcanic ash. Surface analysis on volcanic ash suggested that most of the phreatomagmatic eruptions producing the tuff ring were dry with superheated steam but little vapour condensation occurred allowing adhesion of fine material on surfaces. Considering the c. 20 km plume height calculated for the climactic eruption column (Phase 1), the prevailing winds directed the cloud to the south, but due to the decrease in the plume height (Phase 2), the cloud was later directed to the northeast. According to the direction of seasonal winds, it is suggested that Dikkartın erupted during winter.