Sequence modeling in zircon double-dating of early Holocene Mt. Erciyes domes (Central Anatolia)
Sequence modeling in zircon double-dating of early Holocene Mt. Erciyes domes (Central Anatolia)
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DOI：
10.1016/j.quageo.2020.101129
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发表时间：
2021-02-01
影响因子：
2.7
通讯作者：
Schmitt, Axel K.
中科院分区：
文献类型：
--
作者：
Friedrichs, Bjarne;Atici, Gokhan;Schmitt, Axel K.
埃尔西耶斯山（3917米）是土耳其安纳托利亚中部最高的层状火山，根据最近确定的三次全新世早期圆顶喷发，它被认为是活跃的，这些喷发也与地中海和黑海的火山喷发有关。尽管Erciyes火山的全新世活动已得到证实，但这些事件的喷发年代地层学及其对附近开塞利大都市区（人口约140万）的潜在危害仍然知之甚少。本文采用基于(U-Th)/He热年代学和U-Th- pb结晶年龄的锆石双定年（ZDD）方法，利用晶内结晶年龄差异进行不平衡校正。通过序列建模，对各个ZDD年龄进行了细化，重建了Erciyes山外围4个早全新世圆顶的喷发时间。结合岩石学、火山学和地层学约束的层序建模得出了以下喷发年龄（不确定性为1 sigma）：地层直接叠加的Perikartn和Karagullu喷发年龄为8.8 +/- 0.8 ka， Dikkartn喷发年龄为8.9 +/- 0.5 ka，位于开塞利周界的Ylanl Dag喷发年龄为9.4 +/- 1.3 ka。一个假设所有四个全新世早期圆顶同时喷发的模型表明，它的年龄为8.9±0.4 ka。ZDD鉴定了Erciyes山较早的喷发阶段，在约85-88 ka（陨落沉积物和Carik Tepe熔岩）和约105 ka（来自两个外围火山锥的包体）。锆石结晶年龄揭示了Erciyes山下约800 ka以来持续的岩浆活动，与火山活动年代一致，并在约2-3 Ma之前的岩浆阶段，包括广泛的Valibaba Tepe Ignimbrite的喷发，其U-Pb锆石年龄为2.73 +/- 0.02 Ma。第四纪构造的体积估计值约为300 km(3)，碰撞后Erciyes火山的综合长期喷发岩浆通量约为0.4 km(3)/ka，在晚更新世-全新世通量估计值>0.1 km(3)/ka的不确定性范围内，基于圆顶体积和喷发年龄。四个演化后的圆顶几乎同时喷发，其中三个有相当大的早期爆炸性喷发，需要综合多个同时喷发的影响进行危险评估。
Mt. Erciyes (3917 m), the highest stratovolcano in Central Anatolia, Turkey, is considered active based on three recently dated early Holocene dome eruptions that were also correlated with tephras in the Mediterranean and the Black Sea. Despite the demonstrated Holocene activity of Mt. Erciyes, the eruptive chronostratigraphy of these events and their hazard potential for the nearby Kayseri metropolitan area (population similar to 1.4 million) remain poorly constrained. Here, we apply zircon double-dating (ZDD) based on (U-Th)/He thermochronology and U-Th-Pb crystallization ages, where intra-grain crystallization age differences were used for disequilibrium correction. Individual ZDD ages were refined via sequence modeling to reconstruct the eruption timing of four early Holocene domes peripheral to Mt. Erciyes.Sequence modeling, which incorporated petrological, volcanological, and stratigraphic constraints, yielded the following eruption ages (uncertainties stated at 1 sigma): 8.8 +/- 0.8 ka for stratigraphically directly superimposed Perikartn and Karagullu, 8.9 +/- 0.5 ka for Dikkartn, and 9.4 +/- 1.3 ka for previously undated Ylanl Dag, located within the perimeter of Kayseri. A model where all four early Holocene domes are assumed to have erupted simultaneously suggests an age of 8.9 +/- 0.4 ka. Earlier eruptive phases of Mt. Erciyes were identified by ZDD at ca. 85-88 ka (fall-out deposits and Carik Tepe lava) and at ca. 105 ka (xenoliths from two peripheral scoria cones).Zircon crystallization ages reveal protracted magmatic activity beneath Mt. Erciyes since ca. 800 ka, in agreement with dated volcanic activity, and preceding magmatic phases at ca. 2-3 Ma that included the eruption of the widespread Valibaba Tepe Ignimbrite with a U-Pb zircon age of 2.73 +/- 0.02 Ma. A volume estimate for the Quaternary edifice of similar to 300 km(3) translates into an integrated long-term eruptive magma flux of similar to 0.4 km(3)/ka for post-collisional Mt. Erciyes, within uncertainty of the Late Pleistocene-Holocene flux estimate of >0.1 km(3)/ka based on dome volumes and eruption ages. The near-synchronous eruptions of a suite of four evolved domes, in three cases with sizable early explosive venting, calls for a hazard assessment that combines the impact of multiple simultaneous eruptions.