Volatile emission during the eruption of Baitoushan Volcano (China/North Korea) ca. 969 AD
Volatile emission during the eruption of Baitoushan Volcano (China/North Korea) ca. 969 AD
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DOI：
10.1007/s004450050004
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发表时间：
2000-02
影响因子：
3.5
通讯作者：
S. Horn;H. Schmincke
中科院分区：
文献类型：
--
作者：
S. Horn;H. Schmincke
3[岩浆体积（DRE）：24 ± 5 km 3]。 主要阶段（CA）95体积%）主要以广布的沉降毯和近缘熔结凝灰岩沉积的共晶火山灰为代表。火山柱估计已达到约。25公里，从而进入平流层。晚期（5 vol. %）以粗面岩为代表，主要以中等熔结熔结凝灰岩形式侵位。粗面岩10-20 vol. % 斑晶，主要为斜长石、钙钛矿和铁橄榄石。原生玻璃质熔体包裹体没有泄漏的迹象，只发现在斑晶的comenditic火山灰，而那些在斑晶的粗面岩失透。的comendite岩浆被解释为已从粗面岩岩浆的结晶分离所代表的熔融包裹体斑晶的comendite火山口。在喷发过程中释放到大气中的挥发物的质量估计使用岩石学方法。共晶基质玻璃的平均H2O浓度为1.5重量%（可能主要是次生的）和相应的熔体包裹体的含量为5.2wt.%。 长石和石英中的熔体包裹体存在最高的卤素浓度，氯的计算平均值为4762 ppm，氟的计算平均值为4294 ppm。共晶基质玻璃由富氟（3992 ppm F）和贫氟（2431 ppm F）组表示，平均氯为3853 ppm。共晶基质玻璃和熔体夹杂物的所有硫分析中只有20%高于≥ 250 ppm S的检测限。 出疹前和出疹后H2O浓度之间的差异至少为3.7 ± 0.6重量% 考虑到基质玻璃的再水化和熔体夹杂物的可能泄漏。出疹前和出疹后的卤素浓度之差为Cl 909 ± 90 ppm，F 1863 ± 280 ppm和302 ± 40 ppm。 根据熔体包裹体中最大S浓度（455 ppm S）的平均值和检测限（205 ± 40 ppm S）估算S的差异。 根据喷发的岩浆体积和挥发性数据，计算出注入大气的挥发性物质的质量为：H2O 1796 ±453百万吨，氯45±10百万吨，氟42±11百万吨，硫2±0.6百万吨。 白头山火山在公元969 ±20年爆发，是过去2000年来最大的火山爆发之一，被认为对气候产生了重大但可能是短暂的影响。
3[magma volume (DRE): 24 ± 5 km3]. The main phase (ca. 95 vol.%) is represented by comenditic tephra deposited dominantly as widespread fallout blankets and proximal ignimbrites. The eruption column is estimated to have reached ca. 25 km and thus entered the stratosphere. A late phase (5 vol.%) is represented by trachyte emplaced chiefly as moderately welded ignimbrites. The comendites contain ∼ 3, and the trachytes 10–20 vol.% phenocrysts, mainly anorthoclase, hedenbergite, and fayalite. Primary glassy melt inclusions with no signs of leakage were found only in phenocrysts in the comenditic tephra, whereas those in phenocrysts in the trachytes are devitrified. The comendite magma is interpreted to have been generated by fractional crystallization from a trachyte magma represented by melt inclusions in the phenocrysts in the comendite tephra. The mass of volatiles emitted to the atmosphere during the eruption was estimated using the petrologic method. The average H2O concentration of the comenditic matrix glass is 1.5 wt.% (probably largely secondary) and of the corresponding melt inclusions ∼ 5.2 wt.%. Melt inclusions in feldspar and quartz present the highest halogen concentrations with a calculated average for chlorine of 4762 ppm and for fluorine of 4294 ppm. The comenditic matrix glasses are represented by a fluorine-rich (3992 ppm F) and fluorine-poor group (2431 ppm F), averaging 3853 ppm for chlorine. Only 20% of all sulfur analyses of the comenditic matrix glasses and melt inclusions are above the detection limit of ≥ 250 ppm S. The difference between pre- and post-eruptive concentration of H2O is at least 3.7 ± 0.6 wt.% H2O taking into consideration re-hydration of the matrix glass and possible leakage of melt inclusions. The difference between pre- and post-eruptive concentrations of the halogens amounts to 909 ± 90 ppm Cl, and 1863 ± 280 ppm and 302 ± 40 ppm F. The difference for S was estimated based on the average of the maximum S concentrations in the melt inclusions (455 ppm S) and the detection limit, resulting in 205 ± 40 ppm S. The calculated mass of volatiles injected into the atmosphere, based on the erupted magma volume and volatile data, is 1796 ± 453 megatons for H2O, 45 ± 10 megatons for chlorine, 42 ± 11 megatons for fluorine, and 2 ± 0.6 megatons for sulfur. The 969 ± 20 AD eruption of Baitoushan Volcano, one of the largest eruptions of the past 2000 years, is thought to have had a substantial but possibly short-lived effect on climate.