Opacitization conditions of hornblende in Bezymyannyi volcano andesites (March 30, 1956 eruption)
Opacitization conditions of hornblende in Bezymyannyi volcano andesites (March 30, 1956 eruption)
复制标题
Bezymyannyi火山安山岩角闪石的乳浊化条件（1956年3月30日喷发）
DOI：
10.1134/s0869591108010025
复制
发表时间：
2008
期刊：
影响因子：
1.5
通讯作者：
O. Dirksen
中科院分区：
文献类型：
--
作者：
P. Plechov;A. Tsai;V. Shcherbakov;O. Dirksen
本文研究了堪察加半岛Bezymyannyi火山灾难性喷发（1956年3月30日）安山岩中角砾颗粒周围的不透明岩边缘发育的条件。不英岩边缘是由角闪石与熔体的双交代反应产生的，其分带为：角闪石→ Px + Pl + Ti-Mag → Px + Pl → Px →熔体。生物交代反应伴随着活性CaO从边缘的去除，添加SiO2，和更复杂的行为的其他成分。角闪石还表现出在近等化学条件下的体积分解反应。在等压条件下，在约6千巴的压力下，不透明的轮辋。角闪岩不稳定的主要原因是由于新的热岩浆部分注入，岩浆房从890 °C加热到1005°C。注射和开始喷发之间的时间间隔是根据不透明边缘的厚度估计的，不超过37天。因此，1956年3月30日的喷发与1955年11月的火山活动无关，而是与1956年2月至3月的新岩浆注入有关。
The paper is devoted to the conditions under which opacite rims developed around hornblende grains in andesite of the catastrophic eruption (March 30, 1956) of Bezymyannyi volcano, Kamchatka. The opacite rims were produced by a bimetasomatic reaction between hornblende and melt with the development of the following zoning: hornblende → Px + Pl + Ti-Mag → Px + Pl → Px → melt. Biometasomatic reaction was accompanied by the active removal of CaO from the rim, addition of SiO2, and more complicated behavior of other components. The hornblende also shows reactions of its volumetric decomposition under near-isochemical conditions. The opacite rims developed under isobaric conditions, at a pressure of approximately 6 kbar. The main reason for the instability of the hornblende was the heating of the magma chamber from 890 to 1005°C due to new hot magma portion injection. The time interval between the injection and the start of eruption was estimated from the thickness of the opacite rims and did not exceed 37 days. Hence, the March 30, 1956, eruption was not related to the volcanic activity in November of 1955 but to the injection of a fresh magma portion in February–March of 1956.