Remobilization of Andesite Magma by Intrusion of Mafic Magma at the Soufriere Hills Volcano, Montserrat, West Indies
Remobilization of Andesite Magma by Intrusion of Mafic Magma at the Soufriere Hills Volcano, Montserrat, West Indies
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DOI：
10.1093/petrology/41.1.21
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发表时间：
2000
影响因子：
3.9
通讯作者：
M. Murphy;R. Sparks;J. Barclay;M. Carroll;T. Brewer
中科院分区：
文献类型：
--
作者：
M. Murphy;R. Sparks;J. Barclay;M. Carroll;T. Brewer
1995年至1999年喷发的苏弗里埃山火山，蒙特塞拉特，产生了一个富含晶体的安山岩含quenchThe苏弗里埃山火山，蒙特塞拉特，位于纹理镁铁质包裹体，这表明已被熔融的证据小安的列斯群岛岛弧在西印度群岛，开始时纳入宿主岩浆。在1995年7月18日爆发的单个晶体，经过大约350年的休眠安山岩记录了不同的历史。角闪石斑晶不同于（Young等人，1998年b）。火山爆发之前是一个原始的和未改变的强烈氧化和假变形的地震群，这是在1992年1月开始的。无水反应产物。斜长石斑晶通常是以前的地震危机发生在蒙特塞拉特反向分区，往往与尘土飞扬的筛纹理。1896-1897年、1932-1935年和1966-1967年出现反环带边缘（Powell，1938年;也常见于斜方辉石斑晶上。Shepherd等人，1971年）。最初的潜水和潜水体，斜方辉石原子岩浆活动的平均温度为858 ± 20 °C，随后是斑晶核的挤出，而反向分区的边缘记录了1995年11月安山质熔岩圆顶的温度。火山碎屑流，约880至1050 °C。矿物边缘的不稳定的圆顶，成分，分区模式和纹理的重力塌陷产生的不均匀性被解释为反映一直是整个居民岩浆喷发的不均匀再加热和再活化的活动的主导形式，但爆炸活动期间，生产体侵入较热的镁铁质岩浆。也发生了对流再活化浮石流和福尔斯（Robertson等人将经历过的斑晶混合在一起，1998; Young等人，1998年b）。圆顶增长停止不同的热历史，取决于接近入侵突然在1998年3月和进一步的活动，5月镁铁质岩浆。低温和高结晶度是1999年主要涉及重力崩溃的解释，反映了一个凉爽的，高度结晶圆顶和火山灰喷发时期的存在下，与一些小规模的岩浆体苏弗里埃山火山。火山爆发事件。根据观测结果，结合地震活动性、挤出率和二氧化硫通量数据，苏弗里埃山火山是唯一的活动中心，表明目前的火山爆发是由蒙特塞拉特火山引发的。这座火山是至少是最近流入的热镁铁质岩浆的复合物。五个安山质熔岩圆顶，两侧是火山碎屑沉积物。Rea（1974）确定了另外四个火山中心，
The 1995–1999 eruption of the Soufriere Hills volcano, MontINTRODUCTION serrat, has produced a crystal-rich andesite containing quenchThe Soufriere Hills volcano, Montserrat, located in the textured mafic inclusions, which show evidence of having been molten Lesser Antilles island arc in the West Indies, began to when incorporated into the host magma. Individual crystals in the erupt on 18 July 1995, after about 350 years of dormancy andesite record diverse histories. Amphibole phenocrysts vary from (Young et al., 1998b). The eruption was preceded by a pristine and unaltered to strongly oxidized and pseudomorphed by period of seismic swarms, which began in January 1992. anhydrous reaction products. Plagioclase phenocrysts are commonly Previous earthquake crises have occurred on Montserrat reverse zoned, often with dusty sieve textures. Reverse zoned rims are in 1896–1897, 1932–1935 and 1966–1967 (Powell, 1938; also common on orthopyroxene phenocrysts. Pyroxene geothermometry Shepherd et al., 1971). Initial phreatic and phregives an average temperature of 858 ± 20 °C for orthopyroxene atomagmatic activity was followed by extrusion of an phenocryst cores, whereas reverse zoned rims record temperatures andesitic lava dome in November 1995. Pyroclastic flows, from about 880 to 1050 °C. The heterogeneity in mineral rim generated by gravitational collapse of the unstable dome, compositions, zoning patterns and textures is interpreted as reflecting have been the dominant form of activity throughout the non-uniform reheating and remobilization of the resident magma eruption, but periods of explosive activity, producing body by intrusion of hotter mafic magma. Convective remobilization pumice flows and falls, have also occurred (Robertson et results in mixing together of phenocrysts that have experienced al., 1998; Young et al., 1998b). Dome growth ceased different thermal histories, depending on proximity to the intruding suddenly in March 1998 and further activity up to May mafic magma. The low temperature and high crystallinity are 1999 has mainly involved gravitational collapses of the interpreted as reflecting the presence of a cool, highly crystalline dome and periods of ash venting, with some small-scale magma body beneath the Soufriere Hills volcano. The petrological vulcanian explosive events. observations, in combination with data on seismicity, extrusion rate The Soufriere Hills volcano is the only active centre and SO2 fluxes, indicate that the current eruption was triggered by on Montserrat. The volcano is a composite of at least recent influx of hot mafic magma. five andesitic lava domes, flanked by pyroclastic deposits. Rea (1974) identified four other volcanic centres, all