Fumarole migration and fluid geochemistry at Poás Volcano (Costa Rica) from 1998 to 2001
Fumarole migration and fluid geochemistry at Poás Volcano (Costa Rica) from 1998 to 2001
复制标题
1998 年至 2001 年波阿斯火山（哥斯达黎加）的喷气孔迁移和流体地球化学
DOI：
10.1144/gsl.sp.2003.213.01.15
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
F. Bergamaschi
中科院分区：
文献类型：
--
作者：
O. Vaselli;F. Tassi;A. Minissale;G. Montegrossi;E. Duarte;E. Fernández;F. Bergamaschi
摘要本文报道了1998年2月至2001年2月对波阿斯火山（哥斯达黎加）活火山口湖及其周围地区的火山口、温泉和气体排放的地球化学调查结果。泉水是高度酸性的硫酸盐沃茨，温度接近沸点，而气体化学的特点是典型的岩浆物种，如SO2，HF，HCl，H2和CO。他们从南到东北的火山口内壁逆时针移动，而那些位于火山口南部，靠近火山口湖南部的火山碎屑锥减少或完全消失，在1999年和2000年。这种转变的特征还在于岩浆气体组分的化学变化。尽管水分子发生了化学变化，但在这段时间里，湖泊的组成几乎没有变化。这一事实，加上化学剖面与湖的深度，表明该湖是一个非常有效的岩浆流体冷凝器。湖泊的明显化学分层表明，由于湖底存在液态硫和/或由于新岩浆成分的不断涌入，大气降水的稀释作用并不完全。
Abstract We report the results of a geochemical survey of fumaroles, thermal springs, and gas discharges from areas in and around the active crater lake of Poás volcano (Costa Rica) from February 1998 to February 2001. The springs are highly acidic-sulphate waters with temperatures approaching boiling point, whereas gas chemistry is characterized by typical magmatic species, such as SO2, HF, HCl, H2, and CO. From February 1998 new fumarolic fields formed inside the southern part of the crater. They moved anticlockwise from the S to the NE inner walls of the crater, while those located in the southern part of the crater and close to the pyroclastic cone south of the crater lake diminished or disappeared altogether, during 1999 and 2000. This shift was also characterized by chemical variation of the magmatic gas species. In spite of the chemical changes of fumaroles, the composition of the lake changed little during this time. This fact, together with the chemical profile with depth of the lake, suggests that the lake is a very efficient condenser of magmatic fluids. An apparent chemical stratification of the lake suggests that dilution with meteoric water is not complete, due to the presence of liquid sulphur at the lake bottom and/or due to the continuous influx of new magmatic components.