Volatiles in submarine volcanic rocks from the Mariana Island arc and trough
Volatiles in submarine volcanic rocks from the Mariana Island arc and trough
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DOI：
10.1016/0016-7037(79)90196-0
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发表时间：
1979-03
影响因子：
5
通讯作者：
Michael O. Garcia;N. Liu;D. W. Muenow
中科院分区：
文献类型：
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作者：
Michael O. Garcia;N. Liu;D. W. Muenow
从马里亚纳岛弧北方1170 m水深处挖掘出的安山岩的淬火枕状边缘中，对玻璃进行高温质谱分析，结果表明H2O含量大大减少（~ 1 wt.%）和更多的CO2（~ 0.24 wt.%）比以前报道的火山弧岩石要多。斜长石斑晶内的玻璃蒸汽包裹体淬火边缘的CO2 H2 O的比例为1：1。这些结果类似于马里亚纳海槽（弧后盆地）玄武岩样品的分析。与弧后盆地样品相比，弧岩中的F和Cl含量普遍较高，S含量较低。这些结果有利于模型的岛弧岩浆的生产，涉及俯冲板片的熔融，而不仅仅是上覆地幔楔的熔融，因为需要从橄榄岩（10-15重量%）产生岛弧岩浆的高挥发分含量。海槽样品虽然在非挥发性成分上与洋中脊岩石相似，但H2O含量要高得多。CO2含量偏高，S含量偏低。要么是近地表挥发分的加入使岩浆富集，要么是H2 O在弧后盆地熔岩的生成和演化中比洋中脊玄武岩的成因中更重要。
High temperature mass spectrometric analyses of glasses from quenched pillow rims of andesites dredged from 1170 m water depth in the northern portion of the Mariana Island arc indicate substantially less H 2 O (~ 1 wt.%) and more CO 2 (~ 0.24 wt.%) than previously reported for volcanic arc rocks. Glass-vapor inclusions within plagioclase phenocrysts from quenched rims have CO 2 H 2 O ratios of 1: 1. These results are similar to analyses of basaltic samples from the Mariana Trough (a back-arc basin). Generally, F and Cl contents are higher and S lower in the arc rocks compared to the samples from the back-arc basin. These results favor models for the production of island arc magmas which involve melting of the subducted slab, rather than just melting of the overlying mantle wedge because of the high volatile content needed to produce island arc magmas from peridotite (10–15 wt.%). The trough samples, although similar in non-volatile composition to mid-ocean ridge rocks, have much higher H 2 O. somewhat higher CO 2 and lower S contents. Either near surface addition of voiatiles has enriched the magmas or H 2 O must be a more important component in the generation and evolution of back-arc basin lavas than in the genesis of mid-ocean ridge basalts.