Multiple subduction components in the mantle wedge: Evidence from eruptive centers in the Central Southern volcanic zone, Chile
Multiple subduction components in the mantle wedge: Evidence from eruptive centers in the Central Southern volcanic zone, Chile
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地幔楔中的多重俯冲成分：来自智利中南部火山带喷发中心的证据
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发表时间：
2002
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影响因子：
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通讯作者：
J. Ryan
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作者：
R. Hickey‐Vargas;M. Sun;L. Lopez;H. M. Roa;M. Reagan;J. Morris;J. Ryan
在安第斯山脉中南部火山带，与同时喷发的比利亚里卡玄武岩相比，来自大型复合中心Volcan比利亚里卡附近的小喷发中心的玄武岩缺乏流体移动的元素，如B、Cs、Rb、K、Pb、Ba和U。新的1 0 Be和U系列同位素数据表明，贫流体移动的元素的小喷发中心玄武岩具有较小的1 0 Be/ 9 Be比值（1.6-1.9 × 10 - 11）和（2 38 U/ 2 30 Th）活度比接近1.0，而比利亚里卡玄武岩则表现出2 3 8 U富集和较大的1 0 Be/ 9 Be比值（4 0 ~ 6 4 × 10 - 1 1）。这些结果表明，小型喷发中心玄武岩包括来自俯冲岩石圈的物质，这些物质在地幔楔中储存了350 k. y。至3百万年。这些材料缺乏流体移动的元素，这可能反映了在凝固过程中的流体排出或它们在最初较热的俯冲环境中的形成。与此相反，复合中心玄武岩的样品物质富含流体移动的元素，这些元素最近从俯冲岩石圈转移到地幔楔中。结果证实，俯冲带地幔楔包括俯冲物质添加到楔在长和短的时间尺度。
In the Andean Central Southern volcanic zone, basalts from small eruptive centers near the large composite center Volcan Villarrica are poor in fluid mobile elements, such as B, Cs, Rb, K, Pb, Ba, and U, compared with concurrently erupted Villarrica basalts. New 1 0 Be and U-series isotopic data for these centers show that fluid mobile element-poor small eruptive center basalts have small 1 0 Be/ 9 Be ratios (1.6-1.9 × 10 - 1 1 ) and ( 2 3 8 U/ 2 3 0 Th) activity ratios near 1.0, whereas basalts from Villarrica show 2 3 8 U enrichment and larger 1 0 Be/ 9 Be ratios (4.0-6.4 × 10 - 1 1 ). These results suggest that small eruptive center basalts include materials derived from the subducted lithosphere that were stored in the mantle wedge for 350 k.y. to 3 m.y. That these materials are poor in fluid mobile elements may reflect fluid expulsion during solidification or their formation in an initially hotter subduction setting. In contrast, the composite center basalts sample materials rich in fluid mobile elements that were recently transferred into the mantle wedge from the subducted lithosphere. The results confirm that mantle wedges in subduction zones include subducted materials added to the wedge over both long and short time scales.