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首页> 外文期刊>Contributions to Mineralogy and Petrology >Do extrusion ages reflect magma generation processes at depth? An example from the Neogene Volcanic Province of SE Spain
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Do extrusion ages reflect magma generation processes at depth? An example from the Neogene Volcanic Province of SE Spain

机译:挤压年龄是否能反映出深部的岩浆生成过程?西班牙东南部新近纪火山省的一个例子

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The high-K calc-alkaline volcanic rocks along the Neogene Volcanic Province of SE Spain represent crustal anatectic melts mixed with mantle components during the opening of the Alborán Sea. Partially melted metapelitic enclaves, along with the geochemical signature, provide evidence of their crustal source. U–Pb SHRIMP geochronology on monazite and zircon from enclaves and their hosting lavas in the localities of El Hoyazo, Mazarrón and Mar Menor reveals variable delays between the melting at depth and the eruption of the volcanics. These data indicate that: (1) the most important event of anatexis in the Neogene spanned at least the 3 m.y. interval between 12 and 9 Ma; (2) there is no trend in age of crustal melting; and (3) the delay between magma generation and extrusion varies from more than 3 m.y. at El Hoyazo to ~0.5 m.y. and possibly 2.5 m.y. at Mar Menor, with no significant delay measurable at Mazarrón. The variable time delay between anatexis and lava extrusion indicates that radiometric ages of volcanics may provide misleading information on the timing of magma genesis occurring at depth. This highlights the pitfall of basing detailed geodynamic models on volcanic extrusion ages alone. Keywords Anatexis - Geochronology - Monazite - SHRIMP - Southern Spain - Volcanism - Zircon Communicated by J. Hoefs.
机译:沿着西班牙东南部新近纪火山省的高K钙碱性火山岩代表了阿尔波良海开放期间地壳的高熔岩熔液与地幔成分的混合。部分融化的成岩圈以及地球化学特征提供了它们地壳来源的证据。在El Hoyazo,Mazarrón和Mar Menor地区的飞地及其寄主熔岩上的独居石和锆石的U–Pb SHRIMP年代学揭示了深度融化和火山喷发之间的可变延迟。这些数据表明:(1)新基因中最重要的厌食症事件至少跨越了3个月。 12至9 Ma之间的间隔; (2)地壳融化的年龄没有趋势; (3)岩浆产生和挤压之间的延迟大于3m.y。在El Hoyazo到约0.5毫米可能是2.5毫米在Mar Menor工作,在Mazarrón工作没有明显的延误。厌食和熔岩挤压之间的可变时间延迟表明,火山的辐射年龄可能会提供有关深部岩浆发生时间的误导性信息。这突出了仅根据火山喷发年龄建立详细的地球动力学模型的陷阱。关键字Anatexis-年代学-独居石-SHRIMP-西班牙南部-火山作用-锆石,由J. Hoefs沟通。

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