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首页> 外文期刊>New Zealand journal of geology & geophysics >The sub-Antarctic Antipodes Volcano: a < 0.5 Ma HIMU-like Surtseyan volcanic outpost on the edge of the Campbell Plateau, New Zealand
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The sub-Antarctic Antipodes Volcano: a < 0.5 Ma HIMU-like Surtseyan volcanic outpost on the edge of the Campbell Plateau, New Zealand

机译：亚南极安第斯火山：新西兰坎贝尔高原边缘的<0.5 Ma HIMU样的Surtseyan火山前哨

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摘要

The sub-Antarctic Antipodes Islands group, located on the edge of the Campbell Plateau, is composed of Surtseyan-like tuff cones, porphyritic lavas and dykes, overlain by scoriaceous cinder cones. The youthful nature is indicated by well-preserved cones and craters, raised boulder beaches, pollen and spores comparable to the present-day vegetation in peat underlying one lava flow, and published Ar/Ar ages of ≤0.5 Ma. The alkaline crystalline rocks record a fractionation lineage that was controlled by progressive removal of clinopyroxene and olivine at shallow depths with minimal interaction with continental crust. A compilation of isotopic data confirms that the magmas were derived from a mantle source containing a high-time integrated U/Pb (HIMU)-like component. Although this source component has been recognised in many Zealandia intraplate volcanoes, the Antipodes Volcano lavas contain consistently high (206)~Pb/(204)~Pb and low (87)~Sr/(86)~Sr ratios, making the geochemical suite an excellent baseline for HIMU studies. The distinctive isotope ratios and chemistries are comparable with those of some anhydrous Pb- and K-depleted peridotitic mantle xenoliths from intraplate volcanoes in Zealandia. If the lithospheric mantle contributed to the source of Antipodes Volcano, the Pb and K anomalies in the lavas may not require residual amphibole/phlogopite and/or sulphide in their source region. Furthermore, comparison with the peridotite suite indicates that the Zealandia lithospheric mantle is isotopically heterogeneous and thus not all the Zealandia Cretaceous-Cenozoic intraplate volcanoes need have tapped a HIMU-like reservoir.
机译：位于坎贝尔高原边缘的亚南极安提波德群岛群由像Surtseyan的凝灰岩锥，斑岩熔岩和堤坝组成，上面覆盖着针状灰渣锥。保存完好的圆锥体和火山口，凸起的巨石滩，花粉和孢子可与时至今日的植被形成一层熔岩流的泥炭相媲美，并且Ar / Ar年龄≤0.5Ma，表明了这种年轻的性质。碱性晶体岩石记录了一个分馏谱系，该谱系是通过在浅层深度逐步去除斜辉石和橄榄石以及与大陆壳的相互作用最小化而控制的。同位素数据的汇编证实了岩浆来自地幔源，该地幔源含有类似高时间积分的U / Pb（HIMU）成分。尽管这种来源成分已在许多西兰西亚板内火山中得到认可，但安提波德斯火山熔岩始终具有较高的（206）〜Pb /（204）〜Pb和较低的（87）〜Sr /（86）〜Sr比值，这使得地球化学组合HIMU研究的极佳基线。独特的同位素比率和化学性质与来自西兰西亚板内火山的一些无水的Pb和K贫化的橄榄岩地幔异种岩相当。如果岩石圈地幔是造成安提波德火山的源头，那么熔岩中的Pb和K异常可能在其源头区域不需要残留的闪石/金云母和/或硫化物。此外，与橄榄岩套件的比较表明，西兰西亚岩石圈地幔是同位素异质的，因此并非所有西兰西亚白垩纪-新生代板内火山都需要挖掘像HIMU一样的储层。

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