Evidence for Extending Anomalous Miocene Volcanism at the Edge of the East Antarctic Craton
Evidence for Extending Anomalous Miocene Volcanism at the Edge of the East Antarctic Craton
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南极东部克拉通边缘异常中新世火山活动扩展的证据
DOI：
10.1002/2018gl077237
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发表时间：
2018
影响因子：
5.2
通讯作者：
M. Studinger
中科院分区：
文献类型：
--
作者：
K. Licht;T. Groth;J. Townsend;A. J. Hennessy;S. Hemming;T. Flood;M. Studinger
利用野外观察，岩石学，地球化学，地质年代学和地球物理数据，我们推断存在一个以前未知的中新世冰下火山中心~230公里的南极。火山活动的证据来自于南横贯南极山脉冰碛中沉积的含橄榄石杏仁状/泡状玄武岩和玻璃质碎屑岩的巨石。5个样品的~（40）Ar/~（39）Ar年龄和冰碛物碎屑锆石的U-Pb年龄表明岩浆活动在25-17 Ma之间。火山活动的可能来源是距离采样点60公里处的一个环形-735 nT磁异常。水下的火山岩结构表明，在早中新世期间，火山岩在冰下或在冰块边缘的水中喷发。这些岩石记录了南极洲最南端的新生代火山活动，并扩大了与西南极裂谷系有关的最古老熔岩的已知范围。它们可能是南横贯南极山脉下岩石圈下沉的表现。
Using field observations followed by petrological, geochemical, geochronological, and geophysical data, we infer the presence of a previously unknown Miocene subglacial volcanic center ~230 km from the South Pole. Evidence of volcanism is from boulders of olivine‐bearing amygdaloidal/vesicular basalt and hyaloclastite deposited in a moraine in the southern Transantarctic Mountains. 40Ar/39Ar ages from five specimens plus U‐Pb ages of detrital zircon from glacial till indicate igneous activity 25–17 Ma. The likely source of the volcanism is a circular −735 nT magnetic anomaly 60 km upflow from the sampling site. Subaqueous textures of the volcanics indicate eruption beneath ice or into water at the margin of an ice mass during the early Miocene. These rocks record the southernmost Cenozoic volcanism in Antarctica and expand the known extent of the oldest lavas associated with West Antarctic Rift system. They may be an expression of lithospheric foundering beneath the southern Transantarctic Mountains.