Chapter 5.1b Northern Victoria Land: petrology
Chapter 5.1b Northern Victoria Land: petrology
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第 5.1b 章北维多利亚土地：岩石学
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发表时间：
2021
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通讯作者：
J. Smellie
中科院分区：
文献类型：
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作者：
S. Rocchi;J. Smellie
摘要 与西南极裂谷系统有关的新生代岩浆岩直接穿过南极洲、维多利亚地、玛丽伯德地和埃尔斯沃斯地。北维多利亚地位于西裂谷肩的西北端，拥有与裂谷相关的火成岩活动的最长记录，其独特之处在于：深成岩和同生岩脉群涵盖了大约从公元 100 世纪到 1970 年的时间跨度。 50～20Ma，15Ma至今有火山岩记录。整个火成岩套件的起源存在争议。然而，地球化学和同位素数据与区域构造历史的结合支持了一个对地幔柱不起作用的模型。白垩纪期间的岩浆伸展产生了自动交代的地幔源，在始新世现今的活动期间，通过跨岩石圈断层系统的张拉活动引起的小程度熔融产生了岩浆。始新世-渐新世岩体和岩脉群的侵位主要集中在这些断层系统上。相反，中新世中期火山的位置受到罗斯海沿岸岩石圈颈缩的控制，从而形成了最大的火山建筑物。而在内陆，较小的中央火山和火山渣锥与较厚地壳中岩浆房的建立有关。
Abstract Cenozoic magmatic rocks related to the West Antarctic Rift System crop out right across Antarctica, in Victoria Land, Marie Byrd Land and into Ellsworth Land. Northern Victoria Land, located at the northwestern tip of the western rift shoulder, is unique in hosting the longest record of the rift-related igneous activity: plutonic rocks and cogenetic dyke swarms cover the time span from c. 50 to 20 Ma, and volcanic rocks are recorded from 15 Ma to the present. The origin of the entire igneous suite is debated; nevertheless, the combination of geochemical and isotopic data with the regional tectonic history supports a model with no role for a mantle plume. Amagmatic extension during the Cretaceous generated an autometasomatized mantle source that, during Eocene–present activity, produced magma by small degrees of melting induced by the transtensional activity of translithospheric fault systems. The emplacement of Eocene–Oligocene plutons and dyke swarms was focused along these fault systems. Conversely, the location of the mid-Miocene–present volcanoes is governed by lithospheric necking along the Ross Sea coast for the largest volcanic edifices; while inland, smaller central volcanoes and scoria cones are related to the establishment of magma chambers in thicker crust.