A new stratigraphy for the Latady Basin, Antarctic Peninsula: Part 1, Ellsworth Land Volcanic Group
A new stratigraphy for the Latady Basin, Antarctic Peninsula: Part 1, Ellsworth Land Volcanic Group
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南极半岛拉塔迪盆地的新地层学：第 1 部分，埃尔斯沃斯陆地火山群
DOI：
10.1017/s0016756806002597
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发表时间：
2006
影响因子：
2.3
通讯作者：
I. Millar
中科院分区：
文献类型：
--
作者：
M. Hunter;T. Riley;D. Cantrill;M. Flowerdew;I. Millar
南极半岛南部埃尔斯沃思地东部侏罗纪波斯特山组由与冈瓦纳大陆内裂谷作用有关的凝灰岩组成。在确定少量玄武岩和沉积相边缘的火山沉积物，导致重新分类的火山单位到埃尔斯沃思土地火山群。这是正式细分为两个地层：波斯特山组（英语：Mount Poster Formation）（英语：Mount Poster Formation）（英语：Mount Poster Formation）（英语：Mount Poster Formation）和斯威尼组（英语：Sweeney Formation）（玄武岩和沉积相）。波斯特山组流纹层是一个厚度大于1 km的火山口内层序。斯威尼组的玄武岩相和沉积相与陆地环境中进入或接近水中的沉积相一致。波斯特山组的地球化学与来自长寿的上地壳岩浆房的火山口内流纹的推导是一致的。斯威尼组的玄武岩介于软流圈和岩石圈衍生岩浆之间，几乎没有或没有俯冲改造成分。玄武岩可能代表了玄武质底板的一个罕见的喷发部分，它是当地生成流纹的热源。对波斯特山组火山岩进行了U-Pb离子探针锆石年代学研究，得到其平均喷发年龄为183.4± 1.4Ma。对斯威尼组砂岩中的碎屑锆石分析表明，最大沉积年龄为183±4 Ma，这两个组被认为是同时代的。此外，这些年龄与南部非洲和东南极洲的Karoo-Ferrar火成岩省的喷发相吻合。我们对埃尔斯沃思陆地火山群的解释与巴塔哥尼亚和南极半岛的侏罗纪火山作用是由于该地区的羽流到达而引起的陆内伸展的模型是一致的。
The Jurassic Mount Poster Formation of eastern Ellsworth Land, southern Antarctic Peninsula, comprises silicic ignimbrites related to intracontinental rifting of Gondwana. The identification of less voluminous basaltic and sedimentary facies marginal to the silicic deposits has led to a reclassification of the volcanic units into the Ellsworth Land Volcanic Group. This is formally subdivided into two formations: the Mount Poster Formation (silicic ignimbrites), and the Sweeney Formation (basaltic and sedimentary facies). The Mount Poster Formation rhyolites are an intracaldera sequence greater than 1 km in thickness. The basaltic and sedimentary facies of the Sweeney Formation are consistent with deposition in a terrestrial setting into, or close to, water. The geochemistry of the Mount Poster Formation is consistent with derivation of the intracaldera rhyolites from a long-lived, upper crustal magma chamber. The basalts of the Sweeney Formation are intermediate between asthenosphere- and lithosphere-derived magmas, with little or no subduction-modified component. The basalt could represent a rare erupted part of the basaltic underplate that acted as the heat source for local generation of the rhyolites. U–Pb ion microprobe zircon geochronology of samples from the Mount Poster Formation yield an average eruption age of 183.4±1.4 Ma. Analysis of detrital zircons from a Sweeney Formation sandstone suggest a maximum age of deposition of 183±4 Ma and the two formations are considered coeval. In addition, these ages are coincident with eruption of the Karoo-Ferrar Igneous Province in southern Africa and East Antarctica. Our interpretation of the Ellsworth Land Volcanic Group is consistent with the model that the Jurassic volcanism of Patagonia and the Antarctic Peninsula took place in response to intracontinental extension driven by arrival of a plume in that area.