40Ar/39Ar and U–Pb data from five structural domains constrain the late Neoproterozoic – early Palaeozoic tectonothermal history of the eastern part of the East African–Antarctic Orogen in Sør Rondane. A total of 27 new Ar/Ar ages span 570–474 Ma, roughly corresponding to the age range of three generations of syn- to post-tectonic granitoids. The ages are distinct for the five structural domains. The oldest cooling ages come from the weakly deformed southern part of the SW Terrane of Sør Rondane (SW Terrane S), a sliver of a Tonian island arc, which escaped much of the late Neoproterozoic accretionary deformation. This terrane was intruded by the oldest and largest granitoid complex at c. 640–620 Ma. The oldest Ar/Ar amphibole and biotite ages of 570–524 Ma are from the Main Shear Zone, along the northern margin of the SW Terrane S sliver. It hosts granites of age c. 584–570 Ma strung out along the shear zone. Two younger granitoid phases are recorded in the adjacent four terranes to the west, north and east of the SW Terrane S, and correlate with the younger group of Ar/Ar biotite ages spanning 513–474 Ma. We interpret the magmatic and cooling history of duration > 150 Ma to reflect repeated phases of accretion, magmatism and reactivation, that is, collage-style tectonism, partly pre-dating the incorporation of Sør Rondane into Gondwana. The study area first accreted to the cryptic Valkyrie Craton in Tonian times, was then ‘sandwiched’ between the Kalahari and Indo-Antarctica cratons, and experienced extensional tectonics and elevated heat flux due to lithospheric delamination, which resulted in slow cooling during the Pan-African Orogeny.

中文翻译：

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来自 40Ar/39Ar 和 U-Pb 年代学的南极东部 Sør Rondane 的长期晚新元古代 - 早古生代变形和冷却历史

40氩气/39来自五个结构域的 Ar 和 U-Pb 数据限制了 Sør Rondane 东非 - 南极造山带东部的晚新元古代 - 早古生代构造热史。共有 27 个新的 Ar/Ar 年龄跨度在 570 ～ 474 Ma，大致对应于 3 代同构造后花岗岩的年龄范围。五个结构域的年龄不同。最古老的冷却年龄来自 Sør Rondane 的 SW 地体 (SW Terrane S) 的变形较弱的南部，它是托尼安岛弧的一部分，它逃脱了新元古代晚期的大部分增生变形。这个地体被最古老和最大的花岗岩复合体侵入C。640-620 毫安。最古老的 Ar/Ar 闪石和黑云母年龄为 570-524 Ma，来自主剪切带，沿 SW Terrane S 长条的北缘。它承载着年代久远的花岗岩C。584-570 Ma 沿剪切带排列。在 SW 地体 S 的西部、北部和东部的相邻四个地体中记录了两个较年轻的花岗岩相，与较年轻的 Ar/Ar 黑云母年龄组相关，年龄跨度为 513-474 Ma。我们解释持续时间 > 150 Ma 的岩浆和冷却历史，以反映吸积、岩浆作用和重新激活的重复阶段，即拼贴式构造，部分早于 Sør Rondane 并入冈瓦纳。研究区在托尼纪时期首先形成神秘的瓦尔基里克拉通，然后被“夹在”喀拉哈里和印度-南极洲克拉通之间，由于岩石圈的剥离，经历了伸展构造和热通量升高，导致泛冰期冷却缓慢。非洲造山运动。