Abstract Svenner Islands-Brattstrand Bluffs-Larsemann Hills constitutes ~70 km long coastal outcrops of Princess Elizabeth Land (PEL), comprising complexly deformed metapelites and orthogneisses. Pelitic granulites from these outcrops are investigated in this work. Conventional geothermobarometric estimations and Pseudosection modelling consistently indicate that the peak metamorphic grade throughout the area is high to ultra-high temperature (800–950 °C) at low to medium pressure (2–5 kbar). A high pressure (~10 kbar) relict metamorphic event and a substantial decompression component of ~5 kbar, corresponding to >15 km uplift, are inferred through petrographic as well as pseudosection analysis. Two set of ages are estimated (~800 Ma and ~500 Ma), corresponding to Tonian and Pan-African metamorphic events, respectively. Field data, petrographic studies and ages estimated from orthogneisses from the Brattstrand Bluffs and the Grovnes Peninsula suggest that this unit is a product of in-situ melting of the pelitic granulites. Pelitic granulites of PEL possess similarities with those exposed in the Eastern Ghat Mobile Belt of India. We propose that these sectors represent a contiguous terrane with two major orogenic imprints, reflecting Rodinia and Gondwana amalgamations. An attempt is made to mark out paleo-orogenic belt axes, supported by both field as well as recent aero-magnetic signatures in interior PEL. We support that the parent sediments of the pelitic granulites were deposited during Stenian period, which underwent compressional UHT-HP(?) metamorphism at ~800 Ma. Another extensive basin is proposed at ~600 Ma prior to the Pan-African orogenic event. We propose that the Pan-African orogeny marked the collision of Indo-Australo-Africo-Antarctic cratons and stitched the East Gondwana. We also propose a thinned lithosphere along the system of subglacial lakes-canyons confirmed by ICECAP data. Analog modelling is used to demonstrate the influence of pervasive mechanical anisotropy of the basement in defining the orientation of this rift system and its connection to the Lambert Graben.

中文翻译：

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南极洲东部伊丽莎白公主地地质演化洞察——罗丁时代以来大陆缝合和分裂的线索

摘要 Svenner Islands-Brattstrand Bluffs-Larsemann Hills 构成了约 70 公里长的伊丽莎白公主地 (PEL) 海岸露头，包括复杂变形的变泥质岩和正方麻岩。在这项工作中研究了来自这些露头的泥质麻粒岩。传统的地温气压估计和伪剖面模型一致表明，整个区域的峰值变质等级在低到中压（2-5 kbar）下从高温到超高温（800-950 °C）。通过岩相学和假截面分析推断出高压 (~10 kbar) 残余变质事件和~5 kbar 的大量减压分量，对应于 >15 公里的隆起。估计了两组年龄（~800 Ma 和~500 Ma），分别对应于托尼安和泛非变质事件。现场数据，根据布拉特斯特兰德布拉夫斯和格罗夫内斯半岛的正方麻岩估计的岩相学研究和年龄表明，该单元是泥质麻粒岩原位熔融的产物。PEL 的泥质麻粒岩与印度东加特移动带中暴露的那些相似。我们建议这些部门代表一个具有两个主要造山印记的连续地体，反映了罗迪尼亚和冈瓦纳的合并。试图标出古造山带轴，这得到了内部 PEL 中磁场和最近的航空磁特征的支持。我们支持泥质麻粒岩的母沉积物是在 Stenian 时期沉积的，它在~800 Ma 经历了压缩 UHT-HP(?) 变质作用。在泛非造山事件之前的~600 Ma 提出了另一个广泛的盆地。我们认为泛非造山运动标志着印度-澳大利亚-非洲-南极克拉通的碰撞并缝合了东冈瓦纳。我们还提出了沿冰下湖泊峡谷系统减薄的岩石圈，由 ICECAP 数据证实。模拟建模用于证明基底普遍的机械各向异性在定义该裂谷系统的方向及其与兰伯特地堑的连接方面的影响。