Insights into geological evolution of Princess Elizabeth Land, East Antarctica-clues for continental suturing and breakup since Rodinian time
Insights into geological evolution of Princess Elizabeth Land, East Antarctica-clues for continental suturing and breakup since Rodinian time
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DOI：
10.1016/j.gr.2020.05.002
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发表时间：
2020-05
影响因子：
6.1
通讯作者：
Devsamridhi Arora;N. Pant;M. Pandey;A. Chattopadhyay;J. Greenbaum;M. Siegert;S. Bo;D. Blankenship;N. V. C. Rao;A. Bhandari
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文献类型：
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作者：
Devsamridhi Arora;N. Pant;M. Pandey;A. Chattopadhyay;J. Greenbaum;M. Siegert;S. Bo;D. Blankenship;N. V. C. Rao;A. Bhandari
斯文纳群岛-Brattstrand布拉夫斯-拉斯曼山丘构成了伊丽莎白公主岛(PEL)长约70公里的沿海露头，由复杂变形的变质岩和正麻岩组成。本文对这些露头的泥质麻粒岩进行了研究。常规的地温气压估算和伪切分模拟一致表明，在低至中压(2-5kbar)下，整个地区的峰期变质级别为高至超高温(800-950℃)。通过岩相学和假剖面分析，推断出了一个高压(~10Kbar)的残余变质事件和~5Kbar的实质性降压分量，对应于>；1500万公里的隆升。估算了两套年龄(~800 Ma和~500 Ma)，分别对应于托尼期和泛非变质事件。野外资料、岩石学研究和来自Brattstrand Braff和Grovnes半岛的正片麻岩的年龄估算表明，该单元是泥质麻粒岩就地熔融的产物。PEL的泥质麻粒岩与印度东加特活动带出露的泥质麻粒岩具有相似之处。我们认为，这些地段代表一个连续的地体，具有两个主要的造山印记，反映了Rodinia和Gonwaana的融合。人们试图标明古造山带的轴线，这些轴线既有磁场的支持，也有PEL内部最近的气磁特征的支持。我们支持泥质麻粒岩的母质沉积是在斯捷尼期，经历了挤压的UHT-HP(？)变质作用年龄约为800 Ma。在泛非造山事件之前，提出了另一个约600 Ma的广泛盆地。我们认为，泛非造山活动标志着印度-澳大利亚-非洲-南极克拉通的碰撞，并缝合了东冈瓦那。我们还提出了ICECAP数据证实的沿着冰下湖泊-峡谷系统的岩石圈变薄。用模拟模拟的方法论证了基底普遍存在的力学各向异性对确定该裂谷系统的方位及其与兰伯特地块的联系的影响。
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.