Geochronological constraints on the Late Proterozoic to Cambrian crustal evolution of eastern Dronning Maud Land, East Antarctica: a synthesis of SHRIMP U-Pb age and Nd model age data
Geochronological constraints on the Late Proterozoic to Cambrian crustal evolution of eastern Dronning Maud Land, East Antarctica: a synthesis of SHRIMP U-Pb age and Nd model age data
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DOI：
10.1144/sp308.2
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
K. Shiraishi;D. Dunkley;T. Hokada;C. Fanning;H. Kagami;T. Hamamoto
中科院分区：
文献类型：
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作者：
K. Shiraishi;D. Dunkley;T. Hokada;C. Fanning;H. Kagami;T. Hamamoto
摘要在东南极洲的Dronning Maud Land （DML）东部，有几个离散的、孤立的岩浆和高变质区。从西（东经约20°）到东（东经约50°），分别是Sør Rondane Mountains （SRM）、yamata - belgica Complex （YBC）、l<s:1>佐-霍尔姆Complex （LHC）、Rayner Complex （RC）和Napier Complex （NC）。要在冈瓦纳的背景下理解这个地区，必须区分泛非和格伦维利亚的年龄岩浆和变质事件。结合已发表的各种地体的地质和岩石学研究，对变质岩和深成岩的高分辨率离子探针U-Pb锆石年龄和Nd模式年龄进行了检查。特别地，详细地考察了SRM的演变。对新资料和已发表资料进行的Nd模式年龄汇编表明，东Dronning Maud大陆的主体部分，包括SRM，代表了中元古代晚期（约1000-1200 Ma）的年轻地壳，并伴有较老大陆成分的少量碎片。在SRM的基底中缺乏太古宙成分的证据。中部DML为1100 ~ 1200 Ma广泛的长英质岩浆活动。从变质沉积岩中的碎屑锆石种群可以识别出800-700 Ma岩浆活动期间或之后的沉积和可能的变质作用。约600 ~ 650 Ma时，SRM的NE地体与YBC一起在麻粒岩相条件下变质。在约570 Ma的角闪岩相变质作用中，SRM的西南地体和东北地体交汇在一起，并具有共同的变质和岩浆历史。在560 ~ 500 Ma之间，发生了广泛的a型花岗岩类活动和接触变质作用。相比之下，TDM和继承的锆石年龄表明，大型强子对撞机是一个具有各种元古代和太古宙来源的原岩拼贴体。因此，大型强子对撞机在520-550 Ma的后期变质高峰代表了东南极洲这一地区冈瓦纳合并的最后阶段。
Abstract In eastern Dronning Maud Land (DML), East Antarctica, there are several discrete, isolated magmatic and high-grade metamorphic regions. These are, from west (c. 20°E) to east (c. 50°E), the Sør Rondane Mountains (SRM), Yamato–Belgica Complex (YBC), Lützow-Holm Complex (LHC), Rayner Complex (RC) and Napier Complex (NC). To understand this region in a Gondwanan context, one must distinguish between Pan-African and Grenvillian aged magmatic and metamorphic events. Sensitive high-resolution ion microprobe U–Pb zircon ages and Nd model ages for metamorphic and plutonic rocks are examined in conjunction with published geological and petrological studies of the various terranes. In particular, the evolution of the SRM is examined in detail. Compilation of Nd model ages for new and published data suggests that the main part of eastern Dronning Maud Land, including the SRM, represents juvenile late Mesoproterozoic (c. 1000–1200 Ma) crust associated with minor fragments of an older continental component. Evidence for an Archaean component in the basement of the SRM is lacking. As for central DML, 1100–1200 Ma extensive felsic magmatism is recognized in the SRM. Deposition of sediments during or after magmatism and possible metamorphism at 800–700 Ma is recognized from populations of detrital zircon in metasedimentary rocks. The NE Terrane of the SRM, along with the YBC, was metamorphosed under granulite-facies conditions at c. 600–650 Ma. The SW and NE Terranes of the SRM were brought together during amphibolite-facies metamorphism at c. 570 Ma, and share a common metamorphic and magmatic history from that time. High-grade metamorphism was followed by extensive A-type granitoid activity and contact metamorphism between 560 and 500 Ma. In contrast, TDM and inherited zircon core ages suggest that the LHC is a collage of protoliths with a variety of Proterozoic and Archaean sources. Later peak metamorphism of the LHC at 520–550 Ma thus represents the final stage of Gondwanan amalgamation in this section of East Antarctica.