Magmatic evolution and tectonic setting of metabasites from Lützow-Holm Complex, East Antarctica
Magmatic evolution and tectonic setting of metabasites from Lützow-Holm Complex, East Antarctica
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DOI：
10.1144/sp308.11
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Y. Suda;Y. Kawano;G. Yaxley;H. Korenaga;Y. Hiroi
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文献类型：
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作者：
Y. Suda;Y. Kawano;G. Yaxley;H. Korenaga;Y. Hiroi
摘要 东南极洲吕佐夫-霍尔姆杂岩中的变碱岩相当于变质的超基性岩和具有超基性到中级成分的基性岩，它们以层状和块状出现在石英长石或变沉积片麻岩中。现场产状和全岩地球化学表明，超镁铁质岩石均为堆积岩原岩，而镁铁质岩石主要为玄武岩原岩，包括一些堆积物。此外，在区域背景下，变碱岩的地球化学从奥拉夫王子海岸到吕佐夫-霍尔姆湾地区的西南方向从岛弧转向海底亲和力。钕同位素数据表明，奥拉夫王子海岸和吕措夫-霍尔姆湾北部地区的变质岩源自中元古代地壳活跃生长形成的不成熟大陆地壳，而吕措夫-霍尔姆湾南部地区的变质岩则源自成熟的大陆地壳和较古老的洋壳。因此，这些结果表明吕措-霍尔姆杂岩包括具有不同起源和年龄的岩性单元，这些岩性单元通过多次俯冲合并，并由于泛非造山运动期间东西冈瓦纳的最终碰撞而经历了高级变质作用。
Abstract Metabasites from the Lützow-Holm Complex, East Antarctica, are the equivalent of metamorphosed ultramafic and mafic rocks with ultrabasic to intermediate compositions, which occur as layers and blocks in the quartzo-feldspathic or metasedimentary gneisses. Field occurrences and whole-rock geochemistry suggest that the ultramafic rocks are all cumulitic protoliths, whereas the mafic rocks are mostly basaltic protoliths including some cumulates. Moreover, in a regional context, the geochemistry of metabasites shifts from island arc to ocean-floor affinities in a southwesterly direction from the Prince Olav Coast to the Lützow-Holm Bay area. Neodymium isotopic data suggest that the metamorphic rocks from the Prince Olav Coast and the northern Lützow-Holm Bay areas were derived from immature continental crust formed by active Mesoproterozoic crustal growth, whereas those from the southern Lützow-Holm Bay area were derived from mature continental crust and oceanic crust of older age. Thus, these results suggest that the Lützow-Holm Complex includes lithological units with various origins and ages that were amalgamated by multiple subduction, and underwent high-grade metamorphism as a result of the final collision of East and West Gondwana during the Pan-African orogeny.