Contrasting geological background based on the geochemistry of the mafic metamorphic rocks in central Dronning Maud Land
Contrasting geological background based on the geochemistry of the mafic metamorphic rocks in central Dronning Maud Land
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基于 Dronning Maud 地中部镁铁质变质岩地球化学的对比地质背景
DOI：
10.1017/s0016756823000092
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发表时间：
2023
影响因子：
2.3
通讯作者：
N.
中科院分区：
文献类型：
--
作者：
Baba;S.;Owada;M.;Hokada;T.;Adachi;T.;Nakano;N.
本文报道了唐宁毛德中部四个地点采集的镁铁片麻岩和麻粒岩的地球化学特征，以评价其前驱岩石的构造背景。Dronning Maud中部基性片麻岩和麻粒岩的前驱岩形成于不同的地质背景和构造环境。席尔马赫山的镁铁质片麻岩和麻粒岩来自弧后环境中的玄武岩。已发表的锆石U-Pb年龄和基岩的地球化学变化表明，它们的侵位时代为800~650 Ma，接近峰期变质作用。在Hochlinfjellet的内陆Nunatak中发现了类似的原岩，而在Filchnerfjella中，镁铁质片麻岩/麻粒岩来自边缘大陆弧或岛弧中形成的玄武岩。高度扰动的微量元素模式表明，变质作用影响了变质阶段的地球化学成分。我们的结果表明，不同变质时代的Dronning Maud中部露头含有不同构造环境下形成的前驱岩石中的镁铁质片麻岩/麻粒岩。
This paper reports geochemical characteristics of mafic gneisses and granulites collected from four localities in central Dronning Maud Land to evaluate the tectonic setting of their precursor rocks. Precursor rocks for the mafic gneisses and granulites in central Dronning Maud Land were formed in different geological backgrounds and tectonic settings. The mafic gneisses and granulites in the Schirmacher Hills were derived from basaltic rocks in a back-arc setting. Published U–Pb zircon ages and the geochemical variation of the basement rocks indicate their emplacement between 800 and 650 Ma, close to peak metamorphism. While similar protoliths were recognized in the inland nunataks of Hochlinfjellet, in Filchnerfjella the mafic gneisses/granulites were derived from basaltic rocks formed in marginal continental arcs or island arcs. Highly disturbed trace-element patterns indicate that the metamorphic process influenced the geochemical composition during the prograde metamorphic stage. Our results imply that the outcrops in central Dronning Maud Land with different metamorphic ages contain mafic gneisses/granulites from precursor rocks formed under different tectonic settings.