Pan-African event in the East Antarctica : significance in the formation of the Gondwana

1. 利用SHRIMP U-Pb锆石年龄、Sm-Nd和Rb-Sr矿物年龄以及整个岩石等时线年龄，研究了Rayner杂岩（RC）的变质和原岩年龄。在RC内，我们已经确定了不同的元古代到寒武纪事件；沿海露头-520-540 Ma，内陆露头-900-1000 Ma。这些时代被认为代表了两个高级变质事件。另一组U-Pb锆石年龄在-780-800 Ma，与先前报道的770 Ma火成岩活动一致。我们打算进一步调查这一事件的范围和性质。新的U-Pb锆石资料表明，原认为代表元古界Rayner杂岩西缘的部分地区在寒武纪（泛非）经历了高变质作用，我们认为它是Lutzow-Holm杂岩（LHC）的向东延续。本文研究了从日野角LHC中得到的变闪长岩和泥质片麻岩的Rb-Sr和Sm-Nd同位素。结合初始比值和前人的锆石U-Pb研究结果，我们认为-1000 Ma的年龄指示了闪长岩的火成岩结晶时间。泥质片麻岩可能来源于中元古代的表壳物质，是龙脉岩体的寄主岩。然而，由于样品采集区域的范围或地质体的异质成因，在这些岩石中没有记录到在大型强子对撞机中普遍存在的-500 Ma高变质年龄。对NIPR新安装的x射线荧光分析仪进行了数据校准，并使用XRF对Sor Rondane Mountains， Yamato Mountains和RC进行了地球化学研究。结果将在NIPR的数据库中进行汇编。总之，泛非事件对这些地形的影响比以前认为的要大得多，我们认为碰撞构造在其中起了重要作用。进一步的变质岩和深成岩的地球化学和同位素研究正在进行中。少

1. The metamorphic and protolith ages of the Rayner Complex(RC) have been examined using SHRIMP U-Pb zircon ages in combination with Sm-Nd and Rb-Sr mineral and whole rock isochron ages. Within the RC we have determined distinct Proterozoic to Cambrian events ; -520-540 Ma at the coastal outcrops, -900-1000 Ma in more inland outcrops. These ages are considered to represent two high-grade metamorphic events. Another grouping of U-Pb zircon ages at -780-800 Ma is consistent with previously reported 770 Ma igneous activity. we intend to further examine the extent and nature of this event. The new U-Pb zircon data show that part of the area formerly considered to represent the western margin of the Proterozoic Rayner Complex underwent high grade metamorphism during the Cambrian (Pan-African) and we propose that it is an eastward continuation of the Lutzow-Holm Complex (LHC).2. A Rb-Sr and Sm-Nd isotope study of meta-trondhjemites and a pelitic gneiss from Cape Hinode, LHC,has been performe … More d. Taking into account the initial ratios and the previous zircon U-Pb study, we concluded that the -1000 Ma age indicates the time of igneous crystallization of the trondhjemite. The pelitic gneiss, which probably originated from middle Proterozoic supracrustal material, is the host rock of the trondhjemite intrusion. However, the -500 Ma high grade metamorphic age, which is ubiquitous in the LHC,is not documented in these rocks, because of either the extent sample collection area or allochtonous origin of the terrane.3. Data calibration for a X-ray fluorescence analyzer which was newly intstalled at NIPR was performed and geochemical studies at the Sor Rondane Mountains, Yamato Mountains and RC were carried out using the XRF.The results are compiled in the database at NIPR.In conclusion, the Pan-African event extensively affected these terranes much more than previously considered and we presume the collisional tectonics playd an important role. Further geochemical and isotopic examination of the metamorphic and plutonic rocks from these area is ongoing. Less