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

东南极洲泛非事件：对冈瓦纳大陆形成的意义

基本信息

批准号：
06640591
负责人：
SHIRAISHI Kazuyuki
金额：
$ 1.15万
依托单位：
National Institute of Polar Research
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640591/
关键词：
East Antarctica Geochronology Metamorphism Ion Microprobe SHRIMP Gondwana Pan-African Proterozoic

项目摘要

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

1.利用SHRIMP锆石U-Pb年龄，结合Sm-Nd、Rb-Sr矿物和全岩等时线年龄，研究了Rayner杂岩的变质年龄和原岩年龄。在RC中，我们确定了不同的元古代至寒武纪事件;沿海露头为-520-540 Ma，内陆露头为-900-1000 Ma。这些年龄被认为代表了两个高级变质事件。另一组锆石U-Pb年龄为-780-800 Ma，与以前报道的770 Ma岩浆活动相一致。我们打算进一步研究这一事件的范围和性质。新的U-Pb锆石数据表明，在寒武纪（泛非洲），原被认为代表元古宙Rayner杂岩西缘的部分区域经历了高级变质作用，我们认为它是Lutzow-Holm杂岩（LHC）的向东延续。本文对日本海之角（Cape Hinode，LHC）变质奥长花岗岩和泥质片麻岩进行了Rb-Sr和Sm-Nd同位素研究。 ...更多信息 D.结合初始比值和前人锆石U-Pb研究，我们认为-1000Ma年龄指示了奥长花岗岩的岩浆结晶时间。泥质片麻岩是奥长花岗岩的容矿岩石，可能来源于中元古界表壳物质。然而，由于样品收集区域的范围或地体的外来起源，在大型强子对撞机中普遍存在的-500Ma高级变质年龄在这些岩石中没有记录。3.本文对NIPR新装备的X射线荧光分析仪进行了数据校正，并利用该仪器对Sor Ronaldo山、Yamato山和RC山进行了地球化学研究，结果已编入NIPR数据库。目前正在对这些地区的变质岩和深成岩进行进一步的地球化学和同位素检查。少