权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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矿物年龄和全岩等时线年龄，对雷纳杂岩的变质年龄和原岩年龄进行了研究。在研究区内，我们确定了元古界至寒武纪的不同事件：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，与先前报道的770 Ma的火成岩活动相一致。我们打算进一步研究这一事件的范围和性质。新的锆石U-Pb数据表明，以前被认为代表元古界雷纳杂岩西缘的部分地区在寒武纪(泛非洲)经历了高级变质作用，我们认为它是Lutzow-Holm杂岩(LHC)向东的延续。用…研究了LHc希诺德角变质奥长花岗岩和泥质片麻岩的Rb-Sr和Sm-ND同位素考虑到初始年龄和前人的锆石U-Pb研究，我们认为-1000 Ma的年龄指示了奥长花岗岩的火成结晶时间。泥质片麻岩可能起源于中元古代表壳物质，是奥长花岗岩侵入体的赋存岩石。然而，由于样品采集区的范围或地体的同源作用，这些岩石中没有记录到大型强震活动中普遍存在的-500 Ma高级变质年龄。对NIPR新安装的X射线荧光分析仪进行了数据标定，并利用XRF进行了Sor Rondane山、Yamato山和RC的地球化学研究。结果被汇编到NIPR的数据库中。结论是，泛非事件对这些地体的影响比以前认为的要大得多，我们推测碰撞构造起了重要作用。对这些地区的变质岩和深成岩的进一步地球化学和同位素检查正在进行中。较少