• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Geosphere >The missing link of Rodinia breakup in western South America: A petrographical, geochemical, and zircon Pb-Hf isotope study of the volcanosedimentary Chilla beds (Altiplano, Bolivia)
【24h】

The missing link of Rodinia breakup in western South America: A petrographical, geochemical, and zircon Pb-Hf isotope study of the volcanosedimentary Chilla beds (Altiplano, Bolivia)

机译：南美洲罗迪尼亚分手的缺失联系：Volanationary Chilla床（Altiplano，Bolivia）的岩体，地球化学和锆石PB-HF同位素研究

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The assembly of Rodinia involved the collision of eastern Laurentia with southwestern Amazonia at ca. 1 Ga. The tectonostratigraphic record of the central Andes records a gap of ～300 m.y. between 1000 Ma and 700 Ma, i.e., from the beginning of the Neoproterozoic Era to the youngest part of the Cryogenian Period. This gap encompasses the time of final assembly and breakup of the Rodinia supercontinent in this region. We present new petrographic and whole-rock geochemical data and U-Pb ages combined with Hf isotope data of detrital zircons from the volcanosedimentary Chilla beds exposed on the Altiplano southwest of La Paz, Bolivia. The presence of basalt to andesite lavas and tuffs of continental tholeiitic affinity provides evidence of a rift setting for the volcanics and, by implication, the associated sedimentary rocks. U-Pb ages of detrital zircons ( n = 124) from immature, quartz-intermediate sandstones have a limited range between 1737 and 925 Ma. A youngest age cluster ( n = 3) defines the maximum depositional age of 925 ± 12 Ma. This is considered to coincide with the age of deposition because Cryogenian and younger ages so typical of Phanerozoic units of this region are absent from the data. The zircon age distribution shows maxima between 1300 and 1200 Ma (37% of all ages), the time of the Rond?nia–San Ignacio and early Sunsás (Grenville) orogenies in southwestern Amazonia. A provenance mixing model considering the Chilla beds, Paleozoic Andean units, and data from eastern Laurentia Grenville sources shows that 90% of the clastic input was likely derived from Amazonia. This is also borne out by multidimensional scaling (MDS) analysis of the data. We also applied MDS analysis to combinations of U-Pb age and Hf isotope data, namely ε Hf(t) and 176 Hf/ 177 Hf values, and demonstrate again a very close affinity of the Chilla beds detritus to Amazonian sources. We conclude that the Chilla beds represent the first and hitherto only evidence of Rodinia breakup in Tonian time in Andean South America.
机译：罗迪尼亚的大会涉及东桂伦蒂亚与西南西南亚马逊的碰撞。 1 Ga。中央安排的构造图案记录记录了〜300 m.y的差距。在1000 mA和700 ma之间，即，从新蛋白质的开始到低温期的最年轻部分。这种差距包括在该地区的最终组装和罗迪尼亚超级镇静的时间。我们提出了新的岩手和全岩地球化学数据和U-PB Ages，与玻利维亚的Altiplano西南部暴露的Volcanatiangary Chilla床中的碎屑锆石的HF同位素数据相结合。玄武岩的存在于山羊座和大陆烟草亲和力的凝灰岩提供了对火山虫的裂缝设置的证据，并通过暗示了相关的沉积岩。从不成熟的卵形氧化锆（n = 124）的U-Pb老年，石英中间砂岩的含量有限，在1737和925 mA之间的有限范围。最小的年龄簇（n = 3）定义了925±12 mA的最大沉积年龄。这被认为是与沉积时代重合，因为这种区域的低温和较年轻的年龄如此区域的典型的典型的年龄。锆石年龄分布显示了1300至1200 mA（占所有年龄段的37％）的最大值，摇滚的时间？Nia-San Ignacio和Sunsás（格伦维尔的早期Sunsás（格伦维尔）Oronogenies在西南部的西南部。考虑到Chilla床，古生代Andean单位和来自东方劳伦蒂亚格伦维尔消息来源的数据的出处混合模型表明了＆ 90％的碎屑输入可能来自亚马逊。这也被数据的多维缩放（MDS）分析所承认。我们还将MDS分析应用于U-PB时代和HF同位素数据的组合，即εHF（t）和176hF / 177 HF值，并再次向夏令时对亚马逊来源的非常密切的亲和力。我们得出结论，辣椒床代表了第一个和迄今为止只有罗迪尼亚分手在安安底安安底省南美洲的唯一证据。

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号