...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of the Geological Society >Constraints on the timing of Scandian deformation and the nature of a buried Grampian terrane under the Caledonides of northwestern Ireland
【24h】

Constraints on the timing of Scandian deformation and the nature of a buried Grampian terrane under the Caledonides of northwestern Ireland

机译：斯堪的纳维亚变形时间和西北爱尔兰喀里多尼德群岛下埋藏的格兰屏地层的性质受到限制

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In the Caledonides of northwestern Ireland there is little evidence for the crystalline basement to the Dalradian Supergroup, though ascertaining its nature is a critical prerequisite for palaeogeographical reconstructions. In Donegal a lamprophyre intrusion has sampled material with isotopic composition, age and fabrics that permit the investigation of the hidden basement of this region. U-Pb and Lu-Hf isotopes in concert with structural analysis are used to elucidate the origin of three morphologically distinct zircon populations from the lamprophyre. The first of these comprises c. 828 to c. 1660 Ma rounded inherited grains. The second population, of 476 ± 3 Ma large xenocrystic grains, displays oscillatory zoned cores embayed by cross-cutting overgrowths, implying a multi-stage magmatic genesis. The third population, of 437 ± 5 Ma high aspect ratio euhedral grains, is interpreted to date the magmatic crystallization of the lamprophyre. Hf isotopic data from the Silurian and Neo- to Mesoproterozoic zircons yield crustal residence ages of 1.0-2.3 Ga. However, the Ordovician grains have εHf_i values of c. -20 and model ages of 2.7-2.8 Ga. These data are consistent with the presence of either Archaean crust or an underthrust Ordovician magmatic rock with an Archaean source component, at depth in NW Ireland. Felsic xenoliths, interpreted to be derived from the country rock Dalradian metasediments, exhibit a pre-entrainment foliation and are randomly oriented relative to the foliation within the lamprophyre matrix, indicating deformation prior to c. 437 Ma, probably related to the Grampian orogeny. The host lamprophyre contains a magmatic foliation parallel to a foliation in the country rock, implying synkinematic emplacement during regional NW-SE compression at 437 Ma.
机译：在爱尔兰西北部的喀里多尼德群岛，很少有证据证明达拉迪安超群的晶体基底，尽管确定其性质是古地理重建的关键先决条件。在多尼戈尔，一个煌斑岩侵入体的采样材料具有同位素组成，年龄和织物，可以对该区域的隐蔽地下室进行调查。 U-Pb和Lu-Hf同位素与结构分析相结合，用于阐明来自煌斑岩的三种形态独特的锆石种群的起源。这些中的第一个包括c。 828至c 1660年，Ma遗传了圆形谷物。第二个种群为476±3 Ma的大异种晶粒，显示出横切的过分生长物掩盖的振荡带状核，这意味着多阶段岩浆成因。第三群为437±5 Ma的高长宽比正反面晶粒，据解释为迄今为止煌斑岩的岩浆结晶。志留系和新中元古代锆石的Hf同位素数据得出的地壳停留年龄为1.0-2.3 Ga。然而，奥陶纪晶粒的εHf_i值为c。 -20和2.7-2.8 Ga的模型年龄。这些数据与爱尔兰西北部深处存在的古生硬壳或底下奥陶纪岩浆岩和古生烃成分一致。笛卡尔异岩被解释为源自乡村岩石Dalradian沉积物，表现出夹带前叶面，并且相对于煌斑岩基质内的叶面随机取向，表明在c之前发生了变形。 437 Ma，可能与格兰坪造山运动有关。主体煌斑岩包含与岩体中的岩浆平行的岩浆岩浆，这意味着在437 Ma的区域NW-SE压缩过程中发生了动力学运动。

著录项

相似文献

  • 外文文献
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