...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>THE CANADIAN MINERALOGIST >GEOCHEMICAL AND ISOTOPIC EVOLUTION OF THE ANORTHOSITIC PLUTONS OF THE LARAMIE ANORTHOSITE COMPLEX: EXPLANATIONS FOR VARIATIONS IN SILICA ACTIVITY AND OXYGEN FUGACITY OF MASSIF ANORTHOSITES
【24h】

GEOCHEMICAL AND ISOTOPIC EVOLUTION OF THE ANORTHOSITIC PLUTONS OF THE LARAMIE ANORTHOSITE COMPLEX: EXPLANATIONS FOR VARIATIONS IN SILICA ACTIVITY AND OXYGEN FUGACITY OF MASSIF ANORTHOSITES

机译：拉拉米钙铝硅铁矿复合体的钠盐化学地球化学和同位素演化：硅质钙铁硅铝石的二氧化硅活性和氧逸度变化的解释

获取原文
获取原文并翻译 | 示例
   

获取外文期刊封面封底 >>

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

摘要

The Laramie anorthosite complex includes three anorthositic plutons: the Poe Mountain, Chugwater, and Snow Creek intrusions. The Poe Mountain and Chugwater bodies exhibit mappable magmatic stratigraphy that records fractionation processes in a magma chamber at or near the present level of exposure followed by doming and expulsion of residual liquid. The Snow Creek pluton is more poorly exposed, although layering is locally observed, and there is geochemical evidence for removal of interstitial liquid in the eastern portion of the body. The three plutons were emplaced in close succession. The U-Pb zircon and baddeleyite geochronology of anorthosite from the Chugwater and Snow Creek plutons, and a monzodiorite dike, indicates that the Chugwater is the oldest of the bodies, with a weighted average ~207Pb/~206Pb age of five samples of 1435.5 ± 0.3 Ma. The Snow Creek anorthosite intrudes the previously dated 1434 Ma Poe Mountain anorthosite and is, in turn, cut by the 1432.8 ± 2.4 Ma monzodiorite dike. The LAC and associated granites of the Sherman batholith suite were emplaced over a period no greater than 12 million years, and possibly in as little as three million years. Despite their similar ages, each of the LAC anorthosite plutons displays a distinctive assemblage of minerals. The Poe Mountain anorthosite is characterized by olivine, augite, low Ca-pyroxene, ilmenite and magnetite, and plagioclase in the range An_43_53. The Chugwater anorthosite generally contains no olivine but is composed of augite, low Ca-pyroxene, ilmenite and magnetite, and iridescent plagioclase in the range An_50-56 The Snow Creek anorthosite is characterized by a lack of olivine and magnetite and the presence of iridescent plagioclase of composition An_47 to An_56; it is commonly quartz-bearing. These assemblages record a range of silica activities and oxygen fugacities. Higher activities of silica and fugacities of oxygen are correlated with greater amounts of crustal assimilation, as indicated by Nd and Sr isotopic compositions and the presence of inherited components in zircon. We demonstrate that crustal assimilation can produce a range of mineral assemblages and Sr-Nd isotopic compositions in LAC anorthosites crystallized from common mantle-derived parental magmas, and that assimilation of crust is likely an important control on the compositional variations documented in other Proterozoic massif anorthosites.
机译：Laramie钙铝硅钙石复合体包括三个钙铝硅钙镁铁复合体：坡山，楚格沃特和斯诺克里克侵入体。坡山和楚格沃特河体表现出可绘制的岩浆地层，记录了当前暴露水平或接近暴露水平的岩浆室内分馏过程，随后形成了残留液体的隆起和排出。尽管局部观察到分层，但斯诺克里克岩体的暴露程度更差，并且有地球化学证据表明可以清除体内东部的间隙液。三个小节紧挨着放置。楚格沃特和斯诺克里克岩体的钙钛矿的U-Pb锆石和Baddeleyite年代学，以及一个脉闪闪闪的堤坝，表明楚格沃特是最古老的尸体，加权平均〜207Pb /〜206Pb年龄为五个样本，为1435.5± 0.3毫安Snow Creek钙长石侵入了早于1434年的Ma Poe Mountain钙长石，然后被1432.8±2.4 Ma的辉闪石脉削减。谢尔曼岩床套件的LAC和相关花岗岩的放置时间不超过1200万年，可能只有300万年。尽管年龄相似，但每种LAC钙铝硅铁原石Plutons都具有独特的矿物质组合。坡山钙长石的特征是橄榄石，钠长石，低钙辉石，钛铁矿和磁铁矿，斜长石在An_43_53范围内。楚格沃特钙硅钙石通常不含橄榄石，但由辉石，低钙辉石，钛铁矿和磁铁矿组成，且虹彩斜长石在An_50-56范围内。雪溪钙镁长石的特征是缺乏橄榄石和磁铁矿，且存在虹彩斜长石组成为An_47至An_56;它通常是石英轴承。这些组合物记录了一系列的二氧化硅活性和氧逸度。 Nd和Sr同位素组成以及锆石中遗传成分的存在表明，二氧化硅的较高活性和氧的逸散性与大量的地壳同化作用有关。我们证明，地壳同化作用可以在由常见的地幔衍生的母岩浆结晶的LAC钙铁长石中产生一系列矿物组合和Sr-Nd同位素组成，并且地壳的吸收很可能是其他元古界块状钙长石中记录的组分变化的重要控制。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
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