...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Contributions to Mineralogy and Petrology >Highly evolved hypabyssal kimberlite sills from Wemindji, Quebec, Canada: insights into the process of flow differentiation in kimberlite magmas
【24h】

Highly evolved hypabyssal kimberlite sills from Wemindji, Quebec, Canada: insights into the process of flow differentiation in kimberlite magmas

机译：来自加拿大魁北克省Wemindji的高度演化的海底金伯利岩基岩：对金伯利岩岩浆流动分化过程的见解

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

Kimberlite sills emplaced in granite located near the town of Wemindji (Quebec, Canada) range from 2 cm to 1.2 m in thickness. The sills exhibit a wide variation in macroscopic appearance from fine-grained aphanitic dolomitic hypabyssal kimberlite to ilmenite/garnet macrocrystal hypabyssal kimberlite. Diatreme or crater facies rocks are not present. Multiple intrusions are present within the sills, and graded bedding and erosional features such as cross-bedding are common. The sills exhibit a wide range in their modal mineralogy with respect to the abundances of spinel, apatite, phlogopite and dolomite. Olivine is the dominant macrocryst, with an average composition of Fo90. Garnet macrocrysts are low chrome (2–3 wt. %) pyrope (G1/G9 garnet). Ilmenite occurs as rounded macrocrysts (7–13 wt. % MgO). Phlogopite microphenocrysts are Ti-poor and represent a solid solution between phlogopite and kinoshitalite end members. Spinel compositions mainly represent the Cr-poor members of the qandilite–ulvöspinel–magnetite series. The principle carbonate comprising the groundmass is dolomite, with lesser later-forming calcite. Accessory minerals include apatite, Sr-rich calcite, Nb-rich rutile, baddeleyite, monazite-(Ce) and barite. While some of these accessory minerals are atypical of kimberlites in general, it is expected that differentiation products of an evolved carbonate-rich kimberlite magma will crystallize these phases. The Wemindji kimberlites offer insight into the process of crystal fractionation and differentiation in evolved kimberlite magmas. The macroscopic textural features observed in the Wemindji sills are interpreted to represent flow differentiation of a mantle-derived, very fluid, low viscosity carbonate-rich kimberlite. The diverse modes and textural features result entirely from flow differentiation and multiple intrusions of different batches of genetically related kimberlite magma. The mineralogy of the Wemindji kimberlites has some similarities to that of the Wesselton and Benfontein calcite kimberlite sills but differs in detail with respect to dominant carbonate (i.e. dolomite versus calcite), and the character of the rare earth-bearing accessory minerals (i.e. monazite-(Ce) versus rare earth fluorocarbonates).
机译：位于Wemindji镇（加拿大魁北克）附近的花岗岩中放置的金伯利石基石的厚度范围为2厘米至1.2 m。窗台的宏观外观变化很大，从细粒的无色白云岩白垩纪金伯利岩到钛铁矿/石榴石大晶体白垩纪金伯利岩。不存在极硬或火山口相岩石。窗台内存在多个侵入物，并且层状层理和侵蚀特征（如交叉层理）很常见。基石在尖晶石，磷灰石，金云母和白云石的含量方面表现出广泛的模态矿物学特征。橄榄石是主要的大晶，平均组成为Fo 90 。石榴石大晶是低铬（2-3％（重量））的发烟石（G1 / G9石榴石）。钛铁矿以圆形大晶体（7-13 wt。％MgO）的形式出现。金云母的微隐晶石是钛贫的，代表了金云母和蛇纹石末端成员之间的固溶体。尖晶石成分主要代表方铅矿-硫磺吡啶-磁铁矿系列中的贫铬成员。构成地基的主要碳酸盐为白云石，较少形成的方解石。辅助矿物包括磷灰石，富含Sr的方解石，富含Nb的金红石，baddeleyite，独居石（Ce）和重晶石。虽然这些辅助矿物中的一些通常不是金伯利岩的非典型矿物，但预计演化出的富含碳酸盐的金伯利岩岩浆的分化产物将使这些相结晶。 Wemindji金伯利岩提供了对演化的金伯利岩岩浆中晶体分级分离过程的见解。在Wemindji窗台上观察到的宏观纹理特征被解释为代表了源自地幔的，非常流动，低粘度的富含碳酸盐的金伯利岩的流动差异。不同的模式和质地特征完全是由于不同批次的遗传相关金伯利岩岩浆的流动分化和多次侵入所致。 Wemindji金伯利岩的矿物学与Wesselton和Benfontein方解石金伯利石基石有些相似，但在主要碳酸盐（即白云石与方解石）以及稀土辅助矿物（即独居石- （Ce）与稀土碳氟化合物的对比）。

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