• 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 >Deep crustal anatexis, magma mixing, and the generation of epizonal plutons in the Southern Rocky Mountains, Colorado
【24h】

Deep crustal anatexis, magma mixing, and the generation of epizonal plutons in the Southern Rocky Mountains, Colorado

机译：科罗拉多州落基山脉深层地壳的食盐动物，岩浆混合以及上层带云母的产生

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

The Never Summer Mountains in north-central Colorado, USA, are cored by two Oligocene, epizonal granitic plutons originally emplaced in the shallow levels of a short-lived (similar to 1 m.y.), small-volume continental magmatic system. The younger Mt. Cumulus stock (28.015 +/- 0.012 Ma) is a syenogranite equivalent compositionally to topaz rhyolites. A comparison to the chemical and isotopic composition of crustal xenoliths entrained in nearby Devonian kimberlites demonstrates that the silicic melts parental to the stock were likely derived from anatexis of local Paleoproterozoic, garnet-absent, mafic lower continental crust. In contrast, the older Mt. Richthofen stock is compositionally heterogeneous and ranges from monzodiorite to monzogranite. Major and trace element abundances and Sr, Nd and Pb isotopic ratios in this stock vary regularly with increasing whole rock wt% SiO2. These data suggest that the Mt. Richthofen stock was constructed from mixed mafic and felsic magmas, the former corresponding to lithosphere-derived basaltic magmas similar isotopically to mafic enclaves entrained in the eastern portions of the stock and the latter corresponding to less differentiated versions of the silicic melts parental to the Mt. Cumulus stock. Zircon U-Pb geochronology further reveals that the Mt. Richthofen stock was incrementally emplaced over a time interval from at least 28.975 +/- 0.020 to 28.742 +/- 0.053 Ma. Magma mixing could have occurred either in situ in the upper crust during basaltic underplating and remelting of an antecedent, incrementally emplaced, silicic intrusive body, or at depth in the lower crust prior to periodic magma ascent and emplacement in the shallow crust. Overall, the two stocks demonstrate that magmatism associated with the Never Summer igneous complex was fundamentally bimodal in composition. Highly silicic anatectic melts of the mafic lower crust and basaltic, mantle-derived magmas were the primary melts in the magma system, with mixing of the two producing intermediate composition magmas such as those from which Mt. Richthofen stock was constructed.
机译：美国科罗拉多州中北部的Never Summer山由两个渐新世的上层花岗岩岩心组成，它们最初被放置在短寿命（约1 m.y.）的小体积大陆岩浆系统的浅层中。年轻的山积云（28.015 +/- 0.012 Ma）是成分相当于黄玉流纹岩的堇青石。与附近泥盆纪金伯利岩夹带的地壳异种石的化学和同位素组成的比较表明，与该储层无关的硅质熔体很可能来自当地古元古代，石榴石缺失，镁铁质下部大陆壳。相比之下，较老的山Richthofen原料在成分上是异质的，范围从单闪闪岩到单闪花岗岩。随着整个岩石的重量百分比SiO2的增加，该储层中的主要元素和痕量元素的丰度以及Sr，Nd和Pb同位素比会定期变化。这些数据表明山。 Richthofen储层是由铁镁质和长英质混合岩浆构成的，前者对应于岩石圈衍生的玄武岩浆，其同位素分布类似于在储层东部夹带的镁铁质飞地，而后者则对应于Mt母体的硅化熔体的低分化版本。积云。锆石U-Pb年代学进一步揭示了Mt.在至少28.975 +/- 0.020到28.742 +/- 0.053 Ma的时间间隔内增量放置Richthofen库存。岩浆混合既可能发生在玄武岩的前期基底和重熔，渐进沉积的硅质侵入体的重熔过程中，也可能发生在上地壳的原位，也可能是在周期性岩浆上升并进入浅地壳之前在下地壳的深处发生。总体而言，这两个股票表明，与从不夏季火成岩相联系的岩浆作用在成分上基本上是双峰的。镁铁质下地壳的高硅质阳极熔液和源自地幔的玄武质岩浆是岩浆系统中的主要熔体，同时混合了两种产生中间成分的岩浆，例如从中提取的岩浆。 Richthofen库存被建造。

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