...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Geosphere >Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?
【24h】

Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

机译：从侏罗纪到第三次北巴巴塔哥拉那人席位的岩浆源组合物的世俗变化：涉及梅哈兰融化吗？

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

摘要

This study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of magmas are represented by the Sr-Nd initial isotopic ratios ( 87 Sr/ 86 Sr and 143 Nd/ 144 Nd) of the plutonic rocks. Our results support the interpretation that source composition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel mélange. Subsequent melting of subducted mélanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast convergence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk mélanges and the peridotite. Our proposal follows model predictions on the formation of mélange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general.
机译：这项研究北巴基塔斯塔基尔（阿根廷和智利）的SR-Nd初始同位素比例的型芦苇的初始同位素比率透露，在岩浆来源方面，可以建立从侏罗纪到Neogene的世俗演变，从岩浆源建立，这反过来是相关的随着构造制度的变化。岩浆源源中的端构件组分的出差和组成由浦项岩石的SR-ND初始同位素比（87SR / 86 SR和143 ND / 144 Nd）表示。我们的结果支持解释，通过将不同的地壳材料和沟槽沉积物掺入俯冲和沉积物俯冲将不同的地壳材料和沟槽沉积物掺入俯冲通道Mélange来解释。随后在地幔深度的熔化掩模和与超微罩的最终反应的熔化是浴质岩浆生成的主要原因，这在涉及的板之间的快速收敛性和高倾斜期间受到青睐。我们提出了父母的二峰岩（= indesite）前体到达下弧地壳，在下面的分级下进行分馏以产生形成浴池的硅熔体（Granodiorites和花岗岩）。通过玄武岩和岩石和恒星的完全反应，多摩托先进前体可以从玄武岩和岩组合物的更令人毛骨制的熔体分馏。我们的提案遵循模型预测，对Mélange催化的形成，将肥沃的岩浆材料携带到Suprasubducked Mantle Wedge的热区域，其中涂料的MAFIC父母岩浆起源于。该模型不仅占Andean浴袍的世俗地球化学变化，而且还避免了经典玄武岩模型的基本悖论：较低的弧形外壳中的超微累积和大陆地壳一般。

著录项

相似文献

  • 外文文献
  • 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