Phosphorus zoning as a recorder of crystal growth kinetics: application to second-generation olivine in mantle xenoliths from the Cima Volcanic Field
Phosphorus zoning as a recorder of crystal growth kinetics: application to second-generation olivine in mantle xenoliths from the Cima Volcanic Field
复制标题
DOI：
10.1007/s00410-017-1376-7
复制
发表时间：
2017-06
影响因子：
3.5
通讯作者：
I. Baziotis;P. Asimow;T. Ntaflos;J. Boyce;F. McCubbin;Antonios Koroneos;D. Perugini;S. Flude;S. Flude;Michael Storey;Michael Storey;Yongsheng Liu;S. Klemme;J. Berndt
中科院分区：
文献类型：
--
作者：
I. Baziotis;P. Asimow;T. Ntaflos;J. Boyce;F. McCubbin;Antonios Koroneos;D. Perugini;S. Flude;S. Flude;Michael Storey;Michael Storey;Yongsheng Liu;S. Klemme;J. Berndt
来自美国加利福尼亚州西马火山场的复合地幔包体含有横穿岩性分层并保存岩石圈熔体渗入事件证据的玻璃状脉体。来自这些矿脉的矿物和玻璃的成分和结构可能会限制渗透过程中反应的速度和程度。我们研究了两个以前未描述的复合包体的玻璃含区，包括光学岩相学和主要元素和微量元素的化学分析，使用电子探针显微分析和激光烧蚀电感耦合等离子体质谱。每条脉的成岩历史包括熔体侵入、伴随围岩反应和结晶的冷却、熔体对玻璃的冷却，以及可能的后期改造。矿脉中奇异的次生橄榄石晶体显示同心富磷(P)分带、富P玻璃包裹体和快速扩散元素(如Li)的分带，我们将其解释为快速不平衡事件的记录和冷却速度约为10°C/h。然而，对其中一个样品中记录的玻璃成分多样性的热力学模拟表明，在最终淬火之前，与基质中的富镁橄榄石发生了广泛的反应。我们的结果是解释许多大陆和海洋环境中岩石圈熔体-岩石反应速率和过程的方法的一个案例研究。
Composite mantle xenoliths from the Cima Volcanic Field (CA, USA) contain glassy veins that cross-cut lithologic layering and preserve evidence of lithospheric melt infiltration events. Compositions and textures of minerals and glasses from these veins have the potential to place constraints on the rates and extents of reaction during infiltration. We studied glass-bearing regions of two previously undescribed composite xenoliths, including optical petrography and chemical analysis for major and trace elements by electron probe microanalysis and laser-ablation inductively coupled plasma mass spectrometry. The petrogenetic history of each vein involves melt intrusion, cooling accompanied by both wall-rock reaction and crystallization, quench of melt to a glass, and possibly later modifications. Exotic secondary olivine crystals in the veins display concentric phosphorus (P)-rich zoning, P-rich glass inclusions, and zoning of rapidly diffusing elements (e.g., Li) that we interpret as records of rapid disequilibrium events and cooling rates on the order of 10 °C/h. Nevertheless, thermodynamic modeling of the diversity of glass compositions recorded in one of the samples demonstrates extensive reaction with Mg-rich olivine from the matrix before final quench. Our results serve as a case study of methods for interpreting the rates and processes of lithospheric melt-rock reactions in many continental and oceanic environments.