Trace element variations in zoned minerals: a record of geochemical and environmental feedback

分区矿物中的微量元素变化：地球化学和环境反馈的记录

• 批准号: 612-2006
• 负责人: Halden, Norman
• 金额: $ 2.46万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=366660
• 关键词: Trace; element; variations; zoned; minerals

Zoning and layered patterns in rocks and minerals occur on a variety of length- and time-scales in many different environments throughout geologic time. Because minerals take time to grow such patterns must record changes in the environment. Zoned patterns may be interpreted as (1) the product of externally forced processes, for example, where there is evidence of chemical disequilibrium or (2) the product of self organization expressed as differences in growth form or oscillatory zoning patterns (OZP).  Distinguishing the two is important.  While in many instances external forcing has succeeded in explaining a number of patterns such as major element variations in minerals (e.g. garnet), externally driven variations cannot adequately explain the repetitive or periodic character of oscillatory patterns observed on a scale of microns in minerals such as apatite and zircon.   Both types of zoning can occur in the same mineral.   Geochemical self organization in minerals can produce very complex patterns and is essentially a short range process largely influenced by diffusion and mineral structure over the few microns encompassing the growth surface of the mineral.  At this local scale, the periodic or other structured patterns are an expression of reaction coupling and diffusive transport entirely in the absence of large-scale external forcing.  There are now a number of examples of spontaneously generated zoning and layered features in rocks and minerals that arise as the product of coupling and feedback between different systems including zonation in accessory minerals, agate, diagenetic carbonates, biogenic carbonate and cyclic layering in mafic and ultramafic rocks.

岩石和矿物质中的分区和分层模式在整个地质时期的许多不同环境中发生在各种长度和时间尺度上。因为矿物需要时间来发展这种模式，必须记录环境中的变化。分区模式可以解释为（1）外部强制过程的乘积，例如，有证据表明化学二蒸馏液或（2）自组织的乘积表示为生长形式或振荡性分区模式（OZP）的差异。区分两者很重要。尽管在许多情况下，外部强迫已经成功地解释了许多模式，例如矿物质的主要元素变化（例如石榴石），但外部驱动的变化无法充分解释在矿物质中观察到的振动性模式的重复或周期性或周期性的振动模式的重复性或周期性，例如磷灰石和磷灰石和锆石。两种类型的分区都可以在同一矿物质中发生。   矿物质中的地球化学自我组织可以产生非常复杂的模式，并且本质上是一个短范围的过程，在很大程度上受到包含矿物生长表面的少数微米的扩散和矿物结构的影响。    在此局部规模上，周期性或其他结构化模式是在没有大规模外部强迫的情况下完全表达反应耦合和分化转运的表达。   现在，有许多例子在岩石和矿物质中对赞助商友好的分区和分层特征进行了例子，这些示例是不同系统之间耦合和反馈的产物，包括辅助矿物质，玛瑙，诊断碳酸盐，生物含量碳酸盐，生物碳酸盐和梅菲克斯和超玛玛岩的环境。