Collaborative Research: Energy-Constrained Geochemical Models for Open System Magma Bodies with Anatexis, Replenishment, Magma Mixing and Fractional Crystallization

合作研究：开放系统岩浆体深熔、补给、岩浆混合和分级结晶的能量约束地球化学模型

• 批准号: 0073932
• 负责人: Frank Spera
• 金额: $ 8.93万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0073932&HistoricalAwards=false
• 关键词: Collaborative; Research; Energy; Constrained; Geochemical

SperaEAR-0073932Existing tools that model the geochemical evolution of open-system magma bodies suffer from several limitations, the most critical of which are lack of accounting of energy-conservation and lack of inclusion of the consequences of wallrock partial melting. A new tool will be developed, called Energy-Constrained Recharge Assimilation Fractional Crystallization (EC-RAFC), that models the geochemical evolution of a magma body-wallrock system. A user-friendly EC-RAFC computer code, written in Visual Basic, will be developed in which energy, mass and species are conserved as magma undergoes, fractional crystallization, magma recharge, and assimilation of partially melted wallrock. Input parameters include thermal and chemical characteristics of the magma body, wallrock, and replenishment magma. The EC-RAFC model will couple phase equilibria and thermochemical constraints by incorporating information from melt productivity functions fa (Ta) and fm(Tm) for user-defined compositions of initial magma, wallrock and replenishment magma. The EC-RAFC computer code will also allow for the development and maintenance of compositionally distinct melt reservoirs within an EC-RAFC magma body, thus enabling application of EC-RAFC to zoned ignimbrites. A critical component of this project is development of code capability that can model melt extraction efficiency that is less than unity so that mass and energy addition can be decoupled. Application of the EC-RAFC simulator to a number of well-documented magmatic systems spanning a range of geologic environments will allow exploration of the potential systematics that exist in the relative roles of fractional crystallization, recharge and assimilation in magma bodies from particular tectonic-magmatic settings (e.g., MOR, continental arcs). This research has the potential to impact the work of the large number of geoscientists who generate and interpret geochemical, geochronological, petrographic and petrologic data from extant and ancient magmatic systems and will parallel the dramatic improvement in the amount and quality of geochemical data describing magmatic systems.

模拟开放系统岩浆体地球化学演化的现有工具存在一些局限性，其中最关键的是缺乏能量守恒的核算和缺乏对围岩部分熔融后果的考虑。将开发一种新的工具，称为能量约束补给同化分数结晶（EC-RAFC），模拟岩浆体-围岩系统的地球化学演化。一个用户友好的EC-RAFC计算机代码，编写在Visual Basic中，将开发能量，质量和物种保存为岩浆经历，分离结晶，岩浆补给，和同化的部分熔融围岩。输入参数包括岩浆体、围岩和补充岩浆的热化学特征。 EC-RAFC模型将耦合相平衡和热化学约束，通过将来自熔体生产力函数fa（Ta）和fm（Tm）的信息用于用户定义的初始岩浆、围岩和补充岩浆的组成。EC-RAFC计算机代码还将允许开发和维护EC-RAFC岩浆体内成分不同的熔体储层，从而使EC-RAFC应用于分区熔结凝灰岩。该项目的一个关键组成部分是代码功能的开发，可以模拟熔体提取效率小于1，使质量和能量添加可以解耦。将EC-RAFC模拟器应用于许多记录良好的岩浆系统，这些岩浆系统跨越一系列地质环境，将允许探索潜在的系统学，这些系统学存在于特定构造-岩浆环境中岩浆体的分离结晶、补给和同化的相对作用中（例如，莫尔，大陆弧）。这项研究有可能影响大量地球科学家的工作，他们从现存和古老的岩浆系统中产生和解释地球化学，地质年代学，岩相学和岩石学数据，并将在描述岩浆系统的地球化学数据的数量和质量方面取得巨大进步。