Thermal Modeling Applied to the Evolution of Contact Metamorphic Aureoles

热模拟应用于接触变质光环的演化

• 批准号: 8816627
• 负责人: Derrill Kerrick
• 金额: $ 9.21万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-01 至 1992-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8816627&HistoricalAwards=false
• 关键词: Thermal; Modeling; Applied; Evolution; Contact

It is proposed to carry out conduction thermal modeling of contact metamorphic aureoles with computer algorithms involving numerical (finite difference) simulations of the thermal evolu- tion of intrusives. Variables that we will be considered in this modeling include: shapes of intrusions (both two- dimensional and three-dimensional modeling), initial temperature of the intrusion and country rocks, latent heat of crystalliza- tion of the magma, magma convection, thermal diffusivities of the rocks, and endothermic metamorphic reactions occurring within the aureoles. Contact aureoles containing metapelitic lithologies serve as excellent locales to investigate these thermal processes because mineral thermometers in these rocks provide good constraints on the temperature field. A primary thrust of our proposed research is to apply our conduction modeling to the thermal development of contact aureoles, and to integrate and compare our results with independent thermometry of the intru- sives and aureole rocks. Our preliminary two-dimensional conduction modeling of the Ottawa and Cupsuptic aureoles in Maine shows that our proposed research will yield considerable insight into the nature of intrusives and the surrounding thermal aureoles. For example, our modeling of these aureoles provides constraints on the percentage of crystals initially present in the intrusives. The Skiddaw aureole in the Lake District of England provides an excellent opportunity to evaluate contact metamorphism overlying the roof of an intrusive. Our modeling of this aureole may provide us with additional important insight into the role of convective fluid circulation in he thermal evolution of contact aureoles above intrusives. The proposed modeling of the Strontian aureole in southern Scotland will provide not only an analysis of the thermal evolution of contact metamorphism around a "mushroom-shaped" intrusion floored by metamorphic rocks, but also improved insight into Lasaga's (1986) provocative kinetic interpretation of the second sillimanite isograd in the Strontian aureole.

建议使用涉及侵入体热演化数值（有限差分）模拟的计算机算法对接触变质光环进行传导热建模。 我们在此建模中考虑的变量包括：侵入体的形状（二维和三维建模）、侵入体和围岩的初始温度、岩浆结晶潜热、岩浆对流、岩石的热扩散率以及光环内发生的吸热变质反应。 含有变泥岩岩性的接触光环是研究这些热过程的绝佳场所，因为这些岩石中的矿物温度计对温度场提供了良好的约束。 我们提出的研究的主要目的是将我们的传导模型应用于接触光环的热发展，并将我们的结果与侵入岩和光环岩石的独立测温进行整合和比较。 我们对渥太华和缅因州杯状光环的初步二维传导模型表明，我们提出的研究将对侵入体和周围热光环的性质产生相当大的洞察力。 例如，我们对这些光环的建模对最初存在于侵入体中的晶体的百分比提供了限制。 英格兰湖区的斯基多光环为评估侵入体顶部的接触变质作用提供了绝佳的机会。 我们对该光环的建模可以为我们提供对流流体循环在侵入体上方接触光环热演化中的作用的额外重要见解。 苏格兰南部 Strontian 光环的拟议模型不仅将提供对围绕变质岩所覆盖的“蘑菇状”侵入体周围接触变质作用的热演化的分析，而且还可以提高对 Lasaga（1986）对 Strontian 光环中第二硅线石等梯度的挑衅性动力学解释的洞察力。