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An autonomous petrological database for geodynamic simulations of magmatic systems
Geophysical Journal International ( IF 2.8 ) Pub Date : 2020-09-01 , DOI: 10.1093/gji/ggaa413
Lisa Rummel 1 , Tobias S Baumann 1 , Boris J P Kaus 1
Affiliation  

Self-consistent modelling of magmatic systems is challenging as the melt continuously changes its chemical composition upon crystallizing, which may affect the mechanical behaviour of the system. Melt extraction and subsequent crystallization creates new rocks while depleting the source region. As the chemistry of the source rocks changes locally due to melt extraction, new calculations of the stable phase assemblages are required to track the rock evolution and the accompanied change in density. As a consequence, a large number of isochemical sections of stable phase assemblages are required to study the evolution of magmatic systems in detail. As state of the art melting diagrams may depend on 9 oxides as well as pressure and temperature, this is a 10-dimensional computational problem. Since computing a single isochemical section (as a function of pressure and temperature) may take several hours, computing new sections of stable phase assemblages during an ongoing geodynamic simulation is currently computationally intractable. One strategy to avoid this problem is to precompute these stable phase assemblages and to create a comprehensive database as a hyperdimensional phase diagram, which contains all bulk compositions that may emerge during petro-thermo-mechanical simulations. Establishing such a database would require repeating geodynamic simulations many times while collecting all requested compositions that may occur during a typical simulation and continuously updating the database until no additional compositions are required. Here, we describe an alternative method that is better suited for implementation on large scale parallel computers. Our method uses the entries of an existing preliminary database to estimate future required chemical compositions. Bulk compositions are determined within boundaries that are defined manually or through principal component analysis (PCA) in a parameter space consisting of clustered database entries. We have implemented both methods within a massively parallel computational framework while utilizing the Gibbs free energy minimization program Perple_X. Results show that our autonomous approach increases the resolution of the thermodynamic database in compositional regions that are most likely required for geodynamic models of magmatic systems.

中文翻译:

用于岩浆系统地球动力学模拟的自主岩石学数据库

岩浆系统的自洽模型具有挑战性,因为熔体在结晶时会不断改变其化学成分,这可能会影响系统的机械性能。熔体提取和随后的结晶会在耗尽源区的同时产生新的岩石。由于源岩的化学性质由于熔融提取而发生局部变化,因此需要新的稳定相组合计算来跟踪岩石的演化以及随之而来的密度变化。因此,需要大量的稳定相集合的等化学部分来详细研究岩浆系统的演化。由于现有技术的熔解图可能取决于9种氧化物以及压力和温度,因此这是10维计算问题。由于计算单个等化学截面(作为压力和温度的函数)可能需要几个小时,因此在进行中的地球动力学模拟过程中,计算稳定相组合的新截面目前在计算上难以实现。避免此问题的一种策略是预先计算这些稳定的相组合并创建一个完整的数据库,作为超维相图,其中包含在石油热机械模拟过程中可能出现的所有本体组成。建立这样一个数据库将需要多次重复地球动力学模拟,同时收集在典型模拟过程中可能发生的所有请求的成分,并不断更新数据库,直到不需要其他成分为止。这里,我们描述了一种更适合在大型并行计算机上实现的替代方法。我们的方法使用现有的初步数据库的条目来估计将来所需的化学成分。散装成分是在由群集数据库条目组成的参数空间中手动定义或通过主成分分析(PCA)定义的边界内确定的。我们在利用Gibbs自由能最小化程序Perple_X的同时,在大规模并行计算框架中实现了这两种方法。结果表明,我们的自主方法提高了岩浆系统地球动力学模型最可能需要的组成区域中热力学数据库的分辨率。我们的方法使用现有的初步数据库的条目来估计未来所需的化学成分。散装成分是在由群集数据库条目组成的参数空间中手动定义或通过主成分分析(PCA)定义的边界内确定的。我们在利用Gibbs自由能最小化程序Perple_X的同时,在大规模并行计算框架中实现了这两种方法。结果表明,我们的自主方法提高了岩浆系统地球动力学模型最可能需要的组成区域中热力学数据库的分辨率。我们的方法使用现有的初步数据库的条目来估计将来所需的化学成分。散装成分是在由群集数据库条目组成的参数空间中手动定义或通过主成分分析(PCA)定义的边界内确定的。我们在利用Gibbs自由能最小化程序Perple_X的同时,在大规模并行计算框架中实现了这两种方法。结果表明,我们的自主方法提高了岩浆系统地球动力学模型最可能需要的组成区域中热力学数据库的分辨率。散装成分是在由群集数据库条目组成的参数空间中手动定义或通过主成分分析(PCA)定义的边界内确定的。我们在利用Gibbs自由能最小化程序Perple_X的同时,在大规模并行计算框架中实现了这两种方法。结果表明,我们的自主方法提高了岩浆系统地球动力学模型最可能需要的组成区域中热力学数据库的分辨率。散装成分是在由群集数据库条目组成的参数空间中手动定义或通过主成分分析(PCA)定义的边界内确定的。我们在利用Gibbs自由能最小化程序Perple_X的同时,在大规模并行计算框架中实现了这两种方法。结果表明,我们的自主方法提高了岩浆系统地球动力学模型最可能需要的组成区域中热力学数据库的分辨率。
更新日期:2020-09-01
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