| 鞠东阳,庞润连,李瑞,杜蔚. 2022. 热力学计算模拟对初始月幔结构的约束. 岩石学报, 38(4): 1025-1042 |
| 热力学计算模拟对初始月幔结构的约束 |
| 作者 | 单位 | E-mail | | 鞠东阳 | 中国科学院地球化学研究所, 矿床地球化学国家重点实验室, 贵阳 550081
中国科学院大学, 北京 100049 | | | 庞润连 | 中国科学院地球化学研究所, 矿床地球化学国家重点实验室, 贵阳 550081 | | | 李瑞 | 中国科学院地球化学研究所, 矿床地球化学国家重点实验室, 贵阳 550081
中国科学院大学, 北京 100049 | | | 杜蔚 | 中国科学院地球化学研究所, 矿床地球化学国家重点实验室, 贵阳 550081
中国科学院比较行星学卓越创新中心, 合肥 230026 | duwei@mail.gyig.ac.cn |
|
| 基金项目：本文受国家自然科学基金项目（41773052、41973058）资助. |
| 摘要： |
| 月球岩浆洋结晶形成的初始月球内部结构是其后续演化过程的开端，其结晶过程受月球岩浆洋的初始深度和物质组成这两个参数的制约。由于缺少直接来自月球深部的岩石样品，目前关于月球岩浆洋演化过程的探讨主要依赖实验和计算模拟手段。岩浆洋模型中形成的月壳厚度是否与探测结果一致是月球岩浆洋演化模型合理性的重要约束。最新的GRAIL （Gravity Recovery and Interior Laboratory）探测数据推算月壳厚度为34~43km，低于阿波罗时期认为的约70km，这对已有的月球岩浆洋演化模型提出了挑战。本文采用并修正FXMOTR程序包，针对月球岩浆洋在不同的初始深度和物质组成情况下的结晶过程，进行了一系列热力学计算模拟。通过量化月球岩浆洋的初始深度和物质组成对月壳厚度的影响，结合关于月球内部微量元素分配的研究结果，对比了月球岩浆洋结晶后期的残余熔体与原始克里普组分（urKREEP）的成分。本文的模拟结果显示，一个全月幔熔融且初始成分为月球初始上月幔组成（LPUM）的岩浆洋将在其深部结晶2.5%石榴子石，形成的月壳厚度符合GRAIL的约束，并且结晶出了合适的urKREEP成分。在此模型的基础上获取了月球初始的内部成分和密度结构，并对后期月幔翻转（Overturn）的程度进行了探讨。 |
| 英文摘要： |
| The initial lunar internal structure formed by the crystallization of the Lunar Magma Ocean (LMO) is the beginning of its subsequent evolution, and the crystallization process is governed by two parameters:the initial depth and the composition of the LMO. Due to the lack of rock samples directly from the deep interior of the Moon, current studies on the evolution of LMO mainly rely on experimental and computational simulations. The LMO evolution models were evaluated by comparing the thickness of the lunar crust formed through LMO differentiation with detected results. The latest Gravity Recovery and Interior Laboratory (GRAIL) mission suggests that the lunar crust's thickness is 34~43km, lower than 70km estimated from Apollos' data, which challenges all the former models on the LMO evolution. In this paper, we adopt and modify the FXMOTR package to simulate the crystallization process of LMOs with different initial depths and compositions. We quantify the effect of the initial depth and composition on the thickness of the lunar crust, and combine the results of studies on the partitioning of trace elements in the lunar interior to calculate the changes in the lunar mantle's trace element composition through crystallization and compare the rare-earth elements (REE) composition of the residual melt with the urKREEP, primeval KREEP component (incompatible K, REE, and P rich). Results from our simulation show that an LMO extent to its core-mantle boundary with composition as Lunar Primitive Upper Mantle (LPUM) can form a crust with thickness close to the GRAIL data and a reasonable urKREEP layer. There is about 2.5% garnet crystallized after olivine during equilibrium crystallization remaining in the lunar lower mantle. Based on this model, we simulate the whole lunar internal structure on composition and density, and discuss its mantle overturn process. |
| 关键词：月球岩浆洋演化 月壳厚度 月球初始内部结构 石榴子石 热力学计算 |
| 投稿时间：2021-04-09 修订日期：2021-11-05 |
|
|
HTML
查看全文
查看/发表评论
下载PDF阅读器 |
|
|
|
|
|
