Planetary evolution: Moon a case study of thermal evolution

行星演化：月球热演化的案例研究

• 批准号: 265560107
• 负责人: Dr. Vera Assis Fernandes, Ph.D.
• 金额: --
• 依托单位: Institut für Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/265560107?language=en
• 关键词: Planetary; evolution; Moon; case; study

Besides the Earth, the Moon provides the most comprehensive global data sets to understand the thermo-chemical evolution of a planetary body. This internal evolution of the Moon is expressed on the lunar surface by widespread basaltic volcanism. Composition and timing of lava emplacement can be determined by measuring mineralogical, chemical and isotopic composition and chronology rock samples. Together with global remote sensing data including images, topographic, spectral, chemical, and gravimetric data, this rock data can be placed into a selenologic context. So far global remote sensing images of the lunar surface suggest a 3.2 Ga lasting period of volcanism, but a significantly shorter period of only 1.8 Ga of volcanic activity was reported by radiometric ages from Apollo, and Luna mission samples and lunar meteorites. In contrast to gram sized Apollo mission samples, the mg sized rake samples from Apollo 15 basaltic regolith, and the Apollo 17 samples studied in the preceding period of this project, provide plenty of basaltic fragments that probably are more diverse and representative for the regional volcanic history. I aim to continue exploring this diversity in Apollo 15 regolith fragments by integrating (1) mineral and chemical composition (SEM, EMPA and LA-ICP-MS) with (2) 40Ar-39Ar chronologic data of the basalt fragments, and 3) in-situ U-Pb when accessory minerals are present. The aim is to evaluate the evolution of the lunar mantle heterogeneities. This integrated multidisciplinary strategy has not been fully explored.The new data obtained from Apollo 15 basaltic fragments, together with the data already acquired from Apollo 17 samples, represent two distinct lunar volcanic provinces, within and outside the Procellarum-KREEP Terrain, respectively. Lunar volcanism in these two distinct settings provides important constraints on the thermo-chemical evolution of the Moon, and the processes that generated these melts. Using the new mineralogical and chemical composition, and chronologic data together with mineral-melt partition coefficients, I aim to determine the thermo-chemical evolution of the mantle under the Imbrium and Serenitatis basins. Presently, the known elemental and isotopic variations of lunar samples cannot be completely modelled with the four distinct mantle reservoirs as sources for low- and high-Ti basalts, KREEEP rocks, and anorthosites. This seems indicative of heterogeneities within the lunar mantle and regional variations in the chemical evolution, and magma generation through time. The results will be used further in global 3D thermo-chemical models computed with the finite difference/finite volume code StagYY to better understand the magmatic evolution of a planet without plate tectonics.

除了地球，月球提供了最全面的全球数据集，以了解行星体的热化学演化。月球内部的演化在月球表面表现为广泛的玄武岩火山活动。熔岩侵位的成分和时间可以通过测量岩石样品的矿物学、化学和同位素成分以及年代学来确定。连同全球遥感数据，包括图像，地形，光谱，化学和重力数据，这种岩石数据可以放置到一个月的背景。到目前为止，月球表面的全球遥感图像表明火山活动持续了3.2 Ga，但阿波罗和月球使命任务样品和月球陨石的放射性年龄报告了一个明显更短的火山活动期，只有1.8 Ga。与克级阿波罗使命样品相比，来自阿波罗15号玄武岩风化层的毫克级耙样品和本项目前期研究的阿波罗17号样品提供了大量玄武岩碎片，这些碎片可能更多样化，更能代表区域火山历史。我的目标是继续探索阿波罗15号风化层碎片的这种多样性，将（1）矿物和化学成分（SEM，EMPA和LA-ICP-MS）与（2）玄武岩碎片的40 Ar-39 Ar年代学数据相结合，以及（3）存在辅助矿物时的原位U-Pb。目的是评估月球地幔非均匀性的演化。从阿波罗15号玄武岩碎片中获得的新数据，以及从阿波罗17号样品中获得的数据，分别代表了Procellarum-KREEP地形内外两个不同的月球火山区。在这两种不同的环境中，月球火山活动对月球的热化学演化以及产生这些熔化的过程提供了重要的限制。使用新的矿物学和化学成分，以及矿物熔体分配系数的年代学数据，我的目标是确定下的Imperial和Serenitatis盆地的地幔的热化学演化。目前，已知的元素和同位素变化的月球样品不能完全模拟与四个不同的地幔水库的来源，低钛和高钛玄武岩，KREEEP岩石，斜长岩。这似乎表明了月球地幔内部的不均匀性和化学演化的区域变化，以及随着时间的推移岩浆的产生。研究结果将进一步用于用有限差分/有限体积代码StagYY计算的全球三维热化学模型，以更好地了解没有板块构造的行星的岩浆演化。