On the evolution of the lunar magma ocean
<p>The Earth and the Moon are observed to be almost indistinguishable over a range of refractory isotopes systems. This thesis aims to test the hypothesis that the lunar magma ocean (LMO) possessed the same elemental composition as that of the terrestrial mantle. In particular, I explore wheth...
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| Tác giả khác: | |
| Định dạng: | Luận văn |
| Ngôn ngữ: | English |
| Được phát hành: |
2021
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| Những chủ đề: |
| _version_ | 1826291669840953344 |
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| author | Baker, E |
| author2 | Wade, J |
| author_facet | Wade, J Baker, E |
| author_sort | Baker, E |
| collection | OXFORD |
| description | <p>The Earth and the Moon are observed to be almost indistinguishable over a
range of refractory isotopes systems. This thesis aims to test the hypothesis that the
lunar magma ocean (LMO) possessed the same elemental composition as that of the
terrestrial mantle. In particular, I explore whether the LMO’s differentiation would
result in liquid and crystal phases that can reproduce the Apollo observations of
the lunar surface. To achieve this, I have conducted a detailed series of experiments
which track the evolution of a hypothetical lunar magma ocean of terrestrial mantle
composition. I have broken the differentiation of the LMO into discrete steps, with
the bulk composition of the next step taken as the melt composition of the previous
step. The final experimental liquid, representing ∼98% crystallisation of the LMO,
is highly enriched in Fe (>30 wt.%) and Ti (∼3 wt.%). To explore the petrogenesis
of the mare basalts and the Ferroan Anorthosite Suite (FAS), I have simulated the
remelting of the lunar cumulate mantle using the MELTS program. By recombining
experimental phases and melts in different proportions, I am able to prove that the
Apollo observations are compatible with a LMO of terrestrial mantle composition.
The mafic crystals present in the ferroan anorthosite suite are best matched to
experimentally produced crystals rather than melt, indicating inefficient flotation
rather than trapped melt has contributed to the ferroan anorthosite suite.</p>
<p>Mineral/melt Rare Earth element (REE) partitioning occurring throughout
the evolution of the lunar magma ocean has been experimentally determined, and
predict heavy REE depletion of final liquids, due to high-temperature pyroxene
crystallisation. Consequently, the ’bow shaped’ trend witnessed in the mare basalts
results from a lunar mantle possessing pyroxene enriched in heavy REE and a light
REE enriched KREEP basalt. I explore the implications of different compositions
on the lunar moment of inertia, finding that an overturn of the lunar mantle is more
significant than any conceivable change in composition.</p>
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| first_indexed | 2024-03-07T03:02:53Z |
| format | Thesis |
| id | oxford-uuid:b18c31f2-11a0-4cc5-8f3e-0e3f698347c2 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:02:53Z |
| publishDate | 2021 |
| record_format | dspace |
| spelling | oxford-uuid:b18c31f2-11a0-4cc5-8f3e-0e3f698347c22022-03-27T04:04:55ZOn the evolution of the lunar magma oceanThesishttp://purl.org/coar/resource_type/c_db06uuid:b18c31f2-11a0-4cc5-8f3e-0e3f698347c2MoonGeologyEnglishHyrax Deposit2021Baker, EWade, JBernard , WSara, RBallentine, C<p>The Earth and the Moon are observed to be almost indistinguishable over a range of refractory isotopes systems. This thesis aims to test the hypothesis that the lunar magma ocean (LMO) possessed the same elemental composition as that of the terrestrial mantle. In particular, I explore whether the LMO’s differentiation would result in liquid and crystal phases that can reproduce the Apollo observations of the lunar surface. To achieve this, I have conducted a detailed series of experiments which track the evolution of a hypothetical lunar magma ocean of terrestrial mantle composition. I have broken the differentiation of the LMO into discrete steps, with the bulk composition of the next step taken as the melt composition of the previous step. The final experimental liquid, representing ∼98% crystallisation of the LMO, is highly enriched in Fe (>30 wt.%) and Ti (∼3 wt.%). To explore the petrogenesis of the mare basalts and the Ferroan Anorthosite Suite (FAS), I have simulated the remelting of the lunar cumulate mantle using the MELTS program. By recombining experimental phases and melts in different proportions, I am able to prove that the Apollo observations are compatible with a LMO of terrestrial mantle composition. The mafic crystals present in the ferroan anorthosite suite are best matched to experimentally produced crystals rather than melt, indicating inefficient flotation rather than trapped melt has contributed to the ferroan anorthosite suite.</p> <p>Mineral/melt Rare Earth element (REE) partitioning occurring throughout the evolution of the lunar magma ocean has been experimentally determined, and predict heavy REE depletion of final liquids, due to high-temperature pyroxene crystallisation. Consequently, the ’bow shaped’ trend witnessed in the mare basalts results from a lunar mantle possessing pyroxene enriched in heavy REE and a light REE enriched KREEP basalt. I explore the implications of different compositions on the lunar moment of inertia, finding that an overturn of the lunar mantle is more significant than any conceivable change in composition.</p> |
| spellingShingle | Moon Geology Baker, E On the evolution of the lunar magma ocean |
| title | On the evolution of the lunar magma ocean |
| title_full | On the evolution of the lunar magma ocean |
| title_fullStr | On the evolution of the lunar magma ocean |
| title_full_unstemmed | On the evolution of the lunar magma ocean |
| title_short | On the evolution of the lunar magma ocean |
| title_sort | on the evolution of the lunar magma ocean |
| topic | Moon Geology |
| work_keys_str_mv | AT bakere ontheevolutionofthelunarmagmaocean |