Elasticity variations of lunar crust based on its gravity aspects

• Název práce v češtině: Změny v elastičnosti Měsíční kůry z gravitačních aspektů
• Název v anglickém jazyce: Elasticity variations of lunar crust based on its gravity aspects
• Klíčová slova: gravitační aspekty, elastičnost, Měsíční kúra
• Klíčová slova anglicky: gravity aspects, elasticity, Moon's crust
• Akademický rok vypsání: 2021/2022
• Typ práce: disertační práce
• Jazyk práce: angličtina
• Ústav: Ústav hydrogeologie, inženýrské geologie a užité geofyziky (31-450)
• Vedoucí / školitel: doc. RNDr. Günther Kletetschka, Ph.D.
• Řešitel: skrytý - zadáno a potvrzeno stud. odd.
• Datum přihlášení: 26.09.2022
• Datum zadání: 27.09.2022
• Datum potvrzení stud. oddělením: 27.09.2022

Zásady pro vypracování

Magnetic prospecting
Petrophysics
Matlab
Review of Geophysics

Seznam odborné literatury

Wilhelms, D. E., with sections by McCauley, J. F. & Trask, N. J. The geologic history of the Moon. Report No. 1348, (1987).
Whitaker, E.A., 1981, The lunar Procellarum basin, in Schultz, P.H., and Merrill, R.B., eds., Multi-Ring Basins: Formation and Evolution: proceedings of the Lunar and Planetary Science Conference: New York and Oxford, Pergamon Press, p. 105–111.
Byrne, C. J. The Moon’s Near Side Megabasin and Far Side Bulge. 1 edn, (Springer, New York, NY, 2013).
Bidulsky, R., Bidulska, J. & Grande, M. A. Effect of High-temperature Sintering and Severe Plastic Deformation on the Porosity Distribution. High Temperature Materials and Processes 28, 337-342, doi:10.1515/htmp.2009.28.5.337 (2009).
Zhong, S. J., Parmentier, E. M. & Zuber, M. T. A dynamic origin for the global asymmetry of lunar mare basalts. Earth and Planetary Science Letters 177, 131-140, doi:10.1016/s0012-821x(00)00041-8 (2000).
Garrick-Bethell, I. & Zuber, M. T. An indigenous origin for the South Pole Aitken basin thorium anomaly. Geophysical Research Letters 32, doi:10.1029/2005gl023142 (2005).
Lemoine, F. G. et al. GRGM900C: A degree 900 lunar gravity model from GRAIL primary and extended mission data. Geophysical Research Letters 41, 3382-3389, doi:https://doi.org/10.1002/2014GL060027 (2014).
Klokocnik, J., Kostelecky, J., Bezdek, A. & Kletetschka, G. ARTEFACTS IN GRAVITY FIELD MODELLING. Acta Geodynamica et Geromaterialia 18, 511+ (2021).
Belen’kii, G. L., Salaev, E. Y. & Suleimanov, R. A. Deformation effects in layer crystals. Uspekhi Fizicheskikh Nauk 155, 89-127 (1988).
Neumann, G. A. et al. Lunar impact basins revealed by Gravity Recovery and Interior Laboratory measurements. Science Advances 1, doi:10.1126/sciadv.1500852 (2015).
Bottke, W. F. et al. An Archaean heavy bombardment from a destabilized extension of the asteroid belt. Nature 485, 78-81, doi:10.1038/nature10967 (2012).

Předběžná náplň práce

Viz anglicka verze.

Předběžná náplň práce v anglickém jazyce

Using the specific morphology of the impact craters over the Moon’s surface, the student proposes a new method for estimation of the relative variations of the horizontal compliance in terms of normalized Shida coefficient. Student will show that two gravity parameters - DOV and DHG- are changing markedly in the impact sites and hypothesize that the Shida coefficient is proportional with them. Both DOV and DHG characterize the degree of compliance (or elasticity) of the lunar surface. They should have rather small value range for craters between 60 to 180 km in diameter in the NSM and Aitken basins, and larger outside NSM and Aitken basins, on the highlands. The highlands should have larger Shida values compared with the lowlands. The low elasticity (high Shida number) over the highlands supports the pre-Nectarian giant impact theory forming NSM. According to this hypothesis, the elevated lunar crust is composed of more unconsolidated basin ejecta, having more porosity and fragmentation.
The other physical quantities examined are horizontal displacement (HD) and virtual deformation (VD). The analyses show that HD and VD depend on Shida coefficient and gravity gradients. Therefore, in addition to the lower horizontal compliance, the lunar crust over the highlands, possibly made of more porous material (ejecta), indicates smaller HD and VD parameters compared with the megabasins.
The post impact relaxation that basically continues over arbitrary timescales is mostly concerned with the craters with large diameters in which the isostatic compensation works in response to the significant modifications in the crustal thickness. For the comparatively small craters analyzed in this research, the generated crustal variations are controlled by the lithospheric strength; and on Moon, as a small celestial body with no atmosphere and erosion, the impact structure’s morphology remains virtually intact. Thus, unless aimed by oncoming impactors, the small craters’ morphology is untouched in the Moon’s history.
The rigidity considered here is, in fact, an effective rigidity connected with/dependent on some other parameters like porosity and density. As a result, extraction of elasticity mode may give information about the other parameters.
Long wavelength anomaly due to regional elevation and deep density variations have negligible effects on the Shida analysis, and the gravity gradients are strictly dependent on superficial crater morphology.
The analysis of horizontal compliance would reveal that like many other physical parameters- brightness, elevation, thickness, crater density etc- the dichotomy of the Moon manifests in the elasticity of mode revealed by gravity aspects intended to study.
The plan is:
1. Categorization of lunar impact craters in terms of diameter from 60 km to 180 km.
2. Generation of the gravity aspects (Marussi tensor components, deflection of vertical (DOV)
components, divergence of the horizontal gradient of the gravity (DHG), horizontal displacement
(HD), and virtual deformation (VD)) of the Moon.
3. Doing required corrections to make the gravity response of all the craters comparable.
4. Consideration of the long, mid and short wavelength bands effects on the solutions.
5. Extraction of the normalized horizontal compliance parameter over the lunar crust.
6. Extraction of the comparative horizontal displacement (HD), and virtual deformation (VD) of the lunar crust in impact sites