J/AJ/161/187 A new martian crater chronology (Marchi, 2021)
A New Martian Crater Chronology: Implications for Jezero Crater.
Marchi S.
<Astron. J., 161, 187 (2021)>
=2021AJ....161..187M 2021AJ....161..187M
ADC_Keywords: Solar system; Planets
Keywords: Mars ; Solar system terrestrial planets
Abstract:
Crater chronologies are a fundamental tool to assess the relative and
absolute ages of planetary surfaces when direct radiometric dating is
not available. Martian crater chronologies are derived from lunar
crater spatial densities on terrains with known radiometric ages, and
thus they critically depend on the Moon-to-Mars extrapolation. This
extrapolation requires knowledge of the time evolution of the impact
flux, including contributions from various impactor populations,
factors that are not trivially connected to the dynamical evolution of
the early Solar System. In this paper, we will present a new Martian
crater chronology based on current dynamical models, and consider the
main sources of uncertainties (e.g., impactor size-frequency
distribution; dynamical models with late and early instabilities,
etc.). The resulting "envelope" of Martian crater chronologies
significantly differs from previous chronologies. The new Martian
crater chronology is discussed using two interesting applications:
Jezero crater's dark terrain (relevant to the NASA Mars 2020 mission)
and the southern heavily cratered highlands. Our results indicate that
Jezero's dark terrain may have formed ∼3.1Ga, i.e., up to 0.5Gyr older
than previously thought. In addition, available crater chronologies
(including our own) overestimate the number of craters larger than
150km on the southern highlands, suggesting either that large craters
have been efficiently erased over Martian history or that dynamical
models need further refinement. Further, our chronology constrains the
age of Isidis basin to be 4.05-4.2Ga and that of the Borealis basin to
be 4.35-4.40Ga; these are predictions that can be tested with future
sample and return missions.
Description:
In this paper, we will present a new Martian crater chronology based
on current dynamical models.
We adopt an average of results from the dynamical models from
Morbidelli+, 2018Icar..305..262M 2018Icar..305..262M, Brasser+, 2020Icar..33813514B 2020Icar..33813514B,
Raymond+, 2013Icar..226..671R 2013Icar..226..671R, and Nesvorny+, 2017AJ....153..103N 2017AJ....153..103N.
We consider two characteristic impactor Size Frequency Distributions
(SFDs): near-Earth objects (NEO) and Main Belt Asteroids (MBA).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2a.dat 21 101 Martian N1 (≳1km) cumulative crater distributions,
late Near Earth Objects (NEO)
fig2b.dat 21 101 Martian N1 (≳1km) cumulative crater distributions,
early NEO
fig2c.dat 21 101 Martian N1 (≳1km) cumulative crater distributions,
late Main Belt Asteroids (MBA)
fig2d.dat 21 101 Martian N1 (≳1km) cumulative crater distributions,
early NEO
fig3a.dat 21 81 Martian N150 (≳150km) cumulative crater
distribution, late NEO
fig3b.dat 21 81 Martian N150 (≳150km) cumulative crater
distribution, early NEO
fig3c.dat 21 81 Martian N150 (≳150km) cumulative crater
distribution, late MBA
fig3d.dat 21 81 Martian N150 (≳150km) cumulative crater
distribution, early MBA
fig5a.dat 37 43 Martian craters ≳150km SFD for the entire surface
and highlands, NEO
fig5b.dat 37 73 Martian craters ≳150km SFD for the entire surface
and highlands, MBA
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See also:
J/A+A/582/A36 : USNO Martian observations (Robert+, 2015)
J/A+A/603/A55 : WISE/NEOWISE Mars-crossing asteroids (Ali-Lagoa+, 2017)
J/A+A/614/A15 : Mars Express astrometric obs. of Martian moons (Ziese+, 2018)
Byte-by-byte Description of file: fig[23][abcd].dat
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Bytes Format Units Label Explanations
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1- 10 E10.9 Gyr Age Age
12- 21 E10.9 /km2 Ncraters Number of craters/km2
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Byte-by-byte Description of file: fig5[ab].dat
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Bytes Format Units Label Explanations
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1- 16 F16.10 km Diam Crater diameter
18- 37 E20.11 --- MPF Model production fonction (arbitrary units)
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 09-Sep-2021