Argon is the third most abundant gas in the Martian atmosphere.
It has a mean volume ratio of 1.9%.
In term of stable isotopes, Mars is enriched in ³⁸Ar relative to ³⁶Ar, which can be attributed to hydrodynamic escape.

Argon has a radiogenic isotope ⁴⁰Ar, which is produced from the radioactive decay of ⁴⁰K. In contrast, ³⁶Ar is primordial and was incorporated into the atmosphere during the formation of Mars.
Observations indicate that Mars is enriched in ⁴⁰Ar relative to ³⁶Ar, which cannot be attributed to mass-selective loss processes.
A possible explanation for the enrichment is that a significant amount of primordial atmosphere, including ³⁶Ar, was lost by impact erosion in the early history of Mars, while ⁴⁰Ar was emitted to the atmosphere after the impact.
Argon is the third most abundant gas in the Martian atmosphere. It has a mean volume ratio of 1.9%. In term of stable isotopes, Mars is enriched in ³⁸Ar relative to ³⁶Ar, which can be attributed to hydrodynamic escape.
Argon has a radiogenic isotope ⁴⁰Ar, which is produced from the radioactive decay of ⁴⁰K. In contrast, ³⁶Ar is primordial and was incorporated into the atmosphere during the formation of Mars. Observations indicate that Mars is enriched in ⁴⁰Ar relative to ³⁶Ar, which cannot be attributed to mass-selective loss processes. A possible explanation for the enrichment is that a significant amount of primordial atmosphere, including ³⁶Ar, was lost by impact erosion in the early history of Mars, while ⁴⁰Ar was emitted to the atmosphere after the impact.
Atmosphere of Mars