  Within the Type-I seesaw mechanism, quantum effects of the right-handed (RH)
neutrinos in the gravitational background lead to an asymmetric propagation of
lepton and anti-leptons which allows a Ricci scalar and neutrino Dirac-Yukawa
coupling dependent chemical potential and therefore a lepton asymmetry in
equilibrium. At high temperature, lepton number violating scattering processes
try to maintain a dynamically generated lepton asymmetry in equilibrium.
However, when the temperature drops down, the interactions become weaker, and
the asymmetry freezes out. The frozen out asymmetry can act as a pre-existing
asymmetry prior to the standard Fukugita-Yanagida leptogenesis phase ($T_i\sim
M_i$, where $M_i$ is the mass of $i$th RH neutrino). It is then natural to
consider the viability of gravitational leptogenesis for a given RH mass
spectrum which is not consistent with successful leptogenesis from decays.
Primary threat to this gravity-induced lepton asymmetry to be able to
successfully reproduce the observed baryon-to-photon ratio is the lepton number
violating washout processes at $T_i\sim M_i$. In a minimal seesaw set up with
two RH neutrinos, these washout processes are strong enough to erase a
pre-existing asymmetry of significant magnitude. We show that when effects of
flavour on the washout processes are taken into account, the mechanism opens up
the possibility of successful leptogenesis (gravitational) for a mass spectrum
$M_2\gg 10^9 {\rm GeV}\gg M_1$ with $M_1 \gtrsim 6.3 \times 10^6$ GeV. We then
briefly discuss how, in general, the mechanism leaves its imprints on the low
energy CP phases and absolute light neutrino mass scale.
