Abstract Details
| Name: Gurpreet Kaur Affiliation: Panjab University,Chandigarh Conference ID: ASI2015_566 Title : DIFFERENTIATION OF MARS DUE TO RADIOGENIC AND IMPACT HEATING Authors and Co-Authors : G. K. Bhatia and S. Sahijpal, Department of Physics, Panjab University, Chandigarh,India (sandeep@pu.ac.in) Abstract Type : Poster Abstract Category : Sun and the Solar System Abstract : Introduction: Mars is a planetary embryo that escaped further planetary accretion to form Earth sized big planet. 182Hf-182W isotopic systematic of SNC meteorites suggest an early and rapid accretion of Mars in the initial few million years (Ma) during the formation of solar system. The early and rapid accretion of Mars supports the role of heat produced by decay of short lived radio nuclides 26Al and 60Fe. In the earlier works, only the effect of heat produced due to impacts on the surface of accreting Mars was considered which resulted in the formation of a metallic shell instead of an iron core. In the present work, we have numerically simulated the early thermal evolution and differentiation of Mars upto initial ( 25 Ma by considering the effect of heat produced due to decay of 26Al and 60Fe along with heat of impacts on the surface of accreting Mars into an iron core and silicate mantle. Methodology: Partial differentiation equation of heat transfer is solved using finite difference method by incorporating the heat produced due to the decay of 26Al and 60Fe along with impacts. We ran various simulations by considering four important parameters that include onset time of accretion of Mars after the formation of CAIs, accretion duration, initial abundance of 60Fe due to uncertainty in its value and the melt percolation velocity of metallic blobs through silicate melt to form an iron core. Since Mars is a comparatively bigger body as compared to planetesimals and asteroids, the interior of Mars is having very high pressure due to which the melting temperature of iron and silicate will increase. We have modified the melting temperature of iron and silicate in our model based on its dependence on pressure. Upon 40% partial melting of silicate, metallic blobs were moved towards the center of Mars to form an iron core and silicate mantle (CM model). We also ran one simulation to study the core-mantle-crust (CMC model) differentiation of Mars in which upon 20% partial melting of silicate, 26Al-rich basaltic melt was extruded upwards. We ran a set of four simulations to study the dependence of rate of differentiation of Mars on percolation velocity of metallic blobs. Results and Discussion: Results show that the onset of accretion of Mars should commence in the initial 1.5 Ma for early differentiation of Mars. A further delay in the onset of accretion would result in prolonged differentiation or even no segregation. However, an increase in the initial abundance of 60Fe/56Fe results in the differentiation of Mars into iron core and silicate mantle. The melt percolation velocity less than ( 0.1 m yr.-1 reduces the possibility of even planetary scale differentiation of Mars. An early accretion of Mars results in the large scale planetary differentiation of Mars. This seems to be consistent with the records of the Martian meteorites. |