Other
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p51a1411h&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #P51A-1411
Other
[5430] Planetary Sciences: Solid Surface Planets / Interiors, [6225] Planetary Sciences: Solar System Objects / Mars
Scientific paper
Borg and Draper (2003) modeled crystallization of the martian mantle from an early, global magma ocean. They determined that garnet must be an early crystallizing phase at the onset of magma ocean crystallization, followed by subsequent garnet fractionation (the garnet should rain out onto the magma ocean floor due to negative buoyancy) in order to impart a superchondritic CaO/Al2O3 ratio to the residual liquid (aluminum is sequestered into the crystallizing garnet, thus depleting the residual liquid in aluminum and raising the CaO/Al2O3 ratio). This process is required to account for the superchondritic CaO/Al2O3 ratios (~1.0 to 1.5 compared to the chondritic value of ~0.80) seen in the martian basaltic meteorites (shergottites). This ratio should remain relatively unperturbed by subsequent crystallization of olivine ± low-Ca pyroxene. We are in the process of experimentally testing this model of magma ocean crystallization on Mars. The ongoing project consists of three stages: 1) Obtain a run product that is roughly 90% liquid with the correct CaO/Al2O3 ratio to represent the composition of the residual magma ocean after roughly 10% crystal fractionation (garnet ± other minerals), which is required to impart a superchondritic CaO/Al2O3 ratio to the residual liquid. 2) Synthesize a silicate mixture with the composition of the residual magma ocean that is determined in stage 1 and crystallize this mixture at various pressures and temperatures in order to determine the minerals that would crystallize from the magma ocean at various depths. 3) Once a profile of the crystallized magma ocean is determined, we will calculate the composition of the depleted martian mantle. This composition will be synthesized and partially melted at low pressure in an attempt to derive a melt that is a match to the most primitive shergottite parent liquids. We have completed the first stage of the project and determined the base of the magma ocean to be at ~15 to 16 GPa (~1350 to 1450 km in depth). This depth is in agreement with the model of Borg and Draper (2003). We are currently proceeding with the second stage of the project. Following the model of Borg and Draper (2003), we assume equilibrium crystallization up to 80% crystallization and fractional crystallization for the remaining 20%. Therefore, we will crystallize to roughly 80% solid at each of the pressures that we investigate. We will then take a weighted average of the individual cumulate assemblages to calculate the composition of the depleted martian mantle. We assume that the remaining 20% liquid will crystallize into an enriched component within the mantle. The results of our project hold the potential to either bolster the validity of the magma ocean model for Mars, or to undermine it.
Agee Carl B.
Draper David S.
Hutchins K.
No associations
LandOfFree
Experimental Constraints on the Composition and Depth of an Early Magma Ocean on Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Experimental Constraints on the Composition and Depth of an Early Magma Ocean on Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Experimental Constraints on the Composition and Depth of an Early Magma Ocean on Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1497597