Journal
METEORITICS & PLANETARY SCIENCE
Volume 51, Issue 6, Pages 1003-1021Publisher
WILEY
DOI: 10.1111/maps.12644
Keywords
-
Categories
Funding
- UK Science and Technology Facilities Council [ST/H002960/1, ST/K000942/1, ST/L002167/1]
- STFC [ST/K000942/1, ST/N000846/1, ST/H002960/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/H002960/1, ST/K000942/1, ST/N000846/1] Funding Source: researchfish
Ask authors/readers for more resources
Forsterite and clinoenstatite in type IAB chondrules from the Murchison CM carbonaceous chondrite have been partially serpentinized, and the mechanisms of their alteration reveal crystallographic and microstructural controls on the reaction of silicate minerals with parent body aqueous solutions. Grains of forsterite were altered in two stages. Narrow veinlets of Fe-rich serpentine formed first and by the filling of sheet pores. Most of these pores were oriented parallel to (010) and (001) and had been produced by earlier fracturing and/or congruent dissolution. In the second stage, the subset of veinlets that were oriented parallel to (001) was widened accompanying the replacement of forsterite by Mg-Fe serpentine. This reaction proceeded most rapidly parallel to [001], and crystallographic controls on the trajectory of retreating vein walls created fine-scale serrations. Murchison clinoenstatite grains have a skeletal appearance due to the presence of abundant veinlets and patches of phyllosilicate. Two alteration stages can again be recognized, with initial water-mineral interaction producing tochilinite-rich veinlets by the filling of (001)-parallel contraction cracks. Pores then formed by congruent dissolution that was guided principally by orthopyroxene lamellae, and they were subsequently filled by submicrometer-sized crystals of polyhedral serpentine. This finding that Murchison forsterite and clinoenstatite grains have been altered demonstrates that aqueous processing of magnesium silicate minerals started much earlier in CM parent body history than previously believed. Our results also show that the occurrence of polyhedral serpentine can be used to locate former pore spaces within the parent body.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available