Constraints on the ice composition of carbonaceous chondrites from their magnetic mineralogy

Carbonaceous chondrites experienced varying degrees of aqueous alteration on their parent asteroids, which influenced mineralogies, textures, and bulk chemical isotopic compositions. Although this was a crucial event in the history these meteorites, various pathways are not well understood. One phase that formed during magnetite, its morphology abundance vary between within chondrite groups, providing means investigating alteration. We measured magnetic properties first-order reversal curve (FORC) diagrams CM, CI, CO, ungrouped C2 to identify size range magnetite present meteorites. two predominant among meteorites can be distinguished by resultant magnetite. In WIS 91600, Tagish Lake, CI chondrites, forms predominantly from Fe-sulfides as framboids stacked plaquettes. CM CO <0.1 ?m single-domain (SD) 0.1–5 vortex (V) state via direct replacement metal Fe-sulfides. After ruling out differences temperature, water:rock ratios, terrestrial weathering effects, starting mineralogy, we hypothesise primary factor controlling pathway composition ice accreted into each group's body. Nebula condensation sequences predict most feasible method appreciably evolving concentrations ammonia, will have more alkaline hydrous fluid upon melting, leading fundamentally different conditions may caused formation morphologies. As such, suggest past ammonia line, supporting distal or younger accretion asteroids.