Microstructure of calcite in the CM2 carbonaceous chondrite LON 94101: Implications for deformation history during and/or after aqueous alteration

Collisional facilitation of aqueous alteration of CM and CV carbonaceous chondrites

“…Stacey et al (1961) suggested that chondrite petrofabrics could have formed through uniaxial compaction caused by overburden lithostatic pressure. However, that process could not account for multiple episodes of deformation recorded in calcite grains in CM2.2-2.3 LON 94101 (Lindgren et al, 2010(Lindgren et al, , 2011. Multiple collisions at shallow crustal levels were deemed more likely by Lindgren et al (2011).…”

“…However, that process could not account for multiple episodes of deformation recorded in calcite grains in CM2.2-2.3 LON 94101 (Lindgren et al, 2010(Lindgren et al, , 2011. Multiple collisions at shallow crustal levels were deemed more likely by Lindgren et al (2011).…”

“…However, it cannot be established if the impact events that caused the olivine grains in Nogoya to fracture are the same collisions that were responsible for the production of petrofabrics in the CM chondrites. (Some chondrites experienced several distinct impact events; e.g., Lambert et al, 1984;Lindgren et al, 2011. ) Stronger support for aqueous alteration having occurred after impact-fracturing can be found in the highly altered CM2.0 chondrite MET 01070.…”

“…(2) Carbonate veins in the CM2.0 SCO 06043 (Lindgren et al, 2012), CM2.0 ALH84051 (Tyra et al, 2009) and CM2.2-2.3 LON 94101 (Lindgren et al, 2010(Lindgren et al, , 2011 provide additional evidence of fluid flow, presumably through preexisting fractures (e.g., Lindgren et al, 2011). (3) Aligned aragonite crystals in CM2.4/2.5 Murray were formed during late-stage aqueous alteration from fluids that were "focused within zones of high porosity and permeability along a weak compactional fabric in the matrix" (Lee and Ellen, 2008).…”

Hydrothermal preparation of analogous matrix minerals of CM carbonaceous chondrites from metal alloy particles

“…Our suggested dynamical reaction conditions are similar to the alteration conditions of CM chondrites deduced from the study of carbonates in CM chondrites (Lindgren et al, 2011) and deduced from the theoretical calculation of tochilinite (Browning and Bourcier, 1996).…”