Fluid flow and chemical alteration in carbonaceous chondrite parent bodies

Comprehensive study of carbon and oxygen isotopic compositions, trace element abundances, and cathodoluminescence intensities of calcite in the Murchison CM chondrite

“…These observations support the static alteration models to predict the thermal history of the CM and CI chondrite parent bodies (Fujiya et al, 2012(Fujiya et al, , 2013, or to explain O isotopic ratios of CM and CI chondrite components (Clayton andMayeda, 1984, 1999;Leshin et al, 1997). On the other hand, our results are difficult to reconcile with the fluid flow models (Grimm and McSween, 1989;Young et al, 1999;Cohen and Coker, 2000;Young, 2001;Travis and Schubert, 2005;Palguta et al, 2010), which normally assume much higher permeability based on terrestrial analogue materials than that estimated by Bland et al (2009). Previous studies have shown the variation in d 13 C of Murchison calcite by using a combination of chemical methods and mass spectrometry, i.e., bulk analysis (Grady et al, 1988;Guo and Eiler, 2007;Tsutsui and Naraoka, 2008;Alexander et al, 2015).…”

Nebular Versus Parent Body Processing

“…Carbonate oxygen isotopic data appear, for example, to be most consistent with the closedsystem model, but can also be reconciled with the fluid flow model if the CM chondrites sample a restricted region of the CM asteroid (Benedix et al, 2003), just downstream of the model alteration front proposed by Young (2001). However, as shown by the model of Palguta et al (2010), a convecting hydrothermal system is also capable of producing a range of degrees of alteration, distributed heterogeneously within the parent body, that have bulk oxygen isotopic compositions that are consistent with the range observed in the CM chondrites.…”

“…Several models have been proposed to explain the bulk oxygen isotopic composition of CM chondrites, some of which consider the isotopic evolution of carbonates and sulfates. Three general types of models have been considered: (1) a closed-system, two-reservoir model ( Mayeda, 1984, 1999); (2) an exhalative fluid flow model ( Cohen and Coker, 2000;Young, 2001; Young and Russell, 1998;Young et al, 1999), where water is lost at the surface; and (3) a convecting, closed hydrothermal system ( Grimm and McSween, 1989;Palguta et al, 2010;Travis and Schubert, 2005). Palguta et al (2010) were the first to integrate oxygen isotopic evolution into convective models.…”

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates

“…We consider the static water model 20,23 here, although the fluid flow model has been investigated in some previous works [24][25][26][27] . The thermal history is modelled using a onedimensional heat conduction equation in radial form.…”