Minerals carbonaceous chondrite anhydrous

Figure 2 Oxygen isotopic compositions of chondmles from all classes of chondritic meteorites ordinary (O), enstatite (E), carbonaceous (C), and Rumumti-type (R). The TF line and carbonaceous chondrite anhydrous mineral (CCAM) line are shown for reference in this and many subsequent figures. Equations for these lines are TF—5 = 0.525 and CCAM—5 = 0.9415 -4.00 (sources Clayton et al, 1983, 1984, 1991 Weisberg et al., 1991).

Oxygen-isotopic data for bulk CM chondrites and mineral separates (Clayton and Mayeda, 1999) lie along a mixing line with slope 0.7, rather than the slope 0.5 carbonaceous chondrite anhydrous mineral (CCAM) (see line Chapter 1.06). This line is attributable to the mixing of anhydrous 0-rich silicate material in chondrules and CAIs, etc. and hydrated 0-poor material, largely phyllosilicates that occurs in the matrix. The bulk of CM chondrites is weakly... 

Figure 1. Oxygen three-isotope diagram showing isotopic compositions of minerals from Allende CAIs (CCAM = carbonaceous chondrite anhydrous minerals). The other line, labelled TF (terrestrial fractionation) is the locus of data points for terrestrial rocks and waters (data not shown). The bulk oxygen isotopic composition of the Earth is indicated by point E the expected oxygen isotopic composition of the Sun is indicated by point S. The S-notation on the...

The first observations of any samples with A O 0 were for anhydrous mineral separates from carbonaceous chondrites measured by Clayton and colleagues (Clayton et al. 1973). This remarkable discovery was considered prima facie evidence for the preservation of a distinctive nucleosynthetic component, rich in in these meteoritic phases (Clayton et al. 1973 Clayton et al. 1977) and it stimulated the discovery of many... 

Figure 13 A 5 jjim interplanetary dust particle. This is a carbon-rich particle with chondritic elemental composition. It is porous and entirely composed of anhydrous phases. This 10 ° g particle is an aggregate of >10 umelated and unequilibrated grains. The smooth grains are t5fpically single mineral grains such as Fo, En, or pyrrhotite or carbonaceous material, and the <0.5 p,m lumpy grains are usually GEMSs. This is a relatively t5fpical example of the particles that have entry speeds consistent with cometary origin.

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