Carbonaceous chrondrites

The presence of 26Mg excesses correlated with Al/Mg ratios in fifteen Ca-Al-rich inclusions from the Allende and Leoville carbonaceous chrondrites has provided additional strong evidence for the in situ decay of 26A1 (see [9] for a recent review of isotopic anomalies). There are also, however, several examples of minerals whose isotopic compositions depart substantially from a unique Al-Mg isochron, even within a single inclusion [10,11]. Since deviations from the isochron may reflect either differences in the formation age of individual minerals or intrinsic heterogeneities in the initial 26A1/27A1 ratio, the value of the Al-Mg system as a chronometer for early solar system events remains unclear. 

Krahenbuhl, U., Morgan, S. W., Ganapathy, R. and Anders, E., Abundance of 17 trace elements in carbonaceous chrondrites, Geochem. Cosmochim. Acta 37, 1353-1370 (1973). 

The solar abundances of all of the chemical elements are shown in Figure 12.2. These abundances are derived primarily from knowledge of the elemental abundances in Cl carbonaceous chrondritic meteorites and stellar spectra. Note that 99% of the mass is in the form of hydrogen and helium. Notice that there is a general logarithmic decline in the elemental abundance with atomic number with... 

---

See also in sourсe #XX -- [ ]

---