Carbonaceous chondrites characteristics

Table 6 gives information on the types of carbon phases found in carbonaceous chondrites, together with some of their characteristics. 

The study of chondrite matrices is both time-consuming and challenging, principally because of the fine-grained characteristics of the material. Transmission electron microscopy (TEM) has been the analytical technique of choice, because it provides textural and mineralogical information from the micron down to the nanoscale. Here, we briefly overview the main textural and mineralogical characteristics of matrices in very un-equilibrated chondrites, focusing principally on the carbonaceous chondrites. 

Ningqiang is an ungrouped carbonaceous chondrite that shares many petrologic, as well as oxygen isotopic and TL characteristics with CV and CK chondrites (Rubin et al., 1988b Kallemeyn et al., 1991 Koeberl et al., 1987 Mayeda et al., 1988 Guimon et al., 1995 Kallemeyn, 1996). As a result, it has been... 

Chizmadia L. J. and Brearley A. J. (2003) Mineralogy and textural characteristics of fine-grained rims in Yamato 791198 CM2 carbonaceous chondrite constraints on the location of aqueous alteration. In Lunar Planet. Sci. XXXIV, 1419. The Lunar and Planetary Institute, Houston (CD-ROM). 

Ireland T. R. (1988) Correlated morphological, chemical, and isotopic characteristics of hibonites from the Murchison carbonaceous chondrite. Geochim. Cosmochim. Acta 52, 2827-2839. 

Carbon-rich CP IDPs are spectrally red with a redness comparable to the comet-like outer asteroid Pholus (Binzel, 1992). Hydrated CS IDPs that contain layer lattice silicates exhibit spectral characteristics similar to carbonaceous chondrites and main-belt C-type asteroids (Bradley et al., 1996b). 

The concentrations of four typical moderately volatile elements—manganese, sodium, selenium, and zinc—in the various classes of chondritic meteorites are shown in Figure 12, where elements are normalized to magnesium and CI-chondrites. Again there is excellent agreement between solar abundances and Cl-meteorites. A characteristic feature of the chemistry of carbonaceous chondrites is the simultaneous depletion of sodium and manganese in all types of carbonaceous chondrites, except Cl. Ordinary and enstatite chondrites are not or only slightly... 

Meteorites are grouped into three major classes irons, stones and stony-irons. Based on compositional dissimilarities, stony meteorites are subdivided into chondrites and achondrites. Chondrites are the most primitive meteorites based on their near-solar volatile composition and radiometric ages of 4.566 billion years, reflecting their formation during, or shortly after, the birth of the Solar System (5). Within the chondrites, there exists a carbonaceous subclass that contains up to 3 weight-% of organic carbon, a characteristic that contributes to a generally dark appearance. Carbonaceous chondrites themselves are subdivided into CM, Cl, CV and other classes based on a combination of their... 

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