Mapping of carbon concentrations in the Allende meteorite with the ¹²C(d,p)¹³C method

We have “mapped” carbon concentrations in a 4.2 × 4.2 mm area of the Ailende meteorite with the 12 C(d,p) 13 C nuclear method. The x,y resolution perpendicular to the deuteron beam was 65 μm; the depth resolution was 0.6 μm. The matrix of the meteorite contains about 1 wt % carbon, which is uniformly distributed at the 65‐μm level of resolution. The matrix contains most, perhaps close to all, C of this meteorite. The coarse‐grained constituents, such as chondrules, show a very strong enhancement of C in the depth range 2 to about 0 μm; the matrix does not show this enhancement. The enhancement may be due to contamination of the coarse‐grained areas or else to migration of C in solid solution from the interiors of comparatively large crystals to their freshly polished surfaces.