  We present low spectral resolution molecular interferometric observations at
1.2 mm obtained with the Combined Array for Research in Millimetre-wave
Astronomy (CARMA) towards the C-rich AGB star IRC+10216. We have mapped the
emission of several lines of SiS, H13CN, SiO, and SiC2 in the ground and first
excited vibrational states with a high angular resolution of 0.25 arcsec. These
observations have allowed us to partially resolve the emission of the envelope
at distances from the star <50 stellar radii (R*), where the stellar wind is
mainly accelerated. The structure of the molecular emission has been modelled
with a 3D radiation transfer code. The emission of line SiS(v=0,J=14-13) is
best reproduced with a set of maser emitting arcs arranged between 5 and 20 R*.
The abundance of H13CN with respect to H2 decreases from 8e-7 at 1-5 R* to 3e-7
at 20 R*. The SiO observations are explained with an abundance <2e-8 in the
shell-like region between 1 and 5 R*. At this point, the SiO abundance sharply
increases up to (2-3)e-7. The vibrational temperature of SiO increases by a
factor of 2 due North-East between 20 and 50 R*. SiC2 is formed at the stellar
surface with an abundance of 8e-7 decreasing down to 8e-8 at 20 R* probably due
to depletion on to dust grains. Several asymmetries are found in the abundance
distributions of H13CN, SiO, and SiC2 which define three remarkable directions
(North-East, South-Southwest, and South-East) in the explored region of the
envelope. There are some differences between the red- and blue-shifted
emissions of these molecules suggesting the existence of additional asymmetries
in their abundance distributions along the line-of-sight.
