Supersymmetric calculation of mixed Kähler-gauge and mixed Kähler-Lorentz anomalies

We present a manifestly supersymmetric procedure for calculating the contributions from matter loops to the mixed K\"{a}hler-gauge and to the mixed K\"{a}hler- Lorentz anomalies in $N=1, D=4$ supergravity-matter systems. We show how this procedure leads to the well-known result for the mixed K\"{a}hler-gauge anomaly. For general supergravity-matter systems the mixed K\"{a}hler-Lorentz anomaly is found to contain a term proportional to ${\cal R}~2$ with a background field dependent coefficient as well as terms proportional to $(C_{mnpq})~2$ and to the Gauss-Bonnet topological density. We briefly comment on the relationship between the mixed K\"{a}hler-Lorentz anomaly and the moduli dependent threshold corrections to gravitational couplings in $Z_N$ orbifolds.